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Question 1
Correct
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What is the most common application of Nitrates?
Your Answer: Angina
Explanation:In patients with exertional stable angina, nitrates improve exercise tolerance, time to onset of angina, and ST-segment depression during exercise testing. In combination with beta-blockers or calcium channel blockers, nitrates produce greater anti-anginal and anti-ischemic effects.
While they act as vasodilators, coronary vasodilators, and modest arteriolar dilators, the primary anti ischemic effect of nitrates is to decrease myocardial oxygen demand by producing systemic vasodilation more than coronary vasodilation. This systemic vasodilation reduces left ventricular systolic wall stress. -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 2
Correct
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Regarding fat digestion, which of the following statements is CORRECT:
Your Answer: Chylomicrons are exocytosed from enterocytes to enter lacteals and thus the lymphatic system.
Explanation:Dietary fat is chiefly composed of triglycerides (esters of free fatty acids and glycerol which may be saturated or unsaturated). The essential fatty acids are linoleic acid and alpha-linoleic acid, which cannot be manufactured in the body. Dietary fat provides 37 kJ (9 kcal) of energy per gram. Fats are digested almost entirely in the small intestine and are only released from the stomach into the duodenum at the rate at which they can be digested.
Pancreatic lipase is the most significant enzyme for fat digestion. In the duodenum fat is emulsified by bile acids, a process where larger lipid droplets are broken down into much smaller droplets providing a greater surface area for enzymatic digestion. Micelles are arranged so that hydrophobic lipid molecules lie in the centre, surrounded by bile acids arranged such the outer region is hydrophilic. Dietary and synthesised lipids are incorporated into chylomicrons in the Golgi body, which are exocytosed from the basolateral membrane to enter lacteals and thus the lymphatic system. -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 3
Incorrect
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A patient in the Emergency Department had a diagnosis of diabetic ketoacidosis (DKA) and you commence an insulin infusion. Which of these statements concerning endogenous insulin is true?
Your Answer:
Correct Answer: Insulin has a short half-life of around 5-10 minutes
Explanation:Insulin, a peptide hormone, is produced in the pancreas by the beta-cells of the islets of Langerhans.
The beta-cells first synthesise an inactive precursor called preproinsulin which is converted to proinsulin by signal peptidases, which remove a signal peptide from the N-terminus.
Proinsulin is converted to insulin by the removal of the C-peptide.
Insulin has a short half-life in the circulation of about 5-10 minutes.
Glucagon and parasympathetic stimulation stimulates insulin release. -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 4
Incorrect
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A 34-year-old woman was diagnosed with multiple sclerosis two years ago. Her symptoms have been steadily deteriorating, with no intervals of remission in sight.
Which of the following aspects of nerve conduction is disrupted by multiple sclerosis?
Your Answer:
Correct Answer: Saltatory conduction
Explanation:Local currents propagate action potentials down the axons of neurons. This local current flow following depolarisation results in the depolarisation of the neighbouring axonal membrane, and when this region approaches the threshold, more action potentials are generated and so forth. Due to the refractory period, portions of the membrane that have recently depolarized will not depolarize again, resulting in the action potential only being able to go in one direction.
The square root of axonal diameter determines the velocity of the action potential; the axons with the biggest diameter have the quickest conduction velocities. When a neuron is myelinated, the speed of the action potential rises as well.
The myelin sheath is an insulating coating that surrounds certain neural axons. By increasing membrane resistance and decreasing membrane capacitance, the myelin sheath improves conduction. This enables faster electrical signal transmission via a neuron, making them more energy-efficient than non-myelinated neuronal axons.
Electrical impulses are quickly transmitted from one node to the next, causing depolarization of the membrane above the threshold and triggering another action potential, which is then transmitted to the next node. An action potential is rapidly conducted down a neuron in this manner. Saltatory conduction is the term for this.
Multiple sclerosis is an example of a clinical disorder in which the myelin sheath is affected. It is an immune-mediated disorder in which certain nerve cells in the brain and spinal cord become demyelinated. The ability of some areas of the nervous system to properly transmit action potentials is disrupted by demyelination, resulting in a variety of neurological symptoms and indications. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 5
Incorrect
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The following all cause a left shift in the oxygen dissociation curve EXCEPT for:
Your Answer:
Correct Answer: Decrease in pH
Explanation:An increased affinity of haemoglobin for oxygen, shown by a left shift in the oxygen dissociation curve, is caused in the lungs by a rise in pH, a fall in PCO2,a decrease in temperature and a decrease in 2,3 -DPG. Carbon monoxide (CO) binds 240 times more strongly than O2to haemoglobin and by occupying O2-binding sites, reduces oxygen capacity. CO also increases oxygen affinity, shifting the oxygen haemoglobin curve to the left and making O2release to tissues more difficult.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 6
Incorrect
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Which of the following causes increased aldosterone secretion:
Your Answer:
Correct Answer: Decreased blood volume
Explanation:Decreased blood volume stimulates the secretion of renin (because of decreased renal perfusion pressure) and initiates the renin-angiotensin-aldosterone cascade. Angiotensin-converting enzyme (ACE) inhibitors block the cascade by decreasing the production of angiotensin. Hyperosmolarity stimulates antidiuretic hormone (ADH) [not aldosterone] secretion. Hyperkalaemia, not hypokalaemia, directly stimulates aldosterone secretion by the adrenal cortex. ANP inhibits renin secretion, thereby inhibiting the production of angiotensin and aldosterone.
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This question is part of the following fields:
- Physiology
- Renal
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Question 7
Incorrect
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Insulin binds to the insulin receptor (IR) on cell surfaces to exert its action. The IR is a very specific transmembrane receptor belonging to the tyrosine kinase receptor class.
One of these also activates the IR:
Your Answer:
Correct Answer: IGF-I
Explanation:Insulin receptor (IR), in addition to being activated by insulin, is also activated by IGF-I and IGF-II.
The IR is a dimer with two identical subunits spanning the cell membrane and are connected by a single disulphide bond. The two sub-units include: The alpha chain situated on the exterior of the cell membrane and the beta chain spanning the cell membrane in a single segment.
When insulin is detected, the alpha chains move together folding around the insulin making the beta chains move together, converting them into an active tyrosine kinase. This initiates a phosphorylation cascade increasing the expression of GLUT4 and allowing uptake of glucose by cells.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 8
Incorrect
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A patient presents with a history of renal problems, generalised weakness and palpitations. Her serum potassium levels are measured and come back at 6.2 mmol/L. An ECG is performed, and it shows some changes that are consistent with hyperkalaemia.
Which of the following ECG changes is usually the earliest sign of hyperkalaemia? Select ONE answer only.Your Answer:
Correct Answer: Peaked T waves
Explanation:Hyperkalaemia causes a rapid reduction in resting membrane potential leading to increased cardiac depolarisation and muscle excitability. This in turn results in ECG changes which can rapidly progress to ventricular fibrillation or asystole. Very distinctive ECG changes that progressively change as the K+level increases:
K+>5.5 mmol/l – peaked T waves (usually earliest sign of hyperkalaemia), repolarisation abnormalities
K+>6.5 mmol/l – P waves widen and flatten, PR segment lengthens, P waves eventually disappear
K+>7.0 mmol/l – Prolonged QRS interval and bizarre QRS morphology, conduction blocks (bundle branch blocks, fascicular blocks), sinus bradycardia or slow AF, development of a sine wave appearance (a pre-terminal rhythm)
K+>9.0 mmol/l – Cardiac arrest due to asystole, VF or PEA with a bizarre, wide complex rhythm. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 9
Incorrect
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A 36-year-old woman is 22-weeks pregnant and is investigated for a possible thyroid disorder. When her total thyroid hormone levels does not correlate with her thyrometabolic status, her thyroid-binding globulin levels are checked.
What percentage of circulating thyroid hormones is bound to thyroid-binding globulin?Your Answer:
Correct Answer: 70%
Explanation:Only a very small fraction of the thyroid hormones circulating in the blood are free. The majority is bound to transport proteins. Only the free thyroid hormones are biologically active, and measurement of total thyroid hormone levels can be misleading.
The relative percentages of bound and unbound thyroid hormones are:
Bound to thyroid-binding globulin -70%
Bound to albumin -15-20%
Bound to transthyretin -10-15%
Free T3 -0.3%
Free T4 -0.03% -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 10
Incorrect
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A 60-year-old man diagnosed with chronic kidney disease has an elevated creatinine level and a reduced glomerular filtration rate (GFR).
Which statement concerning glomerular filtration is true?Your Answer:
Correct Answer: Creatinine is freely filtered at the glomerulus
Explanation:Glomerular filtration is a passive process. It depends on the net hydrostatic pressure across the glomerular capillaries, the oncotic pressure, and the intrinsic permeability of the glomerulus.
The mean values for glomerular filtration rate (GFR) in young adults are 130 ml/min/1.73m2 in males and 120 ml/min/1.73m2in females.
The GFR declines with age after the age of 40 at a rate of approximately 1 ml/min/year.
The Cockcroft and Gault formula overestimates creatinine in obese patients. This is because their endogenous creatinine production is less than that predicted by overall body weight.
Creatinine is used in the estimation of GFR because it is naturally produced by muscle breakdown, not toxic, not produced by the kidney, freely filtered at the glomerulus, not reabsorbed from the nephron, and does not alter GFR.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 11
Incorrect
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What is the correct adrenaline dose for a patient with pulseless ventricular tachycardia?
Your Answer:
Correct Answer: 10 ml of 1 in 10,000 adrenaline solution
Explanation:Ventricular fibrillation or pulseless ventricular tachycardia (VF/VT) are referred to as shockable rhythm.
IV adrenaline 1 mg (10 mL of 1:10,000 solution) should be administered after 3 shocks and every 3 – 5 minutes/after alternate shocks thereafter for a shockable rhythm.
For a non-shockable rhythm, 1 mg IV adrenaline should be administered as soon as IV access is obtained, and then every 3 – 5 minutes/after alternate shocks thereafter.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 12
Incorrect
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Gastric emptying is inhibited by all of the following EXCEPT for:
Your Answer:
Correct Answer: Parasympathetic stimulation
Explanation:Gastric emptying is decreased by:
Enterogastric inhibitory reflexes stimulated by – Distension of the duodenum, The presence of fats in the duodenum (by stimulating release of cholecystokinin), A fall in the pH of chyme in the duodenum, An increase in the osmolality of chyme in the duodenum, Irritation of the mucosal lining of the duodenum, Hormones: Cholecystokinin, Secretin -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 13
Incorrect
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Question 14
Incorrect
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Regarding the refractory period, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Action potentials can occur in the relative refractory period but the amplitude of the action potential is smaller.
Explanation:Following the action potential, Na+channels remain inactive for a time in a period known as the absolute refractory period where they cannot be opened by any amount of depolarisation. Following this there is a relative refractory period where the temporary hyperpolarisation (due to delayed closure of rectifier K+channels) makes the cell more difficult to depolarise and an action potential can be generated only in response to a larger than normal stimulus. The refractory period limits the frequency at which action potentials can be generated, and ensures that, once initiated, an action potential can travel only in one direction. An action potential is an all or nothing response so the amplitude of the action potential cannot be smaller.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 15
Incorrect
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Regarding calcium channel blockers, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Calcium channel blockers inhibit L-type voltage-sensitive calcium channels in arterial smooth muscle causing vasodilation.
Explanation:Calcium channel blockers inhibit L-type voltage-sensitive calcium channels in arterial smooth muscle, causing relaxation and vasodilation (reduction in peripheral vascular resistance). They also block calcium channels within the myocardium and conducting tissues of the heart which produces a negative inotropic effect by reducing calcium influx during the plateau phase of the action potential.
They have a variety of uses, including:
Hypertension
Angina
Atrial fibrillation
Migraine
Calcium channel blockers have been found to be moderately useful in the prevention of migraines. The best evidence is for this is with verapamil. This may be due to the prevention of the arteriolar constriction that is associated with migraine. They are commonly used for this elsewhere in the world but are not currently licensed for this use in the UK.
The following are common side effects of all calcium-channel blockers:
Abdominal pain
Dizziness
Drowsiness
Flushing
Headache
Nausea and vomiting
Palpitations
Peripheral oedema
Skin reactions
Tachycardia
Verapamil is highly negatively inotropic and reduces cardiac output, slows the heart rate and may impair atrioventricular conduction. It may precipitate heart failure, exacerbate conduction disorders, and cause hypotension at high doses and should not be used with beta-blockers. Nifedipine has less myocardial effects than verapamil and has no antiarrhythmic properties but has more influence on the vessels. Nimodipine is used solely for the prevention and treatment of vascular spasm following aneurysmal subarachnoid haemorrhage. -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 16
Incorrect
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The only statement that is correct regarding diffusion is which of the following?
Your Answer:
Correct Answer: The permeability of a membrane is related to the membrane thickness and composition.
Explanation:Passive diffusion is a process that describes the movement down a concentration gradient. This process accounts for movement across small distances like within the cytosol or across membranes. Factors that affect the diffusion of a substance across a membrane are the permeability (p) of the membrane, a difference in concentration across the membrane and the membrane area over which diffusion occurs. The membrane thickness and composition, and the diffusion coefficient of the substance also affects the permeability. Fick’s law describes the rate of diffusion of a substance within a solution, which can be modified to describe the rate of diffusion across a membrane.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 17
Incorrect
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Angiotensin II is part of the RAAS system. One of its effects is the constriction of efferent arterioles. Which of the following best describes the effect of angiotensin II- mediated constriction of efferent arterioles?
Your Answer:
Correct Answer: Decreased renal plasma flow, increased filtration fraction, increased GFR
Explanation:The Renin-Angiotensin-Aldosterone System (RAAS) is a hormone system composed of renin, angiotensin, and aldosterone. Those hormones are essential for the regulation of blood pressure and fluid balance.
Cases of hypotension, sympathetic stimulation, or hyponatremia can activate the Renin-angiotensin-aldosterone system (RAAS). The following process will then increase the blood volume and blood pressure as a response.
When renin is released it will convert the circulating angiotensinogen to angiotensin I. The ACE or angiotensin-converting enzyme will then catalyst its conversion to angiotensin II, which is a potent vasoconstrictor. Angiotensin II can constrict the vascular smooth muscles and the efferent arteriole of the glomerulus.
The efferent arteriole is a blood vessel that delivers blood away from the capillaries of the kidney. The angiotensin II-mediated constriction of efferent arterioles increases GFR, reduces renal blood flow and peritubular capillary hydrostatic pressure, and increases peritubular colloid osmotic pressure, as a response to its action of increasing the filtration fraction.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 18
Incorrect
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A 58-year-old man showing symptoms of increase in weight, proximal muscular weakening and withering, easy bruising, and acne. You notice that he has a full, plethoric aspect to his face, as well as significant supraclavicular fat pads, when you examine him. His blood pressure is 158/942 mmHg, and his glucose tolerance has lately been impaired. His potassium level is 3.2 mmol/L.
What is the MOST LIKELY diagnosis?Your Answer:
Correct Answer: Cushing’s syndrome
Explanation:Cushing’s syndrome is a group of symptoms and signs brought on by long-term exposure to high amounts of endogenous or exogenous glucocorticoids. Cushing’s syndrome affects about 10-15 persons per million, and it is more common in those who have had a history of obesity, hypertension, or diabetes.
Cushing’s syndrome has a wide range of clinical manifestations that are dependent on the degree of cortisol overproduction. The appearance might be vague and the diagnosis difficult to detect when cortisol levels are just somewhat elevated. On the other hand, in long-term cases of severely increased cortisol levels, the presentation might be colourful and the diagnosis simple.
Cushing’s syndrome has the following clinical features:
Obesity and weight growth in the true sense
Supraclavicular fat pads are fat pads that are located above the clavicle.
Buffalo hump
Fullness and plethora of the face (‘moon facies’)
Muscle atrophy and weakening at the proximal level
Diabetes mellitus, also known as impaired glucose tolerance
Hypertension
Skin thinning and bruising
Depression
Hirsutism
Acne
Osteoporosis
Amenorrhoea or oligomenorrhoeaCortisol levels fluctuate throughout the day, with the greatest levels occurring around 0900 hours and the lowest occurring at 2400 hrs during sleep. The diurnal swing of cortisol levels is lost in Cushing’s syndrome, and levels are greater during the whole 24-hour period. In the morning, levels may be normal, but they may be high at night-time, when they are generally repressed. As a result, random cortisol testing is not an effective screening technique and is not advised.
The following are the two most common first-line screening tests:
Cortisol levels in the urine are measured every 24 hours.
A diagnosis of Cushing’s syndrome can be made if more than two collections measure cortisol excretion more than three times the upper limit of normal.
Physical stress (e.g., excessive exercise, trauma), mental stress (e.g., sadness), alcohol or drug misuse, complex diabetes, and pregnancy can all cause false positives.
Renal dysfunction, inadequate collection, and cyclical Cushing’s disease can all cause false negatives.
The overnight low-dose dexamethasone suppression test (LDDST) involves giving 1 mg of dexamethasone at 11 p.m. and measuring blood cortisol levels at 8 a.m. the next day.
Cushing’s syndrome is diagnosed when cortisol is not suppressed to less than 50 nmol/L.
It might be difficult to tell the difference between mild Cushing’s disease and normal cortisol production.
False positives can occur as a result of depression, severe systemic sickness, renal failure, prolonged alcohol misuse, old age, and the use of hepatic enzyme-inducing medicines, among other things.
False negatives are extremely uncommon in Cushing’s disease patients.A characteristic biochemical picture might also be helpful in confirming the diagnosis of Cushing’s syndrome. The following are the primary characteristics:
Hypokalaemia
Alkalosis metabolique -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 19
Incorrect
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Which of the following medications may lessen warfarin's anticoagulant effect:
Your Answer:
Correct Answer: Phenytoin
Explanation:Phenytoin will decrease the level or effect of warfarin by affecting hepatic/intestinal enzyme CYP3A4 metabolism.
Metronidazole will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C9/10 metabolism.
NSAIDs, when given with Warfarin, increase anticoagulation. -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 20
Incorrect
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Which of these is NOT a naturally occurring anticoagulant:
Your Answer:
Correct Answer: Factor V Leiden
Explanation:It’s crucial that thrombin’s impact is restricted to the injured site. Tissue factor pathway inhibitor (TFPI), which is produced by endothelial cells and found in plasma and platelets, is the first inhibitor to function. It accumulates near the site of harm induced by local platelet activation. Xa and VIIa, as well as tissue factor, are inhibited by TFPI. Other circulating inhibitors, the most potent of which is antithrombin, can also inactivate thrombin and other protease factors directly. Coagulation cofactors V and VIII are inhibited by protein C and protein S. Tissue plasminogen activator (TPA) from endothelial cells facilitates fibrinolysis by promoting the conversion of plasminogen to plasmin.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 21
Incorrect
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Which of the following is most true of the sinoatrial node:
Your Answer:
Correct Answer: Frequency of depolarisation is increased by sympathetic stimulation.
Explanation:Cardiac myocyte contraction is not dependent on an external nerve supply but instead the heart generates its own rhythm, demonstrating inherent rhythmicity. The heartbeat is initiated by spontaneous depolarisation of the sinoatrial node (SAN), a region of specialised myocytes in the right atrium close to the coronary sinus, at a rate of 100-110 beats/min. This intrinsic rhythm is primarily influenced by autonomic nerves, with vagal influences being dominant over sympathetic influences at rest. This vagal tone reduces the resting heart rate down to 60-80 beats/min. To increase heart rate, the autonomic nervous system increases sympathetic outflow to the SAN, with concurrent inhibition of vagal tone. These changes mean the pacemaker potential more rapidly reaches the threshold for action potential generation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 22
Incorrect
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Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The Treppe effect refers to an increase in contractility secondary to an increase in heart rate.
Explanation:Although Ca2+entry during the action potential (AP) is essential for contraction, it only accounts for about 25% of the rise in intracellular Ca2+. The rest is released from Ca2+stores in the sarcoplasmic reticulum (SR). In relaxation, about 80% of Ca2+is rapidly pumped back into the SR (sequestered) by Ca2+ATPase pumps. The Ca2+that entered the cell during the AP is transported out of the cell primarily by the Na+/Ca2+exchanger in the membrane. When more action potentials occur per unit time, more Ca2+enters the cell during the AP plateau, more Ca2+is stored in the SR, more Ca2+is released from the SR and thus more Ca2+is left inside the cell and greater tension is produced during contraction. Increased heart rate increases the force of contraction in a stepwise fashion as intracellular [Ca2+] increases cumulatively over several beats; this is the Treppe effect. Cardiac glycosides such as digoxin have a positive inotropic effect.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 23
Incorrect
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Regarding bicarbonate handling by the proximal tubule, which of the following statements is CORRECT:
Your Answer:
Correct Answer: For each H + secreted into the lumen, one Na + and one HCO 3 - is reabsorbed into the plasma.
Explanation:About 80% of bicarbonate is reabsorbed in the proximal tubule. HCO3-is not transported directly, tubular HCO3-associates with H+secreted by epithelial Na+/H+antiporters to form carbonic acid (H2CO3) which readily dissociates to form carbon dioxide and water in the presence of carbonic anhydrase. CO2and water diffuse into the tubular cells, where they recombine to form carbonic acid which dissociates to H+and HCO3-. This HCO3-is transported into the interstitium largely by Na+/HCO3-symporters on the basolateral membrane (and H+is secreted back into the lumen). For each H+secreted into the lumen, one Na+and one HCO3-are reabsorbed into the plasma. H+is recycled so there is little net secretion of H+at this stage.
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This question is part of the following fields:
- Physiology
- Renal
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Question 24
Incorrect
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A 50-year-old man presents with headaches, lethargy, hypertension, and electrolyte disturbance. A diagnosis of primary hyperaldosteronism is made.
Which biochemical pictures would best support this diagnosis?
Your Answer:
Correct Answer: Hypokalaemic metabolic alkalosis
Explanation:When there are excessive levels of aldosterone outside of the renin-angiotensin axis, primary hyperaldosteronism occurs. High renin levels will lead to secondary hyperaldosteronism.
The classical presentation of hyperaldosteronism when symptoms are present include:
Hypokalaemia
Metabolic alkalosis
Hypertension
Normal or slightly raised sodium levels -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 25
Incorrect
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Which of the following is typically a cause of a normal anion gap metabolic acidosis:
Your Answer:
Correct Answer: Diarrhoea
Explanation:FUSEDCARS can be used to remember some of the causes of a normal anion gap acidosis:
Fistula (pancreaticoduodenal)
Ureteroenteric conduit
Saline administration
Endocrine (hyperparathyroidism)
Diarrhoea
Carbonic anhydrase inhibitors (e.g. acetazolamide)
Ammonium chloride
Renal tubular acidosis
Spironolactone -
This question is part of the following fields:
- Physiology
- Renal
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Question 26
Incorrect
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By which of the following is mean arterial pressure (MAP) primarily determined?
Your Answer:
Correct Answer: Total peripheral resistance and cardiac output
Explanation:Mean arterial pressure (MAP) = Cardiac output (CO) x Total peripheral resistance (TPR).
Cardiac output is dependent on the central venous pressure (CVP). CVP, in turn, is highly dependent on the blood volume.
Any alterations of any of these variables will likely change MAP. -
This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 27
Incorrect
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On reviewing the ECG of a patient with a history of intermittent palpitations, you observe prolonged QT interval.
Which of these can cause prolongation of the QT interval on the ECG?
Your Answer:
Correct Answer: Erythromycin
Explanation:Syncope and sudden death due to ventricular tachycardia, particularly Torsades-des-pointes is seen in prolongation of the QT interval.
The causes of a prolonged QT interval include:
Erythromycin
Amiodarone
Quinidine
Methadone
Procainamide
Sotalol
Terfenadine
Tricyclic antidepressants
Jervell-Lange-Nielsen syndrome (autosomal dominant)
Romano Ward syndrome (autosomal recessive)
Hypothyroidism
Hypocalcaemia
Hypokalaemia
Hypomagnesaemia
Hypothermia
Rheumatic carditis
Mitral valve prolapse
Ischaemic heart disease -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 28
Incorrect
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Which of the following statements is correct regarding the neuronal action potential?
Your Answer:
Correct Answer: Initial depolarisation occurs as a result of a Na + influx.
Explanation:The resting potential in most neurons has a value of approximately -70 mV.
The threshold potential is generally around -55 mV.
Initial depolarisation when there is Na+influx through ligand-gated Na+channels.
Action potential is an all or nothing response. The size of the action potential is constant and so, the intensity of the stimulus is coded by the frequency of firing of a neuron.
K+efflux is responsible for repolarisation. -
This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 29
Incorrect
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Which of the following best describes the correct administration of adrenaline for a shockable rhythm in adult advanced life support?
Your Answer:
Correct Answer: Give 1 mg of adrenaline after the second shock and every 3 - 5 minutes thereafter
Explanation:Give adrenaline 1 mg IV (IO) (10 mL of 1:10,000 solution) after the 2nd shock for adult patients in cardiac arrest with a shockable rhythm. Repeat adrenaline 1 mg IV (IO) every 3-5 minutes whilst ALS continues.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 30
Incorrect
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The proximal convoluted tubule (PCT) is the first part of the renal tubule and lies in the renal cortex. The bulk of reabsorption of solute occurs is the PCT and 100% of glucose is reabsorbed here.
Which of the following is the mechanism of glucose reabsorption in the PCT?Your Answer:
Correct Answer: Secondary active transport
Explanation:Glucose reabsorption occurs exclusively in the proximal convoluted tubule by secondary active transport through the Na.Glu co-transporters, driven by the electrochemical gradient for sodium.
The co-transporters transport two sodium ions and one glucose molecule across the apical membrane, and the glucose subsequently crosses the basolateral membrane by facilitated diffusion. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 31
Incorrect
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Regarding skeletal muscle contraction, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The force of contraction of a muscle can be controlled by increasing recruitment of motor units.
Explanation:Each motor unit contracts in an all or nothing fashion, i.e. if a motor unit is excited, it will stimulate all of its muscle fibres to contract. The force of contraction of a muscle is controlled by varying the motor unit recruitment (spatial summation), and by varying the firing rate of the motor units (temporal summation). During a gradual increase in contraction of a muscle, the first units start to discharge and increase their firing rate, and, as the force needs to increase, new units are recruited and, in turn, also increase their firing rate. For most motor units, the firing rate for a steady contraction is between 5 and 8 Hz. Because the unitary firing rates for each motor unit are different and not synchronised, the overall effect is a smooth force profile from the muscle. Increasing the firing rate of motor units is temporal summation where the tension developed by the first action potential has not completely decayed when the second action potential and twitch is grafted onto the first and so on. If the muscle fibres are stimulated repeatedly at a faster frequency, a sustained contraction results where it is not possible to detect individual twitches. This is called tetanus.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 32
Incorrect
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Oedema can occur as a result of any of the following WITH THE EXCEPTION OF:
Your Answer:
Correct Answer: Increased interstitial hydrostatic pressure
Explanation:Oedema is defined as a palpable swelling produced by the expansion of the interstitial fluid volume. A variety of clinical conditions are associated with the development of oedema, including heart failure, cirrhosis, and nephrotic syndrome. The development of oedema requires an alteration in capillary dynamics in a direction that favours an increase in net filtration and also inadequate removal of the additional filtered fluid by lymphatic drainage. Oedema may form in response to an elevation in capillary hydraulic pressure (which increases the delta hydraulic pressure) or increased capillary permeability, or it can be due to disruption of the endothelial glycocalyx, decreased interstitial compliance, a lower plasma oncotic pressure (which reduces the delta oncotic pressure), or a combination of these changes. Oedema can also be induced by lymphatic obstruction since the fluid that is normally filtered is not returned to the systemic circulation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 33
Incorrect
-
A 64-year-old woman with a history of chronic breathlessness is referred for lung function testing.
Which of the following statements regarding lung function testing is FALSE? Select ONE answer only.Your Answer:
Correct Answer: In restrictive lung disease, the FVC is increased
Explanation:In restrictive lung disorders there is a reduction in the forced vital capacity (FVC) and the forced expiratory volume in one second (FEV1). The decline in the FVC is greater than that of the FEV1, resulting in preservation of the FEV1/FVC ratio (>0.7%).
In obstructive lung disease, FEV1is reduced to <80% of normal and FVC is usually reduced but to a lesser extent than FEV1. The FEV1/FVC ratio is reduced to <0.7.
According to the latestNICE guidelines(link is external), airflow obstruction is defined as follows:
Mild airflow obstruction = an FEV1 of >80% in the presence of symptoms
Moderate airflow obstruction = FEV1 of 50-79%
Severe airflow obstruction = FEV1 of 30-49%
Very severe airflow obstruction = FEV1<30%.
Spirometry is a poor predictor of durability and quality of life in COPD but can be used as part of the assessment of severity.
COPD can only be diagnosed on spirometry if the FEV1 is <80% and FEV1/FVC ratio is < 0.7. -
This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 34
Incorrect
-
Regarding renal clearance, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The MDRD equation uses plasma creatinine to estimate the GFR making an adjustment for age, sex and race.
Explanation:Clearance is defined as the volume of plasma that is cleared of a substance per unit time. Inulin clearance is the gold standard for measurement of GFR but creatinine clearance is typically used instead. Creatinine is freely filtered and not reabsorbed, but there is a little creatinine tubular secretion. In practice, GFR is usually estimated from the plasma creatinine using a formula e.g. the MDRD equation making an adjustment for age, sex and race.
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This question is part of the following fields:
- Physiology
- Renal
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Question 35
Incorrect
-
Regarding gas exchange at the alveolar-capillary membrane, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The rate of diffusion in lungs can be estimated by measuring the diffusing capacity of the lungs for carbon monoxide.
Explanation:Gas exchange between alveolar air and blood in the pulmonary capillaries takes place by diffusion across the alveolar-capillary membrane. Diffusion occurs from an area of high partial pressure to an area of low partial pressure, thus the driving force for diffusion is the alveolar-capillary partial pressure gradient. Diffusion occurs across a membrane and is therefore governed by Fick’s law. Although CO2is larger than O2, it is is much more soluble and diffuses 20 times more rapidly. The diffusing capacity for oxygen (DLO2) cannot be measured directly but the rate of diffusion in the lungs can be estimated by measuring the diffusing capacity of the lungs for carbon monoxide (DLCO).
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 36
Incorrect
-
Regarding postural hypotension, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Postural hypotension usually causes a reflex bradycardia.
Explanation:On standing from a prone position, gravity causes blood to pool in veins in the legs. Central venous pressure (CVP) falls, causing a fall in stroke volume and cardiac output (due to Starling’s law) and thus a fall in blood pressure. Normally this fall in BP is rapidly corrected by the baroreceptor reflex which causes venoconstriction (partially restoring CVP), and an increase in heart rate and contractility, so restoring cardiac output and blood pressure. Impaired autonomic nervous activity in the elderly accounts for the greater likelihood of postural hypotension. Any symptoms of dizziness, blurred vision or syncope is due to a transient fall in cerebral perfusion that occurs before cardiac output and mean arterial pressure (MAP) can be corrected.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 37
Incorrect
-
The juxtacapillary receptors, or J receptors, are sensory cells that play an important role in the control of respiration.
At which of the following anatomical sites are the J receptors located? Select ONE answer only.Your Answer:
Correct Answer: The alveolar walls
Explanation:Juxtacapillary receptors (J receptors) are sensory cells that are located within the alveolar walls in juxtaposition to the pulmonary capillaries of the lung.
The J receptors are innervated by the vagus nerve and are activated by physical engorgement of the pulmonary capillaries or increased pulmonary interstitial volume, for example, in the presence of pulmonary oedema, pulmonary embolus, pneumonia and barotraumas. They may also be stimulated by hyperinflation of the lung.
Stimulation of the J receptors causes a reflex increase in breathing rate and is also thought to be involved in the sensation of dyspnoea. The reflex response that is produced is apnoea, followed by rapid breathing, bradycardia, and hypotension. -
This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 38
Incorrect
-
Regarding fibrinolytics, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Fibrinolytic drugs act as thrombolytics by directly degrading the fibrin mesh and so breaking up thrombi.
Explanation:Fibrinolytic drugs act as thrombolytics by activating plasminogen to form plasmin, which degrades fibrin and so breaks up thrombi.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 39
Incorrect
-
On her most recent blood tests, a 55 year-old female with a history of hypertension was discovered to be hypokalaemic. She is diagnosed with primary hyperaldosteronism.
Which of the following is a direct action of aldosterone?
Your Answer:
Correct Answer: Secretion of H + into the distal convoluted tubule
Explanation:Aldosterone is a steroid hormone produced in the adrenal cortex’s zona glomerulosa. It is the most important mineralocorticoid hormone in the control of blood pressure. It does so primarily by promoting the synthesis of Na+/K+ATPases and the insertion of more Na+/K+ATPases into the basolateral membrane of the nephron’s distal tubules and collecting ducts, as well as stimulating apical sodium and potassium channel activity, resulting in increased sodium reabsorption and potassium secretion. This results in sodium conservation, potassium secretion, water retention, and a rise in blood volume and blood pressure.
Aldosterone is produced in response to the following stimuli:
Angiotensin II levels have risen.
Potassium levels have increased.
ACTH levels have risen.
Aldosterone’s principal actions are as follows:
Na+ reabsorption from the convoluted tubule’s distal end
Water resorption from the distal convoluted tubule (followed by Na+)
Cl is reabsorbed from the distal convoluted tubule.
K+ secretion into the convoluted distal tubule’s
H+ secretion into the convoluted distal tubule’s -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 40
Incorrect
-
All of the following are physiological effects of thyroid hormones except:
Your Answer:
Correct Answer: Increased glycogenesis
Explanation:Thyroid hormones have multiple physiological effects on the body. These include:
1. Heat production (thermogenesis)
2. Increased basal metabolic rate
3. Metabolic effects:
(a) Increase in protein turnover (both synthesis and degradation are increased, although overall effect is catabolic)
(b) Increase in lipolysis
(c)Increase in glycogenolysis and gluconeogenesis
4. Enhanced catecholamine effect – Increase in heart rate, stroke volume and thus cardiac output
5. Important role in growth and development -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 41
Incorrect
-
Glucagon may be used as an antidote for overdose with which of the following:
Your Answer:
Correct Answer: Beta blockers
Explanation:Glucagon is a peptide hormone that is produced and secreted by alpha cells of the islets of Langerhans, which are located in the endocrine portion of the pancreas. The main physiological role of glucagon is to stimulate hepatic glucose output, thereby leading to increases in glycaemia. It provides the major counter-regulatory mechanism to insulin in maintaining glucose homeostasis.
Hypoglycaemia is the principal stimulus for the secretion of glucagon but may also be used as an antidote in beta-blocker overdose and in anaphylaxis in patients on beta-blockers that fail to respond to adrenaline.
Glucagon then causes:
Glycogenolysis
Gluconeogenesis
Lipolysis in adipose tissue
The secretion of glucagon is also stimulated by:
Adrenaline
Cholecystokinin
Arginine
Alanine
Acetylcholine
The secretion of glucagon is inhibited by:
Insulin
Somatostatin
Increased free fatty acids
Increased urea productionGlycolysis is the metabolic pathway that converts glucose into pyruvate. The free energy released by this process is used to form ATP and NADH. Glycolysis is inhibited by glucagon, and glycolysis and gluconeogenesis are reciprocally regulated so that when one cell pathway is activated, the other is inactive and vice versa.
Glucagon has a minor effect of enhancing lipolysis in adipose tissue. Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into glycerol and free fatty acids. It makes fatty acids available for oxidation.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 42
Incorrect
-
What is the pathophysiology of Cushing's syndrome:
Your Answer:
Correct Answer: Glucocorticoid excess
Explanation:Cushing’s syndrome is the name given to the clinical symptoms and signs induced by chronic glucocorticoid excess.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 43
Incorrect
-
Parasympathetic preganglionic neurons originate in which of the following locations:
Your Answer:
Correct Answer: Brainstem and pelvic splanchnic nerves
Explanation:Parasympathetic preganglionic neurones originate in the brainstem from which they run in cranial nerves III, VII, IX and X and also from the second and third sacral segments of the spinal cord. Parasympathetic preganglionic neurones release acetylcholine into the synapse, which acts on cholinergic nicotinic receptors on the postganglionic fibre. Parasympathetic peripheral ganglia are generally found close to or within their target, whereas sympathetic peripheral ganglia are located largely in two sympathetic chains on either side of the vertebral column (paravertebral ganglia), or in diffuse prevertebral ganglia of the visceral plexuses of the abdomen and pelvis. Parasympathetic postganglionic neurones release acetylcholine, which acts on cholinergic muscarinic receptors.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 44
Incorrect
-
The correct statement regarding the parasympathetic nervous system is which of the following?
Your Answer:
Correct Answer: Parasympathetic preganglionic neurones run in cranial nerves III, VII, IX and X.
Explanation:The electron transfer system is responsible for most of the energy produced during respiration. The is a system of hydrogen carriers located in the inner mitochondrial membrane. Hydrogen is transferred to the electron transfer system via the NADH2 molecules produced during glycolysis and the Krebs cycle. As a result, a H+ion gradient is generated across the inner membrane which drives ATP synthase. The final hydrogen acceptor is oxygen and the H+ions and O2 combine to form water.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 45
Incorrect
-
Which of the following statements is correct regarding flow through the cardiovascular system?
Your Answer:
Correct Answer: Turbulent blood flow may be caused by increased cardiac output.
Explanation:Frictional forces at the sides of a vessel cause a drag force on the fluid touching them in laminar blood flow, which creates a velocity gradient where the flow is greatest at the centre. Laminar blood flow may become disrupted and flow may become turbulent at high velocities, especially in large arteries or where the velocity increases sharply at points of sudden narrowing in the vessels, or across valves. There is increased tendency for thrombi formation when there is turbulent blood flow. Clinically, turbulence may be heard as a murmur or a bruit. As a result of elevated cardiac output, there may be turbulent blood flow, even when the cardiac valves are anatomically normal, and as a result, a physiological murmur can be heard. One such example is pregnancy.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 46
Incorrect
-
Urine flow rate = 2 ml/min
Urine concentration of creatinine = 18 mg/ml
Plasma concentration of creatinine = 0.25 mg/ml
What is the estimated glomerular filtration rate (eGFR)?
Your Answer:
Correct Answer: 144 ml/min
Explanation:GFR can be estimated by:
GFR = UCr x V / PCr
Where:
UCr = urine concentration of creatinine
PCr = plasma concentration of creatinine
V = rate of urine flowIn this case GFR = (18 x 2) / 0.25 = 144 ml/min
Note: Creatinine is used to estimate GFR because it is an organic base naturally produced by muscle breakdown, it is freely filtered at the glomerulus, it is not reabsorbed from the nephron, it is not produced by the kidney, it is not toxic, and it doesn’t alter GFR.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 47
Incorrect
-
A 54-year-old woman presents with polyuria and polydipsia. She is known to suffer from bipolar disorder, which has been well controlled by the use of lithium for many years.
What is the SINGLE most likely diagnosis?Your Answer:
Correct Answer: Nephrogenic diabetes insipidus
Explanation:Diabetes insipidus is the inability to produce concentrated urine. It is characterised by the presence of excessive thirst, polyuria and polydipsia. There are two distinct types of diabetes insipidus:
Cranial (central) diabetes insipidus and;
Nephrogenic diabetes insipidus
Cranial diabetes insipidus is caused by a deficiency of vasopressin (anti-diuretic hormone). Patients with cranial diabetes insipidus can have a urine output as high as 10-15 litres per 24 hours, but adequate fluid intake allows most patients to maintain normonatraemia. 30% of cases are idiopathic, and a further 30% are secondary to head injuries. Other causes include neurosurgery, brain tumours, meningitis, granulomatous disease (e.g. sarcoidosis) and drugs, such as naloxone and phenytoin. A very rare inherited form also exists that is associated with diabetes mellitus, optic atrophy, nerve deafness and bladder atonia.
Nephrogenic diabetes insipidus is caused by renal resistance to the action of vasopressin. As with cranial diabetes insipidus, urine output is markedly elevated. Serum sodium levels can be maintained by secondary polydipsia or can be elevated. Causes of nephrogenic diabetes insipidus include chronic renal disease, metabolic disorders (e.g. hypercalcaemia and hypokalaemia) and drugs, including long-term lithium usage and demeclocycline.
In view of the history of long-term lithium use, in this case, nephrogenic diabetes insipidus is the most likely diagnosis. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 48
Incorrect
-
Which of the following cell types in the stomach secretes histamine?
Your Answer:
Correct Answer: Enterochromaffin-like cells
Explanation:The parietal cells operate in close association with another type of cell called enterochromaffin-like cells (ECL cells), the primary function of which is to secrete histamine. The ECL cells lie in the deep recesses of the oxyntic glands and therefore release histamine indirect contact with the parietal cells of the glands.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 49
Incorrect
-
Regarding inflammatory bowel disease, acute mild to moderate disease of the rectum or rectosigmoid should be treated initially with:
Your Answer:
Correct Answer: Local aminosalicylate
Explanation:Acute mild to moderate disease affecting the rectum (proctitis) or the rectosigmoid is treated initially with local application of an aminosalicylate; alternatively, a local corticosteroid can be used but it is less effective. A combination of a local aminosalicylate and a local corticosteroid can be used for proctitis that does not respond to a local aminosalicylate alone.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 50
Incorrect
-
Digoxin is predominantly used for which of the following:
Your Answer:
Correct Answer: Rate control in persistent and permanent atrial fibrillation
Explanation:Digoxin is most useful for controlling the ventricular response in persistent and permanent atrial fibrillation and atrial flutter. Digoxin is usually only effective for controlling the ventricular rate at rest, and should therefore only be used as monotherapy in predominantly sedentary patients with non-paroxysmal atrial fibrillation. It is now rarely used for rapid control of heart rate, as even with intravenous administration, response may take many hours. Digoxin is reserved for patients with worsening or severe heart failure due to left ventricular systolic dysfunction refractory to combination therapy with first-line agents. Digoxin is contraindicated in supraventricular arrhythmias associated with accessory conduction pathways e.g. Wolff-Parkinson-White syndrome.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 51
Incorrect
-
A thyroid function test is done for a 55-year-old woman with non-specific symptoms, the results are shown below:
TSH = 5.2
Free T4 is normal
Free T3 is normal
The most likely diagnosis in this patient is?
Your Answer:
Correct Answer: Subclinical hypothyroidism
Explanation:Hypothyroidism is diagnosed using the results of thyroid function tests (TFTs).
In the early stages of the disease, the earliest biochemical change noticed is a rise in thyroid-stimulating hormone (TSH) levels. Free triiodothyronine (T3) and thyroxine (T4) levels are usually normal.
In primary hypothyroidism, the serum TSH level is usually greater than 10 mU/L, and free T4 levels are below the reference range.
Subclinical hypothyroidism is diagnosed when the serum TSH level is above the reference range, and the free T4 levels are within the reference range. The test should, however, be repeated after 3-6 months to exclude transient causes of raised TSH.
In summary, how to interpret TFTs in cases of suspected hypothyroidism is shown below:
Subclinical hypothyroidism
TSH is raised
Free T4 is normal
Free T3 is normalPrimary hypothyroidism
TSH is raised
Free T4 is lowered
Free T3 is lowered or normalSecondary hypothyroidism
TSH is lowered or normal
Free T4 is lowered
Free T3 is lowered or normal -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 52
Incorrect
-
From which of the following cell types are platelets derived?
Your Answer:
Correct Answer: Megakaryocytes
Explanation:Synthesis of platelets occurs in the bone marrow by fragmentation of megakaryocytes cytoplasm, derived from the common myeloid progenitor cell. The average time for differentiation of the human stem cell to the production of platelets is about 10 days. The major regulator of platelet formation is thrombopoietin and 95% of this is produced by the liver. Normal platelet count is 150 – 450 x 109/L and the normal lifespan of a platelet is about 10 days. Usually about one-third of the marrow output of platelets may be trapped at any one time in the normal spleen.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 53
Incorrect
-
A patient with a high potassium level is at risk of going into cardiac arrest. What changes in the ECG may indicate the incident of cardiac arrest in this patient?
Your Answer:
Correct Answer: Peaked T waves and broad QRS complex
Explanation:Severe hyperkalaemia can result in a heart attack or a life-threatening arrhythmia.
T waves become narrow-based, pointed, and tall if hyperkalaemia is not treated.
The QRS complex widens and eventually merges with the T wave, resulting in a classic sine-wave electrocardiogram. Ventricular fibrillation and asystole are likely to follow.
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This question is part of the following fields:
- Physiology
- Renal
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Question 54
Incorrect
-
Which of the following is NOT a typical electrolyte disturbance caused by furosemide:
Your Answer:
Correct Answer: Hypercalcaemia
Explanation:Adverse effects of loop diuretics include:
Mild gastrointestinal disturbances, pancreatitis and hepatic encephalopathy
Hyperglycaemia
Acute urinary retention
Water and electrolyte imbalance
Hyponatraemia, hypocalcaemia, hypokalaemia, hypomagnesaemia, hypochloraemiaHypotension, hypovolaemia, dehydration, and venous thromboembolism
Metabolic alkalosis
Hyperuricaemia
Blood disorders (bone marrow suppression, thrombocytopenia, and leucopenia)
Visual disturbance, tinnitus and deafness
Hypersensitivity reactions -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 55
Incorrect
-
Which of the following is NOT a function of the commensal intestinal bacterial flora:
Your Answer:
Correct Answer: Breakdown of haem into bilirubin
Explanation:Commensal intestinal bacterial flora have a role in:Keeping pathogenic bacteria at bay by competing for space and nutrientConverting conjugated bilirubin to urobilinogen (some of which is reabsorbed and excreted in urine) and stercobilinogen which is excreted in the faecesThe synthesis of vitamins K, B12, thiamine and riboflavinThe breakdown of primary bile acids to secondary bile acidsThe breakdown of cholesterol, some food additives and drugs
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 56
Incorrect
-
Which of the following best characterizes the correct administration of amiodarone for a shockable rhythm in adults on advanced life support:
Your Answer:
Correct Answer: Give 300 mg IV amiodarone after 3 shocks
Explanation:After three shocks, 300 mg IV amiodarone should be administered. After five defibrillation attempts, a further dose of 150 mg IV amiodarone may be considered. If amiodarone is not available, lidocaine may be used as a substitute, but it should not be given if amiodarone has previously been administered.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 57
Incorrect
-
The last two segments of the nephrons are the distal convoluted tubule (DCT) and collecting duct (CD).
Which cell reabsorbs sodium more in the late DCT and CD?Your Answer:
Correct Answer: Principal cells
Explanation:The main Na+ reabsorbing cells in the late distal convoluted tubule and collecting duct are the principal cells. These make up the majority of the tubular cells.
The exchange is driven by the Na.K.ATPase pumps on the basolateral membrane.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 58
Incorrect
-
In the treatment of hypertensive episodes in pheochromocytoma, which of the following medication types is administered as first-line management:
Your Answer:
Correct Answer: Alpha-blockers
Explanation:The first line of management in controlling blood pressure and preventing intraoperative hypertensive crises is to use a combination of alpha and beta-adrenergic inhibition. In phaeochromocytoma, alpha-blockers are used to treat hypertensive episodes in the short term. Tachycardia can be managed by the careful addition of a beta-blocker, preferably a cardioselective beta-blocker, once alpha blockade has been established. Long term management of pheochromocytoma involves surgery.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 59
Incorrect
-
A patient complains of stomach ache. You see a midline scar in the epigastric area when you examine the abdomen. Upon further interrogation, the patient reveals that she had a subtotal gastrectomy for recurring stomach ulcers several years ago. The stomach mucosa secretes a variety of vital compounds, and her ability to secrete some of these molecules has been harmed as a result of his surgery.
The stomach mucous neck cells secrete which of the following substances?
Your Answer:
Correct Answer: Bicarbonate
Explanation:Foveolar cells, also known as gastric mucous-neck cells, are cells that line the stomach mucosa and are found in the necks of the gastric pits. Mucus and bicarbonate are produced by these cells, which prevent the stomach from digesting itself. At pH 4, the mucous allows the acid to penetrate the lining, while below pH 4, the acid is unable to do so. Viscous fingering is the term for this procedure.
The table below summarizes the many cell types found in the stomach, as well as the substances secreted by each cell type and the function of the secretion:
Cell type/ Substance secreted/ Function of secretion
Parietal cells/ Hydrochloric acid/ Kills microbes and activates pepsinogen
Parietal cells/ Intrinsic factor/Binds to vitamin B12 and facilitates its absorption
Chief cells/ Pepsinogen/ Protein digestion
Chief cells/ Gastric lipase/ Fat digestion
G-cells/ Gastrin/ Stimulates gastric acid secretion
Enterochromaffin-like cells (ECL cells) /Histamine/ Stimulates gastric acid secretion
Mucous-neck cells/ Mucous and bicarbonate/ Protects stomach epithelium from acid
D-cells/ Somatostatin/ Inhibits gastric acid secretion -
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 60
Incorrect
-
When treating diabetic ketoacidosis (DKA), glucose should be given together with insulin as soon as the blood glucose concentration falls below 14 mmol/L in the form of:
Your Answer:
Correct Answer: 10% glucose intravenous infusion at a rate of 125 mL/hour
Explanation:In addition to the sodium chloride 0.9 percent infusion, glucose 10% should be given intravenously (into a large vein with a large-gauge needle) at a rate of 125 mL/hour once blood glucose concentration falls below 14 mmol/litre.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 61
Incorrect
-
Which of the following drugs is first line treatment for a stable regular broad-complex tachycardia:
Your Answer:
Correct Answer: Amiodarone
Explanation:A regular broad-complex tachycardia is likely to be ventricular tachycardia or a regular supraventricular rhythm with bundle branch block. A ventricular tachycardia (or broad-complex tachycardia of uncertain origin) should be treated with amiodarone 300 mg IV over 10 – 60 min, followed by an infusion of 900 mg over the next 24 hours. If previously confirmed as SVT with bundle branch block, the patient should be treated as for narrow-complex tachycardia.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 62
Incorrect
-
The cutaneous circulation is responsible for the skin's blood supply. Because the skin is not a highly metabolically active tissue with low energy requirements, its blood supply differs from that of other tissues. Instead of capillaries, some of the circulating blood volume in the skin passes through arteriovenous anastomoses (AVAs).
Which of the following statements regarding arteriovenous anastomoses is correct?
Your Answer:
Correct Answer: AVAs are innervated by sympathetic fibres originating from the hypothalamus
Explanation:Short vessels called arteriovenous anastomoses (AVAs) link tiny arteries and veins. They have a large lumen diameter. The strong and muscular walls allow AVAs to completely clog the vascular lumen, preventing blood flow from artery to vein (acting like a sphincter). When the AVAs open, they create a low-resistance connection between arteries and veins, allowing blood to flow into the limbs’ superficial venous plexuses. There is no diffusion of solutes or fluid into the interstitium due to their strong muscle walls.
AVAs are densely innervated by adrenergic fibres from the hypothalamic temperature-regulation centre. High sympathetic output occurs at normal core temperatures, inducing vasoconstriction of the AVAs and blood flow through the capillary networks and deep plexuses. When the temperature rises, sympathetic output decreases, producing AVA vasodilation and blood shunting from the artery to the superficial venous plexus. Heat is lost to the environment as hot blood rushes near to the skin’s surface.
AVAs are a specialized anatomical adaptation that can only be found in large quantities in the fingers, palms, soles, lips, and pinna of the ear. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 63
Incorrect
-
Dehydration causes a significant increase in the amount of this hormone?
Your Answer:
Correct Answer: Antidiuretic hormone
Explanation:Antidiuretic hormone induces the kidneys to release less water, resulting in reduced urine production.
In the case of dehydration, ADH levels rise, resulting in a considerable decrease in urine output as well as an increase in plasma protein, blood Hct, and serum osmolality.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 64
Incorrect
-
A 60-year-old man presents with marked breathlessness. He has with a history of ischaemic heart disease. On examination, there is coarse bibasal crackles, marked peripheral oedema and chest X-ray taken is consistent with severe pulmonary oedema. RR is 28 per minute.
Which receptor is responsible for detecting pulmonary oedema and the subsequent increase in respiratory rate?Your Answer:
Correct Answer: Juxtacapillary receptors
Explanation:Pulmonary oedema causes stimulation of the Juxtacapillary receptors (J receptors) leading to a reflex increase in breathing rate. These receptors are also thought to be involved in the sensation of dyspnoea. The J receptors are sensory cells and are located within the alveolar walls in juxtaposition to the pulmonary capillaries.
Aortic baroreceptor are involved in detecting blood pressure
Central chemoreceptors detect changes in CO2 and hydrogen ion within the brain
Atrial volume receptors regulate plasma volume
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 65
Incorrect
-
Regarding diuretics, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Carbonic anhydrase inhibitors have their effect by inhibiting bicarbonate reabsorption.
Explanation:Carbonic anhydrase inhibitors e.g. acetazolamide block the reaction of carbon dioxide and water and so prevent Na+/H+exchange and bicarbonate reabsorption. The increased bicarbonate levels in the filtrate oppose water reabsorption. Proximal tubule sodium reabsorption is also reduced because it is partly dependent on bicarbonate reabsorption.
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This question is part of the following fields:
- Physiology
- Renal
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Question 66
Incorrect
-
Which of the following is NOT a mineralocorticoid effect of corticosteroids:
Your Answer:
Correct Answer: Hyperglycaemia
Explanation:Mineralocorticoid side effects include:hypertensionsodium retentionwater retention and oedemapotassium losscalcium loss
Glucocorticoid side effects include:weight gainhyperglycaemia and diabetesosteoporosis and osteoporotic fracturesmuscle wasting (proximal myopathy)peptic ulceration and perforationpsychiatric reactions -
This question is part of the following fields:
- Endocrine
- Pharmacology
-
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Question 67
Incorrect
-
When a person changes from a supine to an upright position, which of the followingcompensatory mechanismsoccurs:
Your Answer:
Correct Answer: Increased contractility
Explanation:On standing from a prone position, gravity causes blood to pool in veins in the legs. Central venous pressure (CVP) falls, causing a fall in stroke volume and cardiac output (due to Starling’s law) and thus a fall in blood pressure. Normally this fall in BP is rapidly corrected by the baroreceptor reflex which causes venoconstriction (partially restoring CVP), and an increase in heart rate and contractility, so restoring cardiac output and blood pressure. Impaired autonomic nervous activity in the elderly accounts for the greater likelihood of postural hypotension. Any symptoms of dizziness, blurred vision or syncope is due to a transient fall in cerebral perfusion that occurs before cardiac output and mean arterial pressure (MAP) can be corrected.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 68
Incorrect
-
Regarding the partial pressure of gases, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: At high altitude, the oxygen fraction is reduced.
Explanation:At altitude, the oxygen fraction is unaltered but the barometric pressure and thus partial pressure of oxygen is reduced.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 69
Incorrect
-
Glucagon is secreted by which of the following pancreatic cell types:
Your Answer:
Correct Answer: α cells
Explanation:Glucagon is a peptide hormone that is produced and secreted by alpha cells of the islets of Langerhans, which are located in the endocrine portion of the pancreas. The main physiological role of glucagon is to stimulate hepatic glucose output, thereby leading to increases in glycaemia. It provides the major counter-regulatory mechanism to insulin in maintaining glucose homeostasis.
Hypoglycaemia is the principal stimulus for the secretion of glucagon but may also be used as an antidote in beta-blocker overdose and in anaphylaxis in patients on beta-blockers that fail to respond to adrenaline.
Glucagon then causes:
Glycogenolysis
Gluconeogenesis
Lipolysis in adipose tissue
The secretion of glucagon is also stimulated by:
Adrenaline
Cholecystokinin
Arginine
Alanine
Acetylcholine
The secretion of glucagon is inhibited by:
Insulin
Somatostatin
Increased free fatty acids
Increased urea productionGlycolysis is the metabolic pathway that converts glucose into pyruvate. The free energy released by this process is used to form ATP and NADH. Glycolysis is inhibited by glucagon, and glycolysis and gluconeogenesis are reciprocally regulated so that when one cell pathway is activated, the other is inactive and vice versa.
Glucagon has a minor effect of enhancing lipolysis in adipose tissue. Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into glycerol and free fatty acids. It makes fatty acids available for oxidation.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 70
Incorrect
-
On which of the following types of receptors does loperamide act?
Your Answer:
Correct Answer: Opioid receptors
Explanation:Loperamide inhibits acetylcholine release from the myenteric plexus acts by action on opioid mu-receptors, and this then reduces bowel motility. The intestinal transit time is increased, thereby facilitating water reabsorption.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 71
Incorrect
-
Regarding the phases of gastric secretion, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: A high pH in the stomach inhibits gastrin secretion.
Explanation:A low pH in the stomach inhibits gastrin secretion, therefore when the stomach is empty or when acid has been secreted for some time after food has entered it, there is inhibition of acid secretion. However, when food first enters the stomach, the pH rises, and this leads to release of the inhibition and causes a maximum secretion of gastrin. Thus gastric acid secretion is self-regulating.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 72
Incorrect
-
Which of the following is NOT a typical side effect of digoxin:
Your Answer:
Correct Answer: Hypokalaemia
Explanation:Digoxin does not cause hypokalaemia, but hypokalaemia does potentiate digoxin toxicity. The adverse effects of digoxin are frequently due to its narrow therapeutic window and include:
Cardiac adverse effects – Sinoatrial and atrioventricular block, Premature ventricular contractions, PR prolongation and ST-segment depression
Nausea, vomiting and diarrhoea
Blurred or yellow vision
CNS effects – weakness, dizziness, confusion, apathy, malaise, headache, depression, psychosis
Thrombocytopenia and agranulocytosis (rare)
Gynaecomastia in men in prolonged administration -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 73
Incorrect
-
Which of the following corticosteroids has the most potent mineralocorticoid effect:
Your Answer:
Correct Answer: Fludrocortisone
Explanation:Fludrocortisone has the most potent mineralocorticosteroid activity, making it ideal for mineralocorticoid replacement in adrenal insufficiency.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 74
Incorrect
-
ACE inhibitors are indicated for all of the following EXCEPT for:
Your Answer:
Correct Answer: Angina
Explanation:ACE inhibitors have many uses and are generally well tolerated. They are indicated for:
- Heart failure
- Hypertension
- Diabetic nephropathy
- Secondary prevention of cardiovascular events
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 75
Incorrect
-
A 72 year old man is brought to ED by ambulance with sudden onset chest pain, palpitations and shortness of breath. His HR is 160 bpm and BP 90/65. ECG demonstrates new-onset fast atrial fibrillation. Which of the following is the first-line treatment option in this case:
Your Answer:
Correct Answer: Synchronised DC cardioversion
Explanation:All patients with adverse features suggesting life-threatening haemodynamic instability (shock, syncope, heart failure, myocardial ischaemia) caused by new onset atrial fibrillation should undergo emergency electrical cardioversion with synchronised DC shock without delaying to achieve anticoagulation.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 76
Incorrect
-
All of the following statements are correct with regards to protection of the gastric mucosa except which of the following?
Your Answer:
Correct Answer: NSAIDs directly stimulate increased parietal cell acid production.
Explanation:Prostaglandin production, which usually inhibits acid secretion and increases mucus and bicarbonate secretion, is inhibited by NSAIDs.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 77
Incorrect
-
Bile acids are essential for the digestion and absorption of which of the following:
Your Answer:
Correct Answer: Lipids and fat-soluble vitamins
Explanation:Bile acids are synthesised from cholesterol by hepatocyte and excreted into bile. Bile acids are essential for lipid digestion and absorption. Of the bile acids excreted into the intestine, about 95% are reabsorbed into the portal circulation by active transport mechanisms in the distal ileum and recycled by the liver. Many of the bile salts are reabsorbed unaltered, some are converted by intestinal bacteria into secondary bile acids (deoxycholic acid and lithocholic acid) and then reabsorbed and a small proportion escapes reabsorption and is excreted in the faeces.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 78
Incorrect
-
Bendoflumethiazide may cause all of the following electrolyte imbalances EXCEPT for:
Your Answer:
Correct Answer: Hypocalcaemia
Explanation:Common side effects of thiazide diuretics include:
Excessive diuresis, postural hypotension, dehydration, renal impairment
Acid-base and electrolyte imbalance
Hypokalaemia, hyponatraemia, hypomagnesaemia, hypercalcaemia, hypochloraemic alkalosis
Metabolic imbalance
Hyperuricaemia and gout
Impaired glucose tolerance and hyperglycaemia
Altered plasma-lipid concentrations
Mild gastrointestinal disturbances -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 79
Incorrect
-
Capillaries are designed with a small diffusion distance for nutrition and gaseous exchange with the tissues they serve. Capillaries come in a variety of shapes and sizes, each with its own function in transcapillary exchange.
Which of the following types of capillaries is the least permeable in the human body?
Your Answer:
Correct Answer: Continuous capillaries
Explanation:Capillaries are designed with a small diffusion distance for nutrition and gaseous exchange with the tissues they serve. Because oxygen and carbon dioxide are both highly soluble in lipids (lipophilic), they can easily diffuse along a concentration gradient across the endothelial lipid bilayer membrane. In contrast, glucose, electrolytes, and other polar, charged molecules are lipid-insoluble (hydrophilic). These chemicals are unable to pass through the lipid bilayer membrane directly and must instead travel through gaps between endothelial cells.
Capillaries are divided into three types: continuous, fenestrated, and sinusoidal. Each of these capillary types contains different sized gaps between the endothelial cells that operate as a filter, limiting which molecules and structures can pass through.The permeability of capillaries is affected by the wall continuity, which varies depending on the capillary type.
Skeletal muscle, myocardium, skin, lungs, and connective tissue all have continuous capillaries. These capillaries are the least permeable. They have a basement membrane and a continuous layer of endothelium. The presence of intercellular spaces allows water and hydrophilic molecules to pass across. Tight connections between the cells and the glycocalyx inhibit passage via these gaps, making diffusion 1000-10,000 times slower than for lipophilic compounds. The diffusion of molecules larger than 10,000 Da, such as plasma proteins, is likewise prevented by this narrow pore system. These big substances can pass through the capillary wall, but only very slowly, because endothelial cells have enormous holes.The kidneys, gut, and exocrine and endocrine glands all have fenestrated capillaries. These are specialized capillaries that allow fluid to be filtered quickly. Water, nutrients, and hormones can pass via windows or fenestrae in their endothelium, which are connected by a thin porous membrane. They are ten times more permeable than continuous capillaries due to the presence of these fenestrae. Fenestrated capillaries have a healthy basement membrane.
The spleen, liver, and bone marrow all have sinusoidal capillaries, also known as discontinuous capillaries. Their endothelium has huge gaps of >100 nm, and their basement membrane is inadequate. They are highly permeable as a result, allowing red blood cells to travel freely. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 80
Incorrect
-
You evaluate a 80-year-old man who has a history of persistent heart failure and discover that he has generalised oedema.
Which of the following claims regarding capillary hydrostatic pressure (P c) is false?Your Answer:
Correct Answer: P c increases along the length of the capillary, from arteriole to venule
Explanation:The capillary hydrostatic pressure (Pc) is normally between 15 and 30 millimetres of mercury. Pc Decreases along the capillary’s length, mirroring the arteriolar and venule pressures proximally and distally.
Pc is determined by the ratio of arteriolar resistance (RA) to venular resistance (RV).When the RA/RV ratio is high, the pressure drop across the capillary is modest, and Pcis is close to venule pressure.
When the ratio of RA/RV is low, the pressure drop across the capillary is considerable, and Pcis is close to arteriolar pressure.
Pcis closer to the venule pressure and thus more responsive to changes in venous pressure than arteriolar pressure when RA/RV is high.
Pcis the major force behind fluid pushing out of the capillary bed and into the interstitium.
It is also the most variable of the forces affecting fluid transport at the capillary, partly because sympathetic-mediated arteriolar vasoconstriction varies. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 81
Incorrect
-
A 62-year-old woman presents with cold sensitivity, tiredness, and weight gain. A series of blood tests done shows a grossly elevated TSH level and a diagnosis of hypothyroidism is made.
What is the commonest cause of hypothyroidism worldwide?Your Answer:
Correct Answer: Iodine deficiency
Explanation:Hypothyroidism occurs when there is a deficiency of circulating thyroid hormones. It is commoner in women and is most frequently seen in the age over 60.
Iodine deficiency is the commonest cause of hypothyroidism worldwide.
In developed countries, iodine deficiency is not a problem and autoimmune thyroiditis is the commonest cause.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 82
Incorrect
-
Which of the following does NOT predispose to digoxin toxicity in a patient taking digoxin:
Your Answer:
Correct Answer: Hyponatraemia
Explanation:Hypoxia, hypercalcaemia, hypokalaemia and hypomagnesaemia predispose to digoxin toxicity. Care should also be taken in the elderly who are particularly susceptible to digoxin toxicity. Hypokalaemia may be precipitated by use of diuretics. Although hyponatremia can result in the development of other pathological disturbances, it does not potentiate digoxin toxicity.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 83
Incorrect
-
Which of the following comprises a negative feedback mechanism?
Your Answer:
Correct Answer: Detectors, comparators, a variable set point and effectors
Explanation:Negative feedback loops, also known as inhibitory loops, play a crucial role in controlling human health. It is a self-regulating mechanism of some sort.
A negative feedback system is made up of three main components: a detector (often neural receptor cells) that measures the variable in question and provides input to the comparator; a comparator (usually a neural assembly in the central nervous system) that receives input from the detector, compares the variable to the variable set point, and determines whether or not a response is required.
The comparator activates an effector (typically muscular or glandular tissue) to conduct the appropriate reaction to return the variable to its set point.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 84
Incorrect
-
Which of the following is NOT an adverse effect associated with warfarin therapy:
Your Answer:
Correct Answer: Neutropenia
Explanation:Adverse effects of warfarin:
The most common adverse effect of warfarin is bleedingOther common adverse effects of warfarin include nausea, vomiting, diarrhoea, jaundice, hepatic dysfunction, pancreatitis, pyrexia, alopecia, purpura, and rash
Skin necrosis is a rare but serious adverse effect of warfarin; treatment with warfarin should be stopped if warfarin related skin necrosis is suspected
Calciphylaxis is a rare, but a very serious condition that causes vascular calcification and cutaneous necrosis
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 85
Incorrect
-
A 17-year-old type I diabetic patient presents with abdominal pain and vomiting. Measurement of her blood glucose level is done and found to be grossly elevated. She is diagnosed with diabetic ketoacidosis. A fixed rate insulin infusion is given as part of her treatment.
Which of these is an action of insulin?Your Answer:
Correct Answer: Stimulates lipogenesis
Explanation:Insulin is an anabolic hormone. Its actions can be broadly divided into:
Lipid metabolism
Protein metabolism and
Carbohydrate metabolismFor lipid metabolism, insulin:
Stimulates lipogenesis
Inhibits lipolysis by lipaseFor carbohydrate metabolism, insulin:
Decreases gluconeogenesis
Stimulates glycolysis
Promotes glucose uptake in muscle and adipose tissue
Promotes glycogen storage
Increases glycogenesis
Decreases glycogenolysisProtein metabolism:
Stimulates protein synthesis
Accelerates net formation of protein
Stimulates amino acid uptake
Inhibits protein degradation
Inhibits amino acid conversion to glucose -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 86
Incorrect
-
Which of the following does NOT increase free ionised calcium levels:
Your Answer:
Correct Answer: Calcitonin
Explanation:Calcium homeostasis is primarily controlled by three hormones: parathyroid hormone, activated vitamin D and calcitonin.
Parathyroid hormone acts on the kidneys to increase calcium reabsorption in the distal tubule by activating Ca2+entry channels in the apical membrane and the Ca2+ATPase pump in the basolateral membrane (and to decrease phosphate reabsorption in the proximal tubule).
Activated vitamin D acts to increase calcium reabsorption in the distal tubule via activation of a basolateral Ca2+ATPase pump (and to increase phosphate reabsorption).
Calcitonin acts to inhibit renal reabsorption of calcium (and phosphate).
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This question is part of the following fields:
- Physiology
- Renal
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Question 87
Incorrect
-
Which of the following is NOT a function of bile:
Your Answer:
Correct Answer: Digestion of fats into monoglycerides and fatty acids.
Explanation:Bile functions to eliminate endogenous and exogenous substances from the liver (including bilirubin), to neutralise gastric acid in the small intestine, and to emulsify fats in the small intestine and facilitate their digestion and absorption. Bile salts also act as bactericides, destroying many of the microbes that may be present in the food. Bile doesn’t contain digestive enzymes for digestion of lipids into monoglycerides and fatty acids; this is performed mainly by pancreatic lipase.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 88
Incorrect
-
The renal team is currently prescribing erythropoietin to a patient with chronic kidney disease.
Which of the following statements about erythropoietin is correct?Your Answer:
Correct Answer: It protects red blood cell progenitors from apoptosis
Explanation:Erythropoietin is a glycoprotein hormone that regulates the formation of red blood cells (red cell production). It is mostly produced by interstitial fibroblasts in the kidney, which are located near the PCT. It is also produced in the liver’s perisinusoidal cells, however this is more common during the foetal and perinatal periods.
The kidneys produce and secrete erythropoietin in response to hypoxia. On red blood cells, erythropoietin has two main effects:
– It encourages stem cells in the bone marrow to produce more red blood cells.
– It protects red blood cell progenitors and precursors from apoptosis by targeting them in the bone marrow.
As a result of the increased red cell mass, the oxygen-carrying capacity and oxygen delivery increase. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 89
Incorrect
-
Question 90
Incorrect
-
Which of the following best describes digoxin:
Your Answer:
Correct Answer: A positive inotrope and negative chronotrope
Explanation:Digoxin is a cardiac glycoside used in the treatment of atrial fibrillation and flutter, and congestive cardiac failure. It acts by inhibiting the membrane Na/K ATPase in cardiac myocytes. This raises intracellular sodium concentration and increases intracellular calcium availability indirectly via Na/Ca exchange. The increase in intracellular calcium levels causes an increases the force of myocardial contraction (positive inotrope), and slows the heart rate (negative chronotrope).
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 91
Incorrect
-
A 24-year-old athlete drinks a 500 ml hypertonic sports drink before an endurance event he participates in.
Which of the following effects will this cause?Your Answer:
Correct Answer: The interstitial fluid becomes more concentrated
Explanation:Osmosis is the passive movement of water across a semipermeable membrane from a region of low solute concentration to a region of higher solute concentration.
When hypertonic fluid is ingested:
The plasma becomes CONCENTRATED.The cells lose water and shrink
The intracellular fluid becomes more concentrated.
Water and ions move freely from the plasma into the interstitial fluid and the interstitial fluid becomes more concentrated.
The increased osmotic potential draws water out of the cells. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 92
Incorrect
-
Dexamethasone would be most useful for which of the following conditions:
Your Answer:
Correct Answer: Raised intracranial pressure secondary to malignancy
Explanation:Dexamethasone has a very high glucocorticoid activity in conjunction with insignificant mineralocorticoid activity. This makes it particularly suitable for high-dose therapy in conditions where fluid retention would be a disadvantage such as in the management of raised intracranial pressure or cerebral oedema secondary to malignancy. Dexamethasone also has a long duration of action and this, coupled with its lack of mineralocorticoid action makes it particularly suitable for suppression of corticotropin secretion in congenital adrenal hyperplasia. In most individuals a single dose of dexamethasone at night, is sufficient to inhibit corticotropin secretion for 24 hours. This is the basis of the ‘overnight dexamethasone suppression test’ for diagnosing Cushing’s syndrome.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 93
Incorrect
-
Which JVP waveform correlates to atrial systole?
Your Answer:
Correct Answer: The a wave
Explanation:JVP Waveform in Cardiac Cycle Physiology: a wave Right atrial contraction causes atrial systole (end diastole). the c wave During right isovolumetric ventricular contraction, the tricuspid valve bulges into the right atrium, resulting in isovolumetric contraction (early systole). descent by x Rapid ventricular ejection (mid systole) is caused by a combination of right atrial relaxation, tricuspid valve downward movement during right ventricular contraction, and blood ejection from both ventricles. the v-wave Ventricular ejection and isovolumetric relaxation (late systole) occur as a result of venous return filling the right atrium. y lineage Ventricular filling occurs when the tricuspid valve opens, allowing blood to flow rapidly from the right atrium to the right ventricle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 94
Incorrect
-
Regarding antimuscarinic antispasmodics, which of the following statements is CORRECT:
Your Answer:
Correct Answer: They are contraindicated in paralytic ileus.
Explanation:Antimuscarinics are contraindicated in paralytic ileus. Antimuscarinics reduce intestinal motility by blocking muscarinic acetylcholine receptors and relaxing smooth muscle. Hyoscine butylbromide is advocated as a gastrointestinal antispasmodic, but it is poorly absorbed and thus has limited clinical utility. Antimuscarinics cause a reduction in bronchial secretions (they can be used to this effect in palliative patients). Antispasmodics are occasionally of value in treating abdominal cramp associated with diarrhoea but they should not be used for primary treatment. Antispasmodics should be avoided in young children with gastroenteritis because they are rarely effective and have troublesome side effects.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 95
Incorrect
-
Regarding cellular respiration, which of the following statements is CORRECT:
Your Answer:
Correct Answer: When fats are used as the primary energy source, an excess of acetyl-CoA is produced.
Explanation:Cellular respiration is the process by which cells obtain energy in the form of adenosine triphosphate (ATP). ATP transfers chemical energy from the energy rich substances in the cell to the cell’s energy requiring reactions e.g. active transport, DNA replication and muscle contraction.Cellular respiration is essentially a three step process: 1) Glycolysis, 2)The Krebs cycle, 3)The electron transfer system.The main respiratory substrate used by cells is 6-carbon glucose. Fats and proteins can also be used as respiratory substrates. When fats are being used as the primary energy source, in the absence of glucose, an excess amount of acetyl-CoA is produced, and is converted into acetone and ketone bodies. This can occur in starvation, fasting or in diabetic ketoacidosis. Proteins are used as an energy source only if protein intake is very high, or if glucose and fat sources are depleted.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 96
Incorrect
-
Nifedipine commonly causes which of the following adverse effects?
Your Answer:
Correct Answer: Ankle oedema
Explanation:Most common adverse effects of Nifedipine include:
Peripheral oedema (10-30%)
Dizziness (23-27%)
Flushing (23-27%)
Headache (10-23%)
Heartburn (11%)
Nausea (11%) -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 97
Incorrect
-
The action potential is generated by excitable tissues, which are specialized tissues that can generate a meaningful electrical signal. Local currents transport action potentials down the axons of neurons.
Which of the following claims about the action potential's conduction is correct?Your Answer:
Correct Answer: The areas of the membrane that have recently depolarised will not depolarise again due to the refractory period
Explanation:Local currents propagate action potentials down the axons of neurons. Following depolarization, this local current flow depolarizes the next axonal membrane, and when this region crosses the threshold, more action potentials are formed, and so on. Due to the refractory period, portions of the membrane that have recently depolarized will not depolarize again, resulting in the action potential only being able to go in one direction.
The square root of axonal diameter determines the velocity of the action potential; the axons with the biggest diameter have the quickest conduction velocities. When a neuron is myelinated, the speed of the action potential rises as well.
The myelin sheath is an insulating coating that surrounds certain neural axons. By increasing membrane resistance and decreasing membrane capacitance, the myelin coating increases conduction. This enables faster electrical signal transmission via a neuron, making them more energy-efficient than non-myelinated neuronal axons.
Nodes of Ranvier are periodic holes in a myelinate axon when there is no myelin and the axonal membrane is exposed. There are no gated ion channels in the portion of the axon covered by the myelin sheath, but there is a high density of ion channels in the Nodes of Ranvier. Action potentials can only arise at the nodes as a result of this.
Electrical impulses are quickly transmitted from one node to the next, causing depolarization of the membrane above the threshold and triggering another action potential, which is then transmitted to the next node. An action potential is rapidly conducted down a neuron in this manner. Saltatory conduction is the term for this. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 98
Incorrect
-
You are about to give an antimuscarinic agent to a 55 year-old male patient. Which of the following conditions will make you with stop the administration, since it is a contraindication to antimuscarinic agents?
Your Answer:
Correct Answer: Prostatic enlargement
Explanation:Antimuscarinic medications may impair the contractility of bladder smooth muscle, resulting in acute urine retention in men with BPH, and should be avoided or used with caution.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 99
Incorrect
-
Regarding protein digestion, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Oligopeptides are broken down into small peptides and amino acids by pancreatic carboxypeptidases and aminopeptidases located on the brush border.
Explanation:Digestion of dietary protein begins in the stomach where pepsin hydrolyses protein to polypeptides, and continues in the duodenum where pancreatic proteases (trypsin and chymotrypsin) continue the process of hydrolysis forming oligopeptides. These are further broken down into small peptides and amino acids by pancreatic carboxypeptidases and aminopeptidases located on luminal membrane epithelial cells. Free amino acids are absorbed across the apical membrane by secondary active transport coupled with Na+transport into the cell. Amino acids cross the basal membrane into the capillaries by facilitated diffusion.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 100
Incorrect
-
Regarding airway resistance, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: In the lower respiratory tract, airway resistance is mostly determined by the smallest bronchioles.
Explanation:Airway resistance is primarily determined by the airway radius according to Poiseuille’s law, and whether the flow is laminar or turbulent. The major site of airway resistance is the medium-sized bronchi. The smallest airways would seem to offer the highest resistance, but they do not because of their branching parallel arrangement.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 101
Incorrect
-
Vitamin D is a group of secosteroids that play a role in calcium and phosphate control. Vitamin D's hormonally active metabolite is 1,25-dihydroxycholecalciferol.
Which enzyme hydroxylates 25-hydroxycholecalciferol to form 1,25-dihydroxycholecalciferol?Your Answer:
Correct Answer: 1-alpha-hydroxylase
Explanation:The hormone-active metabolite of vitamin D is 1,25-dihydroxycholecalciferol (commonly known as calcitriol). Its activities raise calcium and phosphate levels in the bloodstream.
In the presence of UVB light, 7-dehydrocholesterol is converted to cholecalciferol in the epidermal layer of the skin, resulting in 1,25-dihydroxycholecalciferol.
Cholecalciferol is then converted to 25-hydroxycholecalciferol in the endoplasmic reticulum of liver hepatocytes by 25-hydroxylase (calcifediol).
Finally, 1-alpha-hydroxylase converts 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol in the kidney. The key regulatory point in the formation of 1,25-dihydroxycholecalciferol is 1-alpha-hydroxylase, which is induced by parathyroid hormone or hypophosphatemia.
The following are the primary effects of 1,25-dihydroxycholecalciferol:
Calcium and phosphate absorption in the small intestine is increased.
Calcium reabsorption in the kidneys is increased.
Increases phosphate reabsorption in the kidneys.
Increases the action of osteoclastic bacteria (increasing calcium and phosphate resorption from bone)
Inhibits the action of 1-alpha-hydroxylase in the kidneys (negative feedback) -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 102
Incorrect
-
The Frank-Starling curve is shifted downhill in heart failure due to which of the following?
Your Answer:
Correct Answer: Decrease in contractility
Explanation:The Frank–Starling mechanism states that the left ventricle can increase its force of contraction and hence stroke volume in response to increases in venous return and thus preload.
Changes in afterload or inotropy cause the Frank–Starling curve to rise or fall. In heart failure, the Frank–Starling curve is shifted downward (flattened), requiring higher venous return and filling pressure to enhance contractility and stroke volume.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 103
Incorrect
-
At rest, saliva is produced predominantly by which of the following:
Your Answer:
Correct Answer: Submandibular gland
Explanation:At rest, most saliva is produced by the submandibular gland (65%). When stimulated by the autonomic nervous system, about 50% of saliva is produced by the parotid gland with only 30% produced by the submandibular gland.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 104
Incorrect
-
You review an 83-year-old woman who has stage 5 chronic kidney disease. She has a number of electrolyte problems.
Which ONE of the following decreases the renal reabsorption of phosphate?Your Answer:
Correct Answer: Parathyroid hormone
Explanation:Parathyroid hormone (PTH) is a polypeptide containing 84 amino acids. It is the principal controller of free calcium in the body.
The main actions of parathyroid hormone are:
Increases plasma calcium concentration
Decreases plasma phosphate concentration
Increases osteoclastic activity (increasing calcium and phosphate resorption from bone)
Increases renal tubular reabsorption of calcium
Decreases renal phosphate reabsorption
Increases renal conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (via stimulation of 1-alpha hydroxylase)
Increases calcium and phosphate absorption in the small intestine (indirectly via increased 1,25-dihydroxycholecalciferol) -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 105
Incorrect
-
What is the mechanism of action of captopril:
Your Answer:
Correct Answer: Angiotensin-converting enzyme inhibitor
Explanation:Captopril is an angiotensin-converting enzyme (ACE) inhibitor, which inhibits the conversion of angiotensin I to angiotensin II.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 106
Incorrect
-
An ambulance transports a 40-year-old man to the hospital. He ingested a significant amount of aspirin.
In the early stages of an aspirin overdose, which form of acid-base problem should you anticipate?Your Answer:
Correct Answer: Respiratory alkalosis
Explanation:When you take too much aspirin, you have a mix of respiratory alkalosis and metabolic acidosis. Respiratory centre stimulation produces hyperventilation and respiratory alkalosis in the early phases. The direct acid actions of aspirin tend to create a higher anion gap metabolic acidosis in the latter phases.
Below summarizes some of the most common reasons of acid-base abnormalities:Respiratory alkalosis:
– Hyperventilation (e.g. anxiety, pain, fever)
– Pulmonary embolism
– Pneumothorax
– CNS disorders (e.g. CVA, SAH, encephalitis)
– High altitude
– Pregnancy
– Early stages of aspirin overdoseRespiratory acidosis:
– COPD
– Life-threatening asthma
– Pulmonary oedema
– Respiratory depression (e.g. opiates, benzodiazepines)
– Neuromuscular disease (e.g. Guillain-Barré syndrome, muscular dystrophy
– Incorrect ventilator settings (hypoventilation)
– ObesityMetabolic alkalosis:
– Vomiting
– Cardiac arrest
– Multi-organ failure
– Cystic fibrosis
– Potassium depletion (e.g. diuretic usage)
– Cushing’s syndrome
– Conn’s syndromeMetabolic acidosis (with raised anion gap):
– Lactic acidosis (e.g. hypoxaemia, shock, sepsis, infarction)
– Ketoacidosis (e.g. diabetes, starvation, alcohol excess)
– Renal failure
– Poisoning (e.g. late stages of aspirin overdose, methanol, ethylene glycol)Metabolic acidosis (with normal anion gap):
– Renal tubular acidosis
– Diarrhoea
– Ammonium chloride ingestion
– Adrenal insufficiency -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 107
Incorrect
-
Which of the following is a common adverse effect of glucagon:
Your Answer:
Correct Answer: Nausea
Explanation:Adverse effects include:
Common: Nausea
Uncommon: Vomiting
Rare: Abdominal pain, hypertension, hypotension, tachycardia -
This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 108
Incorrect
-
Regarding bile, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: The sphincter of Oddi contracts to force bile from the gallbladder into the duodenum.
Explanation:Bile is secreted by hepatocytes. It is isotonic and resembles plasma ionically. This fraction of bile is called the bile acid-dependent fraction. As it passes along the bile duct, the bile is modified by epithelial cells lining the duct by the addition of water and bicarbonate ions; this fraction is called the bile acid-independent fraction. Overall, the liver can produce 500 – 1000 mL of bile per day. The bile is either discharged directly into the duodenum or stored in the gallbladder. The bile acid-independent fraction is made at the time it is required i.e. during digestion of chyme. The bile acid-dependent fraction is made when the bile salts are returned from the GI tract to the liver, and is then stored in the gallbladder until needed. The gallbladder not only stores bile but concentrates it by removing non-essential solutes and water, leaving bile acids and pigments, mainly by active transport of Na+into the intercellular spaces of the lining cells which, in turn, draws in water, HCO3-and Cl-from the bile and into the extracellular fluid. Within a few minutes of a meal, particularly when fatty foods have been consumed, the gallbladder contracts and releases bile into the bile duct. The sphincter of Oddi is relaxed, allowing the bile to pass into the duodenum through the ampulla of Vater.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 109
Incorrect
-
A 60-year-old patient with a history of hypertension and chronic kidney disease (CKD) walks into the clinic to discuss her most recent blood results indicating an accelerated progression of CKD.
Which of the following is the correct definition for accelerated progression of CKD?
Your Answer:
Correct Answer: A sustained decrease in GFR of 15 ml/minute/1.73 m 2 per year
Explanation:Chronic kidney disease (CKD) is a disorder in which kidney function gradually deteriorates over time. It’s fairly prevalent, and it typically remains unnoticed for years, with only advanced stages of the disease being recognized. There is evidence that medication can slow or stop the progression of CKD, as well as lessen or prevent consequences and the risk of cardiovascular disease (CVD).
CKD is defined as kidney damage (albuminuria) and/or impaired renal function (GFR 60 ml/minute per 1.73 m2) for three months or longer, regardless of clinical diagnosis.
A prolonged decline in GFR of 25% or more with a change in GFR category within 12 months, or a sustained drop in GFR of 15 ml/minute/1.73 m² per year, is considered accelerated CKD progression.
End-stage renal disease (ESRD) is defined as severe irreversible kidney impairment with a GFR of less than 15 ml/minute per 1.73 m² and a GFR of less than 15 ml/minute per 1.73 m². -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 110
Incorrect
-
The role of the juxtaglomerular (granular) cells of the juxtaglomerular apparatus is:
Your Answer:
Correct Answer: Production of renin
Explanation:Juxtaglomerular cells synthesise renin. These cells are specialised smooth muscle cells that are located in the walls of the afferent arterioles, and there are some in the efferent arterioles.
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This question is part of the following fields:
- Physiology
- Renal
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Question 111
Incorrect
-
What is the pathophysiology of a phaeochromocytoma:
Your Answer:
Correct Answer: Catecholamine-secreting tumour
Explanation:Phaeochromocytomas are catecholamine-secreting tumours which occur in about 0.1% of patients with hypertension. In about 90% of cases they arise from the adrenal medulla. The remaining 10%, which arise from extra-adrenal chromaffin tissue, are termed paragangliomas. Common presenting symptoms include one or more of headache, sweating, pallor and palpitations. Less commonly, patients describe anxiety, panic attacks and pyrexia. Hypertension, whether sustained or episodic, is present in at least 90% of patients. Left untreated phaeochromocytoma can occasionally lead to hypertensive crisis, encephalopathy, hyperglycaemia, pulmonary oedema, cardiac arrhythmias, or even death.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 112
Incorrect
-
A patient presents with a history of excessive thirst, urination and high fluid intake. His blood sugar is normal. You estimate his osmolarity as part of his work-up.
Which of these equations can be used to estimate osmolarity?
Your Answer:
Correct Answer: 2 (Na + ) + 2 (K + ) + Glucose + Urea
Explanation:Osmolality and osmolarity are measurements of the solute concentration of a solution. Although the two terms are often used interchangeably, there are differences in the definitions, how they are calculated and the units of measurement used.
Osmolarity, expressed as mmol/L, is an estimation of the osmolar concentration of plasma. It is proportional to the number of particles per litre of solution.
Measured Na+, K+, urea and glucose concentrations are used to calculate the value indirectly.
It is unreliable in pseudohyponatremia and hyperproteinaemia.The equations used to calculate osmolarity are:
Osmolarity = 2 (Na+) + 2 (K+) + Glucose + Urea (all in mmol/L)
OR
Osmolarity = 2 (Na+) + Glucose + Urea (all in mmol/L)Doubling of sodium accounts for the negative ions associated with sodium, and the exclusion of potassium approximately allows for the incomplete dissociation of sodium chloride.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 113
Incorrect
-
For a tachyarrhythmia caused by hypovolaemic shock, which of the following is the first-line treatment:
Your Answer:
Correct Answer: Synchronised DC shock
Explanation:If there are any adverse symptoms, immediate cardioversion with synchronized DC shock is recommended. If cardioversion fails to stop the arrhythmia and the symptoms persist, amiodarone 300 mg IV over 10–20 minutes should be administered before attempting another cardioversion. The loading dosage of amiodarone is followed by a 24-hour infusion of 900 mg administered into a large vein.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 114
Incorrect
-
An 82 year old man taking warfarin as a maintenance medication comes in to your clinic because of an infection. Which antibiotic is the safest choice for this patient?
Your Answer:
Correct Answer: Cefalexin
Explanation:Alterations in the international normalized ratio (INR) brought about by the concurrent use of antibiotics and warfarin may result in either excessive clotting or excessive bleeding if they are deemed to have a high risk for interaction. As such, there should be careful consideration of the class of antibiotic to be used.
Antibiotics from the following drug classes should generally be avoided as they have a high risk for interaction with warfarin, possible enhancing the anticoagulant effects of warfarin resulting in bleeding: Fluoroquinolones (e.g. ciprofloxacin, levofloxacin), Macrolides (e.g. clarithromycin, erythromycin, azithromycin), Nitroimidazoles (e.g. metronidazole), Sulphonamides (e.g. co-trimoxazole, a combination of trimethoprim and sulfamethoxazole), Trimethoprim, Tetracyclines (e.g. doxycycline).
Low risk antibiotics that have low risk for interaction with warfarin includes cephalexin, from the cephalosporin class, and clindamycin which is a lincomycin.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 115
Incorrect
-
Which of the following is NOT a typical effect caused by adrenaline:
Your Answer:
Correct Answer: Bronchoconstriction
Explanation:Actions of adrenaline:
Cardiovascular system
– Increased rate and force of cardiac contraction
– Vasoconstriction of vessels in skin, mucous membranes and splanchnic bed
– Vasodilation of skeletal muscle vessels
– Increased cardiac output and blood pressure
Respiratory system
– Bronchodilation
– Increased ventilation rate
Gastrointestinal system
– Smooth muscle relaxation
– Contraction of sphincters
– Metabolism
– Decreased insulin release
– Increased glucagon release
– Increased thermogenesis
– Increased glycolysis
– Increased lipolysis
Eye
– Pupillary dilation -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 116
Incorrect
-
Regarding skeletal muscle, which of the following best describes the Z-line:
Your Answer:
Correct Answer: A line dividing muscle fibres into sarcomeres
Explanation:Each muscle fibre is divided at regular intervals along its length into sarcomeres separated by Z-lines. The sarcomere is the functional unit of the muscle.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 117
Incorrect
-
A patient complains of stomach ache. You see a midline scar in the epigastric area when you examine the abdomen. Upon further interrogation, the patient reveals that she had a subtotal gastrectomy for recurring stomach ulcers several years ago. The stomach mucosa secretes a variety of vital compounds, and her ability to secrete some of these molecules has been harmed as a result of his surgery.
The gastric ECL cells secrete which of the following substances?
Your Answer:
Correct Answer: Histamine
Explanation:Enterochromaffin-like cells (ECL cells) are a type of neuroendocrine cell located beneath the epithelium in the stomach glands. They’re most typically located near the parietal cells of the stomach. The ECL cells’ primary role is to produce histamine, which stimulates the formation of stomach acid by the parietal cells.
The table below summarizes the many cell types found in the stomach, as well as the substances secreted by each cell type and the function of the secretion:
Cell type/ Substance secreted/ Function of secretion
Parietal cells/ Hydrochloric acid/ Kills microbes and activates pepsinogen
Parietal cells/ Intrinsic factor/Binds to vitamin B12 and facilitates its absorption
Chief cells/ Pepsinogen/ Protein digestion
Chief cells/ Gastric lipase/ Fat digestion
G-cells/ Gastrin/ Stimulates gastric acid secretion
Enterochromaffin-like cells (ECL cells) /Histamine/ Stimulates gastric acid secretion
Mucous-neck cells/ Mucous and bicarbonate/ Protects stomach epithelium from acid
D-cells/ Somatostatin/ Inhibits gastric acid secretion -
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 118
Incorrect
-
Regarding fluid balance, which of the following statements is CORRECT:
Your Answer:
Correct Answer: About three-quarters of extracellular fluid is interstitial.
Explanation:An ‘average’ person (70 kg male) contains about 40 litres of water in total, separated into different fluid compartments by biological semipermeable membranes; plasma cell membranes between extracellular and intracellular fluid, and capillary walls between interstitial and intravascular fluid. Around two-thirds of the total fluid (27 L) is intracellular fluid (ICF) and one-third of this (13 L) is extracellular fluid (ECF). The ECF can be further divided into intravascular fluid (3.5 L) and interstitial fluid (9.5 L).
Transcellular fluid refers to any fluid that does not contribute to any of the main compartments but which are derived from them e.g. gastrointestinal secretions and cerebrospinal fluid, and has a collective volume of approximately 2 L.
Osmosis is the passive movement of water across a semipermeable membrane from regions of low solute concentration to those of higher solute concentration. -
This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 119
Incorrect
-
A lung function test is being performed on a male patient. For this patient, which of the following volumes for functional residual capacity is considered a normal result?
Your Answer:
Correct Answer: 2.0 L
Explanation:The volume of air that remains in the lungs after a single breath is known as functional residual capacity (FRC). It is calculated by combining the expiratory reserve volume and residual volume. In a 70 kg, average-sized male, a normal functional residual capacity is approximately 2100 mL.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 120
Incorrect
-
Cardiac muscle and skeletal muscle are alike, but there are a few key variations.
Which of the following is NOT a characteristic of skeletal muscle but is a characteristic of cardiac muscle?Your Answer:
Correct Answer: The presence of intercalated discs
Explanation:Cardiac muscle is striated, and the sarcomere is the contractile unit, similar to skeletal muscle. Contracture is mediated by the interaction of calcium, troponins, and myofilaments, much as it occurs in skeletal muscle. Cardiac muscle, on the other hand, differs from skeletal muscle in a number of ways.
In contrast to skeletal muscle cells, cardiac myocytes have a nucleus in the middle of the cell and sometimes two nuclei. The cells are striated because the thick and thin filaments are arranged in an orderly fashion, although the arrangement is less well-organized than in skeletal muscle.
Intercalated discs, which work similarly to the Z band in skeletal muscle in defining where one cardiac muscle cell joins the next, are a very significant component of cardiac muscle.
Adherens junctions and desmosomes, which are specialized structures that hold the cardiac myocytes together, are formed by the transverse sections. The lateral sections produce gap junctions, which join the cytoplasm of two cells directly, allowing for rapid action potential conduction. These critical properties allow the heart to contract in a coordinated manner, allowing for more efficient blood pumping.
Cardiac myocytes have the ability to create their own action potentials, which is referred to as myogenic’. They can depolarize spontaneously to initiate a cardiac action potential. Pacemaker cells, as well as the sino-atrial (SA) and atrioventricular (AV) nodes, control this.
The Purkinje cells and the cells of the bundle of His are likewise capable of spontaneous depolarization. While the bundle of His is made up of specialized myocytes, it’s vital to remember that Purkinje cells are not myocytes and have distinct characteristics. They are larger than myocytes, with fewer filaments and more gap junctions than myocytes. They conduct action potentials more quickly, allowing the ventricles to contract synchronously.
Cardiac myocytes contract by excitation-contraction coupling, just like skeletal myocytes. Heart myocytes, on the other hand, utilise a calcium-induced calcium release mechanism that is unique to cardiac muscle (CICR). The influx of calcium ions (Ca2+) into the cell causes a ‘calcium spark,’ which causes more ions to be released into the cytoplasm.An influx of sodium ions induces an initial depolarisation, much as it does in skeletal muscle; however, in cardiac muscle, the inflow of Ca2+ sustains the depolarisation, allowing it to remain longer. Due to potassium ion (K+) inflow, CICR causes a plateau phase in which the cells remain depolarized for a short time before repolarizing. Skeletal muscle, on the other hand, repolarizes almost instantly.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 121
Incorrect
-
Which of the following is the primary indication for loop diuretics?
Your Answer:
Correct Answer: Acute pulmonary oedema
Explanation:Loop diuretics have long been the cornerstone of pulmonary oedema treatment, with furosemide being the most commonly used of these drugs. Premedication with drugs that decrease preload (e.g., nitro-glycerine [NTG]) and afterload (e.g., angiotensin-converting enzyme [ACE] inhibitors) before the administration of loop diuretics can prevent adverse hemodynamic changes.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 122
Incorrect
-
Which of the following decreases activation of vitamin D:
Your Answer:
Correct Answer: Chronic renal failure
Explanation:Calcium deficiency (low Ca2+ diet or hypocalcemia) activates 1-alpha-hydroxylase in the cells of the renal proximal tubule which catalyses the conversion of vitamin D to its active form, 1,25-dihydroxycholecalciferol. Increased parathyroid hormone (PTH) and hypophosphatemia also stimulate the enzyme. Chronic renal failure is associated with a constellation of bone diseases, including osteomalacia caused by failure of the diseased renal tissue to produce the active form of vitamin D.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 123
Incorrect
-
What is the main mechanism of action of flecainide:
Your Answer:
Correct Answer: Blocks Na+ channels
Explanation:Flecainide inhibits the transmembrane influx of extracellular Na+ ions via fast channels on cardiac tissues resulting in a decrease in rate of depolarisation of the action potential, prolonging the PR and QRS intervals. At high concentrations, it exerts inhibitory effects on slow Ca2+ channels, accompanied by moderate negative inotropic effect.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 124
Incorrect
-
A 59-year-old man presents with a goitre, increased sweating, weight loss, and palpitations. A diagnosis of hyperthyroidism is suspected.
What is the most appropriate first-line investigation?
Your Answer:
Correct Answer: TSH level
Explanation:A thyroid function test is used in the diagnosis of hyperthyroidism.
Serum TSH should be the first-line investigation for patients with suspected hyperthyroidism as it has the highest sensitivity and specificity for hyperthyroidism.A normal TSH level almost always excludes the diagnosis, though there are rare exceptions to this.
Antithyroglobulin antibodies are commonly present in Graves’ disease, but the test has a sensitivity of 98% and specificity of 99, and is not widely available.
Radioactive iodine uptake scan using iodine-123 – shows low uptake in thyroiditis but high in Graves’ disease and toxic multinodular goitre. It is however, not first-line investigation in this case
Thyroid ultrasound scan – is a cost-effective and safe alternative to the radioactive iodine uptake scan.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 125
Incorrect
-
What is the direct mechanism of action of digoxin as a positive inotrope:
Your Answer:
Correct Answer: Inhibition of Na+/K+ ATPase pump
Explanation:Digoxin directly inhibits membrane Na+/K+ ATPase, which is responsible for Na+/K+ exchange across the myocyte cell membrane. This increases intracellular Na+ and produces a secondary increase in intracellular Ca2+ that increases the force of myocardial contraction. The increase in intracellular Ca2+ occurs because the decreased Na+ gradient across the membrane reduces the extrusion of Ca2+ by the Na+/Ca2+ exchanger that normally occurs during diastole. Digoxin and K+ ions compete for the receptor on the outside of the muscle cell membrane, and so the effects of digoxin may be dangerously increased in hypokalaemia.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 126
Incorrect
-
In the foetus at 4 months gestation, where does haematopoiesis mainly occur?
Your Answer:
Correct Answer: Liver and spleen
Explanation:The first place that haematopoiesis occurs in the foetus is in the yolk sac. Later on, it occurs in the liver and spleen, which are the major hematopoietic organs from about 6 weeks until 6 – 7 months gestation. At this point, the bone marrow becomes the most important site. Haemopoiesis is restricted to the bone marrow in normal childhood and adult life.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 127
Incorrect
-
Which of the following is NOT a common side effect of adenosine:
Your Answer:
Correct Answer: Yellow vision
Explanation:Common side effects of adenosine include:
Apprehension
Dizziness, flushing, headache, nausea, dyspnoea
Angina (discontinue)
AV block, sinus pause and arrhythmia (discontinue if asystole or severe bradycardia occur) -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 128
Incorrect
-
Antispasmodic drugs are primarily indicated in which of the following conditions:
Your Answer:
Correct Answer: Irritable bowel syndrome
Explanation:Antispasmodics, such as antimuscarinics, may be used in the management of irritable bowel syndrome. Other antispasmodics used include direct-acting smooth muscle relaxants such as mebeverine, alverine, and peppermint oil. Antispasmodics are contraindicated in bowel obstruction and severe inflammatory bowel disease. Antispasmodics are occasionally of value in treating abdominal cramp associated with diarrhoea but they should not be used for primary treatment. Antispasmodics should be avoided in young children with gastroenteritis because they are rarely effective and have troublesome side effects. Antimuscarinics are contraindicated in urinary retention.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 129
Incorrect
-
Regarding alteplase, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Alteplase is commonly associated with hypotensive effects.
Explanation:Alteplase is a recombinant tissue-type plasminogen activator (tPA), a naturally occurring fibrin-specific enzyme that has selectivity for activation of fibrin-bound plasminogen. It has a short half-life of 3 – 4 minutes and must be given by continuous intravenous infusion but is not associated with antigenic or hypotensive effects, and can be used in patients when recent streptococcal infections or recent use of streptokinase contraindicates the use of streptokinase.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 130
Incorrect
-
Adenosine has a half-life of approximately:
Your Answer:
Correct Answer: 8 - 10 seconds
Explanation:Adenosine stimulates A1-adenosine receptors and opens acetylcholine sensitive K+ channels, increasing K+ efflux. This hyperpolarises the cell membrane in the atrioventricular node and, by inhibiting the calcium channels, slows conduction in the AVN. As it has a very short duration of action (half-life only about 8 – 10 seconds), most side effects are short lived.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 131
Incorrect
-
Which of the following is NOT a pharmacological effect of beta-blockers:
Your Answer:
Correct Answer: Reduced AV conduction time
Explanation:Effects of beta-blockers:
Cardiovascular system:
Reduce blood pressure
Reduce heart rate, contractility and cardiac output
Increase AV conduction time, refractoriness and suppress automaticityEye:
Reduce intraocular pressureRespiratory system:
Cause bronchoconstriction -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 132
Incorrect
-
A patient who is taking ramipril for high blood pressure complains of a dry persistent cough. What is the mechanism of cough in ACE inhibitor therapy:
Your Answer:
Correct Answer: Decreased bradykinin breakdown
Explanation:Blocking ACE also diminishes the breakdown of the potent vasodilator bradykinin which is the cause of the persistent dry cough. Angiotensin-II receptor blockers do not have this effect, therefore they are useful alternative for patients who have to discontinue an ACE inhibitor because of persistent cough.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 133
Incorrect
-
On review of a patient's serum and urine osmolality test result, you note that both osmolarities are decreased. There urine osmolality does not increase with fluid ingestion.
What is the most likely cause?Your Answer:
Correct Answer: Hyponatraemia
Explanation:As part of the investigation of hyponatraemia, serum osmolality is commonly requested in combination with urine osmolality to aid diagnosis.
When:
Serum osmolality is decreased and urine osmolality is decreased with no intake of fluid, the causes are
Hyponatraemia
Overhydration
Adrenocortical insufficiency
Sodium loss (diuretic or a low-salt diet)Serum osmolality is normal or increased and urine osmolality is increased the causes include:
Dehydration
Hyperkalaemia
Hyperglycaemia
Hyponatremia
Mannitol therapy
Diabetes mellitus
Alcohol ingestion
Congestive heart failure
Renal disease and uraemiaSerum osmolality is normal or increased and urine osmolality is decreased the usual cause is diabetes insipidus
Serum osmolality is decreased and urine osmolality is increased the usual cause is syndrome of inappropriate antidiuresis (SIAD)
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 134
Incorrect
-
What is the main mechanism of action of dopamine as an inotropic sympathomimetic:
Your Answer:
Correct Answer: Beta1-receptor agonist
Explanation:Dopamine is a neurotransmitter and a metabolic precursor of the catecholamines. It acts on beta1-receptors in cardiac muscle increasing cardiac contractility, and increases renal perfusion by stimulating dopamine receptors in the renal vasculature. This is of benefit in cardiogenic shock where deterioration of renal function is common.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 135
Incorrect
-
You review the arterial blood gas (ABG) of a patient with lactic acidosis.
Which SINGLE statement regarding lactic acidosis is true?Your Answer:
Correct Answer: Type A lactic acidosis is typically due to tissue hypoxia
Explanation:Lactic acidosis is defined as a pH <7.35 and a lactate >5 mmol/L. It is a common finding in critically ill patients and is often associated with other serious underlying pathologies. The anion gap is raised in lactic acidosis.
There are major adverse consequences of severe acidaemia, which affect all body systems, and there is an associated increase in mortality of critically ill patients with a raised lactate. The mortality associated with lactic acidosis despite full supportive treatment remains at 60-90%.
Acquired lactic acidosis is classified into two subtypes:
Type A is due to tissue hypoxia
Type B is due to non-hypoxic processes affecting the production and elimination of lactate
Lactic acidosis can be extreme after a seizure but usually resolves spontaneously within a few hours.
Left ventricular failure typically results in tissue hypoperfusion and a type A lactic acidosis.
Some causes of type A and type B lactic acidosis are shown below:
Type A lactic acidosis
Type B lactic acidosis
Shock (including septic shock)
Left ventricular failure
Severe anaemia
Asphyxia
Cardiac arrest
CO poisoning
Respiratory failure
Severe asthma and COPD
Regional hypoperfusion
Renal failure
Liver failure
Sepsis (non-hypoxic sepsis)
Thiamine deficiency
Alcoholic ketoacidosis
Diabetic ketoacidosis
Cyanide poisoning
Methanol poisoning
Biguanide poisoning -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 136
Incorrect
-
All of the following statement about the microcirculation are correct except:
Your Answer:
Correct Answer: Over the capillary bed, there is a net absorption of fluid.
Explanation:The hydrostatic pressure along the length of the capillary is usually greater than plasma oncotic pressure. As a result, there is a small net filtration of fluid from the capillary into the interstitial space. The regulation of blood flow into the microcirculation is via the vasoconstriction of small arterioles, which is activated by the sympathetic nervous system through numerous nerve endings in their walls. Unlike proteins, most ions and small molecules diffuse easily across capillary walls and thus the crystalloid osmotic pressure they exert is roughly the same on either side of the capillary wall. Because the plasma colloid osmotic pressure is higher than interstitial colloid osmotic, fluid is drawn intravascularly. A reduction of hydrostatic capillary pressure and transient increase in absorption of fluid is a result of arteriolar constriction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 137
Incorrect
-
Angiotensin II acts to cause all but which one of the following effects:
Your Answer:
Correct Answer: Inhibit release of ADH from the posterior pituitary gland
Explanation:Angiotensin II acts to:
Stimulate release of aldosterone from the zona glomerulosa of the adrenal cortex (which in turn acts to increase sodium reabsorption)
Cause systemic vasoconstriction
Cause vasoconstriction of the renal arterioles (predominant efferent effect thus intraglomerular pressure is stable or increased, thereby tending to maintain or even raise the GFR)
Directly increase Na+reabsorption from the proximal tubule (by activating Na+/H+antiporters)
Stimulate synthesis and release of ADH from the hypothalamus and posterior pituitary respectively
Stimulate the sensation of thirst
Potentiate sympathetic activity (positive feedback)
Inhibit renin production by granular cells (negative feedback) -
This question is part of the following fields:
- Physiology
- Renal
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Question 138
Incorrect
-
In adult advanced life support, which of the following best describes the correct administration of adrenaline for a non-shockable rhythm:
Your Answer:
Correct Answer: Give 1 mg of adrenaline as soon as intravenous access is achieved and every 3 - 5 minutes thereafter
Explanation:IV adrenaline 1 mg (10 mL of 1:10,000 solution) should be given after 3 shocks and every 3 – 5 minutes/after alternate shocks thereafter.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 139
Incorrect
-
Which of the following conditions manifests hyperkalaemia as one of its symptoms?
Your Answer:
Correct Answer: Congenital adrenal hyperplasia
Explanation:Plasma potassium greater than 5.5 mmol/L is hyperkalaemia or elevated plasma potassium level. Among the causes of hyperkalaemia include congenital adrenal hyperplasia.
Congenital adrenal hyperplasia is a general term referring to autosomal recessive disorders involving a deficiency of an enzyme needed in cortisol and/or aldosterone synthesis. The level of cortisol and/or aldosterone deficiency affects the clinical manifestations of congenital adrenal hyperplasia. When it involves hypoaldosteronism, it can result in hyponatremia and hyperkalaemia. While hypercortisolism can cause hypoglycaemia.
The other causes of hyperkalaemia may include renal failure, excess potassium supplementation, Addison’s disease (adrenal insufficiency), renal tubular acidosis (type 4), rhabdomyolysis, burns, trauma, Tumour lysis syndrome, acidosis, and medications such as ACE inhibitors, angiotensin receptor blockers, NSAIDs, beta-blockers, digoxin, and suxamethonium.
Bartter’s syndrome is characterized by hypokalaemic alkalosis with normal to low blood pressure.
Type 1 and 2 renal tubular acidosis both cause hypokalaemia.
Gitelman’s syndrome is a defect of the distal convoluted tubule of the kidney. It causes metabolic alkalosis with hypokalaemia and hypomagnesemia.
And excessive liquorice ingestion causes hypermineralocorticoidism and hypokalaemia as well. Thus, among the choices, only congenital adrenal hyperplasia can cause hyperkalaemia
.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 140
Incorrect
-
The Auerbach's plexus is a set of ganglia that controls peristalsis and is located in the gut wall.
Auerbach's plexus is located in which layer of the gut wall?Your Answer:
Correct Answer: Muscular layer
Explanation:The Auerbach’s plexus, also known as the myenteric plexus, is a collection of ganglia that controls peristalsis and is located in the gut wall.
In the muscular layer of the wall, it is located between the circular and longitudinal muscle layers. It is a linear network of linked neurons that runs the length of the gastrointestinal system. The myenteric plexus generates an increase in gut wall tone and the strength of rhythmical contractions when stimulated.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 141
Incorrect
-
The mechanism of action of abciximab is by:
Your Answer:
Correct Answer: Blocking the binding of fibrinogen to GPIIb/IIIa receptor sites
Explanation:Abciximab is a glycoprotein IIb/IIIa inhibitors and prevents platelet aggregation by blocking the binding of fibrinogen to receptors on platelets.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 142
Incorrect
-
Foetal haemoglobin (HbF) comprises about how much of the total haemoglobin in adults:
Your Answer:
Correct Answer: 0.5 - 0.8%
Explanation:Foetal haemoglobin (HbF) makes up about 0.5 – 0.8 % of total adult haemoglobin and consists of two α and two gamma (γ) globin chains.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 143
Incorrect
-
Where:
Capillary hydrostatic pressure is (P c)Hydrostatic pressure in the interstices is (P I )
Plasma oncotic pressure is (π p)Interstitial oncotic pressure is (π i)
Which of the following formulas best represents fluid flow at the capillary bed?
Your Answer:
Correct Answer: Volume / min = (P c - P i ) - (π p - π i )
Explanation:Starling’s equation for fluid filtration describes fluid flow at the capillary bed.
Filtration forces (capillary hydrostatic pressure and interstitial oncotic pressure) stimulate fluid movement out of the capillary, while resorption forces promote fluid movement into the capillary (interstitial hydrostatic pressure and plasma oncotic pressure). Although the forces fluctuate along the length of the capillary bed, overall filtration is achieved.At the capillary bed, there is fluid movement.
The reflection coefficient (σ), the surface area accessible (S), and the hydraulic conductance of the wall (Lp) are frequently used to account for the endothelium’s semi-permeability, yielding:
Volume / min = LpS [(Pc- Pi) – σ(πp– πi)]
Volume /min = (Pc-Pi) – (πp–πi) describes the fluid circulation at the capillaries.
Where:
Pc= capillary hydrostatic pressure
Pi= interstitial hydrostatic pressure
πp= plasma oncotic pressure
πi= interstitial oncotic pressure -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 144
Incorrect
-
Platelet alpha granules release which of the following?
Your Answer:
Correct Answer: Von Willebrand factor (VWF)
Explanation:There are three types of storage granules contained in platelets. These are dense granules which contain the following:
-ATP
-ADP
-serotonin and calcium alpha granules containing clotting factors
-von Willebrand factor (VWF)
-platelet-derived growth factor (PDGF)
– other proteins lysosomes containing hydrolytic enzymes. -
This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 145
Incorrect
-
Pancreatic ductal alkaline fluid secretion is mainly stimulated by which of the following hormones:
Your Answer:
Correct Answer: Secretin
Explanation:Pancreatic exocrine secretion is controlled by:
Parasympathetic stimulation which enhances secretion of both the enzyme and aqueous components
Sympathetic stimulation which inhibits pancreatic secretion
Secretin which stimulates secretion of the alkaline-rich fluid from ductal cells
Cholecystokinin which stimulates secretion of the enzyme-rich fluid from acinar cellsSomatostatin which inhibits secretion from both acinar and ductal cells
Gastrin which stimulates pancreatic acinar cells to secrete digestive enzymes -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 146
Incorrect
-
A 59-year-old man presents with increased sweating, weight loss, and palpitations. A series of blood tests done found a very low TSH level and a diagnosis of hyperthyroidism is made.
What is the commonest cause of hyperthyroidism?
Your Answer:
Correct Answer: Graves’ disease
Explanation:Hyperthyroidism results from an excess of circulating thyroid hormones. It is commoner in women, and incidence increases with age.
Hyperthyroidism can be subclassified into:
Primary hyperthyroidism – the thyroid gland itself is affected
Secondary hyperthyroidism – the thyroid gland is stimulated by excessive circulating thyroid-stimulating hormone (TSH).Graves’ disease is the most common cause of hyperthyroidism (estimates are that it causes between 50 and 80% of all cases).
Although toxic multinodular goitre, thyroiditis,TSH-secreting pituitary adenoma and drug-induced hyperthyroidism also causes hyperthyroidism, the commonest cause is Graves’ disease.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 147
Incorrect
-
Which of the following is the site of secretion of intrinsic factor:
Your Answer:
Correct Answer: Stomach
Explanation:Intrinsic factor is essential for the absorption of the small amounts of vitamin B12 normally present in the diet from the terminal ileum. The parietal cells of the stomach produce intrinsic factor, and following a gastrectomy, the absorption of vitamin B12 will be markedly reduced, and a deficiency state will exist.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 148
Incorrect
-
Which of the following represents ventricular repolarisation on the ECG:
Your Answer:
Correct Answer: T wave
Explanation:P wave = Atrial depolarisation
QRS complex = Ventricular depolarisation
T wave = Ventricular repolarisation -
This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 149
Incorrect
-
Molecules with a molecular weight of less than which of the following are filtered freely at the glomerular filtration barrier:
Your Answer:
Correct Answer: 7000 Da
Explanation:Molecular weight is the main factor in determining whether a substance is filtered or not – molecules < 7 kDa in molecular weight are filtered freely e.g. glucose, amino acids, urea, ions but larger molecules are increasingly restricted up to 70 kDa, above which filtration is insignificant. Negatively charged molecules are further restricted, as they are repelled by negative charges, particularly in the basement membrane. Albumin has a molecular weight of 69 kDa and is negatively charged, thus only very small amounts are filtered (and all of the filtered albumin is reabsorbed in the proximal tubule), whereas small molecules such as ions, glucose, amino acids and urea pass the filter without hindrance. This means that ultrafiltrate is virtually protein free, but otherwise has an identical composition of that of plasma. The epithelial lining of the Bowman's capsule consists of a single layer of cells called podocytes. The glomerular capillary endothelium is perforated by pores (fenestrations) which allow plasma components with a molecular weight of < 70 kDa to pass freely.
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This question is part of the following fields:
- Physiology
- Renal
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Question 150
Incorrect
-
Which of the following is NOT an adverse effect associated with statin therapy:
Your Answer:
Correct Answer: Aplastic anaemia
Explanation:Adverse effects of statins include:, Headache, Epistaxis, Gastrointestinal disorders (such as constipation, flatulence, dyspepsia, nausea, and diarrhoea), Musculoskeletal and connective tissue disorders (such as myalgia, arthralgia, pain in the extremity, muscle spasms, joint swelling, and back pain), Hyperglycaemia and diabetes, Myopathy and rhabdomyolysis, Interstitial lung disease and Hepatotoxicity
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 151
Incorrect
-
A 50-year-old man managed by the renal team for stage 4 chronic kidney disease which appears to be deteriorating presents with a history of shortness of breath and ankle oedema. His most recent blood tests shows low calcium levels.
Which of these increases the renal reabsorption of calcium?Your Answer:
Correct Answer: Parathyroid hormone
Explanation:Parathyroid hormone (PTH), a polypeptide containing 84 amino acids, is the principal hormone that controls free calcium in the body.
Its main actions are:
Increases osteoclastic activity
Increases plasma calcium concentration
Decreases renal phosphate reabsorption
Decreases plasma phosphate concentration
Increases renal tubular reabsorption of calcium
Increases calcium and phosphate absorption in the small intestine
Increases renal conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 152
Incorrect
-
Regarding bile acids, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: The main primary bile acids are deoxycholic acid and lithocholic acid.
Explanation:Bile acids have a hydrophobic and a hydrophilic end and in aqueous solution, bile salts orient themselves around droplets of lipid forming micelles to keep the lipid droplets dispersed. The principal primary bile acids are cholic acid and chenodeoxycholic acid. They are made more soluble by conjugation with taurine or glycine in the liver. Of the bile acids excreted into the intestine, about 95% are reabsorbed into the portal circulation by active transport mechanisms in the distal ileum and recycled by the liver.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 153
Incorrect
-
Which of the following factors does NOT decrease glucagon secretion:
Your Answer:
Correct Answer: Catecholamines
Explanation:Factors that increase glucagon secretion:
↓ Blood glucose
↑ Amino acids
Cholecystokinin
Catecholamines
AcetylcholineFactors that decrease glucagon secretion:
↑ Blood glucose
Insulin
Somatostatin
Fatty acids, ketoacids -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 154
Incorrect
-
Which of the following is the most potent stimulus of fibrinolysis:
Your Answer:
Correct Answer: Tissue plasminogen activator
Explanation:Fibrinolysis is a normal haemostatic response to vascular injury. Plasminogen, a proenzyme in blood and tissue fluid, is converted to plasmin by activators either from the vessel wall (intrinsic activation) or from the tissues (extrinsic activation). The most important route follows the release of tissue plasminogen activator (TPA) from endothelial cells.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 155
Incorrect
-
Low levels of which of the following arterial blood gas parameters stimulate the peripheral chemoreceptors?
Your Answer:
Correct Answer: Arterial pO 2
Explanation:Chemoreceptors are activated when the chemical composition of their immediate surroundings changes.
Peripheral chemoreceptors, together with central chemoreceptors, regulate respiratory functions. They detect changes in arterial blood oxygen levels. Decreased arterial Po2 (partial pressure of oxygen) reflexly stimulates peripheral chemoreceptors.
When peripheral chemoreceptors detect changes in arterial blood oxygen, they will trigger cardiorespiratory changes such as an increase in breathing and blood pressure. These reflexes are important for maintaining homeostasis during hypoxemia.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 156
Incorrect
-
An arterial blood gas test is performed to a 25-year-old students who presents with confusion, headache, nausea and malaise. The results show that carbon monoxide levels are significantly high. Which of the following carbon monoxide poisoning assertions is true?
Your Answer:
Correct Answer: The PO 2 of the blood in CO poisoning can be normal
Explanation:By combining with haemoglobin to form carboxyhaemoglobin, carbon monoxide (CO) disrupts the blood’s oxygen transport function. CO binds to haemoglobin with a 240-fold higher affinity than oxygen. As a result, even small amounts of CO can bind a large portion of the blood’s haemoglobin, making it unavailable for oxygen transport.
During a suspected carbon monoxide poisoning, the blood PO2 and haemoglobin concentrations will be normal, but the oxygen concentration will be drastically reduced. The oxygen dissociation curve will also shift to the left in the presence of Carboxyhaemoglobin ( haemoglobin and carbon monoxide combination), interfering with oxygen unloading.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 157
Incorrect
-
In the treatment of bradyarrhythmias with adverse characteristics or risk of asystole, what is the initial suggested dose of atropine?
Your Answer:
Correct Answer: 500 micrograms
Explanation:Atropine 500 mcg IV bolus should be administered if there are any adverse features or risk of asystole. If the reaction is not adequate, repeat the steps every 3 to 5 minutes up to a maximum dose of 3 mg. In the case of acute myocardial ischemia or myocardial infarction, atropine should be taken with caution since the increased heart rate may aggravate the ischemia or increase the size of the infarct.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
-
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Question 158
Incorrect
-
Which of the following statements about vitamin B12 absorption is TRUE:
Your Answer:
Correct Answer: On ingestion, vitamin B12 is bound to R protein which protects it from digestion in the stomach.
Explanation:The substance intrinsic factor,
essential for absorption of vitamin B12 in the ileum, is
secreted by the parietal cells along with the secretion of
hydrochloric acid. When the acid-producing parietal
cells of the stomach are destroyed, which frequently
occurs in chronic gastritis, the person develops not only
achlorhydria (lack of stomach acid secretion) but often
also pernicious anaemia because of failure of maturation
of the red blood cells in the absence of vitamin B12 stimulation of the bone marrow. -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 159
Incorrect
-
Digoxin is contraindicated in all of the following EXCEPT for:
Your Answer:
Correct Answer: Asthma
Explanation:Digoxin is contraindicated in:Supraventricular arrhythmias associated with accessory conduction pathways e.g. Wolff-Parkinson-White syndromeVentricular tachycardia or fibrillationHeart conduction problems e.g. second degree or intermittent complete heart blockHypertrophic cardiomyopathy (unless concomitant atrial fibrillation and heart failure but should be used with caution)
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
-
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Question 160
Incorrect
-
The pathophysiology of Addison's disease is as follows:
Your Answer:
Correct Answer: Adrenocortical insufficiency
Explanation:Primary adrenal insufficiency, also known as Addison’s disease, occurs when the adrenal glands cannot produce an adequate amount of hormones despite a normal or increased corticotropin (ACTH) level.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 161
Incorrect
-
Renal potassium excretion is promoted by all but which one of the following:
Your Answer:
Correct Answer: Increased intracellular magnesium
Explanation:Aldosterone: A rise in [K+] in the extracellular fluid of the adrenal cortex directly stimulates aldosterone release. Aldosterone promotes the synthesis of Na+/K+ATPases and the insertion of more Na+/K+ATPases into the basolateral membrane, and also stimulates apical sodium and potassium channel activity, overall acting to increase sodium reabsorption and potassium secretion.
pH changes: Potassium secretion is reduced in acute acidosis and increased in acute alkalosis. A higher pH increases the apical K+channel activity and the basolateral Na+/K+ATPase activity – both changes that promote K+secretion.
Flow rates: Increased flow rates in the collecting duct reduce K+concentration in the lumen and therefore enhance K+secretion. Increased flow also activates BK potassium channels, and ENaC channels which promote potassium secretion and sodium reabsorption respectively.
Sodium delivery: Decreased Na+delivery to the collecting ducts results in less Na+reabsorption and hence a reduced gradient for K+secretion.
Magnesium: Intracellular magnesium can bind and block K+channels inhibiting K+secretion into the tubules. Therefore magnesium deficiency reduces this inhibitory effect and so allows more potassium to be secreted into tubules and can cause hypokalaemia. -
This question is part of the following fields:
- Physiology
- Renal
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Question 162
Incorrect
-
The functional residual capacity (FRC) will be decreased in which of the following:
Your Answer:
Correct Answer: Pulmonary fibrosis
Explanation:Factors decreasing FRC:
Restrictive ventilatory defects e.g. pulmonary fibrosis
Posture – lying supine
Increased intra-abdominal pressure (e.g. obesity, pregnancy, ascites)
Reduced muscle tone of diaphragm e.g. muscle relaxants in anaesthesia, neuromuscular disease -
This question is part of the following fields:
- Physiology
- Respiratory
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Question 163
Incorrect
-
Which of the following drug classes may cause bronchoconstriction:
Your Answer:
Correct Answer: Beta-blockers
Explanation:Beta-blockers, including those considered to be cardioselective, should usually be avoided in patients with a history of asthma, bronchospasm or a history of obstructive airways disease. However, when there is no alternative, a cardioselective beta-blocker can be given to these patients with caution and under specialist supervision. In such cases the risk of inducing bronchospasm should be appreciated and appropriate precautions taken.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 164
Incorrect
-
An infection causes an Addisonian crisis in a male patient with a known history of Addison's disease.
Which of the following is NOT a well-known symptom of an Addisonian crisis?
Your Answer:
Correct Answer: Hyperglycaemia
Explanation:Although Addisonian crisis is a rare illness, it can be fatal if it is misdiagnosed. Hypoglycaemia and shock are the most common symptoms of an Addisonian crisis (tachycardia, peripheral vasoconstriction, hypotension, altered conscious level, and coma).
Other clinical characteristics that may be present are:
Fever
Psychosis
Leg and abdominal pain
Dehydration and vomiting
Convulsions -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 165
Incorrect
-
Which of the following is NOT a common side effect of amiodarone:
Your Answer:
Correct Answer: Blue/green teeth discolouration
Explanation:Common side effects of amiodarone include: Bradycardia, Nausea and vomiting, Thyroid disorders – hypothyroidism and hyperthyroidism, Persistent slate grey skin discoloration, Photosensitivity, Pulmonary toxicity (including pneumonitis and fibrosis), Hepatotoxicity, Corneal microdeposits (sometimes with night glare), Peripheral neuropathy and Sleep disorders.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 166
Incorrect
-
You examine a patient's blood tests and discover that her electrolyte levels are abnormal.
Which of the following is the major extracellular cation?Your Answer:
Correct Answer: Sodium
Explanation:Electrolytes are compounds that may conduct an electrical current and dissociate in solution. Extracellular and intracellular fluids contain these chemicals. The predominant cation in extracellular fluid is sodium, whereas the major anion is chloride. Potassium is the most abundant cation in the intracellular fluid, while phosphate is the most abundant anion. These electrolytes are necessary for homeostasis to be maintained.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 167
Incorrect
-
Question 168
Incorrect
-
Many of the chemical digestion and absorption takes place in the small intestine. Most digestive enzymes in the small intestine are secreted by the pancreas and enter the small intestine through the pancreatic duct.
Which of these digestive enzymes is responsible for breaking down carbohydrates into monosaccharides?Your Answer:
Correct Answer: Glucoamylase
Explanation:Majority of carbohydrates are broken down into monosaccharides (glucose, fructose galactose) and are absorbed by the small intestine. Enzymes released from the brush border break down carbohydrate. Some carbohydrates, such as cellulose, are not digested at all, despite being made of multiple glucose units. This is because the cellulose is made out of beta-glucose that makes the inter-monosaccharide bindings different from the ones present in starch, which consists of alpha-glucose. Humans lack the enzyme for splitting the beta-glucose-bond.
The principal brush border enzymes are dextranase and glucoamylase. Other brush border enzymes are maltase, sucrase, and lactase.
Pancreatic amylase breaks down some carbohydrates (notably starch) into oligosaccharides. Dextranase and glucoamylase, then further break down oligosaccharides.
Trypsin aids in digestion of protein.
Chymotrypsin is a proteolytic enzyme that digests protein
Carboxypeptidase hydrolyses the first peptide or amide bond at the carboxyl or C-terminal end of proteins and peptides
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 169
Incorrect
-
A 71-year-old woman presents with complaints of fatigue and worsening muscle weakness, and blood tests done shows a potassium level of 2.4 mmol/L.
Which is NOT a recognised cause of hypokalaemia?
Your Answer:
Correct Answer: Type 4 renal tubular acidosis
Explanation:A plasma potassium less than 3.5 mmol/L defines hypokalaemia.
Excessive liquorice ingestion causes hypermineralocorticoidism and leads to hypokalaemia.
Gitelman’s syndrome causes metabolic alkalosis with hypokalaemia and hypomagnesaemia. It is an inherited defect of the distal convoluted tubules.
Bartter’s syndrome causes hypokalaemic alkalosis. It is a rare inherited defect in the ascending limb of the loop of Henle.
Type 1 and 2 renal tubular acidosis both cause hypokalaemia
Type 4 renal tubular acidosis causes hyperkalaemia.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 170
Incorrect
-
Question 171
Incorrect
-
In ventricular myocytes, the plateau phase of the action potential comes about through which of the following:
Your Answer:
Correct Answer: Opening of voltage-gated Ca 2+ channels
Explanation:After the intial upstroke of the action potential, Na+channels and currents rapidly inactivate, but in cardiac myocytes, the initial depolarisation activates voltage-gated Ca2+channels (slow L-type channels, threshold approximately – 45 mV) through which Ca2+floods into the cell. The resulting influx of Ca2+prevents the cell from repolarising and causes a plateau phase, that is maintained for about 250 ms until the L-type channels inactivate. The cardiac AP is thus much longer than that in nerve or skeletal muscle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 172
Incorrect
-
What is nimodipine used predominantly in the treatment of?
Your Answer:
Correct Answer: Prevention and treatment of vascular spasm following subarachnoid haemorrhage
Explanation:Nimodipine is a smooth muscle relaxant that is related to nifedipine, but the effects preferentially act on cerebral arteries. It is exclusively used for the prevention and treatment of vascular spasm after an aneurysmal subarachnoid haemorrhage.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 173
Incorrect
-
The hypothalamus produces antidiuretic hormone (ADH), also known as vasopressin, which is a peptide hormone. It is important for maintaining water and electrolyte balance, as well helping control arterial pressure.
To have an effect on blood arteries, ADH binds to which of the following receptors?Your Answer:
Correct Answer: V 1 receptor
Explanation:ADH, or antidiuretic hormone, is a hormone that regulates water and electrolyte balance. It is released in response to a variety of events, the most important of which are higher plasma osmolality or lower blood pressure. ADH increases plasma volume and blood pressure via acting on the kidneys and peripheral vasculature.
It causes vasoconstriction by binding to peripheral V1 Receptors on vascular smooth muscle via the IP3 signal transduction and Rho-kinase pathways. The systemic vascular resistance and arterial pressure rise as a result. High levels of ADH appear to be required for this to have a major impact on arterial pressure, such as in hypovolaemic shock.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 174
Incorrect
-
Lidocaine's antiarrhythmic mode of action is as follows:
Your Answer:
Correct Answer: Blocks inactivated Na+ channels
Explanation:Lidocaine is a class 1B antidysrhythmic; combines with fast Na channels and thereby inhibits recovery after repolarization, resulting in decreasing myocardial excitability and conduction velocity. However, in ischaemic areas, where anoxia causes depolarisation and arrhythmogenic activity, many Na+ channels are inactivated and therefore susceptible to lidocaine.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
-
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Question 175
Incorrect
-
Question 176
Incorrect
-
All of the following are indications for beta-blockers EXCEPT for:
Your Answer:
Correct Answer: Prinzmetal's angina
Explanation:Beta-blockers are contraindicated in Prinzmetal’s angina.Beta-blockers may be indicated in:HypertensionPheochromocytoma (only with an alpha-blocker)AnginaSecondary prevention after ACSArrhythmias including atrial fibrillationHeart failureThyrotoxicosisAnxietyProphylaxis of migraineEssential tremorGlaucoma
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
-
-
Question 177
Incorrect
-
Which of the following does not increase renal phosphate excretion?
Your Answer:
Correct Answer: Vitamin D
Explanation:PO43-renal excretion is regulated several mechanisms. These include:
-parathyroid hormone – increases excretion by inhibiting reabsorption in the proximal tubule
-acidosis – increases excretion
-glucocorticoids – increases excretion
-calcitonin – increases excretion
-activated vitamin D – decreases excretion by increasing reabsorption in the distal tubule -
This question is part of the following fields:
- Physiology
- Renal
-
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Question 178
Incorrect
-
What is the effect of a positive inotrope on the Starling curve:
Your Answer:
Correct Answer: Shifts the curve upwards
Explanation:Contractility (inotropy) is the intrinsic ability of cardiac muscle to develop force at a given muscle length. It is determined by the intracellular [Ca2+] and can be estimated by the ejection fraction. Increases in contractility cause an increase in stroke volume/cardiac output for any level of right atrial pressure or end-diastolic volume, and hence shift the Starling curve upwards. Decreases in contractility cause a decrease in stroke volume/cardiac output for any level of right atrial pressure or end-diastolic volume and hence shift the Starling curve downwards.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 179
Incorrect
-
Which of the following acts to inhibit antidiuretic hormone (ADH) release from the posterior pituitary:
Your Answer:
Correct Answer: Atrial natriuretic peptide
Explanation:ADH release is inhibited by low plasma osmolality, alcohol, caffeine, glucocorticoids and atrial natriuretic peptide (ANP).
ADH release is stimulated primarily by raised plasma osmolality detected by osmoreceptors in the anterior hypothalamus. Other factors that increase ADH release include: extracellular fluid volume depletion, angiotensin II, nausea, pain, stress, exercise, emotion, hypoglycaemia.
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This question is part of the following fields:
- Endocrine
- Physiology
-
-
Question 180
Incorrect
-
Insulin is produced by which of the following pancreatic cells:
Your Answer:
Correct Answer: β cells
Explanation:Insulin is produced by beta cells, located centrally within the islets of Langerhans, in the endocrine tissues of the pancreas. Insulin is a polypeptide hormone consisting of two short chains (A and B) linked by disulphide bonds. Proinsulin is synthesised as a single-chain peptide. Within storage granules, a connecting peptide (C peptide) is removed by proteases to yield insulin. Insulin release is stimulated initially during eating by the parasympathetic nervous system and gut hormones such as secretin, but most output is driven by the rise in plasma glucose concentration that occurs after a meal. The effects of insulin are mediated by the receptor tyrosine kinase.
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This question is part of the following fields:
- Endocrine
- Physiology
-
-
Question 181
Incorrect
-
Adenosine is primarily indicated for which of the following:
Your Answer:
Correct Answer: Paroxysmal supraventricular tachycardia
Explanation:Adenosine is usually the treatment of choice for terminating paroxysmal supraventricular tachycardia including those associated with accessory conduction pathways e.g. Wolff-Parkinson-White syndrome.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
-
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Question 182
Incorrect
-
Regarding chemical control of respiration, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: The blood-brain barrier is freely permeable to HCO3 - ions.
Explanation:CSF is separated from the blood by the blood-brain barrier. This barrier is impermeable to polar molecules such as H+and HCO3-but CO2can diffuse across it easily. The pH of CSF is therefore determined by the arterial PCO2and the CSF HCO3-and is not affected by blood pH.
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This question is part of the following fields:
- Physiology
- Respiratory
-
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Question 183
Incorrect
-
Which of the following is NOT one of insulin's actions:
Your Answer:
Correct Answer: Increased gluconeogenesis
Explanation:Insulin has a number of effects on glucose metabolism, including:
Inhibition of glycogenolysis and gluconeogenesis
Increased glucose transport into fat and muscle
Increased glycolysis in fat and muscle
Stimulation of glycogen synthesis
By inhibiting gluconeogenesis, insulin maintains the availability of amino acids as substrates for protein synthesis. Thus, insulin supports protein synthesis through direct and indirect mechanisms. -
This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 184
Incorrect
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A 42-year-old male patient, presenting with polyuria and polydipsia symptoms had normal blood test results. Upon interview, he had mentioned being in a car accident in which he had a head injury. His polyuria and polydipsia symptoms are most likely associated with which of the following conditions?
Your Answer:
Correct Answer: Cranial diabetes insipidus
Explanation:Polydipsia is the feeling of extreme thirstiness. It is often linked to polyuria, which is a urinary condition that causes a person to urinate excessively. The cycle of these two processes makes the body feel a constant need to replace the fluids lost in urination. In healthy adults, a 3 liter urinary output per day is considered normal. A person with polyuria can urinate up to 15 liters of urine per day. Both of these conditions are classic signs of diabetes.
The other options are also types of diabetes, except for psychogenic polydipsia (PPD), which is the excessive volitional water intake seen in patients with severe mental illness or developmental disability. However, given the patient’s previous head injury, the most likely diagnosis is cranial diabetes insipidus.
By definition, cranial diabetes insipidus is caused by damage to the hypothalamus or pituitary gland after an infection, operation, brain tumor, or head injury. And the patient’s history confirms this diagnosis. To define the other choices, nephrogenic diabetes insipidus happens when the structures in the kidneys are damaged and results in an inability to properly respond to antidiuretic hormone.
Kidney damage can be caused by an inherited (genetic) disorder or a chronic kidney disorder. As with cranial diabetes insipidus, nephrogenic diabetes insipidus can also cause an elevated urine output.
Diabetes mellitus is classified into two types, and the main difference between them is that type 1 diabetes is a genetic disorder, and type 2 diabetes is diet-related and develops over time. Type 1 diabetes is also known as insulin-dependent diabetes, in which the pancreas produces little or no insulin. Type 2 diabetes is termed insulin resistance, as cells don’t respond customarily to insulin.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 185
Incorrect
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Regarding water and electrolyte absorption in the small intestine, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Na+ enters the cell across the apical membrane against its concentration gradient by both membrane channels and transporter protein mechanisms.
Explanation:As the contents of the intestine are isotonic with body fluids and mostly have the same concentration of the major electrolytes, their absorption is active. Water cannot be moved directly, but follows osmotic gradients set up by the transport of ions, primarily mediated by the sodium pump.Na+/K+ ATPase located on the basolateral membrane of the epithelial cells pumps three Na+ ions from the cell in exchange for two K+ ions, against their respective concentration gradients. This leads to a low intracellular concentration of Na+ and a high intracellular concentration of K+. The low intracellular concentration of Na+ ensures a movement of Na+ from the intestinal contents into the cell down its concentration gradient by both membrane channels and transporter protein mechanisms. Na+ is then rapidly pumped again by the basolateral sodium pump. K+ leaves the cell across the basolateral membrane down its concentration gradient linked to an outward movement of Cl- against its concentration gradient (Cl- having entered the cell across the luminal membrane down its concentration gradient).
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 186
Incorrect
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A 60 -year-old man is tested to have low calcium levels . After additional questioning, it becomes clear that he has a calcium-deficient diet.
What is the daily calcium intake recommendation for a healthy adult?Your Answer:
Correct Answer: 1300 mg
Explanation:A daily calcium intake of 1,000 to 1,300 mg is advised for adults. Women have a slightly higher calcium need than men and are at a higher risk of developing osteoporosis as they age.
Calcium-rich foods include the following:
Milk, cheese, and butter as dairy products.
Broccoli, spinach, and green beans as green veggies.
Bread, rice, and cereals as whole grain foods.
Sardines, salmon, and other bony fish
Eggs
Nuts
The following foods have the least calcium:
Carrot
Fruits such as kiwis, raspberries, oranges, and papaya
Chicken and pork in meats. -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 187
Incorrect
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An elderly patient presents to ED following a fall after feeling light headed when standing up. You are reviewing his medication and note that he is taking a high dose of furosemide. Loop diuretics act primarily at which of the following sites in the nephron:
Your Answer:
Correct Answer: Thick ascending limb
Explanation:Loop diuretics inhibit the Na+/K+/2Cl- symporter on the luminal membrane in the thick ascending limb of the loop of Henle, thus preventing reabsorption of NaCl and water. These agents reduce reabsorption of Cl- and Na+ and increase Ca2+ excretion and loss of K+ and Mg2+.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 188
Incorrect
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Regarding antacids, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Antacids are contraindicated in hypophosphataemia.
Explanation:Antacids are contraindicated in hypophosphataemia. Liquid preparations are more effective than tablet preparations. Magnesium-containing antacids tend to be laxative whereas aluminium-containing antacids tend to be constipating. Antacids are best taken when symptoms occur or are expected, usually between meals and at bedtime. Antacids should preferably not be taken at the same time as other drugs since they may impair absorption.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 189
Incorrect
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Which of the following is NOT a benefit of low molecular weight heparin (LMWH) over unfractionated heparin therapy:
Your Answer:
Correct Answer: Its effects can be rapidly and completely reversed with protamine sulfate.
Explanation:Advantages of LMWHGreater ability to inhibit factor Xa directly, interacting less with platelets and so may have a lesser tendency to cause bleedingGreater bioavailability and longer half-life in plasma making once daily subcutaneous administration possibleMore predictable dose response avoiding the need for routine anticoagulant monitoringLower associated risk of heparin-induced thrombocytopenia or of osteoporosis
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 190
Incorrect
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A 29 year old patient with known inflammatory bowel disease presents to ED with surgical complications following his recent ileocaecal resection. Removal of the terminal ileum may result in the malabsorption of which of the following:
Your Answer:
Correct Answer: Vitamin B12
Explanation:On ingestion, vitamin B12 is bound to R protein found in saliva and gastric secretions, which protects it from digestion in the stomach. Intrinsic factor is secreted by gastric parietal cells. Receptors for the IF-B12 complex are present in the membrane of epithelial cells of the terminal ileum, which bind the complex and allow uptake of vitamin B12 across the apical membrane by endocytosis. Vitamin B12 is then transported across the basal membrane into the portal blood where it is bound to transcobalamin II and processed by the liver. In pernicious anaemia, there are autoantibodies against gastric parietal cells and intrinsic factor, resulting in vitamin B12 deficiency anaemia.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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