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Question 1
Correct
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A possible diagnosis of Cushing's illness is being investigated in an overweight patient with resistant hypertension. A CRH (corticotropin-releasing hormone) test is scheduled.
Which of the following statements about corticotropin-releasing hormone is correct?Your Answer: It is produced by cells within the paraventricular nucleus of the hypothalamus
Explanation:Corticotropin-releasing hormone (CRH) is a neurotransmitter and peptide hormone. It is generated by cells in the hypothalamic paraventricular nucleus (PVN) and released into the hypothalamo-hypophyseal portal system at the median eminence through neurosecretory terminals of these neurons. Stress causes the release of CRH.
The CRH is carried to the anterior pituitary through the hypothalamo-hypophyseal portal system, where it activates corticotrophs to release adrenocorticotropic hormone (ACTH). Cortisol, glucocorticoids, mineralocorticoids, and DHEA are all produced in response to ACTH.
Excessive CRH production causes the size and quantity of corticotrophs in the anterior pituitary to expand, which can lead to the creation of a corticotrope tumour that generates too much ACTH.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 2
Incorrect
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Regarding the phases of gastric secretion, which of the following statements is INCORRECT:
Your Answer: Most acid secretion occurs in the gastric phase.
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 3
Correct
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Adenosine has a half-life of approximately:
Your 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 4
Incorrect
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A patient presents to ED with heartburn for which they already take regular antacids. Which of the following drugs can be affected if taken with antacids:
Your Answer: Dabigatran
Correct Answer: Digoxin
Explanation:Antacids should preferably not be taken at the same time as other drugs since they may affect absorption. When antacids are taken with acidic drugs (e.g. digoxin, phenytoin, chlorpromazine, isoniazid) they cause the absorption of the acidic drugs to be decreased, which causes low blood concentrations of the drugs, which ultimately results in reduced effects of the drugs. Antacids taken with drugs such as pseudoephedrine and levodopa increase absorption of the drugs and can cause toxicity/adverse events due to increased blood levels of the drugs. Antacids that contain magnesium trisilicate and magnesium hydroxide when taken with some other medications (such as tetracycline) will bind to the drugs, and reduce their absorption and effects.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 5
Incorrect
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Gastrin release from antral G-cells is inhibited by all but which one of the following:
Your Answer: Low gastric pH
Correct Answer: Vagal stimulation
Explanation:Gastrin secretion is inhibited by:
Low gastric pH (negative feedback mechanism)
Somatostatin
Secretin
Gastric inhibitory polypeptide (GIP)
Cholecystokinin -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 6
Incorrect
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Which of the following globin chains makes up normal adult haemoglobin (HbA)?
Your Answer: Two alpha chains and two delta chains
Correct Answer: Two alpha and two beta chains
Explanation:Total adult haemoglobin comprises about 96 – 98 % of normal adult haemoglobin (HbA). It consists of two alpha (α) and two beta (β) globin chains.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 7
Correct
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Regarding the resting membrane potential, which of the following statements is CORRECT:
Your Answer: The resting cell membrane is more permeable to K + ions than to Na + ions.
Explanation:A membrane potential is a property of all cell membranes, but the ability to generate an action potential is only a property of excitable tissues. The resting membrane is more permeable to K+and Cl-than to other ions (and relatively impermeable to Na+); therefore the resting membrane potential is primarily determined by the K+equilibrium potential. At rest the inside of the cell is negative relative to the outside. In most neurones the resting potential has a value of approximately -70 mV.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 8
Correct
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Mannitol is primarily indicated for which of the following:
Your Answer: Cerebral oedema
Explanation:Mannitol is an osmotic diuretic that can be used to treat cerebral oedema and raised intraocular pressure. Mannitol is a low molecular weight compound and is, therefore, freely filtered at the glomerulus and is not reabsorbed. It, therefore, increases the osmolality of the glomerular filtrate and tubular fluid, increasing urinary volume by an osmotic effect. It also does not cross the blood-brain-barrier (BBB).
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 9
Incorrect
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Which of these increases osteoclast activity?
Your Answer: Calcitonin
Correct Answer: Parathyroid hormone
Explanation:Osteoclasts are bone cell that break down bone tissue.
Parathyroid hormone increases osteoclastic activity.
1,25-dihydroxycholecalciferol increases osteoclastic activity
Calcitonin inhibits osteoclastic activity
Bisphosphonates are osteoclast inhibitors.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 10
Incorrect
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Which of the following is not true regarding the structure and function of glomerular filtration membrane?
Your Answer: Fenestrated capillaries give greater permeability
Correct Answer: The absence of a basement membrane reduces impedance to filtration
Explanation:The glomerular filtration membrane is composed of fenestrated capillary endothelium, basement membrane, and filtration slits. It is an organized, semipermeable membrane preventing the passage of most of the proteins into the urine.
The anatomical arrangement of the glomerular filtration membrane maximizes the surface area available for filtration. The arrangement of its arterioles results in high hydrostatic pressures and facilitates filtration.
Fenestrated capillary endothelium of the glomerular filtration membrane is with relatively large pores. It allows the free movement of plasma proteins and solutes but still restricts the movement of blood cells.
Filtration slits are the smallest filters and restrict the movement of plasma proteins but still allow free movement of ions and nutrients.
The glomerular basement membrane (GBM) is a critical component of the glomerular filtration membrane. Thus, it is not true that its absence will reduce the resistance of flow. The basement membrane is true to be more selective and contains negatively charged glycoproteins. However, it still allows free passage of water, nutrients, and ions. Severe structural abnormalities of the GBM can result in protein (albumin) leakage.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 11
Correct
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The renin-angiotensin-aldosterone system (RAAS) controls blood pressure and fluid balance.
Which of the following sites produces the most angiotensinogen?Your Answer: The liver
Explanation:Angiotensinogen is an alpha-2-globulin generated predominantly by the liver and released into the blood. Renin, which cleaves the peptide link between the leucine and valine residues on angiotensinogen, converts it to angiotensin I.
Angiotensinogen levels in the blood are raised by:
Corticosteroid levels have risen.
Thyroid hormone levels have risen.
Oestrogen levels have risen.
Angiotensin II levels have risen. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 12
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: Glomerular filtration is an active process
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 13
Incorrect
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Which of the following is NOT a typical electrolyte disturbance caused by furosemide:
Your Answer: Hypomagnesaemia
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 14
Correct
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A patient is sent in to ED by her GP with hyponatraemia and hyperkalaemia. There is most likely to be a deficiency in which of the following hormones:
Your Answer: Aldosterone
Explanation:A deficiency of aldosterone, as seen in adrenal insufficiency, can result in hyponatraemia and hyperkalaemia.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 15
Incorrect
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Which of the following is NOT a typical clinical feature of diabetic ketoacidosis:
Your Answer: Hypotension
Correct Answer: Cheyne–Stokes respiration
Explanation:Clinical features of DKA:
Symptoms: Polyuria, polydipsia, thirst, lethargy, weight loss, nausea, vomiting, anorexia, abdominal pain, dehydration, headache, altered mental state
Signs: Dry mucous membranes, ketotic breath, tachycardia, hypotension, Kussmaul breathing, focal signs of precipitant e.g. infection -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 16
Correct
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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: 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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Question 17
Incorrect
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By which of the following is mean arterial pressure (MAP) primarily determined?
Your Answer: Stroke volume and heart rate
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 18
Correct
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Regarding the partial pressure of gases, which of the following statements is INCORRECT:
Your 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 19
Incorrect
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Arterial baroreceptors are located primarily in which of the following:
Your Answer: Carotid sinus and right atrium
Correct Answer: Carotid sinus and aortic arch
Explanation:Arterial baroreceptors are located in the carotid sinus and aortic arch, and detect the mean arterial pressure (MAP). A decrease in MAP (such as in postural hypotension, or haemorrhage) reduces arterial stretch and decreases baroreceptor activity, resulting in decreased firing in afferent nerves travelling via the glossopharyngeal nerve (carotid sinus) and vagus nerve (aortic arch) to the medulla where the activity of the autonomic nervous system is coordinated. Sympathetic nerve activity consequently increases, causing an increase in heart rate and cardiac contractility, peripheral vasoconstriction with an increase in TPR, and venoconstriction with an increase in CVP and thus an increase in cardiac output and blood pressure. Parasympathetic activity (vagal tone) decreases, contributing to the rise in heart rate.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 20
Incorrect
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What is the pathophysiology of a phaeochromocytoma:
Your Answer: ACTH-secreting tumour
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 21
Incorrect
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Antidiuretic hormone (ADH) levels are found to be increased in a young lady with unexplained hyponatraemia.
In a healthy patient under normal circumstances, in which of the following conditions would ADH not be released?Your Answer: Hypotension
Correct Answer: Increased alcohol intake
Explanation:Antidiuretic hormone (ADH) is produced in the hypothalamus’s supraoptic nucleus and then released into the blood via axonal projections from the hypothalamus to the posterior pituitary.
It is carried down axonal extensions from the hypothalamus (the neurohypophysial capillaries) to the posterior pituitary, where it is kept until it is released, after being synthesized in the hypothalamus.
The secretion of ADH from the posterior pituitary is regulated by numerous mechanisms:
Increased plasma osmolality: Osmoreceptors in the hypothalamus detect an increase in osmolality and trigger ADH release.Hypovolaemia causes a drop in atrial pressure, which stretch receptors in the atrial walls and big veins detect (cardiopulmonary baroreceptors). ADH release is generally inhibited by atrial receptor firing, but when the atrial receptors are stretched, the firing reduces and ADH release is promoted.
Hypotension causes baroreceptor firing to diminish, resulting in increased sympathetic activity and ADH release.
An increase in angiotensin II stimulates angiotensin II receptors in the hypothalamus, causing ADH production to increase.Nicotine, Sleep, Fright, and Exercise are some of the other elements that might cause ADH to be released.
Alcohol (which partly explains the diuretic impact of alcohol) and elevated levels of ANP/BNP limit ADH release. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 22
Incorrect
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A 58-year-old woman presents with symptoms of increase in weight, proximal muscular weakening and withering, easy bruising, and acne. You notice that she has a full, plethoric aspect to her face, as well as significant supraclavicular fat pads, when you examine her. She has previously been diagnosed with Cushing's syndrome.
Which of the following biochemical profiles best supports this diagnosis?Your Answer: Hyperkalaemic metabolic acidosis
Correct Answer: Hypokalaemic metabolic alkalosis
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.
A typical biochemical profile can help establish a 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 23
Correct
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Which of the following statements regarding the pituitary gland is CORRECT:
Your Answer: Cortisol inhibits release of adrenocorticotropic hormone (ACTH) from the anterior pituitary.
Explanation:Anterior pituitary hormones are released under the control of hypothalamic releasing or inhibiting hormones originating from small neurons with their cell bodies in the hypothalamus and released into the blood at the median eminence. These hypothalamic hormones are transported directly to the anterior pituitary via hypophyseal portal vessels. The anterior pituitary hormones (and the hormones released by their target organs) inhibit further release of hypothalamic and anterior pituitary hormones by negative feedback mechanisms e.g. cortisol inhibits the release of ACTH. Prolactin release from the anterior pituitary is inhibited by dopamine.The posterior pituitary is really a direct extension of the hypothalamus. Oxytocin and ADH are manufactured in the cell bodies of large neurons in the hypothalamus and are transported down the axons of these cells to their terminals on capillaries originating from the inferior hypophyseal artery within the posterior pituitary gland. ADH release is controlled by negative feedback mechanisms based on plasma osmolality and blood volume, oxytocin however is involved in positive feedback mechanisms.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 24
Correct
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A 57-year-old woman receives vitamin B12 injections following a gastrectomy.
Which of the following cell types, if absent, is responsible for her vitamin B12 deficiency?Your Answer: Parietal cells
Explanation:Intrinsic factor, produced by the parietal cells of the stomach, is essential for the absorption of vitamin B12 from the terminal ileum.
After a gastrectomy, the absorption of vitamin B12 is markedly reduced, and a deficiency will occur. -
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 25
Incorrect
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Parasympathetic preganglionic neurons originate in which of the following locations:
Your Answer: Thalamus
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 26
Correct
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Regarding skeletal muscle contraction, which of the following statements is CORRECT:
Your 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 27
Correct
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Which of the following hormones is dysfunctional in diabetes insipidus:
Your Answer: Antidiuretic hormone
Explanation:Diabetes insipidus (DI) may result from a deficiency of ADH secretion (cranial DI) or from an inappropriate renal response to ADH (nephrogenic DI). As a result, fluid reabsorption at the kidneys is impaired, resulting in large amounts of hypotonic, dilute urine being passed with a profound unquenchable polydipsia.
The biochemical hallmarks of DI are:
High plasma osmolality (> 295 mOsm/kg)
Low urine osmolality (< 300 mOsm/kg)
Hypernatraemia (> 145 mmol/L)
High urine volume -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 28
Incorrect
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Water is reabsorbed in which portion of the Henle loop:
Your Answer: All of it
Correct Answer: Thin descending limb
Explanation:The loop of Henle consists of three functionally distinct segments: the thin descending segment, the thin ascending segment, and the thick ascending segment. About 20 percent of the filtered water is reabsorbed in the loop of Henle and almost all of this occurs in the thin descending limb. Na+ and Cl-ions are actively reabsorbed from the tubular fluid in the thick ascending limb via the Na+/K+/2Cl-symporter on the apical membrane. Because the thick ascending limb is water-impermeable, ion reabsorption lowers tubular fluid osmolality while raising interstitial fluid osmolality, resulting in an osmotic difference. Water moves passively out of the thin descending limb as the interstitial fluid osmolality rises, concentrating the tubular fluid. This concentrated fluid descends in the opposite direction of fluid returning from the deep medulla still higher osmolality areas.
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This question is part of the following fields:
- Physiology
- Renal
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Question 29
Incorrect
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During anaerobic respiration, what is the net generation of ATP molecules:
Your Answer: 8
Correct Answer: 2
Explanation:In anaerobic respiration, two ATP molecules are produced for every glucose molecule, as opposed to the 38 molecules of ATP produced in aerobic respiration.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 30
Correct
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A 30-year-old woman with type 1 diabetes mellitus is brought in drowsy and confused. Her BM is 2.2 mmol/l and a dose of IM glucagon is administered.
What is the principal stimulus for the secretion of glucagon?Your Answer: Hypoglycaemia
Explanation:Glucagon, a peptide hormone, is produced and secreted by alpha cells of the islets of Langerhans, located in the endocrine portion of the pancreas.
Its main physiological role is stimulation of hepatic glucose output leading to increase in blood glucose. It is the major counter-regulatory hormone to insulin in maintaining glucose homeostasis.
The principal stimulus for the secretion of glucagon is hypoglycaemia. Hypoglycaemia then stimulates:
Glycogenolysis
Gluconeogenesis
Lipolysis in adipose tissue leading to increased glycaemia.Secretion of glucagon is also stimulated by arginine, alanine, adrenaline, acetylcholine and cholecystokinin
Secretion of glucagon is inhibited by:
Insulin
Somatostatin
Increased free fatty acids
Increased urea production -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
