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Question 1
Correct
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Pre-oxygenation is done prior to intubation to extend the ‘safe apnoea time’.
Which lung volume or capacity is the most important store of oxygen in the body?
Your Answer: Functional residual capacity
Explanation:The administration of oxygen to a patient before intubation is called pre-oxygenation and it helps extend the ‘safe apnoea time’.
The Functional residual capacity (FRC) is the volume of gas that remains in the lungs after normal tidal expiration. It is the most important store of oxygen in the body. The aim of pre-oxygenation is to replace the nitrogen in the FRC with oxygen.
Apnoea can be tolerated for longer periods before critical hypoxia develops if the FRC is large. Patients with reduced FRC reach critical hypoxia more rapidly.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 2
Incorrect
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Which of the following is NOT a common side effect of adenosine:
Your Answer: Flushing
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 3
Correct
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A pheochromocytoma is diagnosed in a 38-year-old female who has had episodes of acute sweating, palpitations, and paroxysmal hypertension.
Which of the following is the MOST SUITABLE INITIAL TREATMENT?Your Answer: Alpha-blocker
Explanation:A phaeochromocytoma is a rare functional tumour that develops in the adrenal medulla from chromaffin cells. Extra-adrenal paragangliomas (extra-adrenal pheochromocytomas) are tumours that arise in the sympathetic nervous system’s ganglia and are closely connected to extra-adrenal paragangliomas (extra-adrenal pheochromocytomas). Catecholamines are secreted by these tumours, which generate a variety of symptoms and indications associated with sympathetic nervous system hyperactivity.
Hypertension is the most prevalent presenting symptom, which can be continuous or intermittent.Symptoms are usually intermittent, occurring anywhere from many times a day to occasionally. The symptoms of the condition tend to grow more severe and frequent as the disease progresses.
The ultimate therapy of choice is surgical resection, and if full resection is done without metastases, hypertension is typically cured.Preoperative medical treatment is critical because it lowers the risk of hypertensive crises during surgery. This is commonly accomplished by combining non-competitive alpha-blockers (such as phenoxybenzamine) with beta-blockers. To allow for blood volume expansion, alpha-blockade should be started at least 7-10 days before surgery. Beta-blockade, which helps to regulate tachycardia and some arrhythmias, can be started after this is accomplished. Hypertensive crises can be triggered if beta-blockade is started too soon.
There should also be genetic counselling, as well as a search for and management of any linked illnesses. -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 4
Correct
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The following all cause a left shift in the oxygen dissociation curve EXCEPT for:
Your 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 5
Correct
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A 68-year-old man is being treated with digoxin for atrial fibrillation. When serum digoxin levels are above the therapeutic range, he is at highest risk for developing digoxin toxicity if he also develops which of the following?
Your Answer: Hypokalaemia
Explanation:Predisposing factors for digoxin toxicity include hypoxia, hypercalcaemia, hypokalaemia and hypomagnesaemia There should also be care taken in the elderly who are particularly susceptible to digoxin toxicity. Hypokalaemia may be precipitated by use of diuretics. Hyponatremia can result in the development of other pathological disturbances, but it does not make digoxin toxicity worse.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 6
Correct
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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: 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 7
Correct
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Which of the following statements is not true regarding ion channels?
Your Answer: Ion channels provide a charged, hydrophobic pore through which ions can diffuse across the lipid bilayer.
Explanation:Ion channels are pore-forming protein complexes that facilitate the flow of ions across the hydrophobic core of cell membranes. They are present in the plasma membrane and membranes of intracellular organelles of all cells, and perform essential physiological functions. They provide a charged, hydrophilic pore through which ions can move across the lipid bilayer. They are selective for particular ions and their pores may be opened or closed. Because of this ability to open and close, ion channels allow the cell to have the ability to closely control the movement of ions across the membrane. Gating refers to the transition between an open and closed ion channel state, and is brought about by a conformationational change in the protein subunits that open or close the ion-permeable pore.
Ion channels can be:
1. voltage-gated these are regulated according to the potential difference across the cell membrane or
2. ligand-gated – these are regulated by the presence of a specific signal molecule. -
This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 8
Correct
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The following all cause a right shift in the oxygen dissociation curve EXCEPT for:
Your Answer: Foetal haemoglobin
Explanation:A decreased affinity of haemoglobin for oxygen (and hence increased ease of dissociation), shown by a right shift in the oxygen dissociation curve, is caused by a fall in pH, a rise in PCO2(the Bohr effect) and an increase in temperature. These changes occur in metabolically active tissues such as in exercise, and encourage oxygen release. The metabolic by-product 2,3-diphosphoglycerate (2,3 -DPG) also causes a right shift; 2, 3 -DPG may also be raised in chronic anaemia, chronic lung disease, or at high altitude. Foetal haemoglobin (HbF) binds 2, 3 -DPG less strongly than does adult haemoglobin (HbA), and so the HbF dissociation curve lies to the left of that for HbA, reflecting its higher oxygen affinity. This helps transfer oxygen from mother to foetus.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 9
Correct
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Which of the following globin chains makes up normal adult haemoglobin (HbA)?
Your 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 10
Correct
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Which law describes the rate of diffusion in a solution?
Your Answer: Fick’s law
Explanation:Fick’s law describes the rate of diffusion in a solution. Fick’s law states that:
Jx = -D A (ΔC / Δx)
Where:
Jx = The amount of substance transferred per unit time
D = Diffusion coefficient of that particular substance
A = Surface area over which diffusion occurs
ΔC = Concentration difference across the membrane
Δx = Distance over which diffusion occurs
The negative sign reflects movement down the concentration gradient -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 11
Correct
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Which of the following statements is correct regarding hyponatraemia?
Your Answer: Correction of serum sodium that is too rapid can precipitate central pontine myelinolysis.
Explanation:Hyponatraemia refers to a serum sodium concentration < 135 mmol/L.
It is safer to quickly correct acute hyponatremia than chronic hyponatremia but correction should not be too fast, especially in chronic hyponatraemia, because of the risk of central pontine myelinolysis. Hyponatraemia is usually associated with a low plasma osmolality.
Under normal circumstances, if serum osmolality is low, then urine osmolality should also be low because the kidneys should be trying to retain solute.
In SIADH, excess ADH causes water retention, but not the retention of solute. Therefore, urine that is concentrated and relatively high in sodium is produced, even though the serum sodium is low (urine osmolality > 100 mosmol/kg). -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 12
Incorrect
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Intracellular [Ca2+] rise in cardiac excitation-contraction coupling is mainly as a result of:
Your Answer: Ca 2+ influx by the Ca 2+ ATPase pump
Correct Answer: Ca 2+ release from sarcoplasmic reticulum
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). APs travel down invaginations of the sarcolemma called T-tubules, which are close to, but do not touch, the terminal cisternae of the SR. During the AP plateau, Ca2+enters the cell and activates Ca2+sensitive Ca2+release channels in the sarcoplasmic reticulum allowing stored Ca2+to flood into the cytosol; this is called Ca2+-induced Ca2+release. The amount of Ca2+released is dependent on how much is stored, and on the size of the initial Ca2+influx during the AP.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 13
Incorrect
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Which of the following is NOT one of insulin's actions:
Your Answer: Increased glycogenesis
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 14
Correct
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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: 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)
РNeuromuscular disease (e.g. Guillain-Barr̩ 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 15
Correct
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The risk of renal impairment in a patient on ACE inhibitor therapy is increased by concomitant treatment with which of the following drug classes:
Your Answer: NSAIDs
Explanation:Concomitant treatment with NSAIDs increases the risk of renal damage, and with potassium-sparing diuretics (or potassium-containing salt substitutes) increases the risk of hyperkalaemia. Hyperkalaemia and other side effects of ACE inhibitors are more common in the elderly and in those with impaired renal function and the dose may need to be reduced.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 16
Correct
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Intrinsic factor is vital for gastrointestinal absorption of which of the following:
Your Answer: Vitamin B12
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 17
Correct
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What is the main mechanism of action of flecainide:
Your 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 18
Correct
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Which of the following is a primary action of aldosterone:
Your Answer: Renal sodium reabsorption
Explanation:Aldosterone acts mainly at the renal distal convoluted tubule (DCT) to cause sodium retention and potassium loss. It increases the synthesis of transport mechanisms in the distal nephron including the Na+pump, Na+/H+symporter, and Na+and K+channels in principal cells, and H+ATPase in intercalated cells. Na+(and thus water) reabsorption and K+and H+secretion are thereby enhanced.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 19
Correct
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Achlorhydria is diagnosed in a 37-year-old individual who has had recurring episodes of gastroenteritis. This is an autoimmune illness of the gastric parietal cells that causes insufficient stomach acid production.
Damage to stomach parietal cells will alter the secretion of which other substance?Your Answer: Intrinsic factor
Explanation:Achlorhydria is an autoimmune illness of the gastric parietal cells that causes insufficient stomach acid production. The parietal cells that have been injured are unable to create the necessary amount of stomach acid. As a result, the pH of the stomach rises, food digestion suffers, and the risk of gastroenteritis rises.
The secretion of hydrochloric acid and intrinsic factor is controlled by the gastric parietal cells, which are epithelial cells in the stomach. These cells can be found in the gastric glands, the fundus lining, and the stomach body.
In response to the following three stimuli, the stomach parietal cells release hydrochloric acid:
H2 Histamine receptors are stimulated by histamine (most significant contribution)
Acetylcholine stimulates M3 Receptors via parasympathetic action.
CCK2 receptors are stimulated by Gastrin.Intrinsic factor, which is essential for vitamin B12 absorption, is also produced by stomach parietal cells.
Omeprazole is a proton pump inhibitor that is both selective and irreversible. It inhibits the H+/K+-ATPase system present on the secretory membrane of gastric parietal cells, which lowers stomach acid secretion.
Ranitidine inhibits histamine H2-receptors in a competitive manner. The reversible inhibition of H2-receptors in gastric parietal cells reduces both the volume and concentration of gastric acid. -
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 20
Incorrect
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Which of the following hormones regulates Na+reabsorption in the proximal tubule:
Your Answer: Aldosterone
Correct Answer: Angiotensin II
Explanation:Angiotensin II increases Na+reabsorption from the proximal tubule (by activating Na+/H+antiporters).
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This question is part of the following fields:
- Physiology
- Renal
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Question 21
Correct
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Polyuria and polydipsia develop in a patient with a history of affective disorder, who has been on long-term lithium treatment. She has a fluid deprivation test done because she is suspected of having nephrogenic diabetic insipidus. Which of the following urine osmolality findings would be the most reliable in confirming the diagnosis?
Your Answer: After fluid deprivation <300 mosmol/kg, after IM desmopressin >800 mosmol/kg
Explanation:The inability to produce concentrated urine is a symptom of diabetes insipidus. Excessive thirst, polyuria, and polydipsia are all symptoms of this condition. There are two forms of diabetes insipidus: Nephrogenic diabetes insipidus and cranial (central) diabetes insipidus.
A lack of ADH causes cranial diabetic insipidus. Patients with cranial diabetes insipidus can have a urine output of up to 10-15 litres per 24 hours, however most patients can maintain normonatraemia with proper fluid consumption. Thirty percent of cases are idiopathic, while another thirty percent are caused by head injuries. Neurosurgery, brain tumours, meningitis, granulomatous disease (e.g. sarcoidosis), and medicines like naloxone and phenytoin are among the other reasons. There is also a very rare hereditary type that is linked to diabetes, optic atrophy, nerve deafness, and bladder atonia.
Renal resistance to the action of ADH causes nephrogenic diabetes insipidus. Urine output is significantly increased, as it is in cranial diabetes insipidus. Secondary polydipsia can keep serum sodium levels stable or raise them. Chronic renal dysfunction, metabolic diseases (e.g., hypercalcaemia and hypokalaemia), and medications, such as long-term lithium use and demeclocycline, are all causes of nephrogenic diabetes insipidus.
The best test to establish if a patient has diabetes insipidus vs another cause of polydipsia is the water deprivation test, commonly known as the fluid deprivation test. It also aids in the distinction between cranial and nephrogenic diabetes insipidus. Weight, urine volume, urine osmolality, and serum osmolality are all measured after patients are denied water for up to 8 hours. At the end of the 8-hour period, 2 micrograms of IM desmopressin is given, and measures are taken again at 16 hours.
The following are the way results are interpreted:
Urine osmolality after fluid deprivation : Urine osmolality after IM desmopressin
Cranial diabetes insipidus: <300 mosmol/kg : >800 mosmol/kg
Nephrogenic diabetes insipidus: <300 mosmol/kg : <300 mosmol/kg
Primary polydipsia: >800 mosmol/kg : >800 mosmol/kg -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 22
Correct
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Pancreatic ductal alkaline fluid secretion is mainly stimulated by which of the following hormones:
Your 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 23
Correct
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Which of the following is NOT a typical electrolyte disturbance caused by furosemide:
Your 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 24
Incorrect
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A somatostatinoma is diagnosed in a 74-year-old patient who has recently developed diabetes mellitus, recurrent episodes of gallstones, and Steatorrhoea. She also has a tumour in the head of her pancreas.
Which of the following is the most likely effect of this tumour?Your Answer: Increase growth hormone levels
Correct Answer: Inhibit gastric acid secretion
Explanation:Somatostatin-producing cells present in the pyloric antrum, duodenum, and pancreatic islets are known as D-cells or delta-cells. Somatostatin inhibits gastric acid secretion by acting directly on acid-producing parietal cells in the stomach via a G-protein coupled receptor.
Somatostatin affects hormones in the following ways:
Inhibits the anterior pituitary’s secretion of growth hormone.
Inhibits the anterior pituitary’s secretion of thyroid-stimulating hormone.The secretion of various gastrointestinal hormones is inhibited (including gastrin, CCK, secretin, motilin, VIP and GIP)
Reduces the rate at which the stomach empties.
Inhibits the release of insulin and glucagon from the pancreas.The pancreas’ exocrine secretory activity is inhibited.
Somatostatin can also slow the digestive process by suppressing the production of hormones such gastrin, secretin, and histamine, which reduces gastric acid secretion.A somatostatinoma is a cancerous tumour of the endocrine pancreas’ D-cells, which make somatostatin. Somatostatin inhibits pancreatic and gastrointestinal hormones when levels are high. The following clinical characteristics are related with somatostatinomas:
Insulin secretion blockage causes diabetes mellitus.
Gallstones by inhibition of CCK and secretin Steatorrhoea via inhibition of CCK and secretinHypochlorhydria is caused by the suppression of gastrin, a hormone that increases gastric acid output regularly.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 25
Correct
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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: 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 26
Correct
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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: 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 27
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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Question 28
Correct
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A 32 year old woman presents with episodes of flushing, headaches and palpitations. On examination her blood pressure is significantly elevated. Which of the following is the most likely diagnosis:
Your Answer: Pheochromocytoma
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 29
Correct
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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: 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 30
Correct
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Which of the following cell types in the stomach secretes histamine?
Your 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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SESSION STATS - PERFORMANCE PER SPECIALTY
