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Question 1
Incorrect
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The enzyme protein gastric lipase is responsible for the breakdown of lipids in the stomach.
Which of the following cell types secretes gastric lipase?Your Answer: ECL cells
Correct Answer: Chief cells
Explanation:Gastric lipase, commonly known as LIPF, is an acidic lipase released by gastric chief cells, which are found deep within the stomach lining’s mucosal layer. It’s an enzymatic protein that’s in charge of fat digestion in the stomach.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 2
Incorrect
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Diabetic ketoacidosis is characterised by which of the following:
Your Answer: Hypovolaemia, hyperglycaemia and ketonuria
Correct Answer: Hyperglycaemia, ketonaemia and acidosis
Explanation:DKA is characterised by the biochemical triad:
1. Hyperglycaemia (> 11 mmol/L)
2. Ketonaemia (> 3 mmol/L)
3. Acidosis (pH < 7.3 +/- HCO3 < 15 mmol/L) -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 3
Incorrect
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Metabolic hyperaemia harmonizes local blood flow with local O2 demand. If there is an increase in metabolic rate, the production of vasoactive metabolites increases. These metabolites act locally on the surrounding arterioles, causes vasodilation and an increase blood supply.
Which of these metabolites is the most potent vasodilator in skeletal muscle?Your Answer: CO 2
Correct Answer: K +
Explanation:Hyperaemia is the process where the body adjusts blood flow to meet the metabolic needs of different tissues in health and disease. Vasoactive mediators that take part in this process include K+, adenosine, CO2, H+, phosphates and H2O2. Although the mechanism is not clear, all these mediators likely contribute to some extent at different points.
Specific organs are more sensitive to specific metabolites:
K+ and adenosine are the most potent vasodilators in skeletal musclesCO2 and K+ are the most potent vasodilators in cerebral circulation.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 4
Incorrect
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Which of the following globin chains makes up haemoglobin A2 (HbA2)?
Your Answer: Two alpha and two beta chains
Correct Answer: Two alpha chains and two delta chains
Explanation:Haemoglobin is a 64.4 kd tetramer consisting of two pairs of globin polypeptide chains: one pair of alpha-like chains, and one pair of non-alpha chains. The chains are designated by Greek letters, which are used to describe the particular haemoglobin (e.g., Hb A is alpha2/beta2).
Two copies of the alpha-globin gene (HBA2, HBA1) are located on chromosome 16 along with the embryonic zeta genes (HBZ). There is no substitute for alpha globin in the formation of any of the normal haemoglobins (Hb) following birth (e.g., Hb A, Hb A2, and Hb F). Thus, absence any alpha globin, as seen when all 4 alpha-globin genes are inactive or deleted is incompatible with extrauterine life, except when extraordinary measures are taken.
A homotetramer of only alpha-globin chains is not thought to occur, but in the absence of alpha chains, beta and gamma homotetramers (HbH and Bart’s haemoglobin, respectively) can be found, although they lack cooperativity and function poorly in oxygen transport. The single beta-globin gene (HBB) resides on chromosome 11, within a gene cluster consisting of an embryonic beta-like gene, the epsilon gene (HBE1), the duplicated and nearly identical fetal, or gamma globin genes (HBG2, HBG1), and the poorly expressed delta-globin gene (HBD). A heme group, consisting of a single molecule of protoporphyrin IX co-ordinately bound to a single ferrous (Fe2+) ion, is linked covalently at a specific site to each globin chain. If the iron is oxidized to the ferric state (Fe3+), the protein is called methaemoglobin.
Alpha globin chains contain 141 amino acids (residues) while the beta-like chains contain 146 amino acids. Approximately 75 percent of haemoglobin is in the form of an alpha helix. The non helical stretches permit folding of the polypeptide upon itself. Individual residues can be assigned to one of eight helices (A-H) or to adjacent non helical stretches.
Heme iron is linked covalently to a histidine at the eighth residue of the F helix (His F8), at residue 87 of the alpha chain and residue 92 of the beta chain. Residues that have charged side groups, such as lysine, arginine, and glutamic acid, lie on the surface of the molecule in contact with the surrounding water solvent. Exposure of the hydrophilic (charged) amino acids to the aqueous milieu is an important determinant of the solubility of haemoglobin within the red blood cell and of the prevention of precipitation.
The haemoglobin tetramer is a globular molecule (5.0 x 5.4 x 6.4 nm) with a single axis of symmetry. The polypeptide chains are folded such that the four heme groups lie in clefts on the surface of the molecule equidistant from one another.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 5
Incorrect
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You review the arterial blood gas (ABG) of a patient with lactic acidosis.
Which SINGLE statement regarding lactic acidosis is true?Your Answer: The mortality associated with lactic acidosis is approximately 10%
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 BÂ 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 6
Incorrect
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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: Calcitonin
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 7
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: Thin ascending limb
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 8
Incorrect
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The movement of molecules across the cell membrane relies greatly on active transport.
Which of the following statements about active transport is correct?Your Answer: Primary active transport involves the use of an electrochemical gradient
Correct Answer: Active transport occurs in glucose absorption from the gut
Explanation:The movement of a material against a concentration gradient, i.e. from a low to a high concentration, is known as active transport. Primary active transport is defined as active transport that involves the use of chemical energy, such as adenosine triphosphate (ATP). Secondary active transport occurs when an electrochemical gradient is used.
The sodium-potassium pump, calcium ATPase pump, and proton pump are all key active transport systems that use ATP. An electrochemical gradient is used by the sodium-calcium co-transporter, which is an example of secondary active transport.
The sodium-dependent hexose transporter SGLUT-1 transports glucose and galactose into enterocytes. Secondary active transport is exemplified here.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 9
Incorrect
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In the treatment of hypertensive episodes in pheochromocytoma, which of the following medication types is administered as first-line management:
Your Answer: Calcium channel blockers
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 10
Incorrect
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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: AVAs are short vessels with little to no smooth muscle in their walls
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 11
Incorrect
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A 30-year-old woman was involved in a road traffic accident and had a class I haemorrhage.
Which physiological parameter is consistent with a diagnosis of class I haemorrhage?
Your Answer: 25% of blood volume lost
Correct Answer: Increased pulse pressure
Explanation:There are 4 classes of haemorrhage. Classification is based on clinical signs and physiological parameters.
In CLASS I:Blood loss (ml) is < or = 750
Blood loss(% blood volume) < or = 15%
Pulse rate (bpm) is <100
Respiratory rate is 14-20
Urine output (ml/hr) is >30
Pulse pressure is normal or increased
Systolic BP is normal
CNS/mental status patient is slightly anxiousIn CLASS II:
Blood loss (ml) is 750 – 1500
Blood loss(% blood volume) is 15 – 30%
Pulse rate (bpm) is 100 – 120
Respiratory rate is 20-30
Urine output (ml/hr) is 20-30
Pulse pressure is decreased
Systolic BP is normal
CNS/mental status patient is mildly anxiousIn CLASS III:
Blood loss (ml) is 1500 – 2000
Blood loss(% blood volume) is 30- 40%
Pulse rate (bpm) is 120 – 140
Respiratory rate is 30-40
Urine output (ml/hr) is 5-15
Pulse pressure is decreased
Systolic BP is decreased
CNS/mental status patient is anxious, confusedIn CLASS IV:
Blood loss (ml) is >2000
Blood loss(% blood volume) is >40%
Pulse rate (bpm) is >140
Respiratory rate is >40
Urine output (ml/hr) is negligible
Pulse pressure is decreased
Systolic BP is decreased
CNS/mental status patient is confused, lethargic -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 12
Incorrect
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When treating diabetic ketoacidosis (DKA), which of the following should be given if the systolic blood pressure is initially less than 90 mmHg:
Your Answer: 500 mL sodium bicarbonate intravenous infusion over 10 - 15 minutes
Correct Answer: 500 mL sodium chloride 0.9% intravenous infusion over 10 - 15 minutes
Explanation:If SBP is less than 90 mmHg , 500 mL sodium chloride 0.9 percent should be administered intravenously over 10–15 minutes, and repeated if SBP remains less than 90 mmHg. When SBP is greater than 90 mmHg, sodium chloride infusion must be maintained at a rate that replaces the deficit.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 13
Incorrect
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Regarding the partial pressure of gases, which of the following statements is INCORRECT:
Your Answer: Dalton's law describes the law of partial pressures.
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 14
Incorrect
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Which of the following does NOT affect the rate of flow of a liquid through a tube:
Your Answer: Viscosity of the liquid
Correct Answer: Surface tension
Explanation:Flow through a tube is dependent upon:
The pressure difference across the ends of the tube (P1– P2)
The resistance to flow provided by the tube (R)
This is Darcy’s law, which is analogous to Ohm’s law in electronics:
Flow = (P1– P2) / R
Resistance in the tube is defined by Poiseuille’s law, which is determined by the diameter of the tube and the viscosity of the fluid. Poiseuille’s law is as follows:
Resistance = (8VL) / (Ï€R4)
Where:
V = The viscosity of the fluid
L = The length of the tube
R = The radius of the tube
Therefore, in simple terms, resistance is directly proportional to the viscosity of the fluid and the length of the tube and inversely proportional to the radius of the tube. Of these three factors, the most important quantitatively and physiologically is vessel radius.
It can be seen that small changes in the radius can have a dramatic effect on the flow of the fluid. For example, the constriction of an artery by 20% will decrease the flow by approximately 60%.
Another important and frequently quoted example of this inverse relationship is that of the radius of an intravenous cannula. Doubling the diameter of a cannula increases the flow rate by 16-fold (r4). This is the reason the diameter of an intravenous cannula in resuscitation scenarios is so important.
*Please note that knowledge of the detail of Poiseuille’s law is not a requirement of the RCEM Basic Sciences Curriculum. -
This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 15
Incorrect
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Regarding bicarbonate handling by the proximal tubule, which of the following statements is CORRECT:
Your Answer: Tubular HCO 3 - associates with tubular H2O + to form carbonic acid, catalysed by carbonic anhydrase.
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 16
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 17
Incorrect
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On which of the following is preload primarily dependent?
Your Answer: Ventricular compliance
Correct Answer: End-diastolic volume
Explanation:Preload refers to the initial stretching of the cardiac myocytes before contraction. It is therefore related to muscle sarcomere length. The sarcomere length cannot be determined in the intact heart, and so, other indices of preload are used, like ventricular end-diastolic volume or pressure. The end-diastolic pressure and volume of the ventricles increase when venous return to the heart is increased, and this stretches the sarcomeres, which increase their preload.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 18
Correct
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Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:
Your 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 19
Incorrect
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Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:
Your Answer: Ca 2+ release from the sarcoplasmic reticulum is stimulated directly by a Na + influx.
Correct Answer: In relaxation, Ca 2+ is transported out of the cell using energy from a Na + gradient.
Explanation: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. 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 which pumps one Ca2+ion out in exchange for three Na+ions in, using the Na+electrochemical gradient as an energy source. 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. Factors that affect intracellular [Ca2+] and hence cardiac contractility are called inotropes.
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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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Which of the following is NOT a typical effect caused by adrenaline:
Your Answer: Increased cardiac output and blood pressure
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 21
Incorrect
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By which of the following is mean arterial pressure (MAP) primarily determined?
Your Answer: Total peripheral resistance 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 22
Incorrect
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Which JVP waveform correlates to atrial systole?
Your Answer: The x descent
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 23
Incorrect
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Regarding defaecation, which of the following statements is CORRECT:
Your Answer: During defaecation contraction of the pelvic floor muscles straightens the rectum.
Correct Answer: Colonic mass movement occurs shortly after a meal due to distension of the stomach and duodenum.
Explanation:Colonic mass movement describes the intense contraction that begins halfway along the transverse colon and pushes the intestinal contents in the proximal colon towards the rectum. It occurs shortly after a meal due to distension of the stomach and duodenum as part of the gastrocolic reflex and if faeces is present in the rectum, stimulates the urge to defecate. Distention of the rectum causes firing of afferent cholinergic parasympathetic fibres. The internal sphincter is made up of circular smooth muscle innervated by the autonomic fibres, and the more distal external sphincter is composed of striated muscle innervated by motor fibres from the pudendal nerve. During defaecation, relaxation of pelvic muscles straightens the rectum.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 24
Incorrect
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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: Beta-blocker
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 25
Correct
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Which of the following statements is correct with regards to insulin receptors?
Your Answer: Insulin has its intracellular effects via activation of tyrosine kinase.
Explanation:Most cells have insulin receptors present on them which can be sequestered into the cell to inactivate them. These receptors consist of two extracellular alpha subunits which contain the insulin-binding site and two transmembrane beta subunits. Because insulin is a polypeptide hormone, it must act via cell surface receptors as it is unable to readily cross the cell membrane. On binding to the receptor, the beta subunit of insulin autophosphorylation, which activates tyrosine kinase. As a result, there is an intracellular cascade of phosphorylation, causing a translocation of the glucose transporter GLUT4 and GLUT-1 to the plasma membrane of the affected cell. This facilitates glucose entry.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 26
Correct
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Which of the following increases the tendency for oedema to occur?
Your Answer: Increased venous pressure
Explanation:When more fluid is filtered out of the capillaries than can be returned to the circulation by the lymphatics, oedema occurs. Changes that increase capillary hydrostatic pressure or decrease plasma oncotic pressure will increase filtration.
Arteriolar constriction reduces hydrostatic capillary pressure and transiently increase absorption of fluid.
Dehydration increases plasma protein concentration and therefore increases plasma oncotic pressure and absorption. Capillary hydrostatic pressure and filtration are increased when there is increased venous pressure. -
This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 27
Incorrect
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A CT pulmonary angiography of a patient with a massive pulmonary embolus will most likely show which of the following signs?
Your Answer: Decreased alveolar dead space
Correct Answer: Increased alveolar dead space
Explanation:A CT pulmonary angiogram is an angiogram of the blood vessels of the lungs. It is a diagnostic imaging test used to check for pulmonary embolism.
A pulmonary embolism is caused by a blood clot or thrombus that has become lodged in an artery in the lung and blocks blood flow to the lung. A patient with pulmonary embolism may feel an abrupt onset of pleuritic chest pain, shortness of breath, and hypoxia. Also, pulmonary embolism can result in alveolar dead space.
Dead space represents the volume of ventilated air that does not participate in gas exchange. The alveolar dead space is caused by ventilation/perfusion imbalances in the alveoli. It is defined as the sum of the volumes of alveoli that are ventilated but not perfused.
Aside from pulmonary embolism, smoking, bronchitis, emphysema, and asthma are among the other causes of alveolar dead space.
The other types of dead space are the following: Anatomical dead space is the portion of the airways that conducts gas to the alveoli. This is usually around 150 mL, and there is no possibility of gas exchange in these areas. Physiological dead space is the sum of anatomical and alveolar dead spaces.
Physiological dead space can account for up to 30% of the tidal volume.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 28
Incorrect
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You've been asked to give a discussion to a group of medical students about skeletal muscle physiology and its use in clinical medicine. They pose a series of difficult questions to you.
Which of the following definitions for the A-band of the sarcomere is correct?
Your Answer: Zones of thin filaments extending from either side of the Z-lines
Correct Answer: A band that contains the entire length of a single thick filament (myosin)
Explanation:Myofibrils, which are around 1 m in diameter, make up each myofiber. The cytoplasm separates them and arranges them in a parallel pattern along the cell’s long axis. These myofibrils are made up of actin and myosin filaments that are repeated in sarcomeres, which are the myofiber’s basic functional units.
Myofilaments are the filaments that make up myofibrils, and they’re made mostly of proteins. Myofilaments are divided into three categories:
Myosin filaments are thick filaments made up mostly of the protein myosin.
Actin filaments are thin filaments made up mostly of the protein actin.
Elastic filaments are mostly made up of the protein titin.
The sarcomere is a Z-line segment that connects two adjacent Z-lines.
The I-bands are thin filament zones that run from either side of the Z-lines to the thick filament’s beginning.
Between the I-bands is the A-band, which spans the length of a single thick filament.
The H-zone is a zone of thick filaments that is not overlaid by thin filaments in the sarcomere’s centre. The H-zone keeps the myosin filaments in place by surrounding them with six actin filaments each.
The M-band (or M-line) is a disc of cross-connecting cytoskeleton elements in the centre of the H-zone.
The thick filament is primarily made up of myosin. The thin filament is primarily made up of actin. Actin, tropomyosin, and troponin are found in a 7:1:1 ratio in thin filaments. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 29
Incorrect
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Cystic fibrosis patients have a weakened lung surfactant system. Which of the following cell types is in charge of surfactant secretion?
Your Answer: Submucosal glands
Correct Answer: Type II pneumocytes
Explanation:Alveolar type II cells are responsible for four primary functions: surfactant synthesis and secretion, xenobiotic metabolism, water transepithelial transport, and alveolar epithelium regeneration following lung injury.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 30
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 31
Incorrect
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Regarding the refractory period, which of the following statements is INCORRECT:
Your Answer: The relative refractory period is due to a temporary hyperpolarisation.
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 32
Correct
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What is the mechanism of action of captopril:
Your Answer: Inhibition of the conversion of angiotensin I to angiotensin II
Explanation:Angiotensin-converting enzyme inhibitors (ACE inhibitors) e.g. captopril inhibit the conversion of angiotensin I to angiotensin II, and thus have a vasodilatory effect, lowering both arterial and venous resistance. The cardiac output increases and, because the renovascular resistance falls, there is an increase in renal blood flow. This latter effect, together with reduced aldosterone release, increases Na+ and H2O excretion, contracting the blood volume and reducing venous return to the heart.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 33
Incorrect
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Regarding loop diuretics, which of the following statements is INCORRECT:
Your Answer: Oral bumetanide acts within 1 hour and diuresis is complete within 6 hours.
Correct Answer: The risk of hypokalaemia is greater with loop diuretics than with an equipotent dose of a thiazide diuretic.
Explanation:Hypokalaemia can occur with both thiazide and loop diuretics. The risk of hypokalaemia depends on the duration of action as well as the potency and is thus greater with thiazides than with an equipotent dose of a loop diuretic. Hypokalaemia is dangerous in severe cardiovascular disease and in patients also being treated with cardiac glycosides. Often the use of potassium-sparing diuretics avoids the need to take potassium supplements. In hepatic failure, hypokalaemia caused by diuretics can precipitate encephalopathy, particularly in alcoholic cirrhosis.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 34
Incorrect
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An 80-year-old patient with a history of chronic heart failure presents to you. Examination reveals widespread oedema.
Which statement about plasma oncotic pressure (π p ) is true?Your Answer: Hypoalbuminaemia will increase π p
Correct Answer: The influence of π p on fluid movement is negligible if the capillary reflection co-efficient is 0.1
Explanation:Plasma oncotic pressure (Ï€p) is typically 25-30 mmHg.
70% of π p is generated by albumin so Hypoalbuminemia will decrease π p
The osmotic power of albumin is enhanced by the Gibbs-Donnan effect.
The influence of π p on fluid movement is negligible if the capillary reflection coefficient is 0.1. Another way of saying a vessel is highly permeable is saying the reflection coefficient is close to 0.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 35
Incorrect
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Intrinsic factor is vital for gastrointestinal absorption of which of the following:
Your Answer: Vitamin A
Correct 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 36
Correct
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Which of the following ions is more abundant in extracellular fluid than in intracellular fluid:
Your Answer: Cl -
Explanation:Protein and phosphate are the primary intracellular anions, while chloride (Cl-) and bicarbonate are the predominant extracellular anions (HCO3-).
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 37
Incorrect
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What is the approximate lifespan of the mature erythrocyte:
Your Answer: 30 days
Correct Answer: 120 days
Explanation:Erythrocytes have a normal lifespan of about 120 days. Mature erythrocytes are biconcave discs with no nucleus, ribosomes or mitochondria but with the ability to generate energy as ATP by the anaerobic glycolytic pathway. The red cell membrane consists of a bipolar lipid layer with a membrane skeleton of penetrating and integral proteins anchoring carbohydrate surface antigens. The shape and flexibility of red cells allows them to deform easily and pass through capillaries.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 38
Incorrect
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A patient has a cardiac output of 4.8 L/min and a heart rate of 80 bpm, therefore their stroke volume is:
Your Answer: 40 mL
Correct Answer: 60 mL
Explanation:Cardiac output (CO) = Stroke volume (SV) x Heart rate (HR).
Therefore SV = CO/HR
= 4.8/80
= 0.06 L = 60 mL. -
This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 39
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: 50%
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 40
Correct
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The transport of oxygen from maternal to fetal circulation is made possible by fetal haemoglobin. Which of the statements about fetal haemoglobin (HbF) is also correct?
Your Answer: The oxygen dissociation curve for foetal haemoglobin is shifted to the left of that of adult haemoglobin
Explanation:Fetal haemoglobin is the most common type of haemoglobin found in the foetus during pregnancy. It transports oxygen from the maternal circulation to the fetal circulation. It can easily bind to oxygen from the maternal circulation because it has a high affinity for oxygen. From 10 to 12 weeks of pregnancy to the first six months after birth, the erythroid precursor cells produce fetal haemoglobin. In comparison to adult haemoglobin, fetal haemoglobin has two alpha and two gamma subunits, whereas adult haemoglobin has two alpha and two beta subunits in its major form.
And, unlike adult haemoglobin, the oxygen dissociation curve of fetal haemoglobin is left-shifted. Myoglobin is an oxygen storage molecule with a very high affinity for oxygen. Only when the partial pressure of oxygen is exceeded does it release oxygen.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 41
Incorrect
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Dexamethasone would be most useful for which of the following conditions:
Your Answer: Mineralocorticoid replacement in adrenal insufficiency
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 42
Incorrect
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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 lipids into fatty acid and glycerol?Your Answer: Chymotrypsin
Correct Answer: Pancreatic lipase
Explanation:The principal enzyme involved in lipid digestion is pancreatic lipase. It breaks down triglycerides into free fatty acids and monoglycerides. Pancreatic lipase works with the help of emulsifying agents secreted by the liver and the gallbladder. The main emulsifying agents are the bile acids, cholic acid and chenodeoxycholic acid. These are conjugated with the amino acids glycine and taurine to form bile salts. Bile salts are more soluble than bile acids and act as detergents to emulsify lipids. The free fatty acids and monoglycerides form tiny particles with these bile salts called micelles. The outer region of the micelle is water-attracting (hydrophilic), whereas the inner core is water-repelling (hydrophobic). This arrangement allows the micelles to enter the aqueous layers surrounding the microvilli and free fatty acids and monoglycerides to diffuse passively into the small intestinal cells.
Pancreatic amylase breaks down some carbohydrates (notably starch) into oligosaccharides.
Chymotrypsin is a proteolytic enzyme that aids in digestion of 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 43
Incorrect
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The myocardium is responsible for creating the force with which the atrial and ventricular muscles contract. It is made up of myocytes, which are heart muscle cells.
Which of the following statements about cardiac muscle anatomy is correct?Your Answer: There are usually multiple nuclei within each myocyte
Correct Answer: Cardiac myocytes have intercalated discs
Explanation:Typically, granuloma has Langerhan’s cells (large multinucleated cells ) surrounded by epithelioid cell aggregates, T lymphocytes and fibroblasts.
Antigen presenting monocytic cells found in the skin are known as Langerhan’s cells.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 44
Incorrect
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Regarding the glomerular filtration barrier, which of the following statements is CORRECT:
Your Answer: Negatively charged molecules are filtered more freely than positively charged ones.
Correct Answer: The main factor determining whether a substance is filtered or not is molecular weight.
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 45
Incorrect
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Which of the following is NOT a typical clinical feature of hypoglycaemia:
Your Answer: Paraesthesia
Correct Answer: Polyuria
Explanation:Clinical features of hypoglycaemia:
Autonomic symptoms: Sweating, feeling hot, anxiety/agitation, palpitations, shaking, paraesthesia, dizziness
Neuroglycopaenic symptoms: Weakness, blurred vision, difficulty speaking, poor concentration, poor coordination, drowsiness, confusion, seizures, coma
Other symptoms: Nausea, fatigue, hunger -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 46
Incorrect
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Myocardial contractility is best correlated with the intracellular concentration of:
Your Answer:
Correct Answer: Ca2+
Explanation:Contractility of myocardial cells depends on the intracellular [Ca2+], which is regulated by Ca2+entry across the cell membrane during the plateau of the action potential and by Ca2+uptake into and release from the sarcoplasmic reticulum (SR).
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 47
Incorrect
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What type of pump is the Na+/K+ATPase pump?
Your Answer:
Correct Answer: An antiporter
Explanation:In order for primary active transport to pump ions against their electrochemical gradient, chemical energy is used in the form of ATP. This is facilitated by the Na+/K+-ATPase antiporter pump, which uses metabolic energy to move 3 Na+ions out of the cell for every 2 K+ions that come in, against their respective electrochemical gradients. As a result, the cell the maintains a high intracellular concentration of K+ions and a low concentration of Na+ions.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 48
Incorrect
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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
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Question 49
Incorrect
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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 50
Incorrect
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Which of the following is NOT an effect of gastrin:
Your Answer:
Correct Answer: Stimulation of insulin release
Explanation:Gastrin acts to:
Stimulate acid secretion from parietal cells (both directly and indirectly by stimulating release of histamine from ECL cells)
Stimulate pepsinogen secretion from chief cells
Increase gastric motility
Stimulate growth of gastric mucosa -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
