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Question 1
Correct
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What is the isolated effect of B2 stimulation on the coronaries?
Your Answer: Vasodilatation
Explanation:Norepinephrine and epinephrine are agonists for all adrenergic receptor subtypes, although with varying affinities. Based on their physiology and pharmacology, adrenergic receptors have been divided into two principal types: alpha and beta. These types have been further differentiated into alpha-1, alpha-2, b1, and b2 receptors.
Alpha-1 Receptors are located on postsynaptic cells in smooth muscle and elicit vasoconstriction.
Alpha-2 receptors are localized on presynaptic membranes of postganglionic nerve terminals that synthesize norepinephrine. When activated by catecholamines, alpha-2 receptors act as negative feedback controllers, inhibiting further norepinephrine release.
Activation of myocardial b1 receptors stimulates the rate and strength of cardiac contraction, and consequently increases cardiac output. b1 Receptor activation also stimulates renin release from the kidney. Another class of antihypertensive agents acts by inhibiting b1 receptors.
Activation of b2 receptors by epinephrine relaxes vascular smooth muscle and results in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 2
Correct
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From which of the following can niacin be synthesized in humans
Your Answer: Tryptophan
Explanation:Niacin, is also known as vitamin B3. The liver can synthesize niacin from the essential amino acid tryptophan, requiring 60 mg of tryptophan to make one mg of niacin.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 3
Correct
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Where is Vitamin B 12 absorbed?
Your Answer: Terminal ileum
Explanation:Protein-bound vitamin B12 must be released from the proteins by the action of digestive proteases in both the stomach and small intestine. Gastric acid releases the vitamin from food particles; therefore antacid and acid-blocking medications (especially proton-pump inhibitors) may inhibit absorption of B12. B12 must be attached to Intrinsic Factor (IF) for it to be efficiently absorbed, as receptors on the enterocytes in the terminal ileum of the small bowel only recognize the B12-IF complex; in addition, intrinsic factor protects the vitamin from catabolism by intestinal bacteria.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 4
Correct
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A 62 year old man arrives at the clinic with a history of cough and intermittent haemoptysis for the last 3 months. He has a 50 pack year smoking history and is currently waiting for bronchoscopy to assess a left lower lobe collapse. The patient also has a marked muscle weakness and wasting of proximal muscles of his shoulders and pelvic girdle. His wife states that lately he has been unable to eat solids. Which of the following statements would be true regarding this scenario?
Your Answer: He may have a photosensitive facial rash
Explanation:The patient has presented with signs of small cell lung cancer. The associated proximal muscle weakness is most probably due to dermatomyositis which occurs as a paraneoplastic syndrome associated with lung carcinoma. In most cases, the first symptom is a distinctive skin rash on the face, eyelids, chest, nail cuticle areas, knuckles, knees or elbows. The rash is patchy and usually a bluish-purple colour. Corticosteroids are helpful in the management of the cutaneous changes and muscle weakness.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 5
Correct
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On which presynaptic receptor does noradrenalin act to inhibit noradrenalin secretion?
Your Answer: Α2 receptor
Explanation:Adregenic receptors are A1, A2, B1, B2, B3. Out of these, the function of the A2 receptor is inhibition of transmitter release including nor adrenalin and acetylcholine of the autonomic nervous system.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 6
Correct
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A case-control study is being designed to look at the relationship between eczema and a new vaccine for yellow fever. What is the usual outcome measure in a case-control study?
Your Answer: Odds ratio
Explanation:A case–control study (also known as case–referent study) is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Case–control studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have that condition/disease (the cases) with patients who do not have the condition/disease but are otherwise similar (the controls).An odds ratio (OR) is a statistic that quantifies the strength of the association between two events, A and B. The odds ratio is defined as the ratio of the odds of A in the presence of B and the odds of A in the absence of B or vice versa.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 7
Correct
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The chief cells of the stomach secrete which of the following?
Your Answer: Pepsinogens
Explanation:A gastric chief cell (or peptic cell, or gastric zymogenic cell) is a type of cell in the stomach that releases pepsinogen and gastric lipase.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 8
Correct
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The enzyme responsible for telomeres maintaining their length after cell division is called:
Your Answer: Telomerase
Explanation:Telomerase is the enzyme responsible for maintenance of the length of telomeres by addition of guanine-rich repetitive sequences. Telomerase activity is exhibited in gametes and stem and tumor cells.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 9
Correct
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Which of the following do not pass through the cavernous sinus?
Your Answer: CN 2
Explanation:Oculomotor nerve (N3), trochlear nerve (N4), ophthalmic and mandibular divisions of the trigeminal nerve (N5) pass along its lateral border. The abducent nerve (N6) passes through it along with the internal carotid artery.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 10
Correct
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Which of the following is NOT a component of bile?
Your Answer: Unconjugated bilirubin
Explanation:The composition of gallbladder bile is 97% water, 0.7% bile salts, 0.2% bilirubin, 0.51% fats (cholesterol, fatty acids and lecithin), and 200 meq/l inorganic salts (electrolytes).
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 11
Correct
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During exercise, a man consumes 2L O2/min, his arterial 02 content is 190 ml/l and the 02 content of his mixed venous blood is 130ml/l. His cardiac output is approximately:
Your Answer: 33l/min
Explanation:In Fick’s original method, the following variables are measured:VO2, oxygen consumption in ml of pure gaseous oxygen per minute. This may be measured using a spirometer within a closed rebreathing circuit incorporating a CO2 absorberCa, the oxygen concentration of blood taken from the pulmonary vein (representing oxygenated blood)Cv, the oxygen concentration of blood from an intravenous cannula (representing deoxygenated blood)From these values, we know that:VO2 = (CO x Ca) – (CO x Cv)where CO = Cardiac Output, Ca = Oxygen concentration of arterial blood and Cv = Oxygen concentration of mixed venous blood.This allows us to sayCO = VO2/{Ca – Cv}and hence calculate cardiac output.Therefore CO = 2/(0.190-0.130) = 33l/minNote that (Ca – Cv) is also known as the arteriovenous oxygen difference.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 12
Correct
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With regard to cell membrane proteins:
Your Answer: Carriers are involved in facilitated diffusion
Explanation:Pumps use a source of free energy such as ATP to transport ions against a gradient and is an example of active transport. Unlike channel proteins which only transport substances through membranes passively, carrier proteins can transport ions and molecules either passively through facilitated diffusion, or via secondary active transport. Channels are either in open state or closed state. When a channel is opened, it is open to both extracellular and intracellular. Pores are continuously open to both environments, because they do not undergo conformational changes. They are always open and active.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 13
Correct
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Which of the following foods contain Vitamin B 12?
Your Answer: Liver, meat
Explanation:No fungi, plants, nor animals (including humans) are capable of producing vitamin B12. Only bacteria and archaea have the enzymes needed for its synthesis. Proved food sources of B12 are animal products (meat, fish, dairy products).
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This question is part of the following fields:
- Haematology
- Medicine
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Question 14
Correct
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A lesion that interrupts one optic nerve causes blindness:
Your Answer: In the eye on the same side as the optic nerve
Explanation:The optic nerve on each side contains medial and lateral fibers originating from the retina. Medial fibers cross at the optic chiasm and become the optic tract ending in the visual cortex of the occipital lobe. If there is a lesion interrupting the “optic nerve” on one side, the same side eye will be completely blind.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 15
Incorrect
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Where in the gastrointestinal tract are valvulae conniventes?
Your Answer: Colon
Correct Answer: Jejunum
Explanation:The circular folds (valves of Kerckring or valvulae conniventes) are large valvular flaps projecting into the lumen of the small intestine.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 16
Correct
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One function of the liver is synthesis and storage of protein. Which of the following will result in hypoalbuminemia?
Your Answer: All of the above
Explanation:Both trauma and sepsis cause an acute inflammatory response causing plasma leakage of albumin. Nephropathy causes leakage of albumin from glomeruli and excretion of albumin in urine known as albuminuria. A hypercatabolic state is characterized by increased circulating catabolic hormones and increase break down of proteins.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 17
Incorrect
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Which of the following does not lower ventricular rate in atrial fibrillation?
Your Answer: Occulocardiac reflex
Correct Answer: Adrenaline
Explanation:Adrenaline is a sympathetic neurotransmitter which increases the heart rate. During atrial fibrillation the atria is contracting at more than 200 beats/min. Acetylcholine is a parasympathetic neurotransmitter decreasing the heart rate. Digital also depresses the conduction at the AV conduction. Vagal discharge and occulocardiac reflux decrease the heart rate and convert the tachycardia into normal sinus rhythm.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 18
Correct
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Concerning coronary arteries, what is the net effect of B2 stimulation on the heart (e.g. Running athlete)?
Your Answer: Vasodilation via production of metabolites
Explanation:The coronary arterioles contain α-adrenergic receptors, which cause vasoconstriction, and β-adrenergic receptors, which cause vasodilation. Activity in the noradrenergic nerves to the heart and injections of norepinephrine cause coronary vasodilation. However, norepinephrine also increases the heart rate and the force of cardiac contraction, and the vasodilation is due to production of vasodilator metabolites in the myocardium secondary to the increase in its activity. As exercise has the same effect as sympathetic stimulation, it will result in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 19
Correct
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A 35-year-old man was brought to the ER with acute confusion. He's a known case of bipolar disorder under treatment with mood stabilizers. Blood investigations revealed lithium toxicity. A decision is made to start the patient on sodium bicarbonate. What is the rationale behind the use of sodium bicarbonate in this patient?
Your Answer: Increases urine alkalinity
Explanation:The rationale behind the use of sodium bicarbonate is that it increases the alkalinity of the urine promoting lithium excretion. The preferred treatment in severe cases would be haemodialysis.Lithium is a mood-stabilizing drug used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression. It has a very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys. Lithium toxicity generally occurs following concentrations > 1.5 mmol/L.Toxicity may be precipitated by dehydration, renal failure, diuretics (especially Bendroflumethiazide), ACE inhibitors, NSAIDs and metronidazole.Features of toxicityCoarse tremor (a fine tremor is seen in therapeutic levels)HyperreflexiaAcute confusionSeizureComaManagementMild-moderate toxicity may respond to volume resuscitation with normal salineHaemodialysis may be needed in severe toxicitySodium bicarbonate is sometimes used but there is limited evidence to support this. By increasing the alkalinity of the urine it promotes lithium excretion.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 20
Correct
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Which of the following associations is false?
Your Answer: Mandibular nerve – foramen lacerum
Explanation:– The olfactory nerves pass through the cribriform plate- The maxillary division of the trigeminal nerve passes through the foramen rotundum- The facial nerve passes through the stylomastoid foramen- The mandibular division of the trigeminal nerve pass through the foramen ovale- The glossopharyngeal nerve passes through the jugular foramen.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 21
Correct
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In a normal heart rate at rest, the left ventricular end-diastolic volume is ….
Your Answer: 100-130 ml
Explanation:In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole. Because greater EDVs cause greater distention of the ventricle, EDV is often used synonymously with preload, which refers to the length of the sarcomeres in cardiac muscle prior to contraction (systole). End-diastolic volume: Right = 144 mL(± 23mL) & Left = 142 mL (± 21 mL).
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 22
Correct
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Choose the standard method for comparing distributions in data sets (such as between the expected frequency of an event and the observed frequency of an event) from the list of options.
Your Answer: Chi squared (X²) test
Explanation:The Chi-squared test evaluates if two variables are related. The other statistical tests mentioned do not perform this function.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 23
Correct
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In Hirschsprung disease which one is incorrect
Your Answer: Due to congenital absence of myenteric and submucosal plexuses
Explanation:During normal prenatal development, cells from the neural crest migrate into the large intestine (colon) to form the networks of nerves called the myenteric plexus (Auerbach plexus) (between the smooth muscle layers of the gastrointestinal tract wall) and the submucosal plexus (Meissner plexus) (within the submucosa of the gastrointestinal tract wall). In Hirschsprung’s disease, the migration is not complete and part of the colon lacks these nerve bodies that regulate the activity of the colon. The affected segment of the colon cannot relax and pass stool through the colon, creating an obstruction.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 24
Correct
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Iron absorption occurs primarily in which part of the GIT?
Your Answer: Duodenum
Explanation:Like most mineral nutrients, the majority of the iron absorbed from digested food or supplements is absorbed in the duodenum by enterocytes of the duodenal lining.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 25
Correct
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Where in the course of the gastrointestinal tract does the first significant digestion of fat begin in a normal human being?
Your Answer: Duodenum
Explanation:The enzyme lipase which is responsible for digestion of fat is secreted by the exocrine pancreas in the 2nd part of the duodenum at the point where the pancreatic duct opens. It opens together with the common bile duct which contains bile that emulsify fat aiding in digestion. The oesophagus, stomach and mouth do not contain enzymes related to fat digestion.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 26
Correct
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Preload:
Your Answer: Is the degree to which the myocardium is stretched before is contracts
Explanation:Preload is end diastolic volume. It is the degree to which the heart muscle fiber is stretched when it fills up completely just before the heart contracts.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 27
Incorrect
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Closure of the tricuspid valve is marked by which of the following features of the jugular venous waveform?
Your Answer: a wave
Correct Answer: c wave
Explanation:The jugular venous pressure (JVP) classically has three upward deflections and two downward deflections. The upward deflections are the a (atrial contraction), c (ventricular contraction and resulting bulging of tricuspid into the right atrium during isovolumetric systole) and v = venous filling. The downward deflections of the wave are the x (the atrium relaxes and the tricuspid valve moves downward) and the y descent (filling of ventricle after tricuspid opening).
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 28
Correct
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In the malaria life cycle , parasites which remain dormant in the liver are known as :
Your Answer: Hypnozoites
Explanation:The life-cycles of Plasmodium species involve several different stages both in the insect and the vertebrate host. These stages include sporozoites, which are injected by the insect vector into the vertebrate host’s blood. Sporozoites infect the host liver, giving rise to merozoites and (in some species) hypnozoites. These move into the blood where they infect red blood cells. In the red blood cells, the parasites can either form more merozoites to infect more red blood cells, or produce gametocytes which are taken up by insects which feed on the vertebrate host. In the insect host, gametocytes merge to sexually reproduce. After sexual reproduction, parasites grow into new sporozoites, which move to the insect’s salivary glands, from which they can infect a vertebrate host bitten by the insect
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 29
Correct
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The principal enzyme of lipid digestion is:
Your Answer: Lipase
Explanation:Lipase is the principle enzyme that digest lipids. Amylase digest carbohydrates. Colipase is a co-enzyme that optimize the activity of lipase. Trypsin digest proteins and cholesterol esterase digest cholesterol.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 30
Correct
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Which neurotransmitter is released from the postganglionic fibers in the sympathetic division?
Your Answer: Noradrenalin
Explanation:Noradrenalin Is the neurotransmitter that is released from the postganglionic fibers of the sympathetic division. It is stored in granules at the sympathetic knobs. It Is a methyl derivative.
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This question is part of the following fields:
- Medicine
- Neurology
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