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Question 1
Incorrect
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Where is the lower border of the liver usually found?
Your Answer: 10th rib midclavicular line on right
Correct Answer: 10th rib anterior axillary line on right
Explanation:Assessment of liver margins is important clinically to determine the size of the liver and is done via percussion during the physical examination. The liver typically extends from the fifth intercostal space or 6th rib to the right costal margin in the midclavicular line and the 10th rib on anterior axillary line.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 2
Correct
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With regard to X linked disorders which of the following are true
Your Answer: X linked recessive disorders usually present in males and only very rarely present in homozygous females
Explanation:All are true for autosomal recessive disorders. Dominance rules for sex-linked gene loci are determined by their behaviour in the female: because the male has only one allele (except in the case of certain types of Y chromosome aneuploidy), that allele is always expressed regardless of whether it is dominant or recessive.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 3
Incorrect
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Which is NOT true of vitiligo?
Your Answer: There is no known cure
Correct Answer: A positive family history is not a risk factor
Explanation:The cause of Vitiligo is typically unknown. It is believed to be due to genetic susceptibility that is triggered by an environmental factor such that an autoimmune disease occurs. This results in the destruction of skin pigment cells. Risk factors include a family history of the condition or other autoimmune diseases, such as hyperthyroidism, alopecia areata, and pernicious anaemia. Vitiligo is classified into two main types: segmental and non-segmental. Most cases are non-segmental meaning they affect both sides and typically get worse with time. The prevalence of vitiligo is 0.5-1% of populations worldwide. Typical sites include backs of hands, wrists, knees, neck and around body orifices. The Koebner phenomenon refers to skin lesions appearing on lines of trauma. This occurs in vitiligo secondary to scratching.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 4
Correct
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The coronary sinus, which empties into the right atrium, serves to?
Your Answer: Drain the venous supply of the myocardium
Explanation:The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers deoxygenated blood to the right atrium, as do the superior and inferior vena cava.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 5
Correct
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Which statement describes endogenous transmission the best?
Your Answer: Commensal flora that gain access to an inappropriate area
Explanation:All answers A, B, C, and D are examples of exogenous infections. Endogenous infection is an infection by organisms that normally reside in the body but have previously been dormant.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 6
Correct
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The thalamic nuclei that project over wide regions of the neocortex are:
Your Answer: Specific relay nuclei
Explanation:The thalamus is considered the relay station for sensory and motor stimuli. There are three basic types of thalamic nuclei: relay nuclei, association nuclei and non-specific nuclei. Relay nuclei receive very well defined inputs and project this signal to functionally distinct areas of the cerebral cortex. These include the nuclei that relay primary sensations and also the nuclei involved in feedback of cerebellar signals and basal gangliar output.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 7
Correct
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Currents caused by opening of which of the following channels contribute to the repolarization phase of the action potential of the ventricular muscle fibers?
Your Answer: Potassium channels
Explanation:Depolarization occurs due to opening of the voltage gated sodium channels. Repolarization occurs due to opening of the voltage gates potassium channels causing an out flux of potassium ions, decreasing the membrane potential towards resting potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 8
Correct
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Which of the following forms the language areas of the cerebral cortex?
Your Answer: All of the above
Explanation:Broca’s area, Wernicke’s area, the submarginal sulcus and the angular gyrus all form the language areas of the cerebral cortex.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 9
Correct
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Which of the following factors serve to decrease cardiac output?
Your Answer: Standing from a lying position
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement, increased body temperature and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Correct
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Which neurotransmitter is made from hydroxylation and decarboxylation of tryptophan?
Your Answer: Serotonin
Explanation:Serotonin is synthesized from the essential amino acid tryptophan. The rate-limiting step is the conversion of the amino acid to 5-hydroxytryptophan by tryptophan hydroxylase. This is then converted to serotonin by the aromatic L-amino acid decarboxylase.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 11
Correct
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A study is carried out to assess the efficacy of a new anti-epileptic drug for children with absence seizures. The total number of the children selected for the study was 400, from which 150 children were assigned to take the new drug and 250 children were assigned in the control group. After a period of four months, only 15 children taking the new drug had a seizure compared to 100 children from the control group who had seizure. What is the correct value regarding the relative risk reduction?
Your Answer: 75%
Explanation:Relative risk reduction (RRR) tells you by how much the treatment reduced the risk of bad outcomes relative to the control group who did not have the treatment. In the previous example, the relative risk reduction of fever and rash in the group of the children on the intervention was 40 per cent (1 – 0.6 = 0.4 or 40 per cent). RRR = (EER -CER) / CER = (0.1 – 0.4) / 0.4 = -0.75 or 75% reduction.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 12
Correct
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Which of the following is matched correctly with regard to stem cells of the bone marrow?
Your Answer: Hemopoietic stem cells - basophils
Explanation:Hematopoietic stem cells (HSCs) or hemocytoblasts are the stem cells that give rise to all the other blood cells through the process of haematopoiesis. They give rise to both the myeloid and lymphoid lineages of blood cells. (Myeloid cells include monocytes, macrophages, neutrophils, basophils, eosinophils, erythrocytes, dendritic cells, and megakaryocytes or platelets. Lymphoid cells include T cells, B cells, and natural killer cells.)
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This question is part of the following fields:
- Haematology
- Medicine
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Question 13
Correct
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Regarding the innervation of cerebral blood vessels, which of the following triggers a vasoconstrictor effect?
Your Answer: Neuropeptide-Y
Explanation:Substance P is a potent vasodilator, VIP or vasoactive intestinal peptide has vasodilator properties in the intestines. PHM 27 is a potent calcitonin receptor agonist; endogenous analogue of human VIP. CGRP or Calcitonin Gene-Related Peptide is a vasodilator which is found to play an important role in migraines. Neuropeptide Y is a strong vasoconstrictor.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 14
Incorrect
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The small opening in the cochlea through which the upper scala vestibuli and lower scala tympani communicates is called the:
Your Answer: Secondary tympanic membrane opening
Correct Answer: Helicotrema
Explanation:The helicotrema is the part of cochlear labyrinth where the scala tympani and the scala vestibuli meet.
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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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In the clotting mechanism, activation of factor IX can occur through the direct actions of:
Your Answer: Thrombin & factor VIa
Correct Answer: Factor VIIa & XIa
Explanation:Factor IX is processed to remove the signal peptide, glycosylated and then cleaved by factor XIa (of the contact pathway) or factor VIIa (of the tissue factor pathway). When activated into factor IXa, in the presence of Ca2+, membrane phospholipids, and a Factor VIII cofactor, it hydrolyses one arginine-isoleucine bond in factor X to form factor Xa. Factor IX is inhibited by antithrombin.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 16
Correct
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A 55 year old cardiac patient is comfortable at rest but heavy housework results in fatigue, palpitations or dyspnoea. What New York Heart Association class best describes the severity of their disease?
Your Answer: NYHA Class II
Explanation:New York Heart Association functional classification:
Class I: no limitation is experienced in any activities; there are no symptoms from ordinary activities.
Class II: slight, mild limitation of activity; the patient is comfortable at rest or with mild exertion.
Class III: marked limitation of any activity; the patient is comfortable only at rest.
Class IV: any physical activity brings on discomfort and symptoms occur at rest.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 17
Correct
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Select the correct statement regarding the macro anatomy of the thyroid gland.
Your Answer: It surrounds the trachea at the front of the neck.
Explanation:The thyroid is located around the trachea, in the anterior portion of the neck. It is formed by two lobes which are connected by an isthmus. The presence of a pyramidal lobe, or third lobe, is considered to be a normal anatomical variant. It originates from the primitive pharynx and the neural crest and has a rich vascular supply.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 18
Correct
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Which of the following conditions results from chromosomal ‘non-disjunction’?
Your Answer: All of the options
Explanation:Non-disjunction can result in aneuploidy i.e. abnormal number of chromosomes in a cell. It results due to uneven division of chromosomes in the meiosis 1 or 2 phase. All the above mentioned examples are of non-disjunction.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 19
Incorrect
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A 25-year-old student consumed a bottle of vodka at a party, the next day he finds that he feels excessively thirsty and is passing more urine than usual. Which of the following mechanisms best explains the polyuria due to excessive alcohol consumption?
Your Answer: Ethanol increases aquaporin proteins in the proximal convoluted tubule
Correct Answer: Ethanol inhibits ADH secretion
Explanation:Ethanol reduces the calcium-dependent secretion of anti-diuretic hormone (ADH) by blocking channels in the neurohypophyseal nerve terminal.Thus, ethanol’s inhibitory effect helps to explain the increased diuresis experienced during intoxicated states as well as increased free water loss; without appropriate ADH secretion, more water is excreted by the kidneys.Nausea associated with hangovers is mainly due to vagal stimulation to the vomiting centre. Following a particularly severe episode of alcohol excess, people may experience tremors due to increased glutamate production by neurons to compensate for the previous inhibition by ethanol.Management of alcoholism:Nutritional support: – Alcoholic patients should receive oral thiamine if their ‘diet may be deficient’.Pharmacological management:- Benzodiazepines for acute withdrawal- Disulfiram promotes abstinence – alcohol intake causes a severe reaction due to inhibition of acetaldehyde dehydrogenase. Patients should be aware that even small amounts of alcohol (e.g. In perfumes, foods, mouthwashes) can produce severe symptoms. Contraindications include ischaemic heart disease and psychosis.- Acamprosate reduces craving, known to be a weak antagonist of NMDA receptors, improves abstinence in placebo-controlled trials.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 20
Incorrect
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Regarding Polymerase Chain Reaction, all are true except:
Your Answer: DNA is initially denatured by heat into single stranded DNA prior to cooling
Correct Answer: There is a linear rise of DNA copies during amplification.
Explanation:All are true except there is a linear rise of DNA copies during amplification. There is an exponential rise in amplification of DNA.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 21
Correct
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How does the proximal convoluted tubule excrete H+?
Your Answer: Via Na+/H+ antiporter.
Explanation:H+ secretion from cells across the luminal membrane is mostly in exchange for Na+ ions, and to a small extent, through a proton ATPase. Secreted H+ react with filtered HC03- to form H2CO3.
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This question is part of the following fields:
- Medicine
- Renal
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Question 22
Incorrect
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Sinus bradycardia may be caused by disease of which of the following:
Your Answer: Right posterior descending
Correct Answer: Right coronary artery
Explanation:Disease of the right coronary artery may cause sinus bradycardia and AV nodal block.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 23
Incorrect
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Question 24
Incorrect
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Which protein in the HIV genome is responsible for binding to the host CD4 cells?
Your Answer: p10
Correct Answer: gp120
Explanation:HIV can infect a variety of immune cells such as CD4+ T cells, macrophages, and microglial cells. HIV-1 entry to macrophages and CD4+ T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells and also with chemokine coreceptors.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 25
Incorrect
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Endolymph in the inner ear is rich in:
Your Answer: Mg
Correct Answer: K
Explanation:Cochlear fluids namely endolymph and perilymph have different compositions. Perilymph is a typical extracellular fluid, with ionic composition comparable to plasma or cerebrospinal fluid. The main cation is sodium. Endolymph is a totally unique extracellular fluid, with an ion composition unlike that which is found anywhere else in the body. The major cation in the endolymph is potassium and there is virtually no sodium.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 26
Incorrect
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A 40-year-old patient under treatment for gout gave a history of progressive weakness of his limbs over 2 months. He noticed that it was particularly difficult for him to get up from the toilet seat and to get out of his car. He also felt some tingling and numbness of his toes at night, which was distressing. He was taking several medications which included Ibuprofen, perindopril, colchicine, vitamin supplements, and indapamide.On examination his pulse was 85/min, blood pressure was 140/90 mmHg and fundi revealed arteriovenous nipping. He had proximal lower limb weakness of 4/5 and absent ankle reflexes. Plantar reflexes were upgoing on both sides. His serum creatinine phosphokinase level was normal.What is the most likely diagnosis?
Your Answer: Perindopril toxicity
Correct Answer: Colchicine toxicity
Explanation:The given clinical scenario is suggestive of myo-neuropathy and is most likely to be caused by colchicine toxicity. It gives rise to subacute proximal muscle weakness and on occasions can lead to an acute necrotizing myopathy. Creatine phosphokinase may be normal or may be elevated.Weakness resolves when the drug is discontinued but the neuropathic features remain.Death is usually a result of respiratory depression and cardiovascular collapse.Treatment is symptomatic and supportive, and the treatment for colchicine poisoning includes lavage and measures to prevent shock.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 27
Incorrect
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During strenuous exercise the following arterial change can take place in a fit athlete:
Your Answer: CO2 can increase
Correct Answer: No change takes place
Explanation:The changes which occur in arterial pH, PO2 and PCO2 values during exercise are usually small. Arterial PO2 often rises slightly because of hyperventilation although it may eventually fall at high work rates. During vigorous exercise, when sufficient oxygen for flux through the Krebs cycle is not available, the increased reliance on glycolysis results in increased accumulation of lactic acid, which initially leads to an increase in PaCO2 . However, this is counteracted by the stimulation of ventilation and as a result PaCO2 is decreased. This provides some respiratory compensation for further lactic acid production and prevents a decline in blood pH, which remains nearly constant during moderate exercise.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 28
Correct
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Coronary vasoconstriction can be caused by:
Your Answer: Beta blockage
Explanation:Coronary arteries contain alpha and beta receptors. The alpha receptor stimulates vasoconstriction and beta receptors stimulate vasodilation. When the chronotropic and inotropic effects of noradrenergic receptors are blocked by a B blocking drug, stimulation of the noradrenergic nerves will cause coronary vasoconstriction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 29
Incorrect
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The infoldings or spaces between the bases of the villi are known as
Your Answer: Microfolds of the intestine
Correct Answer: Crypts of Lieberkühn
Explanation:An intestinal gland (also crypt of Lieberkühn and intestinal crypt) is a gland found in the intestinal epithelium lining of the small intestine and large intestine (colon) between the villi.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 30
Incorrect
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Regarding the anatomy of the intestine, the muscularis propria contains all of which of the following constituents?
Your Answer: Circular muscle, mesothelium, submucosa
Correct Answer: Circular muscle, myenteric plexus, longitudinal muscle
Explanation:The muscularis mucosa/propria consists of the inner circular muscles and the outer longitudinal muscles. Between these muscles is the myenteric plexus.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 31
Incorrect
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Ventricular depolarization plus ventricular repolarization is shown by the _____ interval
Your Answer: RT
Correct Answer: QT
Explanation:The QT interval represents ventricular depolarization as well as ventricular repolarization.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 32
Incorrect
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When is the blood pressure at its lowest during pregnancy?
Your Answer: Post partum
Correct Answer: Second trimester
Explanation:It is lowest during the second trimester.
Previous studies have reported changes in blood pressure (BP) throughout pregnancy, and it was generally accepted that in clinically healthy pregnant women, BP falls gradually at first trimester, reaching the lowest around 22–24 weeks, rising again from 28 weeks, and reaching preconception levels by 36 weeks of gestation
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 33
Incorrect
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Portal vein receives its blood from all the following except:
Your Answer: Pancreas
Correct Answer: Kidney
Explanation:The portal vein receives blood from the intestines via the superior and inferior mesenteric veins, from stomach via the gastric veins and from the spleen and pancreas via splenic vein. The kidney is supplied by the renal artery and drains into the renal vein into the inferior venacava.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 34
Incorrect
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The blood supply to the greater curvature of the stomach is via the:
Your Answer: Gastroduodenal artery
Correct Answer: Right and left gastro-epiploic arteries
Explanation:The blood supply to the greater curvature of the stomach is via the left and the right gastro-epiploic arteries branching from the splenic artery near the hilum.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 35
Incorrect
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A 55 year old female presents with progressive dyspnoea, dry cough and fever. She started methotrexate therapy six weeks ago. The current regimen includes methotrexate 15 mg/ week, folic acid 5 mg/day and aspirin 75 mg/day. There is no history of any other chronic illness. Vitals are as follows: Temp: 37.8C, pulse: 100 beats/min, BP: 110/80mmHg and SaO2: 90% on air. Examination reveals synovitis in both wrists, and metacarpophalangeal joints. On auscultation, there are scattered crepitations. Blood test reports are given below:Haemoglobin: 13.1g/dl (13.0 – 18.0 g/dL)WBC: 8.2 x109/l (4 – 11 x 109/l)Neutrophils: 5.1×109/l (1.5 – 7 x 109/l)Platelets: 280 x109/l (150 – 400 x 109/L)ESR: 48 mm/hr (0 – 30 mm/1st hr)Urea, electrolytes and creatinine: normalCXR: patchy airspace shadows bilaterallyWhat is the most likely diagnosis?
Your Answer: Community acquired pneumonia
Correct Answer: Methotrexate pneumonitis
Explanation:Pneumonitis is a serious and unpredictable side-effect of treatment with methotrexate (MTX) that may become life-threatening. The typical clinical symptoms include progressive shortness of breath and cough, often associated with fever. Hypoxaemia and tachypnoea are always present and crackles are frequently audible. Chest radiography reveals a diffuse interstitial or mixed interstitial and alveolar infiltrate, with a predilection for the lower lung fields. Pulmonary function tests show a restrictive pattern with diminished diffusion capacity. Lung biopsy reveals cellular interstitial infiltrates, granulomas or a diffuse alveolar damage pattern accompanied by perivascular inflammation. Most patients present in the first few months of starting methotrexate. It is important that all patients receiving methotrexate be educated concerning this potential adverse reaction and instructed to contact their physicians should significant new pulmonary symptoms develop while undergoing therapy. If methotrexate pneumonitis is suspected, methotrexate should be discontinued, supportive measures instituted and careful examination for different causes of respiratory distress conducted. This may be treated with corticosteroids once underlying infection has been excluded.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 36
Incorrect
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During which phase of the cell cycle does DNA synthesis occur?
Your Answer: G1
Correct Answer: S
Explanation:DNA synthesis occurs in the S phase of the cell cycle. In the G1 phase the cell prepares to divide. In G2 the cellular organelles divide and in the M phase mitosis occur. In the G0 phase the cell becomes quiescent and does not divide further
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This question is part of the following fields:
- Genetics
- Medicine
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Question 37
Incorrect
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Which substance has the lowest taste threshold concentration, in other words which substance can be present in the lowest concentration before taste buds will respond?
Your Answer: Sodium chloride (salt)
Correct Answer: Strychnine hydrochloride (bitter)
Explanation:The lowest concentration of a gustatory stimulus to which the taste buds respond is considered to be the threshold concentration for that substance. The threshold concentration for strychnine is 0.0001 mm; this is because it allows the body to detect potentially dangerous substances (bitter plant components) at lower concentrations.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 38
Incorrect
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A 56 year old obese female presents due to moderate pain in her finger joints which occurs mostly at the end of the day which gets better with rest. There is also some associated swelling. On examination, there is enlargement of her distal interphalangeal joints and tenderness to palpation. Which of the following is the most likely diagnosis?
Your Answer: Gout
Correct Answer: Osteoarthritis
Explanation:Osteoarthritis (OA) is a disabling joint disease characterized by a noninflammatory degeneration of the joint complex (articular cartilage, subchondral bone, and synovium) that occurs with old age or from overuse. It mainly affects the weight-bearing and high-use joints, such as the hip, knee, hands, and vertebrae. Despite the widespread view that OA is a condition caused exclusively by degenerative “wear and tear” of the joints, newer research indicates a significant heterogeneity of causation, including pre-existing peculiarities of joint anatomy, genetics, local inflammation, mechanical forces, and biochemical processes that are affected by proinflammatory mediators and proteases. Major risk factors include advanced age, obesity, previous injuries, and asymmetrically stressed joints. In early-stage osteoarthritis, patients may complain of reduced range of motion, joint-stiffness, and pain that is aggravated with heavy use. As the disease advances, nagging pain may also occur during the night or at rest. Diagnosis is predominantly based on clinical and radiological findings. Classic radiographic features of OA do not necessarily correlate with clinical symptoms and appearance. RA involves proximal interphalangeal joints not distal. Gout occurs as a result of overproduction or underexcretion of uric acid and frequently involves first toe. Fibromyalgia is a disorder characterized by widespread musculoskeletal pain accompanied by fatigue, sleep, memory and mood issues.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 39
Incorrect
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Which of the following statements is not true about mitochondrial chromosomes?
Your Answer: Encode proteins involved in mitochondrial function i.e. ATP production from oxidative phosphorylation
Correct Answer: Mitochondrial chromosomes play no role in the transmission of disease from generation to generation.
Explanation:All the above mentioned statements are true except that mitochondrial DNA is passed from the mother to the child. If the child inherits the defective mitochondrial gene it will manifest some form of the disease. Commonly inherited diseases related to mitochondrial abnormality are Leber hereditary optic neuropathy and myoclonic epilepsy with ragged red fibers (MERRF).
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This question is part of the following fields:
- Genetics
- Medicine
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Question 40
Incorrect
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Pacemaker cells in the SA node and the AV node are connected by?
Your Answer: Organelle
Correct Answer: Gap junctions
Explanation:Gap junctions allows for rapid propagation of the action potential from one cell to the other. The cells of the heart are connected by gap junctions.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 41
Incorrect
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What is the mechanism of action of sildenafil citrate?
Your Answer: Inhibition of α-glycosidase
Correct Answer: Inhibition of phosphodiesterase V
Explanation:Sildenafil citrate (Viagra) is the first oral drug to be widely approved for the treatment of erectile dysfunction. It is a potent and selective inhibitor of type-V phosphodiesterase, the primary form of the enzyme found in human penile erectile tissue, thereby preventing the breakdown of cyclic guanosine monophosphate (cGMP), the intracellular second messenger of nitric oxide.Uses:It is used for the treatment of erectile dysfunction, idiopathic pulmonary hypertension, premature ejaculation, high altitude illness, penile rehabilitation after radical prostatectomy, angina pectoris, and lower urinary tract symptoms.Adverse effects:Mild headache, flushing, dyspepsia, cyanopsia, back pain, and myalgias – due to a high concentration of PDE11 enzyme in skeletal muscle, which shows significant cross-reactivity with the use of tadalafil.It can also cause hypotension, dizziness, and rhinitis.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 42
Incorrect
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A 50-year-old patient was started on ezetimibe, for his cholesterol a few days back. Which among the following statements is true regarding ezetimibe?
Your Answer: A reduction in serum digoxin concentrations can occur
Correct Answer: Its principal action is to reduce intestinal cholesterol absorption
Explanation:Ezetimibe is a cholesterol-lowering agent that acts to prevent cholesterol absorption by directly inhibiting cholesterol receptors on enterocytes.It does not affect the absorption of drugs (e.g. digoxin, thyroxine) or fat-soluble vitamins (A, D and K) as the anion-exchange resins do. It does not affect the cytochrome P450 enzyme system.The increased risk of myositis associated with the statins is not seen with ezetimibe.The most common adverse effects include headache, runny nose, and sore throat. Less common reactions include body aches, back pain, chest pain, diarrhoea, joint pain, fatigue, and weakness.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 43
Incorrect
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The brainstem reticular formation, consists of which important control system responsible for consciousness and sleep?
Your Answer: RES reticular encephalic system
Correct Answer: RAS reticular activating system
Explanation:The reticular formation is a set of interconnected nuclei that are located along the brainstem. Reticular activating system (RAS) is a set of connected nuclei in the brain that is responsible for regulating wakefulness and sleep wake transitions and is the most influential component in the reticular formation.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 44
Incorrect
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Which of the following predominate in the adrenal medulla?
Your Answer: ACTH secreting cells
Correct Answer: Epinephrine secreting cells
Explanation:Chromaffin cells, also known as pheochromocytes, are cells located in the adrenal medulla which specialize in the synthesis, storage, and secretion of catecholamines: 80% epinephrine and 20% norepinephrine is released into the bloodstream. For this reason, they are considered to be neuroendocrine cells.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 45
Incorrect
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On which chromosome is the gene for insulin located?
Your Answer: Chromosome 6
Correct Answer: Chromosome 11
Explanation:Humans have 23 pairs of chromosomes, and usually, two pairs of copies of chromosome 11. It is one of the most complex, gene-rich chromosomes in the human genome, and it is associated with a number of diseases. Studies have shown they the human insulin gene is located on the short arm of chromosome 11.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 46
Correct
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In cardiac muscle, which of the following is directly responsible for the release of Ca2+ stored in the sarcoplasmic reticulum (calcium-induced calcium release)?
Your Answer: Ryanodine receptor (RyR)
Explanation:Ryanodine receptor (RyR) is a ligand-gated Ca2+ channel with Ca2+ as its natural ligand. In skeletal muscle, Ca2+ entry from ECF by this route is not required for Ca2+ release. Instead, the DHPR that serves as the voltage sensor unlocks release of Ca2+ from the nearby SR via physical interaction with the RyR. The release is amplified through ca-induced ca release. However, in cardiac muscle, it is the influx of extracellular Ca2+ through the voltage-sensitive DHPR in the T system that triggers ca-induced ca release trough the RyR at the SR.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 47
Incorrect
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The following is true about the carotid arterial supply to the brain:
Your Answer: Its contribution to brain arterial flow falls second to that of basilar arteries
Correct Answer: Following carotid occlusion, precapillary anastomoses are unable to prevent infarction
Explanation:The brain has two sources of blood supply; the internal carotid arteries which are the anterior segment or the main artery that supplies the anterior portion of the brain, and the vertebral arteries which is the posterior segment which supplies the posterior portion of the brain. The internal carotid arteries branch and form two major arteries anterior and middle cerebral arteries. The right and left vertebral arteries fuse together at the level of the pons on the anterior surface of the brainstem to form the midline basilar artery. The basilar artery joins the blood supply from the internal carotids in an arterial ring at the base of the brain called the circle of Willis. The anterior and posterior communicating arteries conjoin the two major sources of cerebral vascular supply via the circle of Willis improving the chances of any region of the brain continuing to receive blood if one of the major arteries becomes occluded.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 48
Incorrect
-
ANP and BNP in the circulation act on the kidney to?
Your Answer: Does not act on the kidney at all
Correct Answer: Increase sodium excretion
Explanation:The physiologic actions of BNP are similar to those of ANP and include decrease in systemic vascular resistance and central venous pressure as well as an increase in natriuresis (sodium excretion). The net effect of these peptides is a decrease in blood pressure due to the decrease in systemic vascular resistance and, thus, afterload.
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This question is part of the following fields:
- Medicine
- Renal
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Question 49
Incorrect
-
During quiet breathing the diaphragm’s role accounts for what percent of respiration?
Your Answer: 10%
Correct Answer: 75%
Explanation:The contraction of the diaphragm accounts for approximately 75% of the air movement during normal breathing.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 50
Incorrect
-
During which stage of sleep is muscle tone in the limbs most reduced?
Your Answer: Stage 2
Correct Answer: REM
Explanation:Rapid eye movement (REM) stage is marked by extensive physiological changes in the body, such as accelerated respiration, increased brain activity and muscle relaxation. People dream during REM sleep, perhaps as a result of excited brain activity and the paralysis of major voluntary muscles.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 51
Correct
-
Regarding the structure of the 3 pituitary glycoprotein hormones FSH, LH, and TSH, which of the following is true about the α- and β-subunits of each hormone?
Your Answer: Maximal physiological activity occurs only on their combination
Explanation:Glycoprotein hormones (GPHs) are the most complex molecules that function as hormones. They each consist of two different subunits, α and β, which are non-covalently associated. The combination of these subunits results in an increase in their activity and β structure.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 52
Incorrect
-
What is the function of secondary messengers?
Your Answer: Communication from intracellular to extracellular signalling pathways
Correct Answer: Communication from extracellular to intracellular signalling pathways
Explanation:First messengers may not physically cross the phospholipid bilayer to initiate changes within the cell directly. This functional limitation necessitates the cell to devise signal transduction mechanisms to transduce first messenger into second messengers, so that the extracellular signal may be propagated intracellularly. Second messengers are intracellular signalling molecules released by the cell to trigger physiological changes such as proliferation, differentiation, migration, survival, and apoptosis. Secondary messengers are therefore one of the initiating components of intracellular signal transduction cascades.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 53
Incorrect
-
Hydroxyl radicals are broken down by which of the following substance?
Your Answer: Hydroxyl reductase
Correct Answer: Antioxidants
Explanation:Unlike superoxide, which can be detoxified by superoxide dismutase, the hydroxyl radical cannot be eliminated by an enzymatic reaction but it is believed can be counteracted by antioxidants.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 54
Incorrect
-
Which one of the following is least associated with photosensitivity?
Your Answer: Psoriasis
Correct Answer: Acute intermittent porphyria
Explanation:Sunlight, especially its ultraviolet radiation component, can cause increased or additional types of damage in predisposed individuals, such as those taking certain phototoxic drugs, or those with certain conditions associated with photosensitivity, including:- Psoriasis- Atopic eczema- Erythema multiforme- Seborrheic dermatitis- Autoimmune bullous diseases (immunobullous diseases)- Mycosis fungoides- Smith–Lemli–Opitz syndrome- Porphyria cutanea tardaAlso, many conditions are aggravated by strong light, including:- Systemic lupus erythematosus- Sjögren’s syndrome- Sinear Usher syndrome- Rosacea- Dermatomyositis- Darier’s disease- Kindler-Weary syndromeAcute intermittent porphyria (AIP) belongs to the group inborn errors of metabolism and most patients with AIP are not light sensitive.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 55
Incorrect
-
Question 56
Incorrect
-
If UA = concentration of A in urine, V = urine flow per unit time, and PA = arterial plasma level of A, renal clearance of A is equal to?
Your Answer: PA/(UA x V)
Correct Answer: (UA x V)/PA
Explanation:Renal clearance = [Urine concentration (UA) x Urine flow (V)]/[Plasma concentration (PA)]
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This question is part of the following fields:
- Medicine
- Renal
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Question 57
Incorrect
-
Which caspase is part of both the intrinsic and extrinsic apoptotic pathways?
Your Answer: Caspase-5
Correct Answer: Caspase-3
Explanation:Once initiator caspases are activated in both the intrinsic and extrinsic pathway, they produce a chain reaction, activating several other executioner caspases (Caspase 3, Caspase 6 and Caspase 7).
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 58
Incorrect
-
Cyclic AMP activates the following enzyme
Your Answer: Phosphodiesterase
Correct Answer: Protein Kinase A
Explanation:Cyclic AMP works by activating protein kinase A (PKA, or cAMP-dependent protein kinase). Protein kinase A can also phosphorylate specific proteins that bind to promoter regions of DNA, causing increases in transcription.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 59
Incorrect
-
Which one of the following diseases is correctly matched with the animal reservoir:
Your Answer: Leishmaniasis = Cats
Correct Answer: Leptospirosis = Rats
Explanation:Creutzfeldt–Jakob disease = consuming beef or beef products.Brucellosis = ingestion of unpasteurized milk or undercooked meat from infected animals.Leptospirosis is transmitted by both wild and domestic animals. The most common animals that spread the disease are rodents.Lyme disease is transmitted to humans by the bite of infected ticks of the Ixodes genus.Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania and spread by the bite of certain types of sandflies.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 60
Correct
-
All of the following features may suggest malignant changes in a melanocytic naevi, EXCEPT?
Your Answer: Decrease in size
Explanation:Melanocytic naevi are skin tumours produced by melanocytes. They usually present in childhood but increase during puberty. The mnemonic A-B-C-D, is used by institutions to assess for suspicion of malignancy. The letters stand for asymmetry, border, colour, and diameter. If a mole starts changing in size, colour, shape or, especially, if the border of a mole develops ragged edges or becomes larger than a pencil eraser, it would be an appropriate time to consult with a physician. Other warning signs include if it begins to crust over, bleed, itch, or become inflamed.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 61
Incorrect
-
HCL is secreted by which cells in the stomach
Your Answer: G cells
Correct Answer: Parietal cells
Explanation:Parietal cells are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the body of the stomach.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 62
Correct
-
Regarding gustatory sensation:
Your Answer: The sensory taste buds on the anterior two-thirds of the tongue travel to the chorda tympani branch of the facial nerve
Explanation:There are three morphologically distinct types of taste buds including; circumvallate, fungiform and foliate. Circumvallate are rounded structures arranged in a v on the back of the tongue. The posterior third travels to glossopharyngeal nerve.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 63
Incorrect
-
The inverse stretch reflex causing muscle relaxation when excessive force is applied to a muscle is mediated by which sensory organ?
Your Answer: Endoplasmic organ
Correct Answer: Golgi tendon organ
Explanation:Both the muscle spindle and Golgi tendon body are proprioceptors. The Golgi tendon reflex is a normal component of the reflex arc of the peripheral nervous system. In a Golgi tendon reflex, skeletal muscle contraction causes the antagonist muscle to simultaneously lengthen and relax. This reflex is also called the inverse myotatic reflex, because it is the inverse of the stretch reflex.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 64
Incorrect
-
Which segment of the nephron is impermeable to water?
Your Answer: Descending limb of Henle
Correct Answer: Ascending limb of Henle
Explanation:Considerable differences aid in distinguishing the descending and ascending limbs of the loop of Henle. The descending limb is permeable to water and noticeably less permeable to salt, and thus only indirectly contributes to the concentration of the interstitium. Unlike the descending limb, the thin ascending limb is impermeable to water, a critical feature of the counter current exchange mechanism employed by the loop.
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This question is part of the following fields:
- Medicine
- Renal
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Question 65
Correct
-
What is the effect of oxytocin on the breast?
Your Answer: Milk ejection
Explanation:Oxytocin is a peptide hormone and neuropeptide, produced by the hypothalamus and released by the posterior pituitary. It causes the milk ejection or let-down reflex, causing the milk to be transported to the subareolar sinuses, allowing it to be released through the nipple. This response is initiated by the act of suckling by the baby, but it can be conditioned to be triggered by different stimuli.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 66
Incorrect
-
Question 67
Incorrect
-
Regarding transportation of iron in the body, the process in which iron is transported from the enterocyte into the blood occurs using which transporter protein:
Your Answer: Transferrin
Correct Answer: Ferroportin
Explanation:Divalent metal transporter 1 (DMT1) transport several divalent metals including iron across the enterocyte’s cell membrane into the cell. The cell can then release it into the body via the only known iron exporter in mammals, ferroportin.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 68
Incorrect
-
Which one of the following is able to move across cell membranes by passive diffusion?
Your Answer: Glucose
Correct Answer: CO2
Explanation:The cell membrane is permeable to water molecules and a few other small, uncharged, molecules like oxygen (O2) and carbon dioxide (CO2). Larger molecules like glucose or charged ions are unable to cross passively.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 69
Incorrect
-
Which glucose transporter is responsible for the uptake of dietary glucose from the gut?
Your Answer: GLUT1 45k
Correct Answer: SGLT1
Explanation:SGLT 1 is responsible for the uptake of glucose via secondary active transport from the small intestine and the renal tubules.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 70
Correct
-
A 45 year old man presents with fever, malaise, weight loss and myalgias that have been occurring for a month. You suspect polyarteritis nodosa and arrange for some lab investigations. Which of the following abnormality would most likely be present?
Your Answer: Elevated creatinine
Explanation:People with polyarteritis nodosa often exhibit anaemia of chronic disease. Leucocytosis and eosinophilia may also be present. ANCA is only rarely positive. As polyarteritis nodosa affects the kidneys as well, the creatinine is elevated in most cases.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
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Question 71
Incorrect
-
With regards to the function of the p53 protein produced by the p53 gene, which of the following statements is incorrect?
Your Answer: Mutations in this protein may slow down the cell cycle causing mutations to persist
Correct Answer: It permits repair of mutations and other defects in RNA
Explanation:The p53 protein is a crucial tumor suppressor and plays several key roles in maintaining cellular integrity:
- Nuclear transcription factor: p53 is a nuclear transcription factor that regulates the expression of various genes involved in cell cycle control, DNA repair, apoptosis, and senescence.
- DNA repair: p53 permits repair of mutations and other defects in DNA (not RNA). It activates the transcription of genes involved in DNA repair mechanisms, allowing the cell to correct errors before proceeding with the cell cycle.
- Cell cycle regulation: p53 can induce the expression of p21, a protein that inhibits cyclin-dependent kinases, thereby halting the cell cycle at the G1/S checkpoint to allow time for DNA repair or to trigger apoptosis if the damage is irreparable. Mutations in p53 may fail to halt the cell cycle, allowing mutations to persist and potentially leading to cancer.
- Apoptosis: If DNA damage is extensive and cannot be repaired, p53 triggers apoptosis to prevent the propagation of damaged cells.
- Suppression of proto-oncogenes: p53 indirectly contributes to the suppression of proto-oncogenes by preventing the proliferation of cells with damaged DNA, thereby reducing the risk of oncogenic transformation.
Given these functions, the statement that p53 “permits repair of mutations and other defects in RNA” is incorrect, as p53 is primarily involved in the repair of DNA, not RNA.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 72
Incorrect
-
Which of the following antiarrhythmic drugs may be used in the treatment of long QT syndrome?
Your Answer: Sotalol
Correct Answer: Atenolol
Explanation:Beta-blockers are the mainstay of treatment in long QT syndrome. Implantable cardioverter-defibrillators are the most effective treatment in genotypes with a high risk of recurrence.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 73
Correct
-
In a 30 year old male with hypertrophic obstructive cardiomyopathy (HOCM), which of the following is not associated with increased risk of sudden death?
Your Answer: Age
Explanation:Hypertrophic cardiomyopathy (HCM) is a disease in which a portion of the myocardium (heart muscle) is enlarged without any obvious cause, creating functional impairment of the heart. It is the leading cause of sudden death in young athletes. The major risk factors for sudden death (SD) are recent unexplained syncope unlikely to be neurocardiogenic; HCM-related SD in first-degree or other close relatives; repetitive and/or prolonged nonsustained ventricular tachycardia (NSVT) episodes on Holter or extended ambulatory monitoring; massive left ventricular hypertrophy (LVH) (wall thickness ≥30 mm); extensive/diffuse late gadolinium enhancement (LGE); end-stage heart failure usually with systolic dysfunction; and thin-walled akinetic LV apical aneurysm with regional scarring.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 74
Incorrect
-
Which cells produce the immunoglobulin proteins involved in mediating humoral immunity?
Your Answer: Memory B cell
Correct Answer: Differentiated forms of B lymphocytes known as plasma cells
Explanation:After the B cells have been activated by a certain antigens, they transform into plasma cells. These plasma cells are responsible for the generation of antibodies (or immunoglobulins Ig) which are also known as regulators of humoral immunity. There are fives classes of Ig: IgA, IgG, IgM, IgE and IgD
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This question is part of the following fields:
- Immunology
- Medicine
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Question 75
Incorrect
-
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: Central nervous system membrane stabiliser
Correct 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 76
Incorrect
-
Why does arterial blood pressure drop during pregnancy?
Your Answer: Oestrogen relaxes vascular smooth muscle
Correct Answer: Progesterone relaxes vascular smooth muscle
Explanation:Progesterone relaxes vascular smooth muscle thus resulting In a decrease in total peripheral resistance. This accounts for the increase in the cardiac output.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 77
Incorrect
-
Which of the following is not true regarding mitochondrial chromosome disorders?
Your Answer: Mitochondrial chromosome defects are inherited from one’s mother
Correct Answer: Because mitochondrial chromosomes have no introns in their genes, any point mutation has a low likelihood of having an effect.
Explanation:Any point mutation in any part of the mitochondrial DNA will lead to a mutated mitochondria and will likewise have its ill effect on the body.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 78
Incorrect
-
The chemosensitive area in the medulla responds to:
Your Answer: Low oxygen and high carbon dioxide
Correct Answer: High hydrogen and high carbon dioxide
Explanation:The chemosensitive area in the medulla responds mainly to high pH levels and carbon dioxide levels. Baroreceptors in the carotid and aortic body respond mainly to oxygen and carbon dioxide partial pressure in blood.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 79
Incorrect
-
There is a measure of dispersion of a set of data from its mean. Which of following is the best term which can describe the above?
Your Answer: Probability
Correct Answer: Standard deviation (root mean square deviation)
Explanation:Standard deviation is defined as the measure of dispersion of a set of data from its mean. It measures the absolute variability of a distribution; the higher the dispersion or variability, the greater is the standard deviation and greater will be the magnitude of the deviation of the value from their mean.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 80
Incorrect
-
Which of the following involving the scalp may produce alopecia (hair loss)?
Your Answer: Bullous pemphigoid
Correct Answer: Discoid lupus erythematosus
Explanation:Causes of hair loss include:
- Dissecting cellulitis
- Fungal infections (such as tinea capitis)
- Folliculitis
- Secondary syphilis
- Demodex folliculorum
- Lupus erythematosus (hair loss may be permanent due to scarring of the hair follicles).
Psoriasis and seborrheic dermatitis commonly involve the scalp but do not produce hair loss.
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This question is part of the following fields:
- Dermatology
- Medicine
-
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Question 81
Incorrect
-
Which of the following results in the resting membrane potential of a myocyte?
Your Answer: Activation of the inward rectifier channels
Correct Answer: Activation of outward K+ channels
Explanation:Phase 0 is caused by the sodium current. Voltage gated sodium channels open leading to the influx of sodium into the cardiac muscle cell. Phase 1 is the rapid transient repolarization phase which is caused by the inactivation of the voltage gated sodium channels and opening of the voltage gated potassium channels along with opening of the slow calcium channels. Phase 2 which is the plateau is caused by opening of the slow calcium channels. Phase 4 is caused by closing of the slow calcium channels and opening of the potassium channels leading to efflux of potassium leading to the establishment of the resting membrane potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 82
Correct
-
During which phase are the 2 chromatids pulled apart at the centromere?
Your Answer: Anaphase
Explanation:During the prometaphase the microtubule organizing centre completely develops. The spindle fibers attach to the chromosome and the centriole. It is in the Anaphase however that the spindle fibers contract pulling the sister chromatids apart. Later in the anaphase a cleave furrow beings to forms.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 83
Incorrect
-
Vasodilatation of coronary arteries is caused by:
Your Answer: Carbon-monoxide
Correct Answer: Hypoxia
Explanation:The heart is highly metabolically active and boasts the highest oxygen consumption by mass of any organ. This demand for oxygen is met by the coronary circulation, which is responsible for delivering blood to the myocardium and represents approximately 5% of cardiac output. Vasodilation may be due to the local effect of hypoxia on coronary vessels, or local metabolic vasodilation, or the activation of β-adrenoceptors or some combination of these mechanisms.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 84
Incorrect
-
Which of the following runs in the upper part of the falx cerebri?
Your Answer: Tentorium cerebella
Correct Answer: Superior sagittal sinus
Explanation:Falx cerebri is a sickle cell fold of dura between the two hemispheres. Its posterior part blends with the superior part of the tentorium cerebelli. The superior sagittal sinus runs in its upper fixed margin, the inferior sagittal sinus in the free concave margin and the straight sinus along its attachment to the tentorium cerebelli.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 85
Correct
-
The following occurs as a result of 2,3 Bisphosphoglycerate binding to deoxyhaemoglobin
Your Answer: A reduction in deoxyhaemoglobin's affinity for oxygen
Explanation:2,3-BPG acts as a heteroallosteric effector of haemoglobin, lowering haemoglobin’s affinity for oxygen by binding preferentially to deoxyhaemoglobin. An increased concentration of BPG in red blood cells favours formation of the T, low-affinity state of haemoglobin and so the oxygen-binding curve will shift to the right.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 86
Correct
-
Concerning S3, which of the following statements is INCORRECT?
Your Answer: Coincide with atrial contraction
Explanation:A third heart sound also called a ventricular gallop occurs at the beginning of diastole after S2 and is lower in pitch than S1 or S2 as it is not of valvular origin. The third heart sound is benign in youth, some trained athletes, and sometimes in pregnancy but if it re-emerges later in life it may signal cardiac problems, such as a failing left ventricle as in dilated congestive heart failure (CHF). S3 is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by blood rushing in from the atria. The reason the third heart sound does not occur until the middle third of diastole is probably that during the early part of diastole, the ventricles are not filled sufficiently to create enough tension for reverberation. It may also be a result of tensing of the chordae tendineae during rapid filling and expansion of the ventricle. In other words, an S3 heart sound indicates increased volume of blood within the ventricle. An S3 heart sound is best heard with the bell-side of the stethoscope (used for lower frequency sounds). A left-sided S3 is best heard in the left lateral decubitus position and at the apex of the heart, which is normally located in the 5th left intercostal space at the midclavicular line. A right-sided S3 is best heard at the lower-left sternal border. The way to distinguish between a left and right-sided S3 is to observe whether it increases in intensity with inhalation or exhalation. A right-sided S3 will increase on inhalation, while a left-sided S3 will increase on exhalation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 87
Incorrect
-
Concerning surface anatomy, where is the apex beat found?
Your Answer: 3rd intercostal space mid clavicular line
Correct Answer: 5th intercostal space mid clavicular line
Explanation:The location of the apex beat may vary but it is mostly found in the left 5th intercostal space 6 cm from the anterior median line or in the mid clavicular line.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 88
Incorrect
-
Which of the following structures lie in close proximity to the thyroid?
Your Answer: The recurrent laryngeal nerves.
Correct Answer: All of the options
Explanation:The thyroid gland receives its blood supply from the inferior and superior thyroid arteries. The recurrent laryngeal nerves emerges from the superior thoracic outlet bounded in part by the thyroid lobe. Two pairs of parathyroid glands lie near the thyroid. The common carotid artery splits into its external and internal branches at the upper border of the thyroid cartilage; these branches are separated by the gland.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
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Question 89
Incorrect
-
Which of the following occurs during a Valsalva manoeuvre?
Your Answer: Low intrathoracic pressures throughout
Correct Answer: An initial rise in blood pressure
Explanation:The Valsalva maneuver involves forced expiration against a closed glottis. It has several phases, each affecting the cardiovascular system differently:
- Phase I: During the initial forced expiration against the closed glottis, there is a transient rise in intrathoracic pressure, which compresses the thoracic aorta and causes a brief increase in blood pressure.
- Phase II: Continued straining leads to decreased venous return to the heart, reducing cardiac output and causing a drop in blood pressure. This phase is characterized by a compensatory increase in heart rate.
- Phase III: Upon releasing the strain, there is a sudden drop in intrathoracic pressure, which momentarily decreases blood pressure.
- Phase IV: Blood pressure then rises rapidly as venous return to the heart is restored, leading to increased cardiac output. This is often followed by a reflex bradycardia (slow heart rate).
Given these phases, the most accurate statement about what occurs during the Valsalva maneuver is the initial rise in blood pressure (Phase I).
Other options explained:
- Forced inspiration against a closed glottis: Incorrect. The Valsalva maneuver involves forced expiration, not inspiration, against a closed glottis.
- Low intrathoracic pressures throughout: Incorrect. The Valsalva maneuver involves high intrathoracic pressures due to forced expiration.
- Disruption of autonomic function: Incorrect. The Valsalva maneuver affects autonomic function but does not disrupt it. Instead, it triggers autonomic responses to changes in blood pressure and heart rate.
- No change: Incorrect. The Valsalva maneuver causes significant changes in blood pressure and heart rate.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 90
Incorrect
-
A 22-year-old female is brought to the emergency department by her friends following the consumption of an unknown drug whilst clubbing. Which of the following features point towards the use of ecstasy?
Your Answer: Respiratory depression
Correct Answer: Temperature of 39.5ºC
Explanation:Hyperthermia (Temperature 39.5 C) points towards the use of ecstasy.MDMA (3,4 – methylenedioxymethamphetamine), or more commonly known as Molly or Ecstasy, is a synthetic psychoactive substance.Patients who consumed MDMA may present in a tachycardic, hypertensive, hyperthermic, and agitated state. Adverse effects, even at minor recreational doses, include increased muscle activity (such as bruxism, restless legs, and jaw clenching), hyperactivity, insomnia, difficulty concentrating and feelings of restlessness.Treatment of MDMA overdose:Emphasis should be on maintaining the airway along with the stabilization of breathing and circulation.Patients may present obtunded due to hyponatremia requiring endotracheal intubation.For the hyperthermic patient, evaporative cooling along with ice packs to the groin and axilla are beneficial.Patients who present in severe toxicity within one hour of ingestion can receive activated charcoal PO or via an NG tube. Antipyretics, such as acetaminophen, should be avoided as they have no role and can worsen an already compromised liver.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 91
Incorrect
-
An example of cholinergic autonomic neurons are:
Your Answer: Sympathetic postganglionic neurons that cause mydriasis.
Correct Answer: Sympathetic postganglionic neurons that innervate sweat glands.
Explanation:All preganglionic neurons in both the sympathetic and parasympathetic nervous system secrete acetylcholine. The postganglionic neurotransmitter of the parasympathetic nervous system in all neurons is acetylcholine. Postganglionic fibers of the sympathetic nervous system mainly secrete Noradrenalin and Adrenalin but at sweat glands and erector pili muscles the postganglionic neurotransmitter is acetylcholine.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 92
Incorrect
-
A 35 year old female, known case of anti phospholipid syndrome, arrives at the clinic due to a swollen and painful left leg. Doppler ultrasonography confirms the diagnosis of a deep vein thrombosis. She was previously diagnosed with DVT 4 months back and was on warfarin therapy (target INR 2-3) when it occurred. How should her anticoagulation be managed?
Your Answer: A further 6 months warfarin, target INR 2 - 3
Correct Answer: Life-long warfarin, increase target INR to 3 - 4
Explanation:If the INR in the range of 2-3 has still resulted in thrombosis, the target INR is increased to 3-4. However, because the risk of bleeding increases as the INR rises, the INR is closely monitored and adjustments are made as needed to maintain the INR within the target range.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 93
Correct
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A 46 year old male, known with Rheumatoid Arthritis presents with a swollen and painful right ankle. No drug allergies are reported. On examination, the vitals are as follows: Temp: 38.8BP: 90/60 mmHgPulse: 110/min. Right ankle examination reveals tenderness, warmth, erythema and tense joint effusion. Blood samples including blood cultures are collected and fluid resuscitation is initiated. Which of the following interventions would be most appropriate for this man?
Your Answer: Administer i.v. flucloxacillin, and arrange joint aspiration urgently
Explanation:Although microscopic analysis of joint fluid aspirate and culture is the basis of septic arthritis diagnosis and should usually be collected before the administration of antibiotics, the patient is showing signs of septic shock. A delay in antibiotics might lead to worsening of symptoms so they are administered first.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 94
Correct
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If O2 makes up 21% of air, then at one atmosphere (760mmHg) it would be expected that the PO2 of inspired air should be 0,21 x 760 = 160mmHg. In the alveoli the actual measure is 149mmHg because…
Your Answer: Water is equilibrated with air
Explanation:There are several factors that determine the value of alveolar partial oxygen pressure including: the pressure of outside air, the partial pressure of inspired oxygen and carbon dioxide, the rates of total body oxygen consumption and carbon dioxide production, the rates of alveolar ventilation and perfusion. The alveolar partial pressure is lower than the atmospheric oxygen partial pressure. One reason is, as the air enters the lungs, it is humidified by the upper airway and thus the partial pressure of water vapour reduces the oxygen partial pressure as water is equilibrated with air.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 95
Incorrect
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The consensual light reflex is co-ordinated mainly in the:
Your Answer: Ciliary nucleus
Correct Answer: Edinger-Westphal nucleus
Explanation:The consensual light reflex occurs when an individual’s right eye is shielded and light shines into the left eye, constriction of the right pupil will occur, as well as the left. This is because the afferent signal sent through one optic nerve connects to the Edinger-Westphal nucleus, whose axons run to both the right and the left oculomotor nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 96
Incorrect
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Microfilaments exist in:
Your Answer: Beneath plasma membranes
Correct Answer: All of the options
Explanation:Microfilaments, also called actin filaments, are filamentous structures in the cytoplasm of cells and form part of the cytoskeleton.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 97
Incorrect
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Complement system help dispose waste products after which natural process?
Your Answer: Malignancy
Correct Answer: Apoptosis
Explanation:The complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism or apoptosis. It is part of the innate immune system.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 98
Incorrect
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The process of DNA amplification and quantification is called:
Your Answer: In situ hybridization
Correct Answer: PCR
Explanation:PCR/polymerase chain reaction is a procedure carried out in a test tube that can be used on the smallest amount of DNA to amplify it, allowing for millions of copies of specific nucleotides to be made.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 99
Correct
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A 56 year old woman presents to the clinic complaining of shoulder pain that she has been experiencing for the last 4 weeks. She does not remember getting injured previously. The pain worsens on movement especially when she is moving the arm quickly. At night, lying on the affected side is painful. Examination reveals no erythema or swelling. However, pain is felt on passive abduction between 60 to 120 degrees and she is unable to abduct the arm past 70-80 degrees. Flexion and extension are intact. What is the most likely diagnosis?
Your Answer: Supraspinatus tendonitis
Explanation:Supraspinatus tendinopathy is a common and disabling condition that becomes more prevalent after middle age and is a common cause of pain in the shoulder. A predisposing factor is resistive overuse. This patient has the classic painful arc that is a sign of shoulder impingement characteristic of supraspinatus tendonitis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 100
Incorrect
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Regarding restriction fragment length polymorphisms (RFLP) and Gene Knockout Mouse Models. All are true except:
Your Answer:
Correct Answer: In knockout mouse models a gene is turned on through targeted mutation
Explanation:In RFLP, polymorphism occurs in 98% of the non coding genome, resulting in no phenotypical change in the organism. A gene is not turned on by a mutation, rather the mutation at the restriction site will alter the DNA and the DNA will now form fragments of different lengths. PCR is a better technique than RFLP.
A knockout, as related to genomics, refers to the use of genetic engineering to inactivate or remove one or more specific genes from an organism. Scientists create knockout organisms to study the impact of removing a gene from an organism, which often allows them to then learn something about that gene’s function.
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This question is part of the following fields:
- Genetics
- Medicine
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