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Question 1
Correct
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Regarding the formation of CSF, which of the following is true?
Your Answer: Its composition resembles that of brain ECF
Explanation:In normal adults CSF volume is around 125ml to 150ml. Turnover of entire volume of cerebrospinal fluid a day is about 3 to 4 times a day. Composition of CSF is similar to that of plasma except that CSF is nearly protein-free compared with plasma and has a different electrolyte level. About 80% of CSF is produced by the choroid plexus. It is also produced by a single layer of column shaped ependymal cells. The composition and rate of CSF generation depends on several factors and is influenced by hormones and the content and pressure of blood and CSF.
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This question is part of the following fields:
- Medicine
- Neurology
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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
Correct
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The isoforms of nitric oxide synthase which are found in the nervous system (NOS1) and endothelial cells (NOS3) are activated by agents that increase which of the following intracellular electrolytes?
Your Answer: Ca
Explanation:Synthesis of nitric oxide is stimulated by activation of the NMDA receptors by certain agents. This leads to opening of the Calcium channels and an influx of calcium into the cell. This will activate the nitric oxide synthase. Nitric oxide is produced on demand.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 4
Correct
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Oxygen enters blood from the alveoli by:
Your Answer: Passive diffusion
Explanation:Oxygen enters blood from the alveoli by simple diffusion along a concentration gradient. Concentration of oxygen and the partial pressure of oxygen in the alveoli are higher than the partial pressure of oxygen in the blood. So, oxygen moves from alveoli into blood via simple diffusion according to the concentration gradient.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 5
Correct
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Which one of the following nerve fibers is involved in proprioception?
Your Answer: An α fiber
Explanation:Proprioception, also known as kinaesthesia, is the sense through which humans perceive their own position and movements. α nerve fibers are specifically involved in transmitting proprioception stimuli.
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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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How does pregnancy affect the cardiac output of a patient?
Your Answer: Increased cardiac output due to increase in heart rate and stroke volume
Explanation:Cardiac Output increases to a similar degree as the blood volume. During the first trimester cardiac output is 30-40% higher than in the non-pregnant state. Steady rises are shown on Doppler echocardiography, from an average of 6.7 litres/minute at 8-11 weeks to about 8.7 litres/minute flow at 36-39 weeks; they are due, primarily, to an increase in stroke volume (35%) and, to a lesser extent, to a more rapid heart rate (15%). There is a steady reduction in systemic vascular resistance (SVR) which contributes towards the hyperdynamic circulation observed in pregnancy
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 7
Correct
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The nucleus tractus solitaries is medullary nucleus that processes the following inputs except:
Your Answer: Sensory input from the semi-circular canal (CN VIII)
Explanation:Located in the brain stem is a series of purely sensory nuclei known as tractus solitaries. Inputs of the nucleus tractus solitaries include:Taste information from the facial nerve (anterior 2/3 of the tongue), glossopharyngeal nerve (posterior 1/3) and vagus nerve (small area on the epiglottis).Sensory information from the ear (auricular branch of the vagus nerve).Chemoreceptors and mechanoreceptors of the general visceral afferent pathway (GVA) in the carotid body via glossopharyngeal nerve, aortic bodies, and the sinoatrial node, via the vagus nerve.Chemically and mechanically sensitive neurons of the general visceral afferent pathway (GVA) with endings located in the heart, lungs, airways, gastrointestinal system, pharynx, and liver via the glossopharyngeal and vagus nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 8
Correct
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A 42 year old obese man complains of a painful swollen ankle. The pain has worsened over the past 2 weeks. He is a diabetic and gives a history of recent alcohol consumption. Joint aspirate shows rhomboid crystals with numerous neutrophils. Radiological examination shows evidence of chondrocalcinosis. Which of the following is the most likely diagnosis?
Your Answer: Pseudogout
Explanation:Pseudogout is a paroxysmal joint inflammation due to calcium pyrophosphate crystal deposition (calcium pyrophosphate dihydrate). Aetiology includes mostly idiopathic (primary form) and secondary form occurring as a result of joint trauma, familial chondrocalcinosis, hyperparathyroidism, hemochromatosis, gout, hypophosphatemia. Clinical presentation: Often asymptomatic. Acute (pseudogout attack): monoarthritis (rarely oligoarthritis), mostly affecting the knees and other large joints (e.g., hips, wrists, and ankles). It may become chronic (can affect multiple joints). Osteoarthritis with CPPD (most common form of symptomatic CPPD): progressive joint degeneration with episodes of acute inflammatory arthritis typical of pseudogout attacks. Arthrocentesis should be performed, especially in acute cases. Polarized light microscopy: detection of rhomboid-shaped, positively birefringent CPPD crystals. Synovial fluid findings: 10,000-50,000 WBCs/μL with > 90% neutrophils. X-ray findings: cartilage calcification of the affected joint (chondrocalcinosis). Fibrocartilage (meniscus, annulus fibrosus of intervertebral disc) and hyaline cartilage (joint cartilage) may be affected.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 9
Incorrect
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Which of the following affects the magnitude of the action potential?
Your Answer: Changes in the external K+ concentration
Correct Answer: Changes in the external Na+ concentration
Explanation:The magnitude of the action potential is determined by the sodium current. Increase in external sodium will result in increased influx of sodium and hence generation of a stronger action potential.
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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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Type 2 hypersensitivity is mediated by:
Your Answer: IgG, IgM & complement
Explanation:In type II hypersensitivity the antibodies, IgG and IgM bind to antigens to form complexes that activate the classical pathway of complement to eliminate cells presenting foreign antigens.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 11
Correct
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In a 70 kg male, the approximate volumes (litres) of water in the different compartments mentioned (intracellular, interstitial, vascular) are:
Your Answer: 28l, 14l, 3.5l
Explanation:In a 70kg male, approximately 60% (42 L) of the total body weight is composed of water divided proportionally in the following compartments:Intracellular fluid (ICF) – Around 67% (28 L) of total body water.Extracellular fluid (ECF) – Approximately 33% (14 L) of the total body fluid. The fluid in the intravascular compartment is about 3 L and is generally about 25% of the volume of ECF.
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This question is part of the following fields:
- Medicine
- Renal
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Question 12
Correct
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In addition to its role in digestion and absorption of fats, bile:
Your Answer: Is the major excretory route for lipid-soluble waste products
Explanation:The end product of haem metabolism is bilirubin and jaundice is caused by increased bilirubin levels in the blood. Gallstones are mainly caused by cholesterol and bile pigments. Bile is the main route of excretion for lipid soluble waste products whereas urine is the main route of excretion of water soluble waste products.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 13
Correct
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The blood supply to the greater curvature of the stomach is via the:
Your 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 14
Correct
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Renin is secreted by which of the following cells?
Your Answer: Juxtaglomerular cells
Explanation:The juxtaglomerular cells are cells in the kidney that synthesize, store, and secrete the enzyme renin. They are specialized smooth muscle cells mainly in the walls of the afferent arterioles, and some in the efferent arterioles, that deliver blood to the glomerulus.
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This question is part of the following fields:
- Medicine
- Renal
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Question 15
Correct
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Which cranial nerve is responsible for the parasympathetic nerve supply of the thorax and upper abdomen?
Your Answer: CN X
Explanation:Cranial nerve X supplies the structures of the thorax and abdomen. All the rest of the cranial nerves supply the structures in the head and neck
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This question is part of the following fields:
- Medicine
- Neurology
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Question 16
Correct
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With regards to environmental temperature, for each degree Celsius of elevation, the metabolic rate rises?
Your Answer: 0.14
Explanation:An increase in body temperature is associated with a higher metabolic rate. Evidence suggests that an increase of 1°C in your body temperature increases your metabolism by 10 to 14%.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 17
Correct
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In the body what are fatty acids broken down to?
Your Answer: Acetyl Co A
Explanation:Fatty acids are broken down into acetyl Co A. The acetyl-CoA produced by beta oxidation enters the citric acid cycle in the mitochondrion by combining with oxaloacetate to form citrate.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 18
Correct
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Which of the following statements regarding psoriasis is incorrect?
Your Answer: Mediated by type 2 helper T cells
Explanation:Psoriasis is a long-lasting autoimmune disease characterized by patches of skin typically red, dry, itchy, and scaly. Psoriasis can affect the nails and produces a variety of changes in the appearance of finger and toe nails including pitting and onycholysis. Nail psoriasis occurs in 40–45% of people with psoriasis affecting the skin and has a lifetime incidence of 80–90% in those with psoriatic arthritis. Psoriasis is mediated by type 1 helper T cells which are involved in the cell mediated response.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 19
Correct
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A 30-year-old woman is admitted for drainage of an abscess in her left forearm. She has revealed that she was regular heroin user and has stopped for the past few days. Clinical signs are pointing towards opioid withdrawal. What is the next step in managing this patient?
Your Answer: Give her 10 mg of methadone syrup and wait 60 min to determine its effect
Explanation:The next step in managing this patient is to give 10 mg and continue administering in 10 mg increments each hour until symptoms are under control.Methadone alleviates opioid withdrawal symptoms and reduces cravings. Methadone is useful for detoxification from longer-acting opioids such as morphine or methadone itself.Methadone should be used with caution if the patient has:Respiratory deficiencyAcute alcohol dependenceHead injuryTreatment with monoamine oxidase inhibitors (MAOIs)Ulcerating colitis or Crohn’s diseaseSevere hepatic impairmentThe dose must be reviewed on a daily basis and adjusted based upon how well the symptoms are controlled and the presence of side effects. The greater the dose of opioids used by the patient, the greater the dose of methadone required to control withdrawal symptoms. To avoid the risk of overdose in the first days of treatment The recommended dosing of methadone is 30mg in two doses of 15mg morning and evening.It is important to note that a methadone dose equivalent to what the patient reports they are taking should never be given. It is rare to need more than 40 mg per 24 hours: beware of overdosing which can lead to respiratory arrest.
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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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Osteopetrosis occurs as a result of a defect in:
Your Answer: Osteoclast function
Explanation:It is a metabolic bone disease caused by defective osteoclastic resorption of immature bone. Osteopetrosis is also known as marble bone disease. Osteoclasts are unable to adequately acidify bone matrix. Impaired bone resorption leads to overly dense bone that is more likely to fracture. It is usually treated with bone marrow transplant and high dose calcitriol.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 21
Correct
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A patient with a VIPoma (VIP secreting tumour) is likely to exhibit which of the following?
Your Answer: Severe diarrhoea
Explanation:Vasoactive inhibitory peptide (VIP) is found in the nerves innervating the GIT. It markedly stimulates the secretion of intestinal electrolytes and also with them water. This results in secretary diarrhoea. Along with that it also relaxes intestinal smooth muscle including the sphincters, it also results in dilation of the peripheral blood vessels and along with this its also inhibits gastric acid secretions. A VIPoma will exaggerate all this.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 22
Incorrect
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A 70-year-old male with advanced COPD currently on treatment with salbutamol (as required) presents for review. After a complete history and examination, you conclude that he requires to be stepped up in his inhalational therapy. The decision to add tiotropium bromide to his regime was taken. Which of the following best describe the mechanism of action of tiotropium?
Your Answer: It may be used freely in patients with prostatic hyperplasia
Correct Answer: It is a long-acting anticholinergic agent
Explanation:Tiotropium is a specific long-acting antimuscarinic agent indicated as maintenance therapy for patients with COPD (chronic obstructive pulmonary disease). It should be used cautiously in patients with narrow-angle glaucoma, prostatic hyperplasia or bladder neck obstruction.The most frequently encountered adverse effects of tiotropium include pharyngitis, bronchitis, sinusitis, dry mouth, cough, and headaches. Paradoxical bronchospasm may also occur as a rare side-effect. Dry mouth occurs in up to 14% of patients taking tiotropium, in keeping with its anticholinergic profile. Rarer side-effects include tachycardia, blurred vision, urinary retention, and constipation.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 23
Incorrect
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The free radical most abundantly formed by the immune system is:
Your Answer: Superoxide
Correct Answer: Hydroxyl radical
Explanation:Neutrophil and macrophage phagocytosis stimulates various cellular processes including the respiratory burst whereby increased cellular oxygen uptake results in the production of the potent oxidant bactericidal agents, hypochlorous acid and hydroxyl radical.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 24
Correct
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Which is NOT a prognostic factor for patients with malignant melanoma?
Your Answer: Diameter of melanoma > 6 mm
Explanation:Features that affect prognosis are tumour thickness in millimetres (Breslow’s depth – the deeper the Breslow thickness the poorer the prognosis.), depth related to skin structures (Clark level – the level of invasion through the dermis), type of melanoma, presence of ulceration, presence of lymphatic/perineural invasion, presence of tumour-infiltrating lymphocytes (if present, prognosis is better), location of lesion, presence of satellite lesions, and presence of regional or distant metastasis. Malignant melanoma tends to grow radially before entering a vertical growth phase. The diameter it reaches has not been found to be a prognostic factor.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 25
Correct
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Which is the most common site for primary cardiac tumours to occur in adults?
Your Answer: Left atrium
Explanation:Myxomas are the most common type of primary heart tumour. The tumour is derived from multipotential mesenchymal cells and may cause a ball valve-type obstruction. About 75% of myxomas occur in the left atrium of the heart, usually beginning in the wall that divides the two upper chambers of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 26
Correct
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Which ventral (motor) root is responsible for triceps?
Your Answer: C7
Explanation:Of the nerve fibers that make up the brachial plexus, C7 mainly forms the radial nerve to innervate the triceps muscle, thus innervating the shoulders, elbow, wrist and hand. C7 is responsible for the triceps reflex.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 27
Correct
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A 50-year-old male was brought to the ER after the accidental consumption of 300 ml of diethylene glycol. Blood investigations were suggestive of metabolic acidosis and renal failure. What is the appropriate management in this patient?
Your Answer: Haemodialysis and oral ethanol
Explanation:Among the given options the most appropriate management in this patient would be ethanol and haemodialysis.Ethanol competes with ethylene glycol for alcohol dehydrogenase and thus, helps manage a patient with ethylene glycol toxicity.Ethylene glycol is a type of alcohol used as a coolant or antifreezeFeatures of toxicity are divided into 3 stages:Stage 1: (30 min to 12 hours after exposure) Symptoms similar to alcohol intoxication: confusion, slurred speech, dizziness (CNS depression)Stage 2: (12 – 48 hours after exposure) Metabolic acidosis with a high anion gap and high osmolar gap. Also tachycardia, hypertensionStage 3: (24 – 72 hours after exposure) Acute renal failureManagement has changed in recent times:Fomepizole, an inhibitor of alcohol dehydrogenase, is now used first-line in preference to ethanol.Ethanol has been used for many years works by competing with ethylene glycol for the enzyme alcohol dehydrogenase this limits the formation of toxic metabolites (e.g. glycolaldehyde and glycolic acid) which are responsible for the hemodynamic/metabolic features of poisoning.Haemodialysis has a role in refractory cases.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 28
Correct
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Concerning the sleep-wake cycle, Melatonin is secreted by which structure in the brain following which environmental conditions?
Your Answer: Pineal gland, darkness
Explanation:Melatonin is secreted by the pineal gland located in the midline attached to the posterior roof of the third ventricle in the brain. Melatonin affects circadian rhythm in the body or the sleep wake cycle. The precursor to melatonin is serotonin and the rate limiting enzyme that converts serotonin to melatonin is low during the day time and reaches its peak during the night.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 29
Correct
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Which enzyme is deficient in the inborn error of metabolism called galactosemia?
Your Answer: Galactose-1-phosphate uridyl transferase
Explanation:Galactosaemia is a rare genetic autosomal recessive metabolic disorder. Lactose is broken down by the enzyme lactase into glucose and galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose (Galactose-1-phosphate uridyltransferase) are severely diminished or missing entirely, leading to toxic levels of galactose 1-phosphate in various tissues.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 30
Correct
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The channel that coalesces the small pancreatic duct radicles before joining the common bile duct is known as the:
Your Answer: Duct of Wirsung
Explanation:The small ducts from the pancreas coalesce into a single duct known as the pancreatic duct or the duct of Wirsung. It usually joins the bile duct at the ampulla of Vater before entering the duodenum.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 31
Correct
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Question 32
Correct
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The parietal cells of the stomach secrete which of the following?
Your Answer: Hydrochloric acid
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 33
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 34
Correct
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Question 35
Correct
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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: 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 36
Correct
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What is the main reason for checking the urea and electrolytes prior to commencing a patient on amiodarone?
Your Answer: To detect hypokalaemia
Explanation:All antiarrhythmic drugs have the potential to cause arrhythmias. Coexistent hypokalaemia significantly increases this risk.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 37
Correct
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Vagotomy leads to the following:
Your Answer: Irregular and chaotic peristalsis
Explanation:The Vagus nerve is primarily responsible for autonomic regulation involved in heart, lung and gastrointestinal function. The gastric branches supply the stomach. The right branch joins the celiac plexus and supplies the intestines. Vagotomy involves cutting of the vagus nerve or its branches which is a now-obsolete therapy that was performed for peptic ulcer disease. Vagotomy causes a decrease in peristalsis and a change in the emptying patterns of the stomach.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 38
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 39
Incorrect
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Impulse conduction through the AV node is slow and depends on the action potential produced by which of the following.
Your Answer: Sodium diffusion
Correct Answer: Calcium flux
Explanation:The action potentials in the SA and AV nodes are largely due to Ca2+, with no contribution by Na+ influx.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 40
Correct
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Question 41
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 42
Correct
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Endothelial cells are attached to adjacent cells by adherent junctions via:
Your Answer: Cadherins
Explanation:Cadherins are calcium dependant molecules that mediate cell to cell adhesions in epithelial and endothelial cells among others.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 43
Correct
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Which one of the following diuretics is associated with metabolic acidosis?
Your Answer: Acetazolamide
Explanation:Acetazolamide is in the diuretic and carbonic anhydrase inhibitor families of medication. It works by decreasing the amount of hydrogen ions and bicarbonate in the body and can thus cause metabolic acidosis and electrolyte changes (hypokalaemia, hyponatremia).
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 44
Correct
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A 39 year old woman with a history of rheumatoid arthritis has recently been switched from methotrexate to leflunomide. Monitoring of full blood count and LFTs has been carried out. Which of the following parameters should also be monitored in this case?
Your Answer: Blood pressure
Explanation:Blood pressure should be routinely measured as leflunomide may cause hypertension and thus an increase in BP. It doesn’t cause changes in blood sugar levels, peak expiratory flow rate or haematuria.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 45
Correct
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Which of the following is a physiological effect of pregnancy on the kidney?
Your Answer: Decreased creatinine
Explanation:A pregnant woman may experience an increase in kidney and ureter size. The glomerular filtration rate (GFR) commonly increases by 50%, returning to normal around 20 weeks postpartum. Plasma sodium does not change because this is offset by the increase in GFR. There is decreased blood urea nitrogen (BUN) and creatinine and potentially glucosuria (due to saturated tubular reabsorption).
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This question is part of the following fields:
- Medicine
- Renal
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Question 46
Correct
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A 73-year-old female is being reviewed in the osteoporosis clinic. She had a fracture of her left hip 5 years ago and was started on alendronate. Following the development of persistent musculoskeletal pain, alendronate was replaced with risedronate, which was also stopped for similar reasons. Strontium ranelate was therefore started but was also stopped due to the development of deep vein thrombosis in the right leg. Her current T-score is -4.1. A decision is made to start a trial of denosumab. What is the mechanism of action of denosumab?
Your Answer: Inhibits RANK ligand, which in turn inhibits the maturation of osteoclasts
Explanation:The principal mechanism by which strontium inhibits osteoclast activity is by enhancing the secretion of osteoprotegerin (OPG) and by reducing the expression of the receptor activator of nuclear factor κB ligand (RANKL) in osteoblasts.Osteoporosis is defined as low bone mineral density caused by altered bone microstructure ultimately predisposing patients to low-impact, fragility fractures.Management:Vitamin D and calcium supplementation should be offered to all women unless the clinician is confident they have adequate calcium intake and are vitamin D repleteAlendronate is the first-line treatment. Around 25% of patients cannot tolerate alendronate, usually due to upper gastrointestinal problems. These patients should be offered risedronate or etidronate.Strontium ranelate and raloxifene are recommended if patients cannot tolerate bisphosphonates.Other medications that are useful in the treatment of osteoporosis are denosumab, teriparatide, raloxifene, etc.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 47
Correct
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Select the correct statement about the microanatomy of the thyroid gland.
Your Answer: The capillaries adjacent to thyroid cells have a fenestrated endothelium.
Explanation:Fenestrated capillaries have a very thin endothelium, which is perforated by numerous fenestrations or pores. Hormones are usually released into these capillaries, reaching their target cells through the circulatory system.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 48
Correct
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Where is retinol mainly stored?
Your Answer: Liver
Explanation:Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids (most notably beta-carotene). The liver stores a multitude of substances, including glucose (in the form of glycogen), vitamin A (1–2 years’ supply), vitamin D (1–4 months’ supply), vitamin B12 (3–5 years’ supply), vitamin K, iron, and copper.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 49
Correct
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Which of the following has the shortest duration:
Your Answer: Atrial systole
Explanation:Atrial systole: 0.1s
Atrial diastole: around 0.4s
Ventricular diastole: 0.4-0.53s
Ventricular systole: 0.27s
PR interval: 0.12-0.2 s
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 50
Correct
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Which of the following is true of the Natriuretic hormones?
Your Answer: They are released in response to hypervolemia
Explanation:Natriuretic hormones are vasodilators released in response to hypervolemia.
Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides NPs (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain.
Atrial natriuretic peptide (ANP) plays a crucial role in blood pressure regulation by inducing natriuresis and diuresis in the kidney, inhibiting renin secretion, aldosterone production, and promoting vasorelaxation. Two paracrine factors derived from endothelial cells play important roles in modulating ANP secretion. Endothelin, a potent vasoconstrictor, stimulates ANP secretion and augments stretch induced ANP secretion. The dramatic increase in ANP release produced by cardiac ischemia appears to be mediated in part by endothelin. Nitric oxide (NO), an important vasodilator, is also produced by endothelial cells and inhibits ANP secretion.
Brain natriuretic peptide (BNP) shares ANP’s receptor but is primarily associated with antifibrotic effects in ventricular remodeling, serving as a biomarker for heart failure and myocardial infarction.
C-type natriuretic peptide (CNP) acts locally in an autocrine/paracrine manner, exerting potent cardiovascular effects, including vasorelaxation and vascular remodeling post-injury. NPs also demonstrate diverse effects beyond cardiovascular and renal systems, such as bronchodilation, anti-inflammatory actions, and metabolic effects on adipose tissue and long bones.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 51
Correct
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A 32 year old male who has recently returned from a trip to Thailand presents with congestion of eyes and swelling of the knee joint. He completed a course of antibiotics for dysentery 4 weeks back. He experiences no dysuria and urine examination is normal. Which further information would be most useful in establishing a diagnosis?
Your Answer: History and physical examination
Explanation:The patient most likely has reactive arthritis which is usually diagnosed on history and clinical examination. The classic triad of symptoms include conjunctivitis, urethritis and arthritis. Arthritis and conjunctivitis may occur 4-6 weeks after a gastrointestinal or genitourinary infection. Arthritis usually occurs acutely, mostly involving the lower limb and is asymmetrical. Blood culture, urine culture and arthrocentesis (joint aspiration) will not yield positive results.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 52
Correct
-
As assessed by immunocytochemistry and electron microscopy, the anterior pituitary gland contains how many different types of cells?
Your Answer: 5
Explanation:The pituitary is divided into three sections
-the anterior lobe which constitute the majority of the pituitary mass and is composed primarily of five hormone-producing cell types (thyrotropes, lactotropes, corticotropes, somatotropes and gonadotropes) each secreting thyrotropin, prolactin, ACTH, growth hormone and gonadotropins (FSH and LH) respectively.
There is also a sixth cell type in the anterior lobe -the non-endocrine, agranular, folliculostellate cells.
The intermediate lobe produces melanocyte-stimulating hormone and endorphins, whereas the posterior lobe secretes anti-diuretic hormone (vasopressin) and oxytocin.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 53
Incorrect
-
A 68 year old female is on long term prednisolone therapy for polymyalgia rheumatica. Which of the following would be the most suitable protection against osteoporosis?
Your Answer: Calcium and vitamin D
Correct Answer: Oral bisphosphonate
Explanation:Prevention of osteoporosis associated with chronic glucocorticoid therapy is done by administrating bisphosphonates. Oral bisphosphonates are indicated for patients aged above 65 who have been on steroid therapy for over 3 months, so as to reduce the risk of steroid induced osteoporosis. HRT is usually done in post menopausal women who have oestrogen related bone resorption.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 54
Correct
-
A 43 year old man with hemochromatosis presents with a painful and swollen right knee. X-ray shows extensive chondrocalcinosis but no fracture. Given the most likely diagnosis, which of the following would be present in the joint fluid aspirate?
Your Answer: Positively birefringent rhomboid-shaped crystals
Explanation:Pseudogout is a paroxysmal joint inflammation due to calcium pyrophosphate crystal deposition (calcium pyrophosphate dihydrate). Arthrocentesis should be performed, especially in acute cases. Polarized light microscopy: detection of rhomboid-shaped, positively birefringent CPPD crystals. Synovial fluid findings: 10,000-50,000 WBCs/μL with > 90% neutrophils. X-ray findings: cartilage calcification of the affected joint (chondrocalcinosis). Fibrocartilage (meniscus, annulus fibrosus of intervertebral disc) and hyaline cartilage (joint cartilage) may be affected.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 55
Correct
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Question 56
Correct
-
Which of the following suggests the presence of mitral regurgitation as well as mitral stenosis?
Your Answer: Displaced apex beat
Explanation:Mitral stenosis on its own does not lead to left ventricular dilatation and hence a displaced apex beat. Thus a displaced apex beat is suggestive of mixed mitral disease. The other options occur in mitral stenosis.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 57
Correct
-
A deficiency in Cyanocobalamin leads to which clinical deficiency syndrome?
Your Answer: Pernicious anaemia
Explanation:The main syndrome of vitamin B12 deficiency is pernicious anaemia. It is characterized by a triad of symptoms:Megaloblastic anaemiaGastrointestinal symptoms &Neurological symptoms
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 58
Correct
-
Which of the following corresponds to an oblique line drawn from the sternal end of the left 3rd costal cartilage to the sternal end of the right 6th costal cartilage?
Your Answer: Atrio-ventricular (coronary) groove
Explanation:The AV groove corresponds to the right border of the heart. The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 59
Correct
-
The functional unit of the liver is called?
Your Answer: Acini
Explanation:From a metabolic perspective, the functional unit is the hepatic acinus (terminal acinus), each of which is centred on the line connecting two portal triads and extends outwards to the two adjacent central veins. The periportal zone I is nearest to the entering vascular supply and receives the most oxygenated blood, making it least sensitive to ischemic injury while making it very susceptible to viral hepatitis. Conversely, the centrilobular zone III has the poorest oxygenation, and will be most affected during a time of ischemia.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 60
Correct
-
Coronary arteries fill up during
Your Answer: Diastole
Explanation:During contraction of the ventricular myocardium (systole), the subendocardial coronary vessels (the vessels that enter the myocardium) are compressed due to the high ventricular pressures. This compression results in momentary retrograde blood flow (i.e., blood flows backward toward the aorta) which further inhibits perfusion of myocardium during systole. However, the epicardial coronary vessels (the vessels that run along the outer surface of the heart) remain open. Because of this, blood flow in the sub endocardium stops during ventricular contraction. As a result, most myocardial perfusion occurs during heart relaxation (diastole) when the subendocardial coronary vessels are open and under lower pressure.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 61
Correct
-
The residual cleft of the intermediate lobe of the pituitary is lined by follicles resembling which human gland?
Your Answer: Thyroid
Explanation:The cells located between the two main pituitary lobes form what is known as the intermediate pituitary. This area secretes melanocyte-stimulating hormone and it is only a few cell layers thick. It is rich in follicles filled with colloid, and lined by basophilic cells. This configuration resembles that of another important gland: the thyroid.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 62
Correct
-
Depolarization spreads rapidly through cardiac muscle fibers because of the presence of:
Your Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in between the cells. They allow for the formation of low resistance passages, which allow ions to diffuse through every muscle fiber rapidly and result in the cardiac muscles functioning as a syncytium, without any protoplasmic bridges involved.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 63
Correct
-
VIP, GIP and somatostatin play an inhibitory role in gastric acid secretion by inactivating?
Your Answer: G cells
Explanation:Gastrin is secreted from the G cells. VIP, GIP and somatostatin all inhibit acid production by inhibiting the G cells.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 64
Correct
-
Arterioles stemming from the coronary artery can also empty into the heart directly via the:
Your Answer: Arteriosinusoidal vessels
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers. They include arteriosinusoidal vessels, which connect the arterioles to the heart chambers. The thebesian veins drain the capillaries into the chambers and the arterioluminal vessels drain small arteries directly into the chambers.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 65
Correct
-
The bradycardia that occurs in patients with raised intracranial pressure is a result of the?
Your Answer: Cushing reflex
Explanation:When intracranial pressure is increased, the blood supply to RVLM neurons is compromised. This results in an increase in their discharge as a result of hypoxia and hypercapnia. The resultant rise in systemic arterial pressure (Cushing reflex) tends to restore the blood flow to the medulla.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 66
Correct
-
Which statement regarding fever is correct:
Your Answer: Body temperature is regulated is by a centre in the floor of the third ventricle
Explanation:The hypothalamus is located on the floor of the third ventricle and is the centre of regulation of body temperature. It uses a set point to regulate other body systems as well. Diurnal variation of temperature is not seen in humans. the principal mediator of fever is interleukin I, although interferon alfa also plays a role. Fever can cause rhabdomyolysis or muscle breakdown
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 67
Correct
-
The mechanism of action of low molecular weight heparin, has the greatest effect on which of the following components of the coagulation cascade?
Your Answer: Factor Xa
Explanation:Mechanism of action of low molecular weight heparin (LMWH): It inhibits coagulation by activating antithrombin III. Antithrombin III binds to and inhibits factor Xa. In doing so it prevents activation of the final common path; Xa inactivation means that prothrombin is not activated to thrombin, thereby not converting fibrinogen into fibrin for the formation of a clot. LMHW is a small fragment of a larger mucopolysaccharide, heparin. Heparin works similarly, by binding antithrombin III and activating it. Heparin also has a binding site for thrombin, so thrombin can interact with antithrombin III and heparin, thus inhibiting coagulation. Heparin has a faster onset of anticoagulant action as it will inhibit not only Xa but also thrombin, while LMWH acts only on Xa inhibition.Compared to heparin, LMWHs have a longer half-life, so dosing is more predictable and can be less frequent, most commonly once per day.Dosage and uses:LMWH is administered via subcutaneous injection. This has long-term implications on the choice of anticoagulant for prophylaxis, for example, in orthopaedic patients recovering from joint replacement surgery, or in the treatment of DVT/PE.Adverse effects:The main risk of LMWH will be bleeding. The specific antidote for heparin-induced bleeding is protamine sulphate.Less commonly it can cause:Heparin-induced thrombocytopenia (HIT)Osteoporosis and spontaneous fracturesHypoaldosteronismHypersensitivity reactions
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 68
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 69
Correct
-
The steps of cardiac cycle in sequence are:
Your Answer: Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.1st stage: diastole, or passive filling is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. 2nd stage: atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle (active filling).3rd stage: isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. 4th stage: ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. 5th stage: isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 70
Incorrect
-
Organophosphates, such as Sarin, have been used as chemical-warfare agents by terrorists. Which of the following statements is true concerning organophosphate poisoning?
Your Answer: Their principal action is the stimulation of acetylcholinesterase activity
Correct Answer: Atropine is useful in the management of organophosphate poisoning
Explanation:The principal action of organophosphates is the inhibition of acetylcholinesterase’s, therefore leading to the accumulation of acetylcholine at muscarinic receptors (miosis, hypersalivation, sweating, diarrhoea, excessive bronchial secretions), nicotinic receptors (muscle fasciculations and tremor) and in the central nervous system (anxiety, loss of memory, headache, coma). Removal from the source of the organophosphate, adequate decontamination, supplemental oxygen and atropine are the initial treatment measures. Pralidoxime, an activator of cholinesterase, should be given to all symptomatic patients.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 71
Incorrect
-
In the olfactory pathway: Mitral cells project to five regions of the olfactory cortex. Which one of the following is not one of the five regions?
Your Answer: Entorhinal cortex
Correct Answer: Posterior olfactory nucleus
Explanation:The olfactory system contains peripheral and central divisions which are connected by transduction structures. Peripheral division consists mainly of the nostrils, ethmoid bone, nasal cavity, and the olfactory epithelium. Olfactory neurons are receptor cells in the epithelium that detect odour molecules dissolved in the mucus and transmit information about the odour to the brain in a process called sensory transduction. Olfactory nerves and fibers transmit information about odours from the peripheral olfactory system to the central olfactory system of the brain. The main olfactory bulb transmits pulses to both mitral and tufted cells, which help determine odour concentration. These cells also note differences between highly similar odours and use that data to aid in later recognition. The cells are different with the mitral having low firing-rates and being easily inhibited by neighbouring cells, while tufted have high rates of firing and are more difficult to inhibit. The uncus houses the olfactory cortex which includes the piriform cortex, amygdala, olfactory tubercle, and para-hippocampal gyrus. Entorhinal cortex is an area of middle temporal lobe that has connection with the para-hippocampal gyrus.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 72
Incorrect
-
Coronary vasoconstriction can be caused by:
Your Answer: Hypoxia
Correct 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 73
Correct
-
Cold receptors are likely to be active at the following temperatures except?
Your Answer: 39 °C
Explanation:Cold and Menthol receptor 1 (CMR1) is a protein that in humans is encoded by TRPM8 gene. It is primarily responsible for the detection of temperatures ranging from 8-28 C. It is an ion channel which upon activation causes the influx of Na+ and Ca+ ions into the cell that leads to the depolarization and generation of an action potential.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 74
Incorrect
-
Which factors increase the end-diastolic volume?
Your Answer: Infiltrative disease
Correct Answer: Constriction of veins
Explanation:End diastolic volume is also known as preload. It is the amount of blood the heart contracts against. Constriction of veins will decrease venous pooling and increase venous return, hence increasing the end diastolic volume. Standing will increase venous pooling hence decreasing venous return and end diastolic volume. Raised intrapericardial pressure will also decrease venous return and hence end diastolic volume.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 75
Incorrect
-
With regards to P53, which statement is NOT true?
Your Answer: P53 plays a role in programmed cell death
Correct Answer: P53 is a RNA binding protein
Explanation:P53 is a tumour suppressor gene. It is not an RNA binding protein. It has been implicated in almost all tumours. It regulates the progression from G1 to the S phase of the cell cycle and is activated in response to damaged DNA.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 76
Incorrect
-
Where are the cell bodies of preganglionic neurons located?
Your Answer: Spinothalamic tract
Correct Answer: Lateral column
Explanation:The cell bodies of the preganglionic neurons are located in the lateral grey column of the spinal cord and in the motor nuclei of the 3rd, 7th, 9th and 10th cranial nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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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
-
A 23 year old man presents with a painful right elbow and left Achilles tendon. He also gives history of dysuria, fever and conjunctivitis. Examination reveals macules and pustules on his hands. He has returned from a trip to Far East 3 weeks ago and admits to having unprotected sex. Which of the following is the most likely diagnosis?
Your Answer: Gonococcal arthritis
Correct Answer: Reactive arthritis
Explanation:Reactive arthritis, (formerly known as Reiter’s syndrome), is an autoimmune condition that occurs after a bacterial infection of the gastrointestinal or urinary tract. It is categorized as a seronegative spondylarthritis because of its association with HLA-B27. Reactive arthritis primarily affects young men and usually presents with musculoskeletal or extra‑articular symptoms. The characteristic triad consists of arthritis, conjunctivitis, and urethritis. The diagnosis is based on clinical features such as patient history and physical examination; there are no specific tests for reactive arthritis. Treatment is primarily symptomatic and consists of the administration of NSAIDs, as most patients recover spontaneously. extraarticular dermatologic manifestations include skin lesions of the glans resembling psoriasis (balanitis circinata); hyperkeratinisation of the palms and soles (keratoderma blenorrhagicum), oral ulcers. Other STDs including HIV, syphilis have different presentations. Psoriatic arthritis is not commonly associated with urethritis and conjunctivitis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
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Question 79
Incorrect
-
In the presence of oxygen , lactate that was produced under anaerobic conditions is converted to:
Your Answer: Oxaloacetate
Correct Answer: Pyruvate
Explanation:Lactate can be used in two ways:Oxidation back to pyruvate by well-oxygenated muscle cells, heart cells, and brain cells. Pyruvate is then directly used to fuel the Krebs cycle orConversion to glucose via gluconeogenesis in the liver and release back into circulation.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 80
Incorrect
-
A 52-year-old man has squamous-cell carcinoma of his lower lip. Which of the following is most likely to be a feature of this type of carcinoma?
Your Answer: It is unrelated to sun exposure
Correct Answer: It is capable of metastasising via the lymphatics
Explanation:Squamous-cell skin cancer usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months and it is more likely to spread to distant areas than basal cell cancer vie the lymphatics. The greatest risk factor is high total exposure to ultraviolet radiation from the Sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen’s disease, arsenic exposure, radiation therapy, poor immune system function, previous basal cell carcinoma, and HPV infection. While prognosis is usually good, if distant spread occurs five-year survival is ,34%
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 81
Incorrect
-
Amongst the following cells, which is responsible for the secretion of defensins?
Your Answer: Eosinophils
Correct Answer: Neutrophils
Explanation:Eosinophils are phagocytic and they are directed against helminths. Basophils are involved in allergic reactions and contain histamine and vasoactive granules in their cytoplasm. Mast cells are similar to basophils. Monocytes differentiate into macrophages in the tissue, secret interleukins and are phagocytic. Neutrophils are phagocytic but are also responsible for secreting defensins.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 82
Incorrect
-
In increasing order of concentration, the main anions in plasma are:
Your Answer: SO42-, Phosphates-, HCO3-, Cl-
Correct Answer: Proteins-, HCO3-, Cl-,
Explanation:Anions are negatively charged ions and include: chloride Cl-, bicarbonate HCO3-, sulphate SO4-2, phosphate HPO4-2, and protein anions. Chloride it the most abundant anion followed by bicarbonate and then protein anions.
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This question is part of the following fields:
- Medicine
- Renal
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Question 83
Incorrect
-
Calcium is transported over the brush border in the gut, via which transporter / channel?
Your Answer: TRPV 5
Correct Answer: TRPV 6
Explanation:Transient Receptor Potential Vanilloid 6 or TRPV 6 is a calcium channel located in the cell membrane which is present in a variety of organs, including small intestine, oesophagus, stomach, colon, placenta, kidney, and uterus. In the intestine, it is located in the apical brush-border membrane of the enterocyte, regulating the entry of calcium into the cell.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 84
Incorrect
-
A 26 year old male presents with right sided elbow and wrist pain and left sided knee and ankle pain that has persisted for about two weeks. He recently returned from a trip to Thailand that last for two weeks. The patient admits to having unprotected sex while on holiday. Examination reveals swelling and tenderness of tendons around joints but no inflammation of the joints. A vesiculopustular skin rash is also observed. What is the most likely cause?
Your Answer: Gout
Correct Answer: Gonococcal arthritis
Explanation:Patients with disseminated gonococcal arthritis may present with dermatitis-arthritis syndrome (60%) of with localized septic arthritis. (40%). Arthritis-dermatitis syndrome includes the classic triad of dermatitis, tenosynovitis, and migratory polyarthritis. Gout usually involves a singe joint and does not cause vesicopustular skin rash. Reactive arthritis has ocular symptoms (conjunctivitis), urethritis, and arthritis. Fungal arthritis occurs rarely and it may occur after a surgical infection or fungal spread hematogenously. it presents with tender, red, hot and swollen joint with loss of range of motion.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 85
Incorrect
-
Which of the following are exclusively innervated by parasympathetic nerves?
Your Answer: Gall bladder
Correct Answer: Circular muscle of iris
Explanation:Circular muscle of iris is exclusively supplied by the parasympathetic nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 86
Incorrect
-
Which of the following enzymes is mainly responsible for the hydrolysis of polysaccharide 1:6a linkages?
Your Answer: Maltase
Correct Answer: Isomaltase
Explanation:Isomaltase is mainly responsible for hydrolysis of 1:6α linkages. Along with maltase and sucrase, it also breaks down maltotriose and maltose.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 87
Incorrect
-
Following an action potential, cytosolic Ca2+ is increased. The binding of free Ca2+ to troponin C results in all of the following except:
Your Answer: Induction of a conformational change in tropomyosin
Correct Answer: Weakening of the troponin i interaction with actin
Explanation:At rest, troponin i is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When Calcium enters into the muscle, it binds with troponin C and cause a structural change in troponin i which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
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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 vitamin deficiencies is associated with xerophthalmia?
Your Answer: Ascorbic acid (vitamin C)
Correct Answer: Vitamin A
Explanation:Xerophthalmia caused by a severe vitamin A deficiency is described by pathologic dryness of the conjunctiva and cornea. The conjunctiva becomes dry, thick and wrinkled. If untreated, it can lead to corneal ulceration and ultimately to blindness as a result of corneal damage.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 89
Incorrect
-
During which stage does the mitotic apparatus dissolute?
Your Answer: Metaphase
Correct Answer: Telophase
Explanation:In telophase the nuclear envelope along with the nucleolus will reappear. The daughter nuclei will enlarge as the chromosome will decondense again. Along with this, cytokinesis will occur. At the end of cytokinesis the daughter centrioles will move from the poles to the intercellular bridge where they will be disassembled and complete the separation of the daughter cells
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This question is part of the following fields:
- Genetics
- Medicine
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Question 90
Correct
-
The coronary arteries supply which part of the heart’s subendocardial region exclusively in diastole?
Your Answer: Left ventricle
Explanation:It is only during diastole that the blood flows to the subendocardial portion of the left ventricle, as the heart muscle relaxes and the coronary arteries regain their patency.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 91
Incorrect
-
Within the hypothalamus, the dopamine-secreting neurones of the intrahypothalamic system have their cell bodies in which nuclei?
Your Answer: Supraoptic
Correct Answer: Arcuate
Explanation:Arcuate nucleus dopaminergic neurons consist of a single group of neurons that project to the median eminence where they release dopamine into the hypophyseal portal circulation to inhibit pituitary prolactin secretion.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
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Question 92
Correct
-
The following is true in relation to coronary venous drainage?
Your Answer: Most venous return ultimately drains into right atrium via the coronary sinus
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 93
Incorrect
-
Regarding cardiac contractility, catecholamines exert their inotropic effect via:
Your Answer: Β2-adrenergic receptors and gs
Correct Answer: Β1-adrenergic receptors and gs
Explanation:Catecholamines exert their inotropic effect on the heart via the B1 adrenergic receptors and Gs, stimulating adenyl cyclase and increasing the production of cAMP.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 94
Correct
-
There will be a proportion of people in a population who have the given condition, disease or attribute at a specified point in time or over a specified period of time. Which of following is the best term which can describe the above?
Your Answer: Incidence
Explanation:Prevalence refers to the total number of cases of a particular disease or condition present in a population at a specific point in time or over a specified period. It provides a measure of how widespread the disease or condition is within the population.
Specificity and sensitivity are terms used to describe the accuracy of diagnostic tests.
Probability refers to the likelihood of an event occurring.
Incidence is a measure of how commonly or frequently a disease occurs in a specified population over a period by providing a quick measurement of new disease diagnoses.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 95
Incorrect
-
The febrile response to PGE2 will be impaired with the knockout of which one of the following prostaglandin receptors?
Your Answer: Ep1
Correct Answer: Ep3
Explanation:Prostaglandin EP3 receptor is a receptor for prostaglandin E2. Fever occurs as a result of the action of prostaglandin E2 and requires EP3 receptors in the preoptic area. Therefore, if there is an absence of EP3 receptors, fever caused by prostaglandin E2 will not occur.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 96
Correct
-
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 97
Incorrect
-
When observing a JVP, which of the following would lead to prominent v waves?
Your Answer: Constrictive pericarditis
Correct Answer: Tricuspid regurgitation
Explanation:The v wave corresponds to Venous filling when the tricuspid valve is closed and venous pressure increases from venous return. In Tricuspid regurgitation there is additional blood from the regurgitant flow and thus this leads to a more prominent V wave.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 98
Correct
-
Which of the following is true regarding platelets?
Your Answer: Normally have a half-life of about 8 days
Explanation:Platelets have no cell nucleus: they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow, and then enter the circulation. They have a half life of 5-9 days.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 99
Incorrect
-
Factors influencing cardiac output include which of the following?
Your Answer: Eating
Correct Answer: All of the above
Explanation:There is a correlation between resting CO and body surface area. The output per min per square meter of body surface (the cardiac index) averages 3.2l.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 100
Incorrect
-
Which of the following is the correct way to calculate the anion gap?
Your Answer: (HCO3 + Cl) – (Na + K)
Correct Answer: (Na + K) – (HCO3 + Cl)
Explanation:The anion gap is the difference between the measured cations (positively charged ions) and the measured anions (negatively charged ions) in serum, plasma, or urine. The magnitude of this difference in the serum is often calculated in medicine when attempting to identify the cause of metabolic acidosis. Anion Gap = ([Na+] + [K+]) − ([Cl−] + [HCO−3])
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This question is part of the following fields:
- Medicine
- Renal
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Question 101
Incorrect
-
Cranial nerves VI, VII, VIII enter/exit the base of the brain at the:
Your Answer: Medulla
Correct Answer: Ponto-medullary junction
Explanation:Cranial nerves III, IV and V exit from the pons, VI, VII, VIII exit from the pontomedullary junction and cranial nerve IX, X, XI, XII exit from the medulla.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 102
Incorrect
-
Sinus bradycardia may be caused by disease of which of the following:
Your Answer: Left marginal artery
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 103
Incorrect
-
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: Anaemia
Correct 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 104
Incorrect
-
The effects of β1 stimulation include the following
Your Answer: Dephosphorylation of phospholambin
Correct Answer: Increased strength of contraction
Explanation:β1 stimulation include the phosphorylation of L type Ca++ channels and phospholamban and increased Ca++ influx from myocytes.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 105
Incorrect
-
A 32 year old female is diagnosed with SLE based on her complaints of polyarthralgia, mouth ulcers and ANA positivity. Labs reveal normal urinalysis, urea and electrolytes. ESR is 90mm in the first hour. How will you manage this patient?
Your Answer: Prednisolone 10 mg/day
Correct Answer: Hydroxychloroquine 200 mg/day
Explanation:Hydroxychloroquine is used in the management of SLE as it prevents disease progression and has relatively mild side effects, for instance headache, nausea etc. Its use reduces the usage of corticosteroids. It is particularly effective when the disease is less severe and there is no organ involvement. Cyclophosphamide and prednisolone are indicated in cases of renal, neurological and lung involvement.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
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Question 106
Incorrect
-
In the clotting mechanism, activation of factor IX can occur through the direct actions of:
Your Answer: Factor XIa & XIIa
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 107
Incorrect
-
In the normal adult, haematopoiesis is present
Your Answer: Skull
Correct Answer: Axial skeleton and proximal ends of long bones
Explanation:In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum.
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This question is part of the following fields:
- Haematology
- Medicine
-
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Question 108
Correct
-
A 22-year-old university student is admitted after taking drugs at a night club. Which of the following features suggest she had taken ecstasy (MDMA)?
Your Answer: A pyrexia of 40°C
Explanation:MDMA commonly known as ecstasy or molly, is a psychoactive drug primarily used as a recreational drug. The desired effects include altered sensations, increased energy, empathy, and pleasure. Features of MDMA abuse include hyponatraemia, tachycardia, hyperventilation, and hyperthermia.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 109
Correct
-
The growth promoting protein anabolic effects of insulin are mediated by:
Your Answer: Phosphatidylinositol 3-kinase
Explanation:Phosphatidylinositol 3-kinase or PI-3Ks are a group of enzymes which are involved in a number of different cellular functions. PI-3Ks interact with insulin and the insulin receptor substrate, regulating glucose uptake. They are an important element in the insulin signalling pathway.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
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Question 110
Incorrect
-
Arachidonic acid is converted to:
Your Answer: Phospholipase A2
Correct Answer: Prostaglandin H2
Explanation:The enzymes cyclooxygenase-1 and -2 (i.e. prostaglandin G/H synthase 1 and 2 {PTGS1 and PTGS2}) metabolize arachidonic acid to Prostaglandin G2 and prostaglandin H2.
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This question is part of the following fields:
- Immunology
- Medicine
-
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Question 111
Incorrect
-
Which one of the following transporters is involved in facilitated diffusion?
Your Answer: P-glycoprotein
Correct Answer: GLUT2
Explanation:GLUT 2 is a bidirectional transporter, allowing glucose to flow in 2 directions via facilitated diffusion. Is expressed by renal tubular cells, liver cells and pancreatic beta cells. It is also present in the basolateral membrane of the small intestine epithelium.
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This question is part of the following fields:
- Cell Biology
- Medicine
-
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Question 112
Correct
-
According to Starling's law of the heart:
Your Answer: The extent of the preload is proportional to the end-diastolic volume
Explanation:Frank starlings law describes that an increase in the venous return or the end diastolic volume will cause an increase in the stroke volume/ preload and also cardiac output. It stems from the fact that increased venous return will increase the stretch on the ventricular muscle fibers. The sarcomere will stretch a considerable length that is needed for maximum contraction and the development of tension in the muscle fiber. The greater the venous return the greater the cardiac output. This relationship is directly proportional.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 113
Incorrect
-
The length of DNA is generally measured in terms of the number of:
Your Answer: Histones
Correct Answer: Base pairs
Explanation:As DNA is made up of nucleotides, its length is measured by the number of base pairs in the DNA molecules.
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This question is part of the following fields:
- Genetics
- Medicine
-
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Question 114
Incorrect
-
Which of the following tracts are involved in the control of vital functions?
Your Answer: Spinocerebellar
Correct Answer: Reticulospinal
Explanation:Reticulospinal tract pass down from the reticular formation of the mid brain, pons and medulla. It descends in the lateral white column. Both sets of fibers enter the anterior grey column and may facilitate or inhibit the gamma and alpha neurons. By this means the reticulospinal tract controls voluntary and reflex activities. It also contains the descending autonomic fiber, thus providing a pathway for the hypothalamus to control the sympathetic and parasympathetic pathways.
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This question is part of the following fields:
- Medicine
- Neurology
-
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Question 115
Incorrect
-
Regarding taste threshold and intensity discrimination:
Your Answer: 50% change in concentration of substance tasted is necessary before an intensity difference can be detected
Correct Answer: 30% change in concentration of substance tasted is necessary before an intensity difference can be detected
Explanation:The ability of humans to differentiate differences in intensity of taste is poor. A 30% change in the concentration of the substance being tasted is required before an intensity difference is perceived.
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This question is part of the following fields:
- Medicine
- Neurology
-
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Question 116
Incorrect
-
Which of the following foods do NOT contain high levels of folate?
Your Answer: Green leafy vegetables
Correct Answer: Yellow vegetables
Explanation:Folate naturally occurs in a wide variety of foods, including vegetables (particularly dark green leafy vegetables), fruits and fruit juices, nuts, beans, peas, dairy products, poultry and meat, eggs, seafood, grains, and some beers. Avocado, beetroot, spinach, liver, yeast, asparagus, and Brussels sprouts are among the foods with the highest levels of folate
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This question is part of the following fields:
- Haematology
- Medicine
-
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Question 117
Incorrect
-
Pendrin is a Cl-/I- exchanger whose function is:
Your Answer: Uptake of iodide across the basolateral membrane into the thyrocyte
Correct Answer: Transfer of iodide across the thyrocyte apical membrane into the colloid
Explanation:Pendrin is an anion transporter present in the inner ear, thyroid and kidney. It regulates the entrance of iodide from the thyroid cell to the colloid space. It has been proposed that its role could be the maintenance of the ionic composition of the endolymph.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
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Question 118
Incorrect
-
The parasympathetic function of the facial nerve is:
Your Answer: Control of ear ossicle function to limit the amount of sound transmitted in the inner ear.
Correct Answer: Secretion of tears from lacrimal glands, secretion of saliva from the sublingual and submandibular salivary glands.
Explanation:Facial nerve (Cranial Nerve VII) has both sensory and motor components so it is a mixed nerve. It carries axons of:General somatic afferent – to skin and the posterior earGeneral visceral efferent – which innervate sublingual, submandibular and lacrimal glands and the mucosa of the nasal cavity.General visceral afferent – provide sensation to soft palate and parts of the nasal cavity.Special visceral efferent – innervate muscles of facial expression and stapedius, the posterior belly of the digastric and the stylohyoid musclesSpecial visceral afferent – provide taste to the anterior two-thirds of the tongue via chorda tympani.
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This question is part of the following fields:
- Medicine
- Neurology
-
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Question 119
Incorrect
-
Which of the following conditions is least likely to exhibit the Koebner phenomenon?
Your Answer: Psoriasis
Correct Answer: Lupus vulgaris
Explanation:The Koebner phenomenon refers to skin lesions appearing on lines of trauma, exposure to a causative agents including: molluscum contagiosum, warts and toxicodendron dermatitis or secondary to scratching rather than an infective or chemical cause include vitiligo, psoriasis, lichen planus, lichen nitidus, pityriasis rubra pilaris, and keratosis follicularis (Darier disease).
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This question is part of the following fields:
- Dermatology
- Medicine
-
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Question 120
Incorrect
-
A 28 year old man presents to the clinic with fatigue, exertional dyspnoea, abdominal discomfort, xerophthalmia and xerostomia. Examination reveals enlargement of the parotid glands bilaterally, hepatomegaly and peripheral motor neuropathy. Lab results are negative for RF, ANA, SS-A and SS-B antibodies. What is the most likely diagnosis?
Your Answer: Lymphoma
Correct Answer: Diffuse infiltrative lymphocytic syndrome (DILS)
Explanation:The Diffuse Infiltrative Lymphocytosis Syndrome (DILS) is a rare multisystemic syndrome described in HIV-infected patients. It is characterised by CD8(+) T-cell lymphocytosis associated with a CD8(+) T-cell infiltration of multiple organs. DILS is usually seen in uncontrolled or untreated HIV infection but can also manifest itself independently of CD4(+) T-cell counts. The syndrome may present as a Sjögren-like disease that generally associates sicca signs with bilateral parotiditis, lymphadenopathy, and extra glandular organ involvement. The latter may affect the lungs, nervous system, liver, kidneys, and digestive tract. Anomalies of the respiratory system are often identified as lymphocytic interstitial pneumonia. Facial nerve palsy, aseptic meningitis or polyneuropathy are among the more frequent neurological features. Hepatic lymphocytic infiltration, lymphocytic interstitial nephropathy and digestive tract lymphocytic infiltration account for more rarely noted complications. Sicca syndrome, organomegaly and/or organ dysfunction associated with polyclonal CD8(+) T-cell organ-infiltration are greatly suggestive of DILS in people living with HIV.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
-
Question 121
Incorrect
-
The thalamic main input from the cortex is via which tracts?
Your Answer: Corticospinal tracts
Correct Answer: Thalamocortical pathway
Explanation:The thalamus is connected to cerebral cortex via the thalamocortical radiation.
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This question is part of the following fields:
- Medicine
- Neurology
-
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Question 122
Incorrect
-
What is the name of the area that indicates the site of active B lymphocyte proliferation?
Your Answer: Medulla
Correct Answer: Germinal centre
Explanation:The cortex of the lymph node consists of the lymphoid nodules and sinusoids and posses a germinal centre from which B cells proliferate.
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This question is part of the following fields:
- Immunology
- Medicine
-
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Question 123
Incorrect
-
Di and tri peptides are absorbed via a different mechanism as amino acids, this is due to the working of which transporter?
Your Answer: GLUT 1
Correct Answer: PEPT 1
Explanation:GLUT and SGLT are glucose transporters. Peptides which are longer that four amino acids are not absorbed. There is abundant absorption of di and tri peptidases in the small intestine. They are absorbed into the epithelial cells of the small intestine via a transporter called PepT1 by co-transport with H+ ions.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
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Question 124
Incorrect
-
The energy needed for glycogen synthesis comes from which compound?
Your Answer: ATP
Correct Answer: UTP
Explanation:Glycogen synthesis is, unlike its breakdown, endergonic—it requires the input of energy. Energy for glycogen synthesis comes from uridine triphosphate (UTP)
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 125
Incorrect
-
What catalyses the conversion of adenosine to inosine?
Your Answer: Nucleosidase
Correct Answer: Adenosine deaminase
Explanation:Adenosine deaminase (ADA) is an enzyme involved in purine metabolism. It is needed for the breakdown of adenosine from food and for the turnover of nucleic acids in tissues. ADA irreversibly deaminates adenosine, converting it to the related nucleoside inosine by the substitution of the amino group for a keto group.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 126
Incorrect
-
Which one of the following nerve fibers has the fastest conduction velocity?
Your Answer: γ fiber
Correct Answer: α fiber
Explanation:α nerve fibers are characterized by being highly myelinated, which confers them with fast conduction properties. They innervate extrafusal skeletal muscle fibers, and their conduction velocity is between 80-120 m/s.
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This question is part of the following fields:
- Medicine
- Neurology
-
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Question 127
Incorrect
-
Which vagus nerve mainly supplies the AV node?
Your Answer: Only has sympathetic enervation
Correct Answer: Left vagus
Explanation:As the AV node develops from the left side of the embryo It is supplied by the left vagus nerve.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 128
Incorrect
-
With regard to cell membrane proteins:
Your Answer: All tend to traverse the whole membrane
Correct 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 129
Incorrect
-
All of the following are consistent with the indicator dilution method except---
Your Answer: When saline is used as an indicator, it is easy to make repeated determinations
Correct Answer: In thermodilution, the indicator used is warm saline
Explanation:In thermodilution, the indicator used is cold saline.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 130
Incorrect
-
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: Glucose (sweet)
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 131
Incorrect
-
A 71-year-old woman residing in a nursing home for a couple of years complains of drooling of saliva and sudden difficulty in swallowing while eating. She is a known hypertensive on treatment. What would be your next step?
Your Answer: CXR
Correct Answer: Endoscopy
Explanation:Dysphagia or difficulty in swallowing. Endoscopy allows for visual examination of the oesophagus and is indicated in patients with dysphagia to determine the underlying aetiology, exclude malignant and premalignant conditions, assess the need for therapy, and perform therapy including dilation.
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This question is part of the following fields:
- Geriatrics
- Medicine
-
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Question 132
Correct
-
Which of the following is first to rise following myocardial infarction?
Your Answer: Myoglobin
Explanation:Myoglobin, is a sensitive indicator of muscle injury and is first to rise following MI within two hours but is nonspecific.Troponin and CK-MB both begin to rise approximately three hours after MI. The cardiac troponins T and I which are released within 4–6 hours of an attack of MI and remain elevated for up to 2 weeks, have nearly complete tissue specificity and are now the preferred markers for assessing myocardial damage.Lactate dehydrogenase (LDH) begins to rise approximately 12 hours after MI.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 133
Incorrect
-
The most resistant area in the brain to hypoxia is:
Your Answer: Basal ganglia
Correct Answer: Brain stem
Explanation:The structures in the brainstem are more resistant to hypoxia than the cerebral cortex and the rest of the brain structures.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 134
Incorrect
-
In Starling’s law of the heart, the decrease in tension developed by muscle contraction at high degrees of stretch is due to:
Your Answer: Leak of calcium from cell membranes of overstretched cardiac muscle
Correct Answer: Disruption of myocardial fibers
Explanation:Starling law states that the force of contraction is directly proportional to the preload. When the heart muscle is stretched beyond its limit the tension that is developed decreases, this is not due to loss of formation of effective myosin and actin cross bridges. The heart muscles despite being fully stretched is never stretched to this point. The reason for this decreased tension is physical disruption of the myocardial fibers.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 135
Incorrect
-
Which one of the following features is least recognised in long-term lithium use?
Your Answer: Diarrhoea
Correct Answer: Alopecia
Explanation:All the above side-effects, with the exception of alopecia, may be seen in patients taking lithium.Common lithium side effects may include:- dizziness, drowsiness;- tremors in your hands;- trouble walking;- dry mouth, increased thirst or urination;- nausea, vomiting, loss of appetite, stomach pain;- cold feeling or discoloration in your fingers or toes;- rash; or.- blurred vision.
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This question is part of the following fields:
- Medicine
- Pharmacology
-
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Question 136
Incorrect
-
In RFLP (restriction fragment length polymorphism), the DNA fragments are separated by length through a process known as:
Your Answer: Deletion
Correct Answer: Agarose gel electrophoresis
Explanation:Samples of DNA from individuals are broken into pieces by restriction enzymes and the fragments are separated according to their lengths via gel electrophoresis. Although now largely obsolete due to the rise of inexpensive DNA sequencing technologies, RFLP analysis was the first DNA profiling technique inexpensive enough to see widespread application.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 137
Correct
-
The net effect of active Vitamin D on calcium and phosphate homeostasis is?
Your Answer: Increase in Ca, increase in phosphate
Explanation:Bone and its metabolism are regulated by several hormones, amongst which is vitamin D. It is heavily involved in the metabolism and homeostasis of calcium and phosphate through several processes. Vitamin D works in the intestine, kidney, bone and parathyroid glands to maintain levels of calcium and phosphate, promoting its absorption, bone resorption, and proper functioning of the parathyroid to maintain adequate serum calcium levels.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
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Question 138
Correct
-
Question 139
Incorrect
-
Where is the site of action of spironolactone?
Your Answer: Ascending loop of Henle
Correct Answer: Distal convoluted tubule
Explanation:Spironolactone is an aldosterone antagonist which acts in the distal convoluted tubule. It is a potassium-sparing diuretic that prevents the body from absorbing too much salt and keeps the potassium levels from getting too low. Spironolactone is used to treat heart failure, high blood pressure (hypertension), or hypokalaemia (low potassium levels in the blood).
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This question is part of the following fields:
- Medicine
- Pharmacology
-
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Question 140
Incorrect
-
Which statement is correct regarding mRNA?
Your Answer: mRNAs are polymers of nucleosides containing a ribose-phosphate unit attached to a base.
Correct Answer: mRNAs are mainly found in the nucleus and cytoplasm of a cell.
Explanation:mRNA is transcribed from DNA and is carried to the cytosol to be translated. Hence it is mainly found in the cytosol and the nucleus of a cell. It is single stranded and contains the base uracil instead of thymine.
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This question is part of the following fields:
- Genetics
- Medicine
-
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Question 141
Incorrect
-
The immunoglobulin found in the highest concentration in humans is
Your Answer: IgA
Correct Answer: IgG
Explanation:Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in the circulation. IgG molecules are created and released by plasma B cells.
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This question is part of the following fields:
- Immunology
- Medicine
-
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Question 142
Incorrect
-
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: Superior labral lesion
Correct 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 143
Correct
-
Where does most fat digestion begin?
Your Answer: Duodenum
Explanation:Digestion of some fats can begin in the mouth where lingual lipase breaks down some short chain lipids into diglycerides. However fats are mainly digested in the small intestine (in the duodenum). The presence of fat in the small intestine produces hormones that stimulate the release of pancreatic lipase from the pancreas and bile from the liver which helps in the emulsification of fats for absorption of fatty acids.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
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Question 144
Incorrect
-
The mitochondrial chromosome is a circular DNA molecule. They encode for proteins needed for ATP production. These proteins are also essential for:
Your Answer: Cell replication
Correct Answer: Apoptotic cell death
Explanation:The intrinsic pathway or the mitochondrial pathway of apoptosis is activated due to the loss of BCL-2 and other antiapoptotic proteins. This loss results in the increased membrane permeability and release of cytochrome C which activates caspases downstream resulting in apoptosis.
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This question is part of the following fields:
- Genetics
- Medicine
-
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Question 145
Incorrect
-
Which statement is correct about the clinical state of methemoglobinemia?
Your Answer: It is due to carbon monoxide reacting with haemoglobin.
Correct Answer: May arise due to a hereditary deficiency of NADH.
Explanation:Methaemoglobin is a form of haemoglobin that contains ferric [Fe3+] iron and has a decreased ability to bind oxygen. Spontaneously formed methaemoglobin is normally reduced by protective enzyme systems, e.g., NADH methaemoglobin reductase, hence a deficiency of NADH may result in increased levels of methaemoglobin
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This question is part of the following fields:
- Haematology
- Medicine
-
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Question 146
Incorrect
-
Myocyte action potentials – Choose the false statement:
Your Answer: The plateau phase is due to Ca2+ influx
Correct Answer: Repolarisation is due to net k+ influx
Explanation:Final repolarization (phase 3) to the resting membrane potential (phase 4) is due to closure of the Ca2+ channels and a slow, delayed increase of K+ efflux through various types of K+ channels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 147
Correct
-
In adults, the major site of haematopoiesis is?
Your Answer: The axial skeleton
Explanation:Bone marrow is the flexible tissue in the interior of bones. In humans, red blood cells are produced by cores of bone marrow in the heads of long bones.
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This question is part of the following fields:
- Haematology
- Medicine
-
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Question 148
Incorrect
-
Which of the following drugs would be the safest to prescribe in a 22 year old man with seropositive rheumatoid arthritis who is planning to start a family?
Your Answer: Leflunomide
Correct Answer: Prednisolone
Explanation:Prednisolone although has many undesirable side effects it may be considered relatively safe compared to the drugs that are provided here. Prolonged treatment with sulphasalazine may depress semen quality and cause irreversible infertility. Methotrexate and leflunomide both inhibit purine/pyrimidine synthesis (the former by inhibiting folate metabolism) and are contraindicated in pregnancy or while trying to conceive. In males, a temporary or permanent decrease in sperm count may occur with cyclophosphamide. Because the recovery of fertility after cyclophosphamide therapy is variable, sperm banking should be considered before treatment is begun.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
-
Question 149
Incorrect
-
An elderly man presents with fever of 38°C and a very severe headache. His BP is 85/50 mm Hg. He has neck stiffness and photophobia. What is the most appropriate management?
Your Answer: Intravenous fluid
Correct Answer: CT head
Explanation:In elderly patients, symptoms suggestive of meningitis could be due to an intracranial mass lesion (such as abscess, tumour or an intracerebral haematoma). Therefore elderly patients are increased risk of cerebral herniation from an LP. A CT head should be done before an LP to exclude a mass lesion.
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This question is part of the following fields:
- Geriatrics
- Medicine
-
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Question 150
Incorrect
-
Gastrin activates all of the following cells except:
Your Answer: Parietal cells
Correct Answer: Mucus neck cells
Explanation:The G cell is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas and duodenum. Gastrin-releasing peptide, as well as the presence of amino acids in the stomach, stimulates the release of gastrin from the G cells. Gastrin stimulates enterochromaffin-like cells to secrete histamine. Gastrin also targets parietal cells by increasing the amount of histamine and the direct stimulation by gastrin, causing the parietal cells to increase HCl secretion in the stomach.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 151
Incorrect
-
Which of the following does not lower ventricular rate in atrial fibrillation?
Your Answer: Digitalis
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 152
Incorrect
-
What happens first during depolarisation of the membrane potential?
Your Answer: Gated K channels open allowing the influx of K
Correct Answer: Gated Na channels open allowing the influx of Na
Explanation:Generation of an action potential in response to a stimulus is a result of a previously maintained resting membrane potential (RMP). Generation of resting membrane potential is mediated mainly by potassium ions. Several membrane proteins maintain RMP by transport of ions in and out of cell. Na+/K+ ATPase pump maintains a concentration gradient of Na+ and K+ ions. Na+ concentration in extracellular fluid is higher compared to intracellular fluid and K+ ion concentration is higher intracellularly. Generation of an action potential facilitates opening of Na+ ion channels which allow for Na+ to diffuse inside the cell according to the concentration gradient.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 153
Incorrect
-
The a-wave is created by:
Your Answer: Increased pulmonary vascular pressure
Correct Answer: Regurgitation of some blood to the great veins when the atria contracts in atrial systole
Explanation:The a-wave created on the venous pulse curve occurs as a result of atrial systole. Due to the pressure build-up in the atria, it causes a back pressure in the vena cava. This pressure is exerted on the valve and this back pressure is what causes a slight increase in the venous pressure.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 154
Incorrect
-
The right border of the heart corresponds to which line on the surface of the chest?
Your Answer: Line drawn from the 4th right costal cartilage to the 5th left intercostal space
Correct Answer: Line drawn from the 3rd right costal cartilage to the 6th right costal cartilage
Explanation:The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 155
Incorrect
-
The brainstem contains which of the following structures?
Your Answer: The subthalamus, midbrain and pons
Correct Answer: The midbrain, pons and medulla
Explanation:Brain stem is the base of the brain that connects the brain to the spinal cord. It consists of the mid brain, pons and medulla oblongata.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 156
Incorrect
-
The V wave in the jugular pulse is caused by:
Your Answer: Atrial contraction
Correct Answer: Atrial filling
Explanation:The v wave reflects the passive increase in pressure and volume of the right atrium as it fills in late systole and early diastole.
The jugular vein pulsations usually have two elevations and two troughs. The first elevation (a wave) corresponds to the slight rise in atrial pressure resulting from atrial contraction. The first descent (x descent) reflects a fall in atrial pressure that starts with atrial relaxation. The second elevation (v wave) corresponds to ventricular systole when blood is entering the right atrium from the vena cavae while the tricuspid valve is closed. Finally, the second descent (y descent) reflects falling right atrial pressure as the tricuspid valve opens and blood drains from the atrium into the ventricle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 157
Incorrect
-
Iron absorption occurs primarily in which part of the GIT?
Your Answer: Terminal ileum
Correct 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 158
Correct
-
“Ploidy” is a term used to refer to the number of chromosomes in cells. Cancer cells are commonly:
Your Answer: Aneuploidy
Explanation:Cancer cells most commonly undergo disordered cell growth and cell division. This results in an additional number of chromosomes called aneuploidy. This is a characteristic of cancer cells along with variation in differentiation of the cells.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 159
Incorrect
-
A 76-year-old man has been admitted with a respiratory tract infection. On examination, he was found to be confused and dyspnoeic with O2 saturation of 88%. He has a 60 pack-year smoking history. An arterial blood gas analysis reveals CO2 retention. He has been deemed unfit for admission into the intensive care unit. The physician elects to begin a doxapram infusion. Among the following statements which best fits with the characteristics of doxapram?
Your Answer: Doxapram is indicated in patients with cerebral oedema
Correct Answer: Epilepsy is a contraindication for doxapram use
Explanation:The statement that fits the characteristics of doxapram is, epilepsy is a contraindication for doxapram use. Concurrent use with theophylline may increase agitation not relaxation.Doxapram is a central respiratory stimulant. In clinical practice, doxapram is usually used for patients who have an acute exacerbation of chronic obstructive pulmonary disease (COPD) who are unsuitable for admission to the intensive therapy unit for ventilatory support. Doxapram infusion may buy an extra 24 h to allow for recovery.Contraindications include: ischaemic heart disease, epilepsy, cerebral oedema, acute stroke, asthma, hypertension, hyperthyroidism, and pheochromocytoma. The infusion may worsen agitation and dyspnoea and lead to hypertension, nausea, vomiting and urinary retention.Drug interactions:Concomitant administration of doxapram and aminophylline (theophylline) can cause increased skeletal muscle activity, agitation, and hyperactivity.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 160
Incorrect
-
Which of the following statements regarding psoriasis is incorrect?
Your Answer: Often occurs on extensor surfaces
Correct Answer: Mediated by type 2 helper T cells
Explanation:Psoriasis is a long-lasting autoimmune disease which is characterized by patches of abnormal skin. These skin patches are typically red, itchy, and scaly commonly on the extensor surfaces. Psoriasis is associated with an increased risk of psoriatic arthritis, lymphomas, cardiovascular disease, Crohn’s disease, and depression. Psoriatic arthritis affects up to 30% of individuals with psoriasis. Psoriasis is mediated by type 1 helper T cells which are involved in the cell mediated response, rather than type 2 helper T cells
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 161
Incorrect
-
The SA and AV nodes are usually supplied by which artery?
Your Answer: Circumflex artery
Correct Answer: Right coronary artery
Explanation:The right coronary artery supplies the right atrium, right ventricle, SA and AV nodes.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 162
Incorrect
-
Translation usually begins at which codon?
Your Answer: UAA
Correct Answer: AUG
Explanation:The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and the most common start codon is AUG.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 163
Incorrect
-
Myocardium requires more oxygen to expel blood in:
Your Answer: An incompetent tricuspid valve
Correct Answer: A stenotic aortic valve
Explanation:In aortic valve stenosis, increased ventricular pressure Is needed to expel the blood into the aorta. Increased pressure means increased contractility hence increase O2 consumption by the heart muscles.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 164
Correct
-
Cholinergic vagal supply to the SA and AV nodes results in slowing of the heart rate via:
Your Answer: M2 muscarinic receptors
Explanation:M2 muscarinic receptors are the receptors for the parasympathetic system to the SA and the AV node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 165
Incorrect
-
A 30-year-old female was brought to the ER in a confused state. The patient works in a photograph development laboratory. On admission, she was hypoxic and hypotensive. A provisional diagnosis of cyanide poisoning was made. What is the definitive treatment?
Your Answer: Desferioxamine
Correct Answer: Hydroxocobalamin
Explanation:Cyanide poisoning: Aetiology:Smoke inhalation, suicidal ingestion, and industrial exposure (specific industrial processes involving cyanide include metal cleaning, reclaiming, or hardening; fumigation; electroplating; and photo processing) are the most frequent sources of cyanide poisoning. Treatment with sodium nitroprusside or long-term consumption of cyanide-containing foods is a possible source.Cyanide exposure most often occurs via inhalation or ingestion, but liquid cyanide can be absorbed through the skin or eyes. Once absorbed, cyanide enters the blood stream and is distributed rapidly to all organs and tissues in the body. Pathophysiology:Inside cells, cyanide attaches itself to ubiquitous metalloenzymes, rendering them inactive. Its principal toxicity results from inactivation of cytochrome oxidase (at cytochrome a3), thus uncoupling mitochondrial oxidative phosphorylation and inhibiting cellular respiration, even in the presence of adequate oxygen stores.Presentation:• ‘Classical’ features: brick-red skin, smell of bitter almonds• Acute: hypoxia, hypotension, headache, confusion• Chronic: ataxia, peripheral neuropathy, dermatitisManagement:• Supportive measures: 100% oxygen, ventilatory assistance in the form of intubation if required.• Definitive: Hydroxocobalamin (iv) is considered the drug of choice and is approved by the FDA for treating known or suspected cyanide poisoning. • Coadministration of sodium thiosulfate (through a separate line or sequentially) has been suggested to have a synergistic effect on detoxification.Mechanism of action of hydroxocobalamin: • Hydroxocobalamin combines with cyanide to form cyanocobalamin (vitamin B-12), which is renally cleared.• Alternatively, cyanocobalamin may dissociate from cyanide at a slow enough rate to allow for cyanide detoxification by the mitochondrial enzyme rhodanese.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 166
Incorrect
-
A 64 year old woman who is of Asian descent and is diabetic (controlled by diet) presents with generalized body aches and difficulty rising from sitting for the last few months. Her blood glucose levels are in the normal range. Lab examination reveals normal blood cell count, low serum phosphate, calcium at the lower range, and raised alkaline phosphatase levels. Radiological examination shows which of the following?
Your Answer: Brodie’s abscess
Correct Answer: Linear areas of low density
Explanation:Osteomalacia is a condition due to defective mineralization of osteoid. Occurs as a result of Vitamin D deficiency secondary to poor dietary intake and sun exposure, malabsorption e.g., inflammatory bowel disease and gastrointestinal bypass surgery. Radiological findings include reduced bone mineral density (a non specific finding), inability to radiologically distinguish vertebral body trabeculae (the film appears poor quality), looser pseudo fractures, fissures, or narrow radiolucent lines (these are the characteristic findings). Osteolytic or punched out lesions may be seen with multiple myeloma and bony metastases. Areas of sclerosis may be observed with conditions like osteosclerosis and Paget disease. A Brodie abscess is a subacute osteomyelitis, which may persist for years before progressing to a chronic, frank osteomyelitis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 167
Correct
-
The lamina propria contains all of the following except:
Your Answer: Neutrophils
Explanation:The connective tissue of the lamina propria is very loose, allowing it to be very cell rich. The cell population of the lamina propria is variable and can include, for example, fibroblasts, lymphocytes, plasma cells, macrophages, eosinophilic leukocytes, and mast cells. It provides support and nutrition to the epithelium, as well as the means to bind to the underlying tissue.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 168
Incorrect
-
Concerning surface anatomy, where is the base of the heart
Your Answer: 5th intercostal space mid clavicular line
Correct Answer: 2nd left costal to 3rd right costal cartilage
Explanation:The base of the heart, also known as the superior border of the heart corresponds to a line connecting the inferior border of the 2nd left costal cartilage to the superior border of the 3rd right costal cartilage.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 169
Incorrect
-
A 78-year-old male with long-standing Alzheimer's disease is being reviewed in your clinic. Which among the following is true regarding memantine, a drug which has been approved for the management of dementia?
Your Answer: Amantadine can increase its unwanted effects
Correct Answer: It is an NMDA-receptor antagonist
Explanation:Memantine is an antagonist of the NMDA (N-Methyl-D-Aspartate)-receptor subtype of glutamate receptor. It is used to slow the neurotoxicity thought to be involved in Alzheimer’s disease and other neurodegenerative diseases.
Drug interactions:
- When given concomitantly with other NMDA-receptor antagonists (e.g., ketamine, amantadine) there is increased risk of psychosis.
- Dopamine agonists, L-dopa, and anticholinergics enhance effects of memantine.
- Antispasmodics (e.g., baclofen) enhance effects, as memantine has some antispasmodic effects.
- Drugs excreted by cationic transporters in the kidney (e.g. quinine, cimetidine, ranitidine) reduce excretion.
- Common adverse effects include dizziness, headache, confusion, diarrhoea, and constipation.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 170
Correct
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Question 171
Incorrect
-
A 45-year-old male is brought to the emergency department after being found collapsed, outside a nightclub. The ER team found an empty bottle of amyl nitrate in his pocket. The patient is hypoxic with an O2 saturation of 84% and is confused. Which of the following is the best treatment for this patient?
Your Answer: Nifedipine
Correct Answer: Methylene blue
Explanation:The best treatment for the patient in question would be methylene blue.The most probable diagnosis in this patient is methemoglobinemia due to the ingestion of amyl nitrate.Amyl nitrate promotes the formation of methaemoglobin, which avidly conserves oxygen and leads to decreased tissue oxygen saturations. Treatment of choice includes methylene blue and vitamin C.Adverse effects:Benign side effects include green or blue discoloration of urine and patients should be forewarned. Significant side effects are based on methylene blue, itself, being an oxidizing agent and an inhibitor of monoamine oxidase A (MAO-A). As an oxidizing agent, methylene blue can actually precipitate methemoglobinemia or haemolysis in high doses or when ineffectively reduced. Methylene blue administration in a patient taking a serotonergic agents may predispose to serotonin syndrome.Note: Although methylene blue administration is controversial in the setting of G6PD-deficiency due to reduced levels of NADPH, it is not contraindicated and should be administered cautiously and judiciously.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 172
Incorrect
-
Empagliflozin was found to reduce the risk of cardiovascular deaths, non-fatal myocardial infarction and non-fatal stroke when added to standard treatment plans in patients with type 2 diabetes mellitus. This information was shared in 2015 by The New England Journal of Medicine and the results were expressed per 1000 patient years. In fact, empagliflozin had an event rate of 37.3/1000 patient years and placebo an event rate of 43.9/1000 patient years. How many patients who are at high cardiovascular risk need to be treated with empagliflozin to prevent a cardiovascular death, a non-fatal myocardial infarction or a non-fatal stroke?
Your Answer: 50
Correct Answer: 150
Explanation:The number needed to treat (NNT) is an absolute effect measure that has been used to assess beneficial and harmful effects of medical interventions. In this case the NNT can be calculated as follows: NNT = 1/ Absolute risk reduction (ARR). ARR=(Control event rate expressed per 1000 patient years) – (Experimental event rate expressed per 1000 patient years) = 43.9-37.3 = 6.6/1000 patient yearsNNT=(Patient years)/ARR = 1000/ 6.6 = 151.5. The closest to 151.5 is 150, thus it is the correct answer.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 173
Correct
-
Which two ducts form the ampulla of Vater?
Your Answer: The common bile duct and the pancreatic duct of Wirsung
Explanation:The ampulla of Vater, also known as the hepatopancreatic ampulla or the hepatopancreatic duct, is formed by the union of the pancreatic duct and the common bile duct. The ampulla is specifically located at the major duodenal papilla.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 174
Incorrect
-
Which of the toxin secretion pathways in the cell membrane of gram– bacteria delivers the toxin extracellular in a 2 stage process to the host?
Your Answer: I
Correct Answer: II
Explanation:Gram negative bacteria contain two membranes and there are about six specialized secretion systems. The secreted proteins play a key role in pathogenesis. Type II secretion systems (T2SS) are conserved in most Gram-negative bacteria, where they transport proteins from the periplasm into the extracellular environment. Because the T2SS channel is only found in the outer membrane, proteins secreted through this apparatus must first be delivered to the periplasm via the Sec or Tat secretion pathways and then to the extracellular environment making it a two-stage process.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 175
Incorrect
-
Which of the following is an incorrect statement regarding the structure of DNA?
Your Answer: The large stretches of helical DNA are coiled around histone proteins.
Correct Answer: The two strands of DNA are held together by cysteine bonds.
Explanation:The two strands of DNA are held together by hydrogen bonds formed between the nucleotide bases.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 176
Incorrect
-
A 40-year-old man is admitted to the Emergency Department in a confused state. He tells you that he consumed two bottles of antifreeze. On examination, his pulse is 120 bpm and blood pressure is 140/90 mmHg. An arterial blood gas analysis shows uncompensated metabolic acidosis. He is transferred to the high dependency unit and ethanol is given via a nasogastric tube. How does ethanol help this patient?
Your Answer: Binds to glycolic acid
Correct Answer: Competes with ethylene glycol for alcohol dehydrogenase
Explanation:Ethanol competes with ethylene glycol for alcohol dehydrogenase and thus, helps manage a patient with ethylene glycol toxicity.Ethylene glycol is a type of alcohol used as a coolant or antifreezeFeatures of toxicity are divided into 3 stages:Stage 1: (30 min to 12 hours after exposure) Symptoms similar to alcohol intoxication: confusion, slurred speech, dizziness (CNS depression)Stage 2: (12 – 48 hours after exposure) Metabolic acidosis with a high anion gap and high osmolar gap. Also tachycardia, hypertensionStage 3: (24 – 72 hours after exposure) Acute renal failureManagement has changed in recent times:Fomepizole, an inhibitor of alcohol dehydrogenase, is now used first-line in preference to ethanol.Ethanol has been used for many years works by competing with ethylene glycol for the enzyme alcohol dehydrogenase this limits the formation of toxic metabolites (e.g. glycolaldehyde and glycolic acid) which are responsible for the hemodynamic/metabolic features of poisoning.Haemodialysis has a role in refractory cases.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 177
Incorrect
-
Select the correct statement regarding terminal bronchioles:
Your Answer: The walls of terminal bronchioles consist partially of cartilage
Correct Answer: Terminal bronchioles form part of the conducting zone
Explanation:Bronchioles divide into even smaller bronchioles, called terminal bronchioles, which are 0.5mm or less in diameter. Terminal bronchioles in turn divide into smaller respiratory bronchioles which divide into alveolar ducts. Terminal bronchioles mark the end of the conducting division of air flow in the respiratory system while respiratory bronchioles are the beginning of the respiratory division where actual gas exchange takes place. Terminal bronchioles are lined with simple cuboidal epithelium containing club cells. Terminal bronchioles contain a limited number of ciliated cells and no goblet cells. Club cells are non-ciliated, rounded protein secreting cells. Their secretions are a non-stick, proteinaceous compound (surfactant) to maintain the airway in the smallest bronchioles.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 178
Correct
-
Alveolar epithelial cells:
Your Answer: Type 2 represent 60% of the cells
Explanation:Type I alveolar cells are squamous (giving more surface area to each cell) and cover approximately 90–95% of the alveolar surface. Type I cells are involved in the process of gas exchange between the alveoli and blood. Type II alveolar cells cover a small fraction of the alveolar surface area. Their function is of major importance in the secretion of pulmonary surfactant, which decreases the surface tension within the alveoli. They are also capable of cellular division, giving rise to more type I alveolar cells when the lung tissue is damaged. These cells are granular and roughly cuboidal. Type II alveolar cells are typically found at the blood-air barrier. Although they only comprise <5% of the alveolar surface, they are relatively numerous (60% of alveolar epithelial cells).
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 179
Incorrect
-
With regards to the deiodinases, where would you find D1?
Your Answer: Brain
Correct Answer: Liver
Explanation:The liver produces an important amount of T3 by outer ring deiodination thanks to its elevated concentration of type I deiodinase. It can also be found in the kidney.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 180
Incorrect
-
The intestine is lined by:
Your Answer: Stratified squamous epithelium
Correct Answer: Simple columnar epithelium
Explanation:In the small intestine, epithelium is simple columnar and specialised for absorption. The epithelium is arranged into villi, creating a brush border and increasing the area for absorption. The epithelium is simple columnar with microvilli.In the colon, epithelium is simple columnar and without villi. Goblet cells, which secrete mucous, are also present.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 181
Incorrect
-
A 50-year-old male was under treatment for bipolar disease. He was brought to the emergency department as he had become increasingly confused over the past two days. He had vomiting and diarrhoea. He was also consuming and passing a lot of water.On examination, he was disoriented. He had vertical nystagmus and was ataxic.What two investigations are likely to lead to the correct diagnosis?
Your Answer: SPECT (Single Photon Emission Computed Tomography) scan of the brain
Correct Answer: Desmopressin test and serum lithium level
Explanation:Desmopressin test (done to differentiate nephrogenic diabetes insipidus from central diabetes insipidus), and serum lithium levels can together confirm a diagnosis of lithium-induced nephrogenic diabetes insipidus.Bipolar disease is most often managed with mood stabilizers like lithium. This patient develops gastrointestinal symptoms followed by an acute confusional state associated with polyuria and polydipsia. These symptoms are suggestive of diabetes insipidus.In a case where these symptoms occur in a bipolar patient under treatment, lithium-induced nephrogenic diabetes insipidus should be considered as the most probable cause.Lithium intoxication can present with symptoms of nausea, vomiting, mental dullness, action tremor, weakness, ataxia, slurred speech, blurred vision, dizziness, especially vertical nystagmus and stupor or coma. Diffuse myoclonic twitching and nephrogenic diabetes insipidus can also occur. Such a clinical syndrome occurs above the serum level of lithium of 1.5–2.0 mEq/L.Management: – Correcting electrolyte abnormalities in patients with acute disease is critical and often life-saving.- Treatment should be initiated with parenteral fluids to replete hypovolemia (normal saline at 200-250 mL/h), followed by administration of hypotonic fluid (0.5% normal saline). – On the restoration of the volume status of the patient forced diuresis should be initiated by the administration of parenteral furosemide or bumetanide accompanied by continued intravenous hypotonic fluid administration to maintain volume status.- Polyuria is managed with hydrochlorothiazide combined with amiloride, acetazolamide.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 182
Correct
-
Which of the following stimulate the release of aldosterone from the adrenal cortex?
Your Answer: Angiotensin 2
Explanation:Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex. Aldosterone causes the renal tubules to increase the reabsorption of sodium and water into the blood, while at the same time causing the excretion of potassium (to maintain electrolyte balance).
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This question is part of the following fields:
- Medicine
- Renal
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Question 183
Correct
-
Bile acids will be prevented from being absorbed by resection of which part of the gastrointestinal tract?
Your Answer: Ileum
Explanation:Bile acids (also called bile salts) are produced in the liver, secreted into the biliary system, stored in the gallbladder and are released after meals stimulated by cholecystokinin. They are important for the digestion and absorption of fats (lipids) in the small intestine. Usually over 95% of the bile acids are absorbed in the terminal ileum and are taken up by the liver and resecreted.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 184
Incorrect
-
A deficiency in Niacin leads to which clinical deficiency syndrome?
Your Answer: Enteritis
Correct Answer: Pellagra
Explanation:Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhoea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over time affected skin may become darker, stiff, begin to peel, or bleed.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 185
Correct
-
In meiosis, the period of prophase 1 involves:
Your Answer: Replicated DNA condensing to form visible chromosomes
Explanation:Prophase 1 has been divided into five different stages (laptotene, zygotene, pachytene, diplotene and diakinesis). In prophase 1, chromosomes are going to condense to become visible, each chromosome will contain two chromatids that are joined at the centromere.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 186
Incorrect
-
Bronchial smooth muscle:
Your Answer: Tone is maximal at 6:00 PM
Correct Answer: Tone is increased by cholinergic discharge
Explanation:The lungs are supplied by both the sympathetic and parasympathetic divisions of the autonomic nervous system. The parasympathetic innervation is supplied by the vagus nerve. The parasympathetic nervous system is the dominant neuronal pathway in the control of airway smooth muscle tone. Stimulation of cholinergic nerves causes bronchoconstriction, mucus secretion, and bronchial vasodilation. Sympathetic innervation is supplied by the T1 to T5 of the spinal cord and act mainly via beta adrenergic receptors. Stimulation of the sympathetic nervous system causes vasoconstriction and bronchodilation.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 187
Incorrect
-
Neurons that are inactive during quiet breathing, become active when the respiratory drive for increased ventilation becomes greater than normal. These are located in the:
Your Answer: Apneustic centre
Correct Answer: Ventral respiratory group
Explanation:The mechanism of control of ventilation is an interplay of multiple regions in the brain. Medullary respiratory centre sets the basic rhythm of breathing. The dorsal respiratory group integrates input from the stretch receptors and the chemoreceptors in the periphery and is composed mainly of inspiratory neurons which controls the basic rhythm of breathing. The ventral respiratory group generates breathing rhythm and integrates data coming in to the medulla. It contains both inspiratory and expiratory neurons. They are primarily active in exercise and stress.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 188
Incorrect
-
The predominant receptors in the hearts conduction system are?
Your Answer: Β2
Correct Answer: Β1
Explanation:All of the components of the intrinsic conduction system contain autorhythmic cells that spontaneously depolarize. In the absence of extrinsic neural or hormonal influences, the SA node pacing rate would be about 100 beats per minute (bpm). The heart rate and cardiac output, however, must vary in response to the needs of the body’s cells for oxygen and nutrients under varying conditions. In order to respond rapidly to changing requirements of the body’s tissues, the heart rate and contractility are regulated by the autonomic nervous system (ANS), hormones, and other factors. The ANS has two interacting systems: the sympathetic and parasympathetic systems.
Sympathetic receptors: There are two types of adrenergic receptors: β and α. In the cardiovascular system there are β1, β2, α1, and α2 adrenergic receptors. β1 adrenergic receptors are expressed in the heart conduction system (in the SA node, AV node, and on atrial and ventricular cardiomyocytes). The activation of β1 receptors increases heart rate (via the SA node), and contractility.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 189
Incorrect
-
What is the role of cyclin and cyklin-dependent kinases in mitosis:
Your Answer: Synthesis of centrosomes
Correct Answer: Phosphorylation of proteins that make up pre-replication complexes
Explanation:There are certain regulators of the cell cycles that mediate progression through the cell cycle. These are cyclins and cyklin-dependent kinases (CDKs). They form a complex that phosphorylates protein involved in the cell cycle.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 190
Incorrect
-
Question 191
Incorrect
-
von Willebrand factor stabilises which clotting factor?
Your Answer: Factor V
Correct Answer: Factor VIII
Explanation:Von Willebrand factor’s primary function is binding to other proteins, in particular factor VIII, and it is important in platelet adhesion to wound sites. It is not an enzyme and, thus, has no catalytic activity. Factor VIII degrades rapidly when not bound to vWF. Factor VIII is released from vWF by the action of thrombin.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 192
Incorrect
-
Intermediate filaments achieve cell to cell contact via:
Your Answer: Focal adherent junctions
Correct Answer: Desmosomes
Explanation:At the plasma membrane, some keratins interact with desmosomes (cell-cell adhesion) and hemidesmosomes (cell-matrix adhesion) via adapter proteins.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 193
Incorrect
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Question 194
Incorrect
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A 30-year-old male is brought to the emergency department following his collapse in a night club. His friends who accompanied him admit that, of recent, he has been using increasing amounts of cocaine. Which among the following is commonly associated with cocaine overdose?
Your Answer: Bradycardia
Correct Answer: Metabolic acidosis
Explanation:Metabolic acidosis is associated with cocaine overdose. In overdose, cocaine leads to agitation, tachycardia, hypertension, sweating, hallucinations, and finally convulsions. Metabolic acidosis, hyperthermia, rhabdomyolysis, and ventricular arrhythmias also occur.Chronic use may be associated with premature coronary artery disease, dilated cardiomyopathy, and increased risk of cerebral haemorrhage.There are 3 stages for acute cocaine toxicity:Stage I: CNS symptoms of headache, vertigo, pseudo hallucinations, hyperthermia, hypertension. Stage II: increased deep tendon reflexes, tachypnoea, irregular breathing, hypertension.Stage III: Areflexia, coma, fixed and dilated pupils, hypotension, ventricular fibrillation, apnoea, and respiratory failure.Treatment:- Airway, breathing, and circulation to be secured. The patient’s fever should be managed, and one should rule out hypoglycaemia as a cause of the neuropsychiatric symptoms. – Cardiovascular toxicity and agitation are best-treated first-line with benzodiazepines to decrease CNS sympathetic outflow.- The mixed beta/alpha blocker labetalol is safe and effective for treating concomitant cocaine-induced hypertension and tachycardia.- Non-dihydropyridine calcium channels blockers such as diltiazem and verapamil have been shown to reduce hypertension reliably, but not tachycardia. – Dihydropyridine agents such as nifedipine should be avoided, as reflex tachycardia may occur. – The alpha-blocker phentolamine has been recommended but only treats alpha-mediated hypertension and not tachycardia.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 195
Correct
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Which of the following substances inhibits pancreatic secretion?
Your Answer: Pancreatic polypeptide
Explanation:Number of hormones and neurotransmitters can stimulate and inhibit pancreatic exocrine secretion. Cholecystokinin, secretin, vasoactive intestinal peptide and substance P stimulate pancreatic secretion. Pancreatic polypeptide, somatostatin inhibit pancreatic secretion.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 196
Incorrect
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The AV Node:
Your Answer: Action potentials are largely due to Ca2+, with no contribution from Na+ influx.
Correct Answer: It decelerates impulses passing to the ventricles
Explanation:The action potentials in the sinoatrial (SA) and atrioventricular (AV) nodes are largely due to Ca2+, with no contribution by Na+ influx. The depolarization continues to conduct slowly through the atrioventricular (AV) node. The AV node is located in the right posterior portion of the interatrial septum. This is small and bean-shaped. The atrial conductive system is organized so that the cardiac impulse does not travel from the atria into the ventricles too rapidly; this delay allows the atria to empty before ventricular contraction begins. It is the AV node and its adjacent conductive fibers that delay this transmission into the ventricles. Conduction through the AV Node is represented on the ECG by the PR interval.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 197
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 198
Incorrect
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In which organelle is the intrinsic apoptotic pathway initiated?
Your Answer: Lysosome
Correct Answer: Mitochondria
Explanation:Apoptosis is a programmed form of cell death involving the degradation of cellular constituents by a group of cysteine proteases called caspases. The caspases can be activated through either the intrinsic (mitochondrial mediated) or extrinsic (death receptor mediated) apoptotic pathways.
The intrinsic apoptotic pathway, also known as the mitochondrial pathway, is primarily initiated within the mitochondria. This pathway is activated in response to various internal stimuli, such as DNA damage, oxidative stress, and other cellular stresses.
When the intrinsic pathway is triggered, several events occur in the mitochondria:
- Release of cytochrome c: Cytochrome c is released from the mitochondrial intermembrane space into the cytoplasm.
- Formation of the apoptosome: Cytochrome c in the cytoplasm binds to apoptotic protease activating factor-1 (Apaf-1) and procaspase-9, forming a complex known as the apoptosome.
- Activation of caspase-9: The apoptosome activates caspase-9, an initiator caspase.
- Caspase cascade: Activated caspase-9 then activates executioner caspases, such as caspase-3, leading to the execution phase of apoptosis, which results in the orderly dismantling of the cell.
The mitochondria play a crucial role in this pathway by regulating the release of pro-apoptotic factors that are essential for the activation of downstream apoptotic processes.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 199
Incorrect
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Regarding oxidative deamination of amino acids, which of the following is true?
Your Answer: Leads to the formation of ribose
Correct Answer: Occurs in the kidney & liver
Explanation:Oxidative deamination is a form of deamination that generates α-keto acids and other oxidized products from amine-containing compounds, and occurs largely in the liver and kidney. Oxidative deamination is an important step in the catabolism of amino acids, generating a more metabolizable form of the amino acid, and also generating ammonia as a toxic by-product. The addition of ubiquitin to a substrate protein is called ubiquitination.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 200
Incorrect
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A 55-year-old male presents with complaints suggestive of erectile dysfunction. He also provides a history of ischaemic heart disease for which he is under treatment. The GP decides to start him on sildenafil citrate. Which of the following medications may contraindicate the use of sildenafil in this patient?
Your Answer:
Correct Answer: Nicorandil
Explanation:The use of nitrates and nicorandil concomitantly with sildenafil citrate is contraindicated.Sildenafil (Viagra) is a phosphodiesterase type V inhibitor used in the treatment of impotence.Contraindications- Patients taking nitrates and related drugs such as nicorandil- Hypotension- Recent stroke or myocardial infarction (NICE recommend waiting 6 months)Side-effects:Visual disturbances e.g. cyanopsia, non-arthritic anterior ischaemic NeuropathyNasal congestionFlushingGastrointestinal side-effectsHeadache
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This question is part of the following fields:
- Medicine
- Pharmacology
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SESSION STATS - PERFORMANCE PER SPECIALTY
