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Question 1
Incorrect
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Which of the following results in the resting membrane potential of a myocyte?
Your Answer: Activation of the l type calcium channels
Correct Answer: Activation of outward K+ channels
Explanation:Phase 0 is caused by the sodium current. Voltage gated sodium channels open leading to the influx of sodium into the cardiac muscle cell. Phase 1 is the rapid transient repolarization phase which is caused by the inactivation of the voltage gated sodium channels and opening of the voltage gated potassium channels along with opening of the slow calcium channels. Phase 2 which is the plateau is caused by opening of the slow calcium channels. Phase 4 is caused by closing of the slow calcium channels and opening of the potassium channels leading to efflux of potassium leading to the establishment of the resting membrane potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 2
Incorrect
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The steps of cardiac cycle in sequence are:
Your Answer:
Correct 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 3
Incorrect
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Visual pathways - Choose the true statement:
Your Answer:
Correct Answer: The lateral geniculate nucleus, magnocellular & parvocellular pathways project to the primary visual cortex
Explanation:The optic chiasm is made by the decussation of optic fibers on the nasal side. The magnocellular pathway carries signals for detection of movement. The parvocellular pathway carries cells for detection of shape, size, colour and clarity. The lateral geniculate nucleus (LGN) is the relay centre in the thalamus for he visual pathway. It has layers of magnocellular cells and parvocellular cells that are interleaved with layers of koniocellular cells. The LGN is the main central connection for the optic nerve to the occipital lobe, particularly the primary visual cortex.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 4
Incorrect
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The position of the kidneys besides the vertebral column retroperitoneally spans levels:
Your Answer:
Correct Answer: T12 – L3
Explanation:The asymmetry within the abdominal cavity, caused by the position of the liver, typically results in the right kidney being slightly lower and smaller than the left, and being placed slightly more to the middle than the left kidney. The left kidney is approximately at the vertebral level T12 to L3, and the right is slightly lower.
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This question is part of the following fields:
- Medicine
- Renal
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Question 5
Incorrect
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Activation of baroreceptor reflex involves:
Your Answer:
Correct Answer: Short term regulation of systemic blood pressure
Explanation:Baroreceptors are found in the heart and the blood vessels. They are the carotid sinus and the aortic arch receptors and respond to the minute to minute change in the blood pressure i.e. a change in the pulsatile pressure and not to a change in the mean arterial pressure. If the pulse pressure decreases, the rate of firing of the receptors decreases, stimulating an increase in the heart rate and blood pressure. Mechanisms that regulate the long term blood pressure control include the renin-angiotensin-aldosterone mechanism.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Incorrect
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Which enzyme deficiency causes Beriberi?
Your Answer:
Correct Answer: Thiamine
Explanation:Beriberi refers to a cluster of symptoms caused primarily by thiamine (vitamin B1) deficiency. Symptoms of beriberi include weight loss, emotional disturbances, impaired sensory perception, weakness and pain in the limbs, and periods of irregular heart rate.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 7
Incorrect
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Conjugation of proteins to which polypeptide marks them for degradation?
Your Answer:
Correct Answer: Ubiquitin
Explanation:Ubiquitin is a small regulatory protein that affects proteins in many ways: it can mark them for degradation via the proteasome, alter their cellular location, affect their activity, and promote or prevent protein interactions. Ubiquitination involves three main steps: activation, conjugation, and ligation,
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 8
Incorrect
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Where is the myenteric plexus (Auerbach’s plexus) located in the GIT?
Your Answer:
Correct Answer: Between the outer longitudinal and middle circular muscle layers.
Explanation:A part of the enteric nervous system, the myenteric plexus exists between the longitudinal and circular layers of muscularis externa in the gastrointestinal tract. It is found in the muscles of the oesophagus, stomach, and intestine.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 9
Incorrect
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Which is primarily responsible for the conversion of T4 to T3 in the periphery?
Your Answer:
Correct Answer: Deiodinase 1
Explanation:Type 1 iodothyronine deiodinase, also known simply as deiodinase 1, is an enzyme which can produce both triiodothyronine (active form) or inactivate metabolites from T4. It is responsible for almost 80% of the conversion of peripheral T4 to T3. Iodothyronine deiodinases are not to be confused with iodotyrosine deiodinases, which are also part of the deiodinase enzymes.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 10
Incorrect
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Inhibition of cell division at the end of G1 occurs through:
Your Answer:
Correct Answer: Unphosphorolated retinoblastoma protein (uRb)
Explanation:A cell’s decision to enter, or re-enter, the cell cycle is made before S-phase in G1 at what is known as the restriction point, and is determined by the combination of promotional and inhibitory extracellular signals that are received and processed. Ultimately unphosphorylated Rb acts as an inhibitor of G1.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 11
Incorrect
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Compact/cortical bone makes up
Your Answer:
Correct Answer: The outer layer of most bones and accounts for 80% of bone in the body
Explanation:Cortical, lamellar, or compact bone, is more dense than spongy bone and it forms the rigid, outer layer of bones, also called cortex. It consists of packed osteons, with a central osteonic canal surrounded by concentric rings. Spaces called lacunae are filled with osteocytes, and channels called canaliculi go from the lacunae to the osteonic canal. The strength of cortical bone allows it to support the body and protect organs. It also stores different elements, such as calcium.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 12
Incorrect
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Regarding carbohydrates absorption;
Your Answer:
Correct Answer: Intestinal absorption of sugars is inhibited by the drug phlorizin
Explanation:The main role of insulin is in the uptake of glucose from blood to tissues where it is metabolised. Glycose transporters in the intestines do not depend on the action of insulin. Phlorizin is a competitive inhibitor of SGLT1 and SGLT2 because it competes with glucose for the binding site, reducing intestinal and renal glucose transport.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 13
Incorrect
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The majority striatal neurons, called medium spiny neurons, utilizes which neurotransmitter?
Your Answer:
Correct Answer: GABA
Explanation:Medium spiny neurons are inhibitory neurons which use GABA (gamma-aminobutyric acid) which exerts inhibitory actions. These cells represent 95% of neurones within the human striatum found in basal ganglia.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 14
Incorrect
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Which of the following normally has a slow depolarizing “prepotential”?
Your Answer:
Correct Answer: Sinoatrial node
Explanation:There are 2 main types of action potentials (AP) in the heart, the slow response and the fast response:The slow response is initiated by the slow calcium-sodium channels, found in the SA node (which is the natural pacemaker of the heart) and the conduction fibers of the AV node.The fast response occurs in the atrial and ventricles muscle cells and the purkinje fibers.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 15
Incorrect
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Eosinophils provide immunity against
Your Answer:
Correct Answer: Multi cellular parasites
Explanation:Eosinophils, are a variety of white blood cells and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 16
Incorrect
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Which enzyme hydrolyses triglycerides in lipoproteins into free fatty acids for storage in fat cells?
Your Answer:
Correct Answer: Lipoprotein lipase
Explanation:Lipoprotein lipase is a water-soluble enzyme that hydrolyses triglycerides in lipoproteins, such as those found in chylomicrons and very low-density lipoproteins (VLDL), into two free fatty acids and one monoacylglycerol molecule.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 17
Incorrect
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An example of cholinergic autonomic neurons are:
Your Answer:
Correct Answer: Sympathetic postganglionic neurons that innervate sweat glands.
Explanation:All preganglionic neurons in both the sympathetic and parasympathetic nervous system secrete acetylcholine. The postganglionic neurotransmitter of the parasympathetic nervous system in all neurons is acetylcholine. Postganglionic fibers of the sympathetic nervous system mainly secrete Noradrenalin and Adrenalin but at sweat glands and erector pili muscles the postganglionic neurotransmitter is acetylcholine.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 18
Incorrect
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Synthesis of haem for haemoglobin occurs in the?
Your Answer:
Correct Answer: Mitochondria of the red blood cells
Explanation:Haemoglobin (Hb) is synthesized in a complex series of steps. The haem part is synthesized in a series of steps in the mitochondria and the cytosol of immature red blood cells, while the globin protein parts are synthesized by ribosomes in the cytosol.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 19
Incorrect
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Renin is secreted by which of the following cells?
Your Answer:
Correct 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 20
Incorrect
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Complement system help dispose waste products after which natural process?
Your Answer:
Correct Answer: Apoptosis
Explanation:The complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism or apoptosis. It is part of the innate immune system.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 21
Incorrect
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Cyclic AMP activates the following enzyme
Your Answer:
Correct Answer: Protein Kinase A
Explanation:Cyclic AMP works by activating protein kinase A (PKA, or cAMP-dependent protein kinase). Protein kinase A can also phosphorylate specific proteins that bind to promoter regions of DNA, causing increases in transcription.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 22
Incorrect
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Coronary flow is reduced during
Your Answer:
Correct Answer: Tachycardia
Explanation:Maximum amount of blood flow in the coronary arteries occur during diastole. When the heart rate increases which is also called tachycardia the duration of diastole decreases. Hence the amount of blood flow to the cardiac muscle also decreases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 23
Incorrect
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The hepatic portal vein is a large vessel formed by which of the following veins?
Your Answer:
Correct Answer: All of the above
Explanation:The portal vein is usually formed by the confluence of the superior mesenteric and splenic veins and also receives blood from the inferior mesenteric, gastric, and cystic veins.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 24
Incorrect
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A deficiency in Niacin leads to which clinical deficiency syndrome?
Your Answer:
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 25
Incorrect
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A 20-year-old male presented to the clinic with a long term history of pins and needles sensation in both hands. He also has prognathism. He also gives a history of recent onset right upper quadrant pain after being started on a new medication for his condition. Which of the following medications acting on his endocrine system can be responsible for this adverse effect?
Your Answer:
Correct Answer: Octreotide
Explanation:The patient (known case of acromegaly) seems to have developed cholelithiasis (presenting with right upper quadrant pain) probably due to octreotide.It is a long-acting analogue of somatostatin which is released from D cells of the pancreas and inhibits the release of growth hormone, glucagon, and insulin.Uses- Acute treatment of variceal haemorrhage- Acromegaly- Carcinoid syndrome- Prevent complications following pancreatic surgery- VIPomas- Refractory diarrhoeaAdverse effectsGallstones (secondary to biliary stasis)Other options:- Bromocriptine – a dopamine agonist with side effects arising from its stimulation of the brain vomiting centre.- Desmopressin – predominantly used in patients with diabetes insipidus by increasing the presence of aquaporin channels in the distal collecting duct to increase water reabsorption from the kidneys. The main side effects include headache and facial flushing due to hypertension.- Metformin – mainly reduces hepatic gluconeogenesis in patients with type 2 diabetes, common side effects include diarrhoea, vomiting, and lactic acidosis- Levothyroxine – synthetic thyroxine used in patients with hypothyroidism, common side effects result from incorrect dosing and mimic the symptoms of hyperthyroidism.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 26
Incorrect
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The brainstem contains which of the following structures?
Your Answer:
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 27
Incorrect
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In Jugular vein pressure the “a” wave represents?
Your Answer:
Correct Answer: Atrial systole
Explanation:The jugular venous pressure (JVP, sometimes referred to as jugular venous pulse) is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different forms of heart and lung disease. Classically three upward deflections and two downward deflections have been described: The upward deflections are the a (atrial contraction), c (ventricular contraction and resulting bulging of tricuspid into the right atrium during isovolumetric systole) and v = venous filling.The downward deflections of the wave are the x (the atrium relaxes and the tricuspid valve moves downward) and the y descent (filling of ventricle after tricuspid opening).
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 28
Incorrect
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When one of the two copies of the autosomes has a mutation and the protein produced by the normal form of the gene cannot compensate. The affected individual has an:
Your Answer:
Correct Answer: Autosomal dominant disorder
Explanation:An autosomal dominant trait will be expressed no matter the consequence. If one chromosome has a mutation the other will not be able to compensate for the mutation hence the protein formed will be mutated and will not function properly.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 29
Incorrect
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“Ploidy” is a term used to refer to the number of chromosomes in cells. Cancer cells are commonly:
Your Answer:
Correct 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 30
Incorrect
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Which of the following skin coloration abnormalities occurs due to adrenal insufficiency due to primary adrenal disease?
Your Answer:
Correct Answer: Hyperpigmentation
Explanation:Addison’s disease, also known as primary adrenal insufficiency, or hypocortisolism is an endocrine disorder. Hyperpigmentation is one of its most common signs; it occurs as a result of an increase in pro-opiomelanocortin to produce more ACTH in response to the decreased levels of cortisol. Pro-opiomelanocortin is a precursor of melanocyte stimulating hormone (MSH), which stimulates melanocytes, causing darkening of the skin.
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This question is part of the following fields:
- Endocrinology
- Medicine
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