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Question 1
Incorrect
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Before a patient is discharged, you are asked to review them. He is a 59-year-old man who was seen with epigastric pain that has since subsided, and he will be seen by his GP in the coming days. He's been hearing a lot about aspirin lately and wants to learn more about it.Which of the following statements about aspirin's mechanism of action is correct?
Your Answer: Inhibition of platelet ADP receptors
Correct Answer: Inhibition of cyclo-oxygenase
Explanation:Aspirin works by inhibiting cyclo-oxygenase in an irreversible manner, resulting in a decrease in prostaglandin and thromboxane production. As a result, platelet activation and aggregation are reduced.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 2
Correct
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A 75-year-old man with rheumatoid arthritis had gained weight, developed resistant hypertension, muscle weakness, and ankle oedema. This patient is most likely suffering from what condition?
Your Answer: Cushing's syndrome
Explanation:Overuse of cortisol medication, as seen in the treatment of patients with chronic asthma or rheumatoid arthritis, can cause Cushing’s syndrome. Weight gain, thin arms and legs, a round face, increased fat around the base of the neck, a fatty hump between the shoulders, easy bruising, wide purple stretch marks primarily on the abdomen, breasts, hips, and under the arms, weak muscles, hirsutism, hypertension, erectile dysfunction, osteoporosis, frontal alopecia, acne, depression, poor wound healing, and polycythaemia are all clinical features of Cushing’s syndrome.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 3
Incorrect
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On which of the following types of receptors does loperamide act?
Your Answer: Dopamine receptors
Correct Answer: Opioid receptors
Explanation:Loperamide inhibits acetylcholine release from the myenteric plexus acts by action on opioid mu-receptors, and this then reduces bowel motility. The intestinal transit time is increased, thereby facilitating water reabsorption.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 4
Incorrect
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A 59-year-old woman presents with a history of tiredness and weight gain and a diagnosis of hypothyroidism is suspected.Which of these changes is likely to appear first in primary hypothyroidism?
Your Answer: Reduced free triiodothyronine (T 3 )
Correct Answer: Increased thyroid-stimulating hormone (TSH)
Explanation:The earliest biochemical change seen in hypothyroidism is an increase in thyroid-stimulating hormone (TSH) levels.Triiodothyronine (T3) and thyroxine (T4) levels are normal in the early stages.TBG levels are generally unchanged in primary hypothyroidism.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 5
Correct
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All of the muscles of the tongue (other than the palatoglossus) are innervated by which of the following nerves:
Your Answer: Hypoglossal nerve
Explanation:All of the muscles of the tongue are innervated by the hypoglossal nerve, except for the palatoglossus, which is innervated by the vagus nerve.
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This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 6
Correct
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Which anatomical structure is divided following an emergency department anterolateral thoracotomy?
Your Answer: Latissimus dorsi
Explanation:Thoracotomy describes an incision made in the chest wall to access the contents of the thoracic cavity. Thoracotomies typically can be divided into two categories; anterolateral thoracotomies and posterolateral thoracotomies. These can be further subdivided into supra-mammary and infra-mammary and, of course, further divided into the right or left chest. Each type of incision has its utility given certain circumstances.A scalpel is used to sharply divide the skin along the inframammary crease overlying the fifth rib. Electrocautery is then used to divide the pectoralis major muscle and serratus anterior muscle. Visualization of the proper operative field can be achieved with the division and retraction of the latissimus dorsi. Either the fourth or fifth intercostal space is then entered after the division of intercostal muscles above the rib to ensure the preservation of the neurovascular bundle. Once the patient is properly secured to the operating table, the ipsilateral arm is raised and positioned anteriorly and cephalad to rest above the head. The incision is started along the inframammary crease and extended posterolaterally below the tip of the scapula. It is then extended superiorly between the spine and the edge of the scapula, a short distance. The trapezius muscle and the subcutaneous tissues are divided with electrocautery. The serratus anterior and latissimus dorsi muscles are identified and can be retracted. The intercostal muscles are then divided along the superior border of the ribs, and the thoracic cavity is accessed.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 7
Correct
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A blood culture was performed from a sample taken from a patient. It was noted that a Gram-positive coccus organism was grown.Among the following microorganisms, which is considered an example of a Gram-positive coccus?
Your Answer: Staphylococcus aureus
Explanation:Bacillus cereus = Gram-positive bacillusNeisseria meningitidis = Gram-negative coccusSalmonella enterica & Escherichia coli = Gram-negative bacilliIn Gram staining, crystal violet is a purple stain that is used to stain the bacteria first. The stained bacteria are decolorized and then stained with a red stain, which is safranin. Bacteria with thick cell walls keep the purple stain and are called Gram-positive. Thin-walled bacteria are easily decolorized so when safranin, the red stain, is placed on the organisms, they become red or Gram-negative. The Staphylococci that are associated with infections in humans are colonizers of various skin and mucosal surfaces. Because the carrier state is common among the human population, infections are frequently acquired when the colonizing strain gains entrance to a normally sterile site as a result of trauma or abrasion to the skin or mucosal surface.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 8
Incorrect
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In a ward round, you come across a patient's treatment chart prescribed an antibiotic to fight his infection. This antibiotic is an inhibitor of cell wall synthesis. Which of the following antimicrobial drugs is prescribed to this patient?
Your Answer: Tetracycline
Correct Answer: Benzylpenicillin
Explanation:Penicillins and cephalosporins are the major antibiotics that inhibit bacterial cell wall synthesis. They inactivate transpeptidases that help cross-link peptidoglycans in cell walls. Isoniazid decreases the synthesis of mycolic acids in mycobacterium.Clarithromycin binds to the 50S subunit of ribosomes and inhibits protein synthesis. Metronidazole and the other 5-nitroimidazole agents inhibit nucleic acid synthesis by forming toxic free radical metabolites in the bacterial cell that damage DNA. Tetracycline bind to 30S and prevent attachment of aminoacyl-tRNA.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 9
Incorrect
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Antidiuretic hormone (ADH) levels are found to be increased in a young lady with unexplained hyponatraemia.In a healthy patient under normal circumstances, in which of the following conditions would ADH not be released?
Your Answer: Increased circulating Angiotensin II
Correct Answer: Increased alcohol intake
Explanation:Antidiuretic hormone (ADH) is produced in the hypothalamus’s supraoptic nucleus and then released into the blood via axonal projections from the hypothalamus to the posterior pituitary.It is carried down axonal extensions from the hypothalamus (the neurohypophysial capillaries) to the posterior pituitary, where it is kept until it is released, after being synthesized in the hypothalamus.The secretion of ADH from the posterior pituitary is regulated by numerous mechanisms:Increased plasma osmolality: Osmoreceptors in the hypothalamus detect an increase in osmolality and trigger ADH release.Hypovolaemia causes a drop in atrial pressure, which stretch receptors in the atrial walls and big veins detect (cardiopulmonary baroreceptors). ADH release is generally inhibited by atrial receptor firing, but when the atrial receptors are stretched, the firing reduces and ADH release is promoted.Hypotension causes baroreceptor firing to diminish, resulting in increased sympathetic activity and ADH release.An increase in angiotensin II stimulates angiotensin II receptors in the hypothalamus, causing ADH production to increase.Nicotine, Sleep, Fright, and Exercise are some of the other elements that might cause ADH to be released.Alcohol (which partly explains the diuretic impact of alcohol) and elevated levels of ANP/BNP limit ADH release.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 10
Incorrect
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Digoxin is contraindicated in all of the following EXCEPT for:
Your Answer: Ventricular tachycardia
Correct Answer: Asthma
Explanation:Digoxin is contraindicated in:Supraventricular arrhythmias associated with accessory conduction pathways e.g. Wolff-Parkinson-White syndromeVentricular tachycardia or fibrillationHeart conduction problems e.g. second degree or intermittent complete heart blockHypertrophic cardiomyopathy (unless concomitant atrial fibrillation and heart failure but should be used with caution)
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 11
Incorrect
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Which of the following hormones regulates Na+reabsorption in the proximal tubule:
Your Answer: Antidiuretic hormone
Correct Answer: Angiotensin II
Explanation:Angiotensin II increases Na+reabsorption from the proximal tubule (by activating Na+/H+antiporters).
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This question is part of the following fields:
- Physiology
- Renal
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Question 12
Incorrect
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In which of the following cases is intravenous phenytoin contraindicated?
Your Answer: Renal impairment
Correct Answer: Second degree heart block
Explanation:Phenytoin Contraindications include:HypersensitivitySinus bradycardiaSinoatrial blockSecond and third degree A-V blockAdams-Stokes syndromeConcurrent use with delavirdineHistory of prior acute hepatotoxicity attributable to phenytoin
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 13
Incorrect
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Cardiac muscle and skeletal muscle are alike, but there are a few key variations. Which of the following is NOT a characteristic of skeletal muscle but is a characteristic of cardiac muscle?
Your Answer: Contraction by excitation-contraction coupling
Correct Answer: The presence of intercalated discs
Explanation:Cardiac muscle is striated, and the sarcomere is the contractile unit, similar to skeletal muscle. Contracture is mediated by the interaction of calcium, troponins, and myofilaments, much as it occurs in skeletal muscle. Cardiac muscle, on the other hand, differs from skeletal muscle in a number of ways.In contrast to skeletal muscle cells, cardiac myocytes have a nucleus in the middle of the cell and sometimes two nuclei. The cells are striated because the thick and thin filaments are arranged in an orderly fashion, although the arrangement is less well-organized than in skeletal muscle.Intercalated discs, which work similarly to the Z band in skeletal muscle in defining where one cardiac muscle cell joins the next, are a very significant component of cardiac muscle.Adherens junctions and desmosomes, which are specialized structures that hold the cardiac myocytes together, are formed by the transverse sections. The lateral sections produce gap junctions, which join the cytoplasm of two cells directly, allowing for rapid action potential conduction. These critical properties allow the heart to contract in a coordinated manner, allowing for more efficient blood pumping.Cardiac myocytes have the ability to create their own action potentials, which is referred to as myogenic’. They can depolarize spontaneously to initiate a cardiac action potential. Pacemaker cells, as well as the sino-atrial (SA) and atrioventricular (AV) nodes, control this.The Purkinje cells and the cells of the bundle of His are likewise capable of spontaneous depolarization. While the bundle of His is made up of specialized myocytes, it’s vital to remember that Purkinje cells are not myocytes and have distinct characteristics. They are larger than myocytes, with fewer filaments and more gap junctions than myocytes. They conduct action potentials more quickly, allowing the ventricles to contract synchronously.Cardiac myocytes contract by excitation-contraction coupling, just like skeletal myocytes. Heart myocytes, on the other hand, utilise a calcium-induced calcium release mechanism that is unique to cardiac muscle (CICR). The influx of calcium ions (Ca2+) into the cell causes a ‘calcium spark,’ which causes more ions to be released into the cytoplasm.An influx of sodium ions induces an initial depolarisation, much as it does in skeletal muscle; however, in cardiac muscle, the inflow of Ca2+ sustains the depolarisation, allowing it to remain longer. Due to potassium ion (K+) inflow, CICR causes a plateau phase in which the cells remain depolarized for a short time before repolarizing. Skeletal muscle, on the other hand, repolarizes almost instantly.Comparison of skeletal and cardiac muscle:Skeletal muscle Cardiac muscleStriation Striated but arrangement less organised Multiple nuclei located peripherally Usually single nucleus (but can be two), located centrallyDiscs None Intercalated discsNo Gap junctions Gap junctions No Pacemaker PacemakerElectrical stimulation: Nervous system (excitation) Pacemaker (excitation)
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 14
Incorrect
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Pancreatic acinar digestive enzyme secretion is mainly stimulated by which of the following hormones:
Your Answer: Pancreatic polypeptide
Correct Answer: Cholecystokinin
Explanation:Exocrine pancreatic secretion is controlled by:Parasympathetic stimulation which enhances secretion of both the enzyme and aqueous componentsSympathetic stimulation which inhibits pancreatic secretionSecretin which stimulates secretion of the alkaline-rich fluid from ductal cellsCholecystokinin which stimulates secretion of the enzyme-rich fluid from acinar cellsSomatostatin which inhibits secretion from both acinar and ductal cellsGastrin which stimulates pancreatic acinar cells to secrete digestive enzymes
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 15
Incorrect
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Which of the following is the most common cause of hyperthyroidism:
Your Answer: TSH-secreting pituitary adenoma
Correct Answer: Graves disease
Explanation:Graves disease is the most common cause of hyperthyroidism. It is an autoimmune disease in which autoantibodies against TSH receptors are produced. These antibodies bind to and stimulate these TSH receptors leading to an excess production of thyroid hormones. Therefore, the signs and symptoms of Graves disease are the same as those of hyperthyroidism, reflecting the actions of increased circulating levels of thyroid hormones: increased heat production, weight loss, increased 02 consumption and cardiac output and exophthalmos (bulging eyes, not drooping eyelids). TSH levels will be decreased (not increased) as a result of the negative feedback effect of increased T3 levels on the anterior pituitary.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 16
Incorrect
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All of the following predisposes to lithium toxicity in patients taking long-term therapy EXCEPT:
Your Answer: Co-administration of diuretics
Correct Answer: Hypernatraemia
Explanation:A common complication of long term lithium therapy results in most cases of lithium intoxication. It is caused by reduced excretion of the drug which can be due to several factors including deterioration of renal function, dehydration, hyponatraemia, infections, and co-administration of diuretics or NSAIDs or other drugs that may interact.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 17
Incorrect
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A 70-year-old man presents with right-sided hemiplegia and loss of joint position sense, vibratory sense, and discriminatory touch. Upon further physical examination, it was observed that her tongue deviates to the left-hand side. An MRI and CT scan was ordered and results showed that he was suffering a left-sided stroke. Branches of which of the following arteries are most likely implicated in the case?
Your Answer: Vertebral artery
Correct Answer: Anterior spinal artery
Explanation:Medial medullary syndrome is a form of stroke that affects the medial medulla of the brain. It is caused by a lesion in the medial part of the medulla, which is due to an infraction of vertebral arteries and/or paramedian branches of the anterior spinal artery.It is characterized by contralateral paralysis of the upper and lower limb of the body, a contralateral decrease in proprioception, vibration, and/or fine touch sensation, paresthesias or less commonly dysesthesias in the contralateral trunk and lower limb, and loss of position and vibration sense with proprioceptive dysfunction. Ipsilateral deviation of the tongue due to ipsilateral hypoglossal nerve damage can also be seen.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 18
Correct
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Approximately what proportion of lymphocytes are B-cells:
Your Answer: 0.2
Explanation:B-cells (20% of lymphocytes) mature in the bone marrow and circulate in the peripheral blood until they undergo recognition of antigen. B-cell immunoglobulin molecules synthesised in the cell are exported and bound to the surface membrane to become the B-cell receptor (BCR) which can recognise and bind to a specific antigen (either free or presented by APCs). The BCR is also important for antigen internalisation, processing and presentation to T helper cells. Most antibody responses require help from antigen-specific T helper cells (although some antigens such as polysaccharide can lead to T-cell independent B-cell antibody production). When the B-cell is activated, the receptor itself is secreted as free soluble immunoglobulin and the B-cell matures into a memory B-cell or a plasma cell (a B-cell in its high-rate immunoglobulin secreting state). Plasma cells are non-motile and are found predominantly in the bone marrow or spleen. Most plasma cells are short-lived (1 – 2 weeks) but some may survive much longer. A proportion of B-cells persist as memory cells, whose increased number and rapid response underlies the augmented secondary response of the adaptive immune system.
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 19
Correct
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The patient is a 61-year-old man with severe central chest pain. An acute myocardial infarction is revealed by his ECG. Clopidogrel is one of the medications he takes as part of his treatment.Clopidogrel's direct mechanism of action is which of the following?
Your Answer: Inhibition of platelet ADP receptors
Explanation:Clopidogrel, a thienopyridine derivative, prevents platelet aggregation and cross-linking by the protein fibrin by inhibiting the ADP receptor on platelet cell membranes (inhibits binding of ADP to its platelet receptor (P2Y12 ADP-receptor).
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 20
Correct
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A patients had a left Colles' fracture, which you were able to repair. It was their second fragility fracture this year, and you'd like to provide them some tips on how to keep their bones healthy.What percentage of the calcium in the body is kept in the bones? Only ONE response is acceptable.
Your Answer: 99%
Explanation:Calcium is stored in bones for nearly all of the body’s calcium, but it is also found in some cells (most notably muscle cells) and the blood. The average adult diet comprises roughly 25 mmol of calcium per day, of which the body absorbs only about 5 mmol.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
