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Question 1
Correct
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What is the earliest physiological effect that causes postural hypotension:
Your Answer: A fall in central venous pressure
Explanation:When autonomic reflexes are impaired or intravascular volume is markedly depleted, a significant reduction in blood pressure occurs upon standing, a phenomenon termed Postural Hypotension (orthostatic hypotension). Orthostatic hypotension can cause dizziness, syncope, and even angina or stroke. When autonomic reflexes are impaired, blood pressure falls progressively after standing because the gravitational pooling of blood in the legs cannot be compensated by sympathetic vasoconstriction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 2
Correct
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A patient suffers a stab wound to the neck. The entry point of the blade is situated within the posterior triangle of the neck.
Which of the following muscles is LEAST likely to be involved? Select ONE answer only.Your Answer: Sternohyoid
Explanation:The anterior triangle is the triangular area of the neck found anteriorly to the sternocleidomastoid muscle. It is formed by the anterior border of sternocleidomastoid laterally, the median line of the neck medially and by the inferior border of the mandible superiorly. The apex of the anterior triangle extends towards the manubrium sterni. The anterior triangle contains:
Muscles: thyrohyoid, sternothyroid, sternohyoid muscles
Organs: thyroid gland, parathyroid glands, larynx, trachea, esophagus, submandibular gland, caudal part of the parotid gland
Arteries: superior and inferior thyroid, common carotid, external carotid, internal carotid artery (and sinus), facial, submental, lingual arteries
Veins: anterior jugular veins, internal jugular, common facial, lingual, superior thyroid, middle thyroid veins, facial vein, submental vein, lingual veins
Nerves: vagus nerve (CN X), hypoglossal nerve (CN XII), part of sympathetic trunk, mylohyoid nerveThe posterior triangle is a triangular area found posteriorly to the sternocleidomastoid muscle. It has three borders; anterior, posterior and inferior borders. The anterior border is the posterior margin of the sternocleidomastoid muscle. The posterior border is the anterior margin of the trapezius muscle, while the inferior border is the middle one-third of the clavicle. The investing layer of deep cervical fascia and integument forms the roof of the space, while the floor is covered with the prevertebral fascia along with levator scapulae, splenius capitis and the scalene muscles. The inferior belly of omohyoid subdivides the posterior triangle into a small supraclavicular, and a large occipital, triangle.
Contents:
Vessels: the third part of the subclavian artery, suprascapular and transverse cervical branches of the thyrocervical trunk, external jugular vein, lymph nodes
Nerves: accessory nerve (CN XI), the trunks of the brachial plexus, fibers of the cervical plexus -
This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 3
Correct
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Regarding endothelin-1, which of the following statements is INCORRECT:
Your Answer: Endothelin-1 release is inhibited by noradrenaline.
Explanation:Endothelin-1 (ET-1) is an extremely potent vasoconstrictor peptide which is released from the endothelium in the presence of many other vasoconstrictors, including angiotensin II, antidiuretic hormone (ADH) and noradrenaline, and may be increased in disease and hypoxia.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 4
Incorrect
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A 50-year-old man presents with headaches, lethargy, hypertension, and electrolyte disturbance. A diagnosis of primary hyperaldosteronism is made.
Which biochemical pictures would best support this diagnosis?
Your Answer: Hyperkalaemic metabolic alkalosis
Correct Answer: Hypokalaemic metabolic alkalosis
Explanation:When there are excessive levels of aldosterone outside of the renin-angiotensin axis, primary hyperaldosteronism occurs. High renin levels will lead to secondary hyperaldosteronism.
The classical presentation of hyperaldosteronism when symptoms are present include:
Hypokalaemia
Metabolic alkalosis
Hypertension
Normal or slightly raised sodium levels -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 5
Correct
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Which of the following is an ECG change typically associated with hyperkalaemia:
Your Answer: Wide QRS complex
Explanation:Hyperkalaemia causes a rapid reduction in resting membrane potential leading to increased cardiac depolarisation and muscle excitability. This in turn results in ECG changes which can rapidly progress to ventricular fibrillation or asystole. Very distinctive ECG changes that progressively change as the K+level increases:
K+>5.5 mmol/l – peaked T waves (usually earliest sign of hyperkalaemia), repolarisation abnormalities
K+>6.5 mmol/l – P waves widen and flatten, PR segment lengthens, P waves eventually disappear
K+>7.0 mmol/l – Prolonged QRS interval and bizarre QRS morphology, conduction blocks (bundle branch blocks, fascicular blocks), sinus bradycardia or slow AF, development of a sine wave appearance (a pre-terminal rhythm)
K+>9.0 mmol/l – Cardiac arrest due to asystole, VF or PEA with a bizarre, wide complex rhythm. -
This question is part of the following fields:
- Physiology
- Renal
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Question 6
Incorrect
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A 58-year-old man with a traumatic brain injury is brought into the ER. A medical student asks you about the processes that occur in the brain following a traumatic injury.
One of these best describes the central nervous systems response to injury.Your Answer: Axonal regeneration is carried out by Schwann cells in the brain
Correct Answer: Degeneration of the axon occurs proximally before it occurs distally
Explanation:Following neuronal injury, as seen in traumatic brain injury, the axon undergoes anterograde degeneration. Degradation starts from the cell body (proximally) and progresses distally. The axon becomes fragmented and degenerates.
The brain shows no reactive changes to injury is incorrect. Following major injury such as stroke, the brain undergoes a process of liquefactive degeneration, which leaves cystic spaces within the brain.
Axonal regeneration does not occur to any significant extent within the central nervous system unlike what is seen in the peripheral nervous system.
Astrocytes undergo reactive gliosis, leaving behind a firm translucent tissue around sites of damage.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 7
Correct
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Diagnosis of HIV is predominantly made through which of the following:
Your Answer: Antibody detection
Explanation:Diagnosis of HIV is predominantly made through detection of HIV antibody and p24 antigen. Viral load (viral PCR) and CD4 count are used to monitor progression of disease.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 8
Incorrect
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A 7-days-old neonate is taken to the emergency department. She's pyretic, lethargic, and unresponsive, and her fontanelle has bulged. Antibiotics are started, and a lumbar puncture reveals Gram-negative rods. Which pathogen is most likely to be the cause:
Your Answer: Neisseria meningitidis
Correct Answer: Escherichia coli
Explanation:Among neonates, group B streptococci (GBS) are the most commonly identified causes of bacterial meningitis, implicated in roughly 50% of all cases. Escherichia coli(Gram-negative rods) accounts for another 20%. Thus, the identification and treatment of maternal genitourinary infections is an important prevention strategy.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 9
Correct
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A 58-year-old male has cellulitis of his left leg. Because he is allergic to penicillin, you start him on erythromycin.
What is erythromycin's mechanism of action?Your Answer: Inhibition of protein synthesis
Explanation:Bacteriostatic antibiotics include erythromycin and other macrolide antibiotics. They work by attaching to the bacterial ribosome’s 50S subunit, preventing translocation and thereby protein synthesis. Macrolide antibiotics are actively concentrated inside leukocytes and delivered to the infection site as a result.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 10
Correct
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Regarding diuretics, which of the following statements is CORRECT:
Your Answer: Carbonic anhydrase inhibitors have their effect by inhibiting bicarbonate reabsorption.
Explanation:Carbonic anhydrase inhibitors e.g. acetazolamide block the reaction of carbon dioxide and water and so prevent Na+/H+exchange and bicarbonate reabsorption. The increased bicarbonate levels in the filtrate oppose water reabsorption. Proximal tubule sodium reabsorption is also reduced because it is partly dependent on bicarbonate reabsorption.
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This question is part of the following fields:
- Physiology
- Renal
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Question 11
Correct
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How is measles primarily transmitted:
Your Answer: Respiratory droplet route
Explanation:Measles belongs to the paramyxoviridae group of viruses. The incubation period is 7-18 days (average 10) and it is spread by airborne or droplet transmission. The classical presentation is of a high fever with coryzal symptoms and photophobia with conjunctivitis often being present. The rash that is associated is a widespread erythematous maculopapular rash. Koplik spots are pathognomonic for measles, and are the presence of white lesions on the buccal mucosa.
Differential diagnoses would include:
Rubella
Roseola infantum (exanthem subitom)
Scarlet fever
Kawasaki disease
Erythema infectiosum (5thdisease)
Enterovirus
Infectious mononucleosis
Diagnosis can be confirmed by the following means:
Salivary swab for measles specific IgM
Serum sample for measles specific IgM
Salivary swab for RNA detection
Possible complications include:
Otitis media
Febrile convulsions
Pneumonia
Bronchiectasis
Diarrhoea
Meningitis
Encephalitis
Immunosuppression
Subacute sclerosing panencephalitis
Death -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 12
Correct
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A 5-year-old girl presents in a paediatric clinic with symptoms of viral gastroenteritis. You encourage the mother to treat the child at home with oral rehydration therapy (ORT), e.g. dioralyte.
Out of the following, which statement is FALSE regarding the use of ORT in the management of gastroenteritis?Your Answer: ORT is sugar-free
Explanation:One of the major complications of gastroenteritis is dehydration. Choosing the correct fluid replacement therapy is essential according to a patient’s hydration status.
Oral rehydration therapy (ORT) refers to the restitution of water and electrolyte deficits in dehydrated patients using an oral rehydration salt (ORS) solution. It is a fluid replacement strategy that is less invasive than other strategies for fluid replacement and has successfully lowered the mortality rate of diarrhoea in developing countries.
Some characteristics of Oral rehydration solutions are:
– slightly hypo-osmolar (about 250 mmol/litre) to prevent the possible induction of osmotic diarrhoea.
– contain glucose (e.g. 90 mmol/L in dioralyte). The addition of glucose improves sodium and water absorption in the bowel and prevents hypoglycaemia.
– also contains essential mineral saltsCurrent NICE guidance recommends that 50 ml/kg is given over 4 hours to treat mild dehydration.
Once rehydrated, a child should continue with their usual daily fluid intake plus 200 ml ORT after each loose stool. In an infant, give ORT at 1-1.5 x the normal feed volume and in an adult, give 200-400 ml after each loose stool. -
This question is part of the following fields:
- Fluids & Electrolytes
- Pharmacology
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Question 13
Correct
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A patient with history of weight loss and diarrhoea was found out to have Giardia lamblia in her stool since returning from a holiday to Nepal.
Which of the following statements is considered true regarding the life cycle of Giardia lamblia?Your Answer: Trophozoites attach to the intestinal wall via a specialised sucking disc
Explanation:Cysts are resistant forms and are responsible for transmission of giardiasis. Both cysts and trophozoites can be found in the faeces (diagnostic stages). The cysts are hardy and can survive several months in cold water. Infection occurs by the ingestion of cysts in contaminated water, food, or by the faecal-oral route (hands or fomites).
In the small intestine, excystation releases trophozoites (each cyst produces two trophozoites).
Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk.
Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in non diarrheal faeces.
Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. While animals are infected with Giardia, their importance as a reservoir is unclear. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 14
Incorrect
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A 6-year-old child with a few itchy honey crusted sores on her left cheek is brought in by her mother. Following a thorough examination of the child, you diagnose impetigo and recommend a course of topical fusidic acid.
Fusidic acid's mode of action is which of the following?Your Answer: Inhibition of cell wall synthesis
Correct Answer: Inhibition of protein synthesis
Explanation:By binding EF-G-GDP, fusidic acid prevents both peptide translocation and ribosome disassembly, which slows protein synthesis. Because it has a novel structure and mechanism of action, it is unlikely to cause cross-resistance with existing antibiotics.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 15
Correct
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Which of the following microbes binds strongly to CD4 antigen:
Your Answer: HIV
Explanation:HIV mainly infects CD4+ T helper cells. Viral replication results in progressive T-cell depletion and impaired cell-mediated immunity with subsequent secondary opportunistic infections and increased risk of malignancy. B-cell function is also reduced as a result of lack of T-cell stimulation.
HIV is not a notifiable disease. -
This question is part of the following fields:
- Microbiology
- Principles
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Question 16
Incorrect
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A 43-year old male is taken to the Emergency Room for a lacerated wound on the abdomen, situated above the umbilicus. A short segment of the small bowel has herniated through the wound.
Which of these anatomic structures is the deepest structure injured in the case above?Your Answer: Aponeurosis of internal oblique
Correct Answer: Transversalis fascia
Explanation:The following structures are the layers of the anterior abdominal wall from the most superficial to the deepest layer:
Skin
Fatty layer of the superficial fascia (Camper’s fascia)
Membranous layer of the superficial fascia (Scarpa’s fascia)
Aponeurosis of the external and internal oblique muscles
Rectus abdominis muscle
Aponeurosis of the internal oblique and transversus abdominis
Fascia transversalis
Extraperitoneal fat
Parietal peritoneum -
This question is part of the following fields:
- Abdomen And Pelvis
- Anatomy
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Question 17
Incorrect
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A patient presents with a laceration on his hand and wrist that has cut the nerve that innervates opponens pollicis.
The opponens pollicis muscle is innervated by which of the following nerves? Select ONE answer only.Your Answer: The palmar digital branch of the median nerve
Correct Answer: The recurrent branch of the median nerve
Explanation:Opponens pollicis is a small, triangular muscle that forms part of the thenar eminence. It originates from the flexor retinaculum and the tubercle of trapezium bone and inserts into the whole length of the first metacarpal bone on its radial side.
Opponens pollicis is innervated by the recurrent branch of the median nerve and receives its blood supply from the superficial palmar arch.
The main action of opponens pollicis is to flex the first metacarpal bone at the carpometacarpal joint, which opposes the thumb towards the centre of the palm. It also medially rotates the first metacarpal bone at the carpometacarpal joint. -
This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 18
Correct
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Eosinophils comprise what percentage of circulating white cells:
Your Answer: 1 - 3%
Explanation:Eosinophils comprise 1 – 3% of circulating white cells. Eosinophils are similar to neutrophils, except that the cytoplasmic granules are coarser and more deeply red staining, and there are rarely more than three nuclear lobes. They are less motile, but longer lived. They enter inflammatory exudates and have a special role in allergic responses, defence against parasites and removal of fibrin formed during inflammation. Thus they play a role in local immunity and tissue repair.
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 19
Incorrect
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Doxycycline is indicated first line for treatment of which of the following infections:
Your Answer: Gonorrhoea
Correct Answer: Chlamydia
Explanation:Doxycycline may be used first line for chlamydia, pelvic inflammatory disease (with metronidazole and ceftriaxone), acute bacterial sinusitis, exacerbation of chronic bronchitis, moderate-severity community acquired pneumonia and high-severity community acquired pneumonia (with benzylpenicillin).
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 20
Correct
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A patient presents with haemoptysis, weight loss, and night sweats. You suspect he may have tuberculosis. He works at an asylum seeker hostel, and has not received a BCG vaccination. In which of the following patient groups would the BCG vaccine be safe to administer?
Your Answer: The patient is asplenic
Explanation:Persons with chronic diseases. Persons with chronic renal disease or undergoing dialysis, and those with hyposplenism or asplenia, may receive BCG vaccine if indicated.
Only 2 absolute contraindications apply to all vaccines:
- anaphylaxis following a previous dose of the relevant vaccine
- anaphylaxis following any component of the relevant vaccine
2 further contraindications apply to live vaccines (both parenteral and oral):
- People who are significantly immunocompromised should not receive live vaccines. This is regardless of whether the immunocompromising condition is caused by disease or treatment.
- Pregnant women should not receive live vaccines, in general. Women should be advised not to become pregnant within 28 days of receiving a live vaccine.
Use of live vaccines in people who are immunocompromised:
People who are immunocomprised are at risk of adverse events or vaccine-related disease if they receive a live vaccine.Live vaccines include:
BCG (bacille Calmette–Guérin) vaccine
oral cholera vaccine (Vaxchora)
Some Japanese encephalitis virus vaccines
MMR (measles-mumps-rubella) vaccine
rotavirus vaccine
oral typhoid vaccine
varicella vaccine
yellow fever vaccine
zoster vaccine (Zostavax) -
This question is part of the following fields:
- Immunological Products & Vaccines
- Pharmacology
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Question 21
Correct
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A 59-year-old otherwise well woman presents with a history of polydipsia and polyuria. There is a past history of kidney stones, and blood tests done reveal the following:
Na: 147 mmol/L (135-147 mmol/L)
K: 4.0 mmol/L (3.5-5.5 mmol/L)
Urea: 7.3 mmol/L (2.0-6.6 mmol/L)
Creatinine: 126 mmol/L (75-125 mmol/L)
Fasting blood glucose: 5.0 mmol/L (3.4-5.5 mmol/L)
Corrected calcium: 3.21 mmol/L (2.05-2.60 mmol/L)
Phosphate: 0.70 mmol/L (0.8-1.4 mmol/L)
Parathyroid hormone: 189 ng/L (10-60 ng/L)
The most likely diagnosis is?Your Answer: Primary hyperparathyroidism
Explanation:Primary hyperparathyroidism the commonest cause of hypercalcaemia. It is commonest in women aged 50 to 60.
The commonest cause of primary hyperparathyroidism is a solitary adenoma of the parathyroid gland (approximately 85% of cases).Primary hyperparathyroidism may present with features of hypercalcaemia such as polyuria, polydipsia, renal stones, bone and joint pain, constipation, and psychiatric disorders.
In primary Hyperparathyroidism:
PTH is elevated
Calcium is elevated
Phosphate is loweredIn secondary Hyperparathyroidism:
PTH is elevated
Calcium is low or low-normal
Phosphate is raised in CRFIn tertiary Hyperparathyroidism:
PTH is elevated
Calcium is elevated
Phosphate is lowered in CRF -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 22
Correct
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At rest, skeletal muscle accounts for between 15-20% of cardiac output and accounts for around 50% of body weight. This can increase to nearly 80% of cardiac output during exercise. Skeletal muscle circulation is highly controlled and has a number of specialized adaptations as a result of this high degree of disparity during exercise, in combination with the diversity in the size of skeletal muscle around the body.
What is the primary mechanism for boosting skeletal muscle blood flow during exercise?
Your Answer: Metabolic hyperaemia
Explanation:In skeletal muscle, blood flow is closely related to metabolic rate. Due to the contraction of precapillary sphincters, most capillaries are blocked off from the rest of the circulation at rest and are not perfused. This causes an increase in vascular tone and vessel constriction. As metabolic activity rises, this develops redundancy in the system, allowing it to cope with greater demand. During exercise, metabolic hyperaemia, which is induced by the release of K+, CO2, and adenosine, recruits capillaries. Sympathetic vasoconstriction in the active muscles is overridden by this. Simultaneously, blood flow in non-working muscles is restricted, preserving cardiac output. During exercise, muscle contractions pump blood through the venous system, raising the pressure differential between arterioles and venules and boosting blood flow via capillaries.
Capillary angiogenesis is evident when muscles are used repeatedly (e.g. endurance training). It is a long-term effect, not a quick fix for increased blood flow.
The local partial pressure of alveolar oxygen is the primary intrinsic control of pulmonary blood flow (pAO2). Low pAO2 promotes arteriole vasoconstriction and vice versa. The hypoxic pulmonary vasoconstriction (HPV) reflex allows blood flow to be diverted away from poorly ventilated alveoli and towards well-ventilated alveoli in order to maximize gaseous exchange.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 23
Incorrect
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Regarding water and electrolyte absorption in the small intestine, which of the following statements is INCORRECT:
Your Answer: K+ leaves the cell across the basolateral membrane down its concentration gradient linked to an outward movement of Cl-.
Correct Answer: Na+ enters the cell across the apical membrane against its concentration gradient by both membrane channels and transporter protein mechanisms.
Explanation:As the contents of the intestine are isotonic with body fluids and mostly have the same concentration of the major electrolytes, their absorption is active. Water cannot be moved directly, but follows osmotic gradients set up by the transport of ions, primarily mediated by the sodium pump.Na+/K+ ATPase located on the basolateral membrane of the epithelial cells pumps three Na+ ions from the cell in exchange for two K+ ions, against their respective concentration gradients. This leads to a low intracellular concentration of Na+ and a high intracellular concentration of K+. The low intracellular concentration of Na+ ensures a movement of Na+ from the intestinal contents into the cell down its concentration gradient by both membrane channels and transporter protein mechanisms. Na+ is then rapidly pumped again by the basolateral sodium pump. K+ leaves the cell across the basolateral membrane down its concentration gradient linked to an outward movement of Cl- against its concentration gradient (Cl- having entered the cell across the luminal membrane down its concentration gradient).
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 24
Correct
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Which of the following classes of drugs may predispose to lithium toxicity:
Your Answer: Thiazide diuretics
Explanation:Excretion of lithium may be reduced by thiazide diuretics, NSAIDs, and ACE inhibitors thus predisposing to lithium toxicity. Loop diuretics also cause lithium retention but are less likely to result in lithium toxicity.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 25
Correct
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When a person changes from a supine to an upright position, which of the followingcompensatory mechanismsoccurs:
Your Answer: Increased contractility
Explanation:On standing from a prone position, gravity causes blood to pool in veins in the legs. Central venous pressure (CVP) falls, causing a fall in stroke volume and cardiac output (due to Starling’s law) and thus a fall in blood pressure. Normally this fall in BP is rapidly corrected by the baroreceptor reflex which causes venoconstriction (partially restoring CVP), and an increase in heart rate and contractility, so restoring cardiac output and blood pressure. Impaired autonomic nervous activity in the elderly accounts for the greater likelihood of postural hypotension. Any symptoms of dizziness, blurred vision or syncope is due to a transient fall in cerebral perfusion that occurs before cardiac output and mean arterial pressure (MAP) can be corrected.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 26
Correct
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The hypothalamus produces antidiuretic hormone (ADH), also known as vasopressin, which is a peptide hormone. It is important for maintaining water and electrolyte balance, as well helping control arterial pressure.
To have an effect on blood arteries, ADH binds to which of the following receptors?Your Answer: V 1 receptor
Explanation:ADH, or antidiuretic hormone, is a hormone that regulates water and electrolyte balance. It is released in response to a variety of events, the most important of which are higher plasma osmolality or lower blood pressure. ADH increases plasma volume and blood pressure via acting on the kidneys and peripheral vasculature.
It causes vasoconstriction by binding to peripheral V1 Receptors on vascular smooth muscle via the IP3 signal transduction and Rho-kinase pathways. The systemic vascular resistance and arterial pressure rise as a result. High levels of ADH appear to be required for this to have a major impact on arterial pressure, such as in hypovolaemic shock.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 27
Incorrect
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A 74-year-old woman with a history of ischaemic heart disease and heart failure is complaining of worsening oedema, bloating, and a loss of appetite. She has ascites and peripheral oedema on examination. Her oedema is being controlled by an oral diuretic, but it appears that this is no longer enough. You discuss her care with the on-call cardiology registrar, who believes she is very likely to have significant gut oedema that is interfering with her diuretic absorption and that she will need to change her medication.
Which of the following oral diuretics is most likely to help you overcome this problem?Your Answer: Bendroflumethiazide
Correct Answer: Bumetanide
Explanation:Bumetanide is primarily used in patients with heart failure who have failed to respond to high doses of furosemide. Bumetanide and furosemide differ primarily in terms of bioavailability and pharmacodynamic potency. In the intestine, furosemide is only partially absorbed, with a bioavailability of 40-50 percent. Bumetanide, on the other hand, is almost completely absorbed in the intestine and has a bioavailability of about 80%. As a result, when it has a better bioavailability than furosemide, it is commonly used in patients with gut oedema.
When taken alone, Bendroflumethiazide is a moderately potent diuretic that is unlikely to control her oedema.
Mannitol is a type of osmotic diuretic used to treat cerebral oedema and high intracranial pressure.
Acetazolamide is a weak diuretic that inhibits carbonic anhydrase. It’s a rare occurrence.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 28
Correct
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The primary mechanism of action of ketamine is:
Your Answer: N-methyl-D-aspartate (NMDA)-receptor antagonist
Explanation:Ketamine is a non-competitive antagonist of the calcium-ion channel in the NMDA (N-methyl-D-aspartate) receptor. It further inhibits the NMDA-receptor by binding to its phencyclidine binding site. Ketamine also acts at other receptors as an opioid receptor agonist (analgesic effects), as an muscarinic anticholinergic receptor antagonist (antimuscarinic effects) and by blocking fast sodium channels (local anaesthetic effect).
Overdose may lead to panic attacks and aggressive behaviour; rarely seizures, increased ICP, and cardiac arrest
Very similar in chemical makeup to PCP (phencyclidine), but it is shorter acting and less toxic
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 29
Correct
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Regarding the resting membrane potential, which of the following statements is CORRECT:
Your Answer: The resting cell membrane is more permeable to K + ions than to Na + ions.
Explanation:A membrane potential is a property of all cell membranes, but the ability to generate an action potential is only a property of excitable tissues. The resting membrane is more permeable to K+and Cl-than to other ions (and relatively impermeable to Na+); therefore the resting membrane potential is primarily determined by the K+equilibrium potential. At rest the inside of the cell is negative relative to the outside. In most neurones the resting potential has a value of approximately -70 mV.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 30
Correct
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Which of the following is NOT an advantage of a cohort study used to investigate the relationship between exposure to a risk factor and a future outcome:
Your Answer: Particularly suitable for rare diseases
Explanation:Advantages: ideal for studying associations between an exposure and an outcome when the exposure is uncommon, the time sequence of events can be assessed, they can provide information on a wide range of disease outcomes, the absolute and relative risk of disease can be measured directly, they can give a direct estimation of disease incidence rates
Disadvantages: costly and can take long periods of time if the outcome is delayed, subject to subject-selection and loss to follow-up bias, large sample size required for rare outcome of interest so it is not useful for rare diseases, prone to confounding -
This question is part of the following fields:
- Evidence Based Medicine
- Study Methodology
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Question 31
Incorrect
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A 16-year-old male with a known case of Haemophilia A is referred to your orthopaedic clinic for evaluation and aspiration of a hemarthrosis of the left knee joint.
Out of the modes of inheritance listed below, which one is present in this disease?Your Answer: Mitochondrial
Correct Answer: X-linked recessive
Explanation:All the Haemophilia’s have an X-linked recessive inheritance pattern, so they only manifest in male patients. Diseases with a mitochondrial inheritance pattern include MELAS syndrome, Leigh syndrome, LHON and MERRF syndrome. Autosomal dominant disorders include Huntingdon disease and Marfan syndrome. X-linked dominant diseases include Fragile X syndrome. Autosomal recessive diseases include cystic fibrosis and sickle cell disease.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 32
Incorrect
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Regarding Clostridium species, which of the following statements is INCORRECT:
Your Answer: They are rod-shaped.
Correct Answer: They are facultative anaerobes.
Explanation:Clostridium spp. are obligatory anaerobic spore-forming Gram-positive bacilli. Toxin production is the main pathogenicity mechanism.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 33
Correct
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The following are all important buffers of H+EXCEPT for:
Your Answer: Calcium
Explanation:Buffers are weak acids or bases that can donate or accept H+ions respectively and therefore resist changes in pH. Buffering does not alter the body’s overall H+load, ultimately the body must get rid of H+by renal excretion if the buffering capacity of the body is not to be exceeded and a dangerous pH reached. Bicarbonate and carbonic acid (formed by the combination of CO2 with water, potentiated by carbonic anhydrase) are the most important buffer pair in the body, although haemoglobin provides about 20% of buffering in the blood, and phosphate and proteins provide intracellular buffering. Buffers in urine, largely phosphate, allow the excretion of large quantities of H+.
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This question is part of the following fields:
- Physiology
- Renal
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Question 34
Correct
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A 49-year-old woman with haemoglobin of 6 g/dL following persistent vaginal bleeding receives blood transfusion. She developed pain and burning at her cannula site and complains of a feeling of “impending doom”, nausea, and severe back pain shortly after transfusion was started. Her temperature is 38.9ºC.
What is the most appropriate treatment?Your Answer: Stop the transfusion and administer IV fluids
Explanation:Acute haemolytic transfusion reactions present with: Feeling of ‘impending doom’ as the earliest symptom, fever and chills, pain and warmth at transfusion site, nausea and vomiting, back, joint, and chest pain. Transfusion should be stopped immediately and IV fluid (usually normal saline) administered.
Supportive measures and paracetamol can be given since patient has fever but it is not the immediate first step.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 35
Correct
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Innate, or non-specific, immunity is the immune system we are born with.
Which of the following is NOT an example of innate immunity? Select ONE answer only.Your Answer: T-lymphocytes
Explanation:Innate, or non-specific, immunity is the immune system we are born with.
There are three aspects of innate immunity:
1. Anatomical barriers, such as:
The cough reflex
Enzymes in tears and skin oils
Mucus – which traps bacteria and small particles
Skin
Stomach acid
2. Humoral barriers, such as:
The complement system
Interleukin-1
3. Cellular barriers, such as:
Neutrophils
Macrophages
Dendritic cells
Natural killer cells
Antibody production is part of the specific, or inducible immune response. T-lymphocytesare responsible for the cell mediated immune response which is part of specific, or inducible immunity. -
This question is part of the following fields:
- General Pathology
- Pathology
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Question 36
Correct
-
Liquefactive necrosis is most commonly seen in which of the following conditions:
Your Answer: Ischaemic stroke
Explanation:Liquefactive necrosis results in the loss of all cellular structure and the formation of a soft, semi-solid mass. This is commonly seen in the brain after a cerebral infarction.
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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Question 37
Incorrect
-
You examine a patient who is experiencing a worsening of his chronic heart failure. You discuss his care with the on-call cardiology registrar, who recommends switching him from furosemide to bumetanide at an equivalent dose. He's on 80 mg of furosemide once a day right now.
What is the recommended dose of bumetanide?Your Answer: 20 mg
Correct Answer: 2 mg
Explanation:Bumetanide is 40 times more powerful than furosemide, and one milligram is roughly equivalent to 40 milligrams of furosemide. This patient is currently taking 80 mg of furosemide and should be switched to a 2 mg bumetanide once daily.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 38
Incorrect
-
A study investigating the risk of suffering a stroke in patients with atrial fibrillation taking the new antiplatelet drug ticagrelor, compared with standard treatment with warfarin is done over a 2-year time period. 30 of the 300 patients taking ticagrelor and 20 of the 500 patients taking warfarin suffered a stroke over the 2-year period.
One of these statements is true regarding the outcomes of this study.
Your Answer: Ticagrelor has no effect on stroke
Correct Answer: Ticagrelor increases the risk of stroke
Explanation:Absolute risk and relative risk are used to assess the strength of a relationship between a disease and a factor that may affect it.
Absolute risk (AR) is the risk of developing a disease over a time period:
AR = the number of events that occur in a group / number of people in that groupThe absolute risk reduction (ARR) is the difference between the absolute risk in the control group (ARC) and the absolute risk in the treated group (ART).
ARR = ARC – ART
The control group is the warfarin group, therefore the ARC is 20/500 (0.04).
Treatment group is the ticagrelor group and ART = 30/300 (0.1).ARR = 0.04 – 0.1 = -0.06. This shows that treatment with ticagrelor increases risk of developing stroke. This is also termed a relative risk increase.
Relative risk, or risk ratio, (RR) is used to compare the risk in the two different groups. It is the ratio of the absolute risks of the disease in the treatment group (ART) to the absolute risk of the disease in the control group (ARC):
RR=ART /ARCTherefore RR = 0.1 / 0.04 = 2.5
RR < 1 means the intervention reduces the risk of the outcome being studied
RR = 1 means the treatment has no effect on the outcome being studied
RR > 1 means the intervention increased the risk of the outcome being studied
Since RR is 2.5, ticagrelor increases the risk of stroke.SUMMARY
Absolute risk reduction is -0.06
Absolute risk in warfarin group = 0.04
Relative risk = 2.5
Ticagrelor has no effect on stroke is incorrect because RR is not =1 -
This question is part of the following fields:
- Evidence Based Medicine
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Question 39
Incorrect
-
Regarding inhaled corticosteroids, which of the following statements is INCORRECT:
Your Answer: Side effects include paradoxical bronchospasm.
Correct Answer: Lower doses of inhaled corticosteroids may be required in smokers.
Explanation:Current and previous smoking reduces the effectiveness of inhaled corticosteroids and higher doses may be necessary.
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This question is part of the following fields:
- Pharmacology
- Respiratory
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Question 40
Incorrect
-
A 20-year-old male has an anaphylactic reaction following a wasp sting.
What type of hypersensitivity reaction is this?
Your Answer:
Correct Answer: Type I
Explanation:Anaphylaxis is an example of a type I hypersensitivity reaction.
It is IgE mediated.
It requires a prior exposure to the antigen. The initial exposure sensitizes the body to the antigen and a second exposure to that antigen leads to an anaphylactic reaction.
Massive calcium influx into the cells leads to mast cell degranulation.
The Immunoglobulin antigen complex binds to Fc receptors on the surface of mast cells. The result is mast cell degranulation and release of histamine, proteoglycans and serum proteases from cytoplasmic granules.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 41
Incorrect
-
A young farmer who is caught under farm machinery and suffering from a major crush injury is taken to the emergency department and requires a quick induction sequence. In this type of injury, which of the following anaesthetic medicines should be avoided?
Your Answer:
Correct Answer: Suxamethonium
Explanation:Suxamethonium is a neuromuscular blocker. It is contraindicated in patients who have experienced massive trauma, hyperkalemic, or burn injuries.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 42
Incorrect
-
You review a patient with a history of Addison’s disease. He takes 100 mg of hydrocortisone per day to control this.
What dose of prednisolone is equivalent to this dose of hydrocortisone? Select ONE answer only.Your Answer:
Correct Answer: 25 mg
Explanation:Prednisolone is four times more potent than hydrocortisone, and therefore, a dose of 25 mg would be equivalent to 100 mg of hydrocortisone.
The following table summarises the relative potency of the main corticosteroids compared with hydrocortisone:
Corticosteroid
Potency relative to hydrocortisone
Prednisolone
4 times more potent
Triamcinolone
5 times more potent
Methylprednisolone
5 times more potent
Dexamethasone
25 times more potent -
This question is part of the following fields:
- Endocrine Pharmacology
- Pharmacology
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Question 43
Incorrect
-
The syndrome of inappropriate antidiuresis due to excessive antidiuretic hormone (ADH) secretion is diagnosed in a male patient with a history of recurrent hyponatraemia.
Which of the following produces ADH?Your Answer:
Correct Answer: Hypothalamus
Explanation:Antidiuretic hormone (ADH), commonly known as vasopressin, is a peptide hormone that controls how much water the body retains.
It is produced in the magnocellular and parvocellular neurosecretory cells of the paraventricular nucleus and supraoptic nucleus in the hypothalamus from a prohormone precursor. It is subsequently carried to the posterior pituitary via axons and stored in vesicles.
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.Stretch receptors in the atrial walls and big veins detect a decrease in atrial pressure as a result of this (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.The main sites of action for ADH are:
The kidney is made up of two parts. ADH’s main job is to keep the extracellular fluid volume under control. It increases permeability to water by acting on the renal collecting ducts via V2 Receptors (via a camp-dependent mechanism). This leads to a decrease in urine production, an increase in blood volume, and an increase in arterial pressure as a result.Vascular system: Vasoconstriction is a secondary function of ADH. ADH causes vasoconstriction via binding to V1 Receptors on vascular smooth muscle (via the IP3 signal transduction pathway). An increase in arterial pressure occurs as a result of this.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 44
Incorrect
-
Which of the following is most true of the sinoatrial node:
Your Answer:
Correct Answer: Frequency of depolarisation is increased by sympathetic stimulation.
Explanation:Cardiac myocyte contraction is not dependent on an external nerve supply but instead the heart generates its own rhythm, demonstrating inherent rhythmicity. The heartbeat is initiated by spontaneous depolarisation of the sinoatrial node (SAN), a region of specialised myocytes in the right atrium close to the coronary sinus, at a rate of 100-110 beats/min. This intrinsic rhythm is primarily influenced by autonomic nerves, with vagal influences being dominant over sympathetic influences at rest. This vagal tone reduces the resting heart rate down to 60-80 beats/min. To increase heart rate, the autonomic nervous system increases sympathetic outflow to the SAN, with concurrent inhibition of vagal tone. These changes mean the pacemaker potential more rapidly reaches the threshold for action potential generation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 45
Incorrect
-
Regarding co-amoxiclav, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Clavulanic acid acts to inhibit cross-linking of bacterial peptidoglycan polymers.
Explanation:Co-amoxiclav consists of amoxicillin with the beta-lactamase inhibitor clavulanic acid. Clavulanic acid itself has no significant antibacterial activity but, by inactivating beta-lactamases, it makes the combination active against beta-lactamase-producing bacteria that are resistant to amoxicillin.The most common adverse effects of co-amoxiclav include nausea, vomiting, skin rash and diarrhoea. Pseudomembranous colitis should be considered if a person develops severe diarrhoea during or after treatment with co-amoxiclav. Cholestatic jaundice can occur either during or shortly after the use of co-amoxiclav. An epidemiological study has shown that the risk of acute liver toxicity was about 6 times greater with co-amoxiclav than with amoxicillin. Cholestatic jaundice is more common in patients above the age of 65 years and in men; these reactions have only rarely been reported in children. Jaundice is usually self-limiting and very rarely fatal.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 46
Incorrect
-
All of the following statements are considered true regarding randomized control trials, except:
Your Answer:
Correct Answer: They can eliminate the need for further studies
Explanation:Meta-analysis is a quantitative, formal, epidemiological study design used to systematically assess previous research studies to derive conclusions about that body of research. Outcomes from a meta-analysis may include a more precise estimate of the effect of treatment or risk factor for disease, or other outcomes, than any individual study contributing to the pooled analysis. The examination of variability or heterogeneity in study results is also a critical outcome.
The benefits of meta-analysis include a consolidated and quantitative review of a large, and often complex, sometimes apparently conflicting, body of literature. The specification of the outcome and hypotheses that are tested is critical to the conduct of meta-analyses, as is a sensitive literature search.Important medical questions are typically studied more than once, often by different research teams in different locations. In many instances, the results of these multiple small studies of an issue are diverse and conflicting, which makes the clinical decision-making difficult. The need to arrive at decisions affecting clinical practise fostered the momentum toward evidence-based medicine. Evidence-based medicine may be defined as the systematic, quantitative, preferentially experimental approach to obtaining and using medical information. Therefore, meta-analysis, a statistical procedure that integrates the results of several independent studies, plays a central role in evidence-based medicine.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 47
Incorrect
-
Which type of collagen is initially laid down in early wound healing:
Your Answer:
Correct Answer: III
Explanation:Fibroblasts migrate to the wound (about 2 – 5 days after wounding), proliferate and secrete extracellular matrix comprising mainly collagen (type III) and fibronectin to plug the gap.
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This question is part of the following fields:
- Pathology
- Wound Healing
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Question 48
Incorrect
-
A 57-year-old male presents to the orthopaedic clinic complaining of pain and swelling in the left knee joint. On examination, the left knee is swollen, tender and erythematous. The patient is booked for joint aspiration, and a diagnosis of pseudogout is made following the aspiration.
Which types of crystals would be seen in the joint aspirate to lead to this diagnosis?Your Answer:
Correct Answer: Positively birefringent brick-shaped crystals
Explanation:Gout and pseudogout are both characterised by crystal deposition in the affected joints. The deposition of urate crystals causes gout, while calcium pyrophosphate crystals cause pseudogout. The crystals can be distinguished microscopically because urate crystals are negatively birefringent needle-shaped crystals, whilst calcium pyrophosphate crystals are positively birefringent brick-shaped crystals.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 49
Incorrect
-
Tiredness, night sweats, and easy bruising are symptoms of a 58-year-old woman. Splenomegaly is observed during the examination.
Which of the following diagnoses is the SINGLE MOST LIKELY?Your Answer:
Correct Answer: Chronic myeloid leukaemia (CML)
Explanation:CML is a myeloproliferative disorder characterised by an abnormal pluripotent haemopoietic stem cell. A cytogenetic abnormality known as the Philadelphia chromosome, which results from a reciprocal translocation between the long arms of chromosomes 9 and 22, causes more than 80% of cases of CML.
CML is a disease that develops slowly over several years. This is known as the ‘chronic stage.’ This stage is usually asymptomatic, and 90 percent of patients are diagnosed at this point, with the disease being discovered frequently as a result of a routine blood test. During this stage, the bone marrow contains less than 10% immature white cells (blasts).
When CML cells expand, symptoms typically begin to appear. The ‘accelerated stage’ is what it’s called. Approximately 10% of people are diagnosed at this point. During this stage, between 10% and 30% of blood cells in the bone marrow are blasts. During this stage, common clinical features include:
Fatigue and exhaustion
Night sweats and fever
Distension of the abdomen
Pain in the left upper quadrant (splenic infarction)
Splenomegaly (commonest examination finding)
Hepatomegaly
Bruising is simple.
Gout is a type of arthritis that affects (rapid cell turnover)
Hyperviscosity is a condition in which the viscosity of (CVA, priapism)
A small percentage of patients experience a ‘blast crisis’ (blast stage). More than 30% of the blood cells in the bone marrow are immature blast cells at this stage. Patients with severe constitutional symptoms (fever, weight loss, bone pain), infections, and bleeding diathesis typically present at this stage.In CML, laboratory findings include:
White cell count is abnormally high (often greater than 100 x 109/l).
Increased number of immature leukocytes causes a left shift.
Anaemia that is mild to moderately normochromic and normocytic.
Platelets can be low, normal, or elevated, and the Philadelphia chromosome can be found in > 80% of patients.
Serum uric acid and ALP levels are frequently elevated.
Tyrosine kinase inhibitors (TKIs), such as imatinib and dasatinib, are the current mainstay of CML treatment.
Allogenic bone marrow transplantation is now only used in cases where TKIs have failed to work. -
This question is part of the following fields:
- Haematology
- Pathology
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Question 50
Incorrect
-
In the Emergency Department, a 35-year-old woman actively seizing is brought in. She is quickly shifted into the resuscitation room and is administered a dose of benzodiazepine. The seizure is quickly terminated.
Once the patient is stable, she tells you she is a known case of epilepsy and takes phenytoin to control it.
Which of the following is the primary mechanism of action of phenytoin?Your Answer:
Correct Answer: Sodium channel blocker
Explanation:Phenytoin is in the anticonvulsants class of drugs and is used in the management and treatment of the following:
1. epilepsy
2. generalized tonic-clonic seizures
3. complex partial seizures
4. status epilepticus.It works by inactivating the voltage-gated sodium channels responsible for increasing the action potential. It is non-specific and targets almost all voltage-gated sodium channel subtypes. More specifically, phenytoin prevents seizures by inhibiting the positive feedback loop that results in neuronal propagation of high-frequency action potentials.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 51
Incorrect
-
A patient suffers an injury to the nerve that innervates piriformis.
The piriformis muscle is innervated by which of the following nerves? Select ONE answer only.Your Answer:
Correct Answer: Nerve to piriformis
Explanation:Piriformis is innervated by the nerve to piriformis, which is a direct branch from the sacral plexus (S1 and S2).
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 52
Incorrect
-
Which of the following virulence factors of E. coli is important for attachment to host epithelial cells in the pathogenesis of urinary tract infections:
Your Answer:
Correct Answer: Pili
Explanation:Escherichia coli is the most common cause of urinary tract infection. Uropathic strains are characterised by pili with adhesion proteins that bind to specific receptors on the urinary tract epithelium. The motility of E. coli aids its ability to ascend the urethra into the bladder or ascend the ureter into the kidney.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 53
Incorrect
-
Which of the following occurs primarily to produce passive expiration:
Your Answer:
Correct Answer: Relaxation of diaphragm and external intercostal muscles
Explanation:Passive expiration is produced primarily by relaxation of the inspiratory muscles (diaphragm and external intercostal muscles) and the elastic recoil of the lungs. In expiration, depression of the sternal ends of the ribs (‘pump handle’ movement), depression of the lateral shafts of the ribs (‘bucket handle’ movement) and elevation of the diaphragm result in a reduction of the thorax in an anteroposterior, transverse and vertical direction respectively. This results in a decreased intrathoracic volume and increased intrathoracic pressure and thus air is forced out of the lungs.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 54
Incorrect
-
You're examining a 58-year-old male who has cellulitis in his left leg. Because he is allergic to penicillin, you start him on erythromycin.
Which of the following statements about erythromycin is correct?Your Answer:
Correct Answer: It can be used to treat Legionnaire’s disease
Explanation:Bacteriostatic antibiotics include erythromycin and other macrolide antibiotics. They work by attaching to the bacterial ribosome’s 50S subunit, preventing translocation and thereby protein synthesis. Macrolide antibiotics are actively concentrated inside leukocytes and delivered to the infection site as a result.
Erythromycin is an orally active antibiotic that can also be given intravenously. It is metabolized in the liver and eliminated in the bile and has a biological half-life of 1.5 hours.
It has a similar antibacterial spectrum to benzylpenicillin (i.e., a narrow spectrum, primarily against Gram-positive pathogens) and can be used as a penicillin substitute in people who are allergic to penicillin.
Erythromycin is unsuccessful in the treatment of meningitis because it does not penetrate the central nervous system well enough. It is efficient against a variety of unusual pathogens, unlike penicillin. -
This question is part of the following fields:
- Infections
- Pharmacology
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Question 55
Incorrect
-
Which of the following is NOT a typical side effect of thiopental sodium:
Your Answer:
Correct Answer: Seizures
Explanation:Extravasation of thiopental during injection can lead to tissue damage. Accidental intra-arterial injection causes vasospasm and may lead to thrombosis and tissue necrosis. Other side effects include involuntary muscle movements on induction, cough and laryngospasm, arrhythmias, hypotension, headache and hypersensitivity reactions. Thiopental sodium has anticonvulsant properties and does not cause seizures.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 56
Incorrect
-
Question 57
Incorrect
-
A 61-year-old woman returns to get the results of recent blood tests she had done for non-specific malaise, lethargy, and weight loss.
The only abnormality discovered during the blood tests was a 580 x 10 9 /l increase in platelets. Her platelets were also elevated on a blood test taken 6 months earlier, according to her previous results. You're aware of the recent emergence of elevated platelet levels as a cancer risk marker and decide to look into it.
Which of the following cancers is most likely to cause isolated thrombocytosis?Your Answer:
Correct Answer: Colorectal cancer
Explanation:Raised platelet levels have emerged as a cancer risk marker, according to a large population-based study published in 2017(link is external). According to the study, 12 percent of men and 6% of women with thrombocytosis were diagnosed with cancer within a year. These figures increased to 18% in men and 10% in women if a second platelet count was taken within 6 months of the first and showed an increased or stable elevated platelet count.
The researchers discovered that thrombocytosis linked to cancer is most common in colorectal and lung cancers, and it is linked to a worse prognosis. Furthermore, one-third of the cancer patients in the study had no other symptoms that would have prompted an immediate cancer referral.
The exact mechanism by which these cancers cause thrombocytosis is unknown, but one theory proposes the existence of pathogenic feedback loops between malignant cells and platelets, with a reciprocal interaction between tumour growth and metastasis, as well as thrombocytosis and platelet activation. Another hypothesis is that thrombocytosis occurs independently of cancer but aids in its spread and progression.
The findings show that routinely testing for thrombocytosis could cut the time it takes to diagnose colorectal and lung cancer by at least two months. In the UK, this could result in around 5500 earlier cancer diagnoses per year.
Because the positive predictive value of thrombocytosis in middle age for cancer (10%) is higher than the positive predictive value for a woman in her 50s presenting with a new breast lump (8.5%), this is clearly an important research paper that should be used to adjust future clinical practise. The current NICE guidelines predate these new research findings, so we’ll have to wait and see how they affect cancer referral guidelines in the UK.
Because there are so many possible cancers associated with thrombocytosis, the treating clinician should take a thorough history and perform a thorough clinical examination if a patient is diagnosed with it. Further investigation and the most appropriate referral route should be aided by this information.
It’s worth noting that the patients in the study had their blood tests done for a medical reason rather than as a random screening test.
If there are no other symptoms to guide investigation and referral (one-third of the patients in the study had no other symptoms), keep in mind that the two most common cancers encountered were colorectal and lung cancer, so a chest X-ray and a faecal immunochemical test (FIT) for faecal blood may be reasonable initial investigations.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 58
Incorrect
-
A medical student is reviewing the chart of a patient who has recently been diagnosed with leukaemia. The chief resident asks him to identify ONE feature that will most support acute leukaemia diagnosis in contrast to chronic leukaemia.
Which one of the following options will he pick?Your Answer:
Correct Answer: The patient is a child
Explanation:Acute lymphocytic leukaemia (ALL) is more common in children than chronic leukaemias, which generally occur in adults. Bone marrow failure occurs early on in the course of the disease in acute leukaemias, and there is the massive proliferation of undifferentiated cells with functioning cells being crowded out. Hepatosplenomegaly occurs in both acute and chronic forms of leukaemia and is not a differentiating feature.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 59
Incorrect
-
If the null hypothesis is wrongly rejected when it is actually true, this is an example of:
Your Answer:
Correct Answer: A test with a type I error
Explanation:A type I error occurs when the null hypothesis is wrongly rejected when it is actually true and we conclude that there is a difference of effect when in reality there is none (a false positive result).
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This question is part of the following fields:
- Evidence Based Medicine
- Statistics
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Question 60
Incorrect
-
A 32 year old woman presents with episodes of flushing, headaches and palpitations. On examination her blood pressure is significantly elevated. Which of the following is the most likely diagnosis:
Your Answer:
Correct Answer: Pheochromocytoma
Explanation:Phaeochromocytomas are catecholamine-secreting tumours which occur in about 0.1% of patients with hypertension. In about 90% of cases they arise from the adrenal medulla. The remaining 10%, which arise from extra-adrenal chromaffin tissue, are termed paragangliomas. Common presenting symptoms include one or more of headache, sweating, pallor and palpitations. Less commonly, patients describe anxiety, panic attacks and pyrexia. Hypertension, whether sustained or episodic, is present in at least 90% of patients. Left untreated phaeochromocytoma can occasionally lead to hypertensive crisis, encephalopathy, hyperglycaemia, pulmonary oedema, cardiac arrhythmias, or even death.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 61
Incorrect
-
A 32-year-old asthmatic patient on theophylline as part of her asthma management presents to the Emergency Department with an unrelated medical condition.
Which of these drugs should be avoided?Your Answer:
Correct Answer: Clarithromycin
Explanation:Macrolide antibiotics (e.g. clarithromycin and erythromycin) are cytochrome P450 enzyme inhibitors. They increase blood levels of theophylline leading to hypokalaemia, and potentially increasing the risk of Torsades de pointes when they are prescribed together.
Co-prescription with theophylline should be avoided.
Factors that enhance theophylline clearance include cigarette smoking, carbamazepine, phenobarbital, phenytoin, primidone, and rifampin.
Medications that inhibit clearance include ethanol, ciprofloxacin, erythromycin, verapamil, propranolol, ticlopidine, tacrine, allopurinol, and cimetidine. -
This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 62
Incorrect
-
Which of the following serology results is consistent with chronic hepatitis B infection:
Your Answer:
Correct Answer: HBsAg positive and anti-HBc IgG positive
Explanation:Disease state vs Serology
Acute hepatitis: BHBsAg, HBeAg, anti-HBc IgM
Chronic hepatitis B (low infectivity): HBsAg (>6/12), anti-HBe, anti-HBc IgG
Chronic hepatitis B (high infectivity): HBsAg (>6/12), HBeAg, anti-HBc IgG
Cleared infection: Anti-HBs, anti-HBe, anti-HBc IgG
Vaccinated: Anti-HBs -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 63
Incorrect
-
Question 64
Incorrect
-
A 62-year-old man complains of chest pain and goes to the emergency room. You diagnose him with an acute coronary syndrome and prescribe enoxaparin as part of his treatment plan.
Enoxaparin inactivates which of the following?Your Answer:
Correct Answer: Thrombin
Explanation:Enoxaparin is a low molecular weight heparin (LMWH) that works in the same way as heparin by binding to and activating the enzyme inhibitor antithrombin III. Antithrombin III inactivates thrombin by forming a 1:1 complex with it. Factor Xa and a few other clotting proteases are also inhibited by the heparin-antithrombin III complex.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 65
Incorrect
-
Fracture of the medial epicondyle would result to the following, except
Your Answer:
Correct Answer: Weakness of abduction of the thumb
Explanation:Thumb abduction is mediated by the abductor pollicis longus and brevis, which are innervated by the radial and median nerves, respectively.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 66
Incorrect
-
Which of these cell types in the stomach releases pepsinogen?
Your Answer:
Correct Answer: Chief cells
Explanation:The gastric chief cells in the stomach wall releases pepsinogen. Pepsinogen is a proenzyme. It mixes with hydrochloric acid in the stomach and is converted to pepsin. Pepsin breaks down proteins into peptides aiding protein digestion.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 67
Incorrect
-
A patient presents with an acute severe asthma attack. Following a poor response to his initial salbutamol nebuliser, you administer a further nebuliser that this time also contains ipratropium bromide.
After what time period would you expect the maximum effect of the ipratropium bromide to occur? Select ONE answer only.Your Answer:
Correct Answer: 30 -60 minutes
Explanation:Ipratropium bromide is an antimuscarinic drug used in the management of acute asthma and COPD. It can provide short-term relief in chronic asthma, but short-acting β2agonists act more quickly and are preferred.
The BTS guidelines recommend that nebulised ipratropium bromide (0.5 mg 4-6 hourly) can be added to β2agonist treatment for patients with acute severe or life-threatening asthma or those with a poor initial response to β2 agonist therapy.
The aerosol inhalation of ipratropium can be used for short-term relief in mild chronic obstructive pulmonary disease in patients who are not already using a long-acting antimuscarinic drug (e.g. tiotropium).Its maximum effect occurs 30-60 minutes after use; its duration of action is 3-6 hours, and bronchodilation can usually be maintained with treatment three times per day.
The commonest side effect of ipratropium bromide is dry mouth. It can also trigger acute closed-angle glaucoma in susceptible patients. Tremor is commonly seen with β2agonists but not with antimuscarinics. Ipratropium bromide should be used with caution in: Men with prostatic hyperplasia and bladder-outflow obstruction (worsened urinary retention has been reported in elderly men), People with chronic kidney disease (CKD) stages 3 and above (because of the risk of drug toxicity), People with angle-closure glaucoma (nebulised mist of antimuscarinic drugs can precipitate or worsen acute angle-closure glaucoma) -
This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 68
Incorrect
-
A CT pulmonary angiography of a patient with a massive pulmonary embolus will most likely show which of the following signs?
Your Answer:
Correct Answer: Increased alveolar dead space
Explanation:A CT pulmonary angiogram is an angiogram of the blood vessels of the lungs. It is a diagnostic imaging test used to check for pulmonary embolism.
A pulmonary embolism is caused by a blood clot or thrombus that has become lodged in an artery in the lung and blocks blood flow to the lung. A patient with pulmonary embolism may feel an abrupt onset of pleuritic chest pain, shortness of breath, and hypoxia. Also, pulmonary embolism can result in alveolar dead space.
Dead space represents the volume of ventilated air that does not participate in gas exchange. The alveolar dead space is caused by ventilation/perfusion imbalances in the alveoli. It is defined as the sum of the volumes of alveoli that are ventilated but not perfused.
Aside from pulmonary embolism, smoking, bronchitis, emphysema, and asthma are among the other causes of alveolar dead space.
The other types of dead space are the following: Anatomical dead space is the portion of the airways that conducts gas to the alveoli. This is usually around 150 mL, and there is no possibility of gas exchange in these areas. Physiological dead space is the sum of anatomical and alveolar dead spaces.
Physiological dead space can account for up to 30% of the tidal volume.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 69
Incorrect
-
Herpes simplex encephalitis has a predilection for which of the following sites:
Your Answer:
Correct Answer: Temporal lobe
Explanation:Herpes simplex virus is the most common cause of infective encephalitis and has a predilection for the temporal lobes. Herpes simplex is transmitted through direct contact. It invades skin locally producing skin vesicles by its cytolytic activity.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 70
Incorrect
-
Which of the following is NOT a benefit of low molecular weight heparin (LMWH) over unfractionated heparin therapy:
Your Answer:
Correct Answer: Its effects can be rapidly and completely reversed with protamine sulfate.
Explanation:Advantages of LMWHGreater ability to inhibit factor Xa directly, interacting less with platelets and so may have a lesser tendency to cause bleedingGreater bioavailability and longer half-life in plasma making once daily subcutaneous administration possibleMore predictable dose response avoiding the need for routine anticoagulant monitoringLower associated risk of heparin-induced thrombocytopenia or of osteoporosis
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 71
Incorrect
-
A dermatological examination on a patient presenting with a lump shows a small visible skin elevation containing an accumulation of pus.
Which one of these best describes the lump you have found on examination?Your Answer:
Correct Answer: Pustule
Explanation:A pustule is a small visible skin elevation containing an accumulation of pus.
A carbuncle is a collection of individual boils clustered together.
A bulla is a visible collection of clear fluid measuring greater than 0.5 cm in diameter.
A furuncle, or boil, is a pyogenic infection of the hair follicle commonly caused by infection with Staphylococcus aureus.
A vesicle is a visible collection of fluid measuring less than 0.5 cm in diameter.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 72
Incorrect
-
A 25 year old man has sustained a fracture to the surgical neck of the humerus after falling from his bike. Examination suggests an axillary nerve injury. The clinical features expected to be seen in this patient are:
Your Answer:
Correct Answer: Weakness of shoulder abduction
Explanation:Axillary nerve injury results in:
1. weakness of arm abduction (paralysis of deltoid),
2. weakness of lateral rotation of the arm (paralysis of teres minor)
3. loss of sensation over the regimental badge area. -
This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 73
Incorrect
-
In the emergency department, a 50-year-old female appears with a lack of sensation over the front two-thirds of her tongue. Taste and salivation are both present. The patient might have damage which of her nerves?
Your Answer:
Correct Answer: Lingual nerve
Explanation:The lingual nerve, a branch of the mandibular nerve, transmits sensation to the anterior two-thirds of the tongue.
The chorda tympani, a branch of the facial nerve, transmits taste to the front two-thirds of the tongue as well as secretomotor innervation to the submandibular and sublingual glands.
As a result, any damage to the lingual nerve can cause changes in salivary secretion on the affected side, as well as a loss of taste in the anterior two-thirds of the tongue and temporary or permanent sensory changes in the anterior two-thirds of the tongue and the floor of the mouth.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 74
Incorrect
-
A 2nd-year medical student is solving an exam paper with questions about the immune system. She comes across a question regarding innate immunity. Innate immunity is the immunity naturally present within the body from birth.
Which ONE of the following is not a part of this type of immunity?Your Answer:
Correct Answer: Antibody production
Explanation:Innate immunity, also called non-specific immunity, refers to the components of the immune system naturally present in the body at birth.
The components of innate immunity include:
1) Natural Killer Cells
2) Neutrophils
3) Macrophages
4) Mast Cells
5) Dendritic Cells
6) Basophils.Acquired or adaptive immunity is acquired in response to infection or vaccination. Although the response takes longer to develop, it is also a more long-lasting form of immunity.
The components of this system include:
1) T lymphocytes
2) B lymphocytes
3) Antibodies -
This question is part of the following fields:
- General Pathology
- Pathology
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Question 75
Incorrect
-
A 22 year old student has recently returned from travelling around Kenya and presents to ED with a headache and persistent fever. Malaria is being considered as a potential diagnosis. Which of the following strains of malaria is most likely:
Your Answer:
Correct Answer: Plasmodium falciparum
Explanation:Malaria is an infectious disease transmitted by female of theAnophelesgenus of mosquito. It is a parasitic infection caused by the genusPlasmodium. Five species are recognized as causing disease in humans;Plasmodium falciparum,Plasmodium ovale,Plasmodium vivax,Plasmodium malariaeandPlasmodium knowlesi.
The classic symptom of malaria is the malarial paroxysm, a cyclical occurrence of a cold phase, where the patient experiences intense chills, a hot stage, where the patient feels extremely hot and finally a sweating stage, where the fever declines and the patient sweats profusely. On examination the patient may show signs of anaemia, jaundice and have hepatosplenomegaly without evidence of lymphadenopathy.Plasmodium falciparum is the most serious form and is responsible for most deaths. Severe or complicated malaria is suggested by the presence of impaired consciousness, seizures, hypoglycaemia, anaemia, renal impairment, respiratory distress and spontaneous bleeding.
Plasmodium falciparum is the most likely type in this case in view of the presentation.
Haemoglobinuria and renal failure following treatment is suggestive of blackwater fever, which is caused byPlasmodium falciparum. An autoimmune reaction between the parasite and quinine causes haemolysis, haemoglobinuria, jaundice and renal failure. This can be fatal.
The benign malarias: P.vivax, P. malariae and P.ovale are usually treated with chloroquine. A course of primaquine is also required in P.vivax and P.ovale infection. Artesunate is the drug treatment of choice for Plasmodium falciparum malaria. Quinine can still be used where artesunate is not available. Often combination therapy with drugs such as doxycycline or fansidar is also required. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 76
Incorrect
-
A tumour is discovered behind the pectinate line during an examination of a 72-year-old patient with rectal bleeding. Which of the following is the lymphatic drainage of the pectinate line?
Your Answer:
Correct Answer: Superficial inguinal nodes
Explanation:The pectinate line is known as the watershed line because it divides the anal canal into two sections. Below the pectinate line, lymphatic drainage drains to the superficial inguinal lymph nodes.
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This question is part of the following fields:
- Abdomen
- Anatomy
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Question 77
Incorrect
-
A 64-year-old man presents with an acute episode of gout. He has a history of chronic heart failure and hypertension. His current medications include ramipril and furosemide.
Which of the following statements regarding the treatment of gout is true? Select ONE answer only.Your Answer:
Correct Answer: Colchicine has a role in prophylactic treatment
Explanation:In the absence of any contra-indications, high-dose NSAIDs are the first-line treatment for acute gout. Naproxen 750 mg as a stat dose followed by 250 mg TDS is a commonly used and effective regime.
Aspirin should not be used in gout as it reduces the urinary clearance of urate and interferes with the action of uricosuric agents. Naproxen, Diclofenac or Indomethacin are more appropriate choices.
Allopurinol is used prophylactically, preventing future attacks by reducing serum uric acid levels. It should not be started in the acute phase as it increases the severity and duration of symptoms.
Colchicine acts on the neutrophils, binding to tubulin to prevent neutrophil migration into the joint. It is as effective as NSAIDs in relieving acute attacks. It also has a role in prophylactic treatment if Allopurinol is not tolerated.
NSAIDs are contra-indicated in heart failure as they can cause fluid retention and congestive cardiac failure. Colchicine is the preferred treatment in patients with heart failure or those who are intolerant of NSAIDs. -
This question is part of the following fields:
- Musculoskeletal Pharmacology
- Pharmacology
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Question 78
Incorrect
-
Regarding the glomerular filtration barrier, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The main factor determining whether a substance is filtered or not is molecular weight.
Explanation:Molecular weight is the main factor in determining whether a substance is filtered or not – molecules < 7 kDa in molecular weight are filtered freely e.g. glucose, amino acids, urea, ions but larger molecules are increasingly restricted up to 70 kDa, above which filtration is insignificant. Negatively charged molecules are further restricted, as they are repelled by negative charges, particularly in the basement membrane. Albumin has a molecular weight of 69 kDa and is negatively charged, thus only very small amounts are filtered (and all of the filtered albumin is reabsorbed in the proximal tubule), whereas small molecules such as ions, glucose, amino acids and urea pass the filter without hindrance. This means that ultrafiltrate is virtually protein free, but otherwise has an identical composition of that of plasma. The epithelial lining of the Bowman's capsule consists of a single layer of cells called podocytes. The glomerular capillary endothelium is perforated by pores (fenestrations) which allow plasma components with a molecular weight of < 70 kDa to pass freely.
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This question is part of the following fields:
- Physiology
- Renal
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Question 79
Incorrect
-
Insulin binds to the insulin receptor (IR) on cell surfaces to exert its action. The IR is a very specific transmembrane receptor belonging to the tyrosine kinase receptor class.
One of these also activates the IR:
Your Answer:
Correct Answer: IGF-I
Explanation:Insulin receptor (IR), in addition to being activated by insulin, is also activated by IGF-I and IGF-II.
The IR is a dimer with two identical subunits spanning the cell membrane and are connected by a single disulphide bond. The two sub-units include: The alpha chain situated on the exterior of the cell membrane and the beta chain spanning the cell membrane in a single segment.
When insulin is detected, the alpha chains move together folding around the insulin making the beta chains move together, converting them into an active tyrosine kinase. This initiates a phosphorylation cascade increasing the expression of GLUT4 and allowing uptake of glucose by cells.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 80
Incorrect
-
Regarding haemophilia A, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: In haemophilia both the APTT and PT are prolonged.
Explanation:Haemophilia A is the most common of the hereditary clotting factor deficiencies. The inheritance is sex-linked but up to one-third of patients have no family history and these cases result from recent mutation. The vast majority of cases are inherited in an X-linked recessive fashion, affecting males born to carrier mothers. Females born to affected fathers can also, rarely, be affected due to homozygosity for the gene, where there is marriage to close relatives.
The defect is an absence or low level of plasma factor VIII. The APTT is prolonged but the PT is normal. Recurrent painful haemarthroses and muscle haematomas dominate the clinical course of severely affected patients and if inadequately treated, lead to progressive joint deformity and disability. Local pressure can cause entrapment neuropathy or ischaemic necrosis. Prolonged bleeding occurs after dental extractions or post-trauma. Spontaneous haematuria and gastrointestinal haemorrhage may occur. The clinical severity of the disease correlates inversely with the factor VIII level. Operative and post-traumatic haemorrhage are life-threatening both in severely and mildly affected patients.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 81
Incorrect
-
An unrelated medical condition brings a 28-year-old asthmatic man to the Emergency Department. When you look over his meds, you notice that he is taking Theophylline to help with his asthma.
Which of the following medicines should you NOT prescribe?Your Answer:
Correct Answer: Ciprofloxacin
Explanation:Ciprofloxacin is a cytochrome P450 enzyme inhibitor that raises theophylline levels in the blood. As a result, co-prescribing theophylline should be avoided.
The medicines that typically impact theophylline’s half-life and plasma concentration are listed in the table below:
Drugs that increase the levels of theophylline in the blood
Drugs that lower theophylline levels in the blood
Calcium channel blockers e.g. Verapamil
Fluconazole
Cimetidine
Quinolones, e.g. ciprofloxacin
Methotrexate
Barbiturates
Carbamazepine
Phenobarbital
Macrolides, e.g. erythromycin
Phenytoin (and fosphenytoin)
Rifampicin
St. John’s wort -
This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 82
Incorrect
-
In a ward round, you come across a patient's treatment chart prescribed an antibiotic to fight his infection. This antibiotic disrupts cell membrane function.
Which of the following antimicrobial drugs is prescribed to this patient?Your Answer:
Correct Answer: Nystatin
Explanation:Nystatin binds ergosterol (unique to the fungi cell membrane) and forms membrane pores that allow K+ leakage, acidification, and subsequent death of the fungus.
Vancomycin inhibits cell wall peptidoglycan formation by binding the D-Ala-D-Ala portion of cell wall precursors.
Flucloxacillin inhibits the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria.
Trimethoprim inhibits bacterial dihydrofolate reductase.
Isoniazid decreases the synthesis of mycolic acids in mycobacteria.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 83
Incorrect
-
Which of the following is first-line for management of status epilepticus:
Your Answer:
Correct Answer: Intravenous lorazepam
Explanation:First-line treatment is with intravenous lorazepam if available. Intravenous diazepam is effective but it carries a high risk of thrombophlebitis so should only be used if intravenous lorazepam is not immediately available. Absorption of diazepam from intramuscular injection or from suppositories is too slow for treatment of status epilepticus. When facilities for resuscitation are not immediately available or if unable to secure immediate intravenous access, diazepam can be administered as a rectal solution or midazolam oromucosal solution can be given into the buccal cavity.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 84
Incorrect
-
The following are all examples of type II hypersensitivity EXCEPT for:
Your Answer:
Correct Answer: Post-streptococcal glomerulonephritis
Explanation:Examples of type II reactions include:
Incompatible blood transfusions
Haemolytic disease of the newborn
Autoimmune haemolytic anaemias
Goodpasture’s syndrome
Rheumatic heart disease
Bullous pemphigoid -
This question is part of the following fields:
- Immune Responses
- Pathology
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Question 85
Incorrect
-
Regarding Gaussian sample distribution, which of the following statements is false?
Your Answer:
Correct Answer: It can be skewed left or right
Explanation:Gaussian distribution, also known as normal distribution, is the most important probability distribution in statistics because it fits many natural phenomena. The normal distribution is a probability function that describes how the values of a variable are distributed. Below are its characteristics:
(1) Bell-shaped and symmetrical about the mean
(2) The mean, median, mode are all equal
(3) The total area under the curve and above the x-axis is equal to 1
(4) It has long tapering tails extending infinitely but never touching the x-axis
(5) It is determined by its parameters: its mean and standard deviation
(6) The standard deviation becomes a more meaningful quality than merely being a measure of dispersionThe mean is the most common measure of central tendency. It is the sum of all observed values divided by the number of observation, and is also known as the ‘average’.
The median is the value that falls in the middle position when the observations are ranked in order from the smallest to the largest. If the number of observations is odd, the median is the middle number. If it is even, the median is the average of the two middle numbers.
The mode is the value that occurs with the greatest frequency in a set of observations, and is commonly used in public health statistics, such as the top 10 causes of mortality.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 86
Incorrect
-
A patient suffers from an injury to his hip and thigh. As a consequence of his injury, the nerve that was damaged innervates the obturator externus muscle.
In which of the following nerves is the obturator externus muscle innervated by?Your Answer:
Correct Answer: Posterior branch of the obturator nerve
Explanation:The obturator externus is innervated by the posterior branch of the obturator nerve, L2-L4.
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 87
Incorrect
-
A 29 year old man presents to ED followed an alleged assault whilst out drinking. He received blunt trauma to his right axilla. He is complaining of difficulty abducting his right arm above the level of his shoulder, and on inspection, the inferior angle of his right scapula protrudes more than that of his left scapula. Which of the following nerves has most likely been affected:
Your Answer:
Correct Answer: Long thoracic nerve
Explanation:Damage to the long thoracic nerve results in weakness/paralysis of the serratus anterior muscle causing difficulty abducting the upper limb above 90 degrees and giving a ‘winged ‘ scapula appearance where the medial border, particularly the inferior angle, of the scapula moves laterally and posteriorly away from the thoracic wall (this becomes more pronounced if the patient presses the upper limb against a wall).
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 88
Incorrect
-
A 52-year-old patient requires procedural sedation for DC cardioversion of atrial fibrillation. You plan on using propofol as the sedative agent.
Propofol works as a result of action on what type of receptor? Select ONE answer only.Your Answer:
Correct Answer: Gamma-aminobutyric acid (GABA)
Explanation:Propofol (2,6-diisopropylphenol) is a short-acting phenol derivative that is primarily used for the induction of anaesthesia.
Its mechanism of action is unclear but is thought to act by potentiating the inhibitory neurotransmitters GABA and glycine, which enhances spinal inhibition during anaesthesia.
The dose for induction of anaesthesia is 1.5-2.5mg/kg. The dose for maintenance of anaesthesia is 4-12 mg/kg/hour. Following intravenous injection, propofol acts within 30 seconds and its duration of action is 5-10 minutes.
Propofol produces a 15-25% decrease in blood pressure and systemic vascular resistance without a compensatory increase in heart rate. It is negatively inotropic and decreases cardiac output by approximately 20%.
The main side effects of propofol are:
Pain on injection (in up to 30%)
Hypotension
Transient apnoea
Hyperventilation
Coughing and hiccough
Headache
Thrombosis and phlebitis -
This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 89
Incorrect
-
In the resus area of your Emergency Department, you are called to a VF cardiac arrest.
During an adult VF arrest, which of the following points should be treated with adrenaline?Your Answer:
Correct Answer: After the 3 rd shock, once chest compressions have been resumed
Explanation:In non-shockable (PEA/asystole) cardiac arrests, adrenaline should be given as soon as circulatory access is gained. The dose is 1 mg via IV or IO (10 mL of 1:10,000 or 1 mL of 1:1000).
Once chest compressions have been resumed after the third shock in a shockable (Vf/pVT) cardiac arrest, adrenaline should be administered. The dosage is one milligram (10 mL of 1:10,000 or 1 mL of 1:1000)
It should be given every 3-5 minutes after that (i.e. alternate loops) and without interrupting chest compressions.
Systemic vasoconstriction is caused by the alpha-adrenergic effects of adrenaline, which raises coronary and cerebral perfusion pressures.Adrenaline’s beta-adrenergic effects are inotropic (increased myocardial contractility) and chronotropic (increased heart rate), and they can increase coronary and cerebral blood flow. However, concomitant increases in myocardial oxygen consumption and ectopic ventricular arrhythmias (especially in the absence of acidaemia), transient hypoxemia due to pulmonary arteriovenous shunting, impaired microcirculation, and increased post-cardiac arrest myocardial dysfunction may offset these benefits.
Although there is no evidence of long-term benefit from its use in cardiac arrest, the improved short-term survival reported in some studies justifies its use.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 90
Incorrect
-
A 52-year old male comes to the out-patient department for a groin mass that protrudes when standing. The patient notes that it is reducible when lying down. On physical examination, there is presence of a cough impulse. The initial assessment is hernia. Further investigation reveals that the mass lies lateral to the epigastric vessels.
Among the types of hernia, which is the most likely diagnosis of the case above?Your Answer:
Correct Answer: Indirect inguinal hernia
Explanation:Inguinal hernias can present with an array of different symptoms. Most patients present with a bulge in the groin area, or pain in the groin. Some will describe the pain or bulge that gets worse with physical activity or coughing. Symptoms may include a burning or pinching sensation in the groin. These sensations can radiate into the scrotum or down the leg. It is important to perform a thorough physical and history to rule out other causes of groin pain. At times an inguinal hernia can present with severe pain or obstructive symptoms caused by incarceration or strangulation of the hernia sac contents. A proper physical exam is essential in the diagnosis of an inguinal hernia. Physical examination is the best way to diagnose a hernia. The exam is best performed with the patient standing. Visual inspection of the inguinal area is conducted first to rule out obvious bulges or asymmetry in groin or scrotum. Next, the examiner palpates over the groin and scrotum to detect the presence of a hernia. The palpation of the inguinal canal is completed last. The examiner palpates through the scrotum and towards the external inguinal ring. The patient is then instructed to cough or perform a Valsalva manoeuvre. If a hernia is present, the examiner will be able to palpate a bulge that moves in and out as the patient increases intra abdominal pressure through coughing or Valsalva.
Groin hernias are categorized into 2 main categories: inguinal and femoral.
Inguinal hernias are further subdivided into direct and indirect. An indirect hernia occurs when abdominal contents protrude through the internal inguinal ring and into the inguinal canal. This occurs lateral to the inferior epigastric vessels. The hernia contents may extend into the scrotum, and can be reduced superiorly then superolaterally. A direct inguinal hernia is protrusion of abdominal contents through the transversalis fascia within Hesselbach’s triangle. The borders of Hesselbach’s triangle are the inferior epigastric vessels superolaterally, the rectus sheath medially, and inguinal ligament inferiorly.
A femoral hernia is a protrusion into the femoral ring. The borders of the femoral ring are the femoral vein laterally, Cooper’s ligament posteriorly, the iliopubic tract/inguinal ligament anteriorly and lacunar ligament medially.
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This question is part of the following fields:
- Abdomen And Pelvis
- Anatomy
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Question 91
Incorrect
-
The correct statement about the glomerular filtration barrier is which of the following?
Your Answer:
Correct Answer: The basement membrane is negatively charged, restricting filtration of negatively charged molecules.
Explanation:The main factor in determining whether a substance is filtered or not is molecular weight. Molecules < 7 kDa in molecular weight e.g. glucose, amino acids, urea, ions are filtered freely, but larger molecules are increasingly restricted up to 70 kDa, and there is very little filtration for anything above this.
There is further restriction of negatively charged molecules because they are repelled by negative charges, particularly in the basement membrane. Albumin, which has a molecular weight of 69 kDa and is negatively charged, is filtered but only in very small amounts. All of the filtered albumin is reabsorbed in the proximal tubule. Small molecules such as ions, glucose, amino acids and urea pass the filter without hindrance. Other than the ultrafiltrate being essentially protein free, it has an otherwise identical composition of plasma. Bowman’s capsule consists of:
– an epithelial lining which consists of a single layer of cells called podocytes
– endothelium which is perforated by pores or fenestrations – this allows plasma components with a molecular weight of < 70 kDa to pass freely. -
This question is part of the following fields:
- Physiology
- Renal
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Question 92
Incorrect
-
A newborn baby girl is delivered vaginally to a 19-year old female, however with complications due to cephalopelvic disproportion. Upon examination by the attending paediatrician, there is a notable 'claw hand' deformity of the left, and sensory loss of the ulnar aspect of the left distal upper extremity.
What is the most probable diagnosis of the case above?Your Answer:
Correct Answer: Klumpke’s palsy
Explanation:Klumpke palsy, named after Augusta Dejerine-Klumpke, is a neuropathy involving the lower brachial plexus. In contrast, the more common Erb–Duchenne palsy involves the more cephalic portion of the brachial plexus C5 to C6. The brachial plexus is a bundle of individual nerves that exit between the anterior and middle scalene muscles in the anterior lateral and basal portion of the neck. Although the most common anatomical presentation of the brachial plexus is between the anterior and middle scalene, there are variations, with the most common being penetration of the anterior scalene. The main mechanism of injury to the lower brachial plexus is hyper-abduction traction, and depending on the intensity, it will lead to signs and symptoms consistent with a neurological insult.
The most common aetiology resulting in Klumpke palsy is a hyper-abduction trauma to the arm that has enough intensity to traction the lower brachial plexus. Trauma during birth can cause brachial plexus injuries, but again hyper-abduction and traction forces to the upper extremity are usually present.
The history presented by the patient usually depicts a long axis hyper-abduction traction injury with high amplitude and velocity. The typical patient presentation is a decrease of sensation along the medial aspect of the distal upper extremity along the C8 and T1 dermatome. The patient might also present myotome findings that can range from decreasing muscular strength to muscular atrophy and positional deformity. For example, if the neurological damage has led to muscular atrophy and tightening, the patient may present with a claw hand. This deformity presents a finger and wrist flexion. The patient may also describe the severe pain that starts at the neck and travels down the medial portion of the arm. One other sign of a lower brachial plexus injury is Horner syndrome; because of its approximation to the T1 nerve root, it may damage the cephalic sympathetic chain. If this happens, the patient will develop ipsilateral ptosis, anhidrosis, and miosis.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 93
Incorrect
-
Which of the following anatomical structures is most likely the cause of oedema and erythema of the arm in a patient who underwent modified radical mastectomy and radiotherapy?
Your Answer:
Correct Answer: Axillary lymph nodes
Explanation:Arm oedema is one of the sequelae after breast cancer surgery and radiation therapy. Arm oedema in the breast cancer patient is caused by interruption of the axillary lymphatic system by surgery or radiation therapy, which results in the accumulation of fluid in subcutaneous tissue in the arm, with decreased distensibility of tissue around the joints and increased weight of the extremity. Chronic inflammatory changes result in both subcutaneous and lymph vessel fibrosis.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 94
Incorrect
-
Question 95
Incorrect
-
Regarding gas gangrene, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Infection is characterised by rapidly spreading tissue myonecrosis with crepitus.
Explanation:Gas gangrene usually occurs within 3 days of injury, and is characterised by pain, rapidly spreading oedema, myositis, necrosis, palpable crepitus and systemic toxicity. Diagnosis is clinical and laboratory confirmation should not delay urgent surgical intervention. Hyperbaric oxygen therapy can be considered in addition to surgery and antibiotic therapy, to stop toxin production and inhibit bacteria from replicating and spreading (as Clostridium spp. are obligate anaerobes).
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 96
Incorrect
-
Regarding the phases of gastric secretion, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: A high pH in the stomach inhibits gastrin secretion.
Explanation:A low pH in the stomach inhibits gastrin secretion, therefore when the stomach is empty or when acid has been secreted for some time after food has entered it, there is inhibition of acid secretion. However, when food first enters the stomach, the pH rises, and this leads to release of the inhibition and causes a maximum secretion of gastrin. Thus gastric acid secretion is self-regulating.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 97
Incorrect
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A patient with a wound infection on his right leg has reddening and oedema of the surrounding muscles. His condition has worsened considerably over the past few hours with the area now appearing blackened. There is also palpable crepitus under the skin. You suspect gas gangrene.
Which statement about Clostridium perfringens is true?Your Answer:
Correct Answer: Gas gangrene is caused by the release of an alpha-toxin
Explanation:Clostridium perfringens, a Gram-positive, anaerobic, spore forming rod-shaped, pathogenic bacterium is the most commonly associated with gas gangrene (85-90% of cases), although other species can also be implicated.
Clostridium perfringens is capsulate and produces a range of toxins. Alpha-toxin is the most important and is the cause of gas gangrene.
Gas gangrene develops when a devitalized wound becomes infected with Clostridium perfringens spores from the environment. The spores germinate and multiplies in the ischaemic conditions, releasing toxins, which further damage tissues.
Usually, the clinical features of gas gangrene appear within 24 hours of injury.
Clostridium perfringens spores are not destroyed by cooking. During slow cooling and unrefrigerated storage, they germinate to form vegetative cells.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 98
Incorrect
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A lesion to which part of the optic radiation will result in contralateral homonymous inferior quadrantanopia?
Your Answer:
Correct Answer: Right parietal lobe
Explanation:A visual loss in the lower left quadrant in both visual fields is an indication of an inferior homonymous. This is due to a lesion of the superior fibres of the optic radiation in the parietal lobe on the contralateral side of the visual pathway.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 99
Incorrect
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One of the following pathogens is a conditional pathogen:
Your Answer:
Correct Answer: Neisseria meningitidis
Explanation:Obligate pathogens include Mycobacterium TB, HIV, Treponema pallidum, and Neisseria gonorrhoeae. Neisseria meningitidis, on the other hand, is a conditional pathogen.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 100
Incorrect
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Fibrinoid necrosis is typically seen in which of the following:
Your Answer:
Correct Answer: Malignant hypertension
Explanation:Fibrinoid necrosis occurs in malignant hypertension where increased arterial pressure results in necrosis of smooth muscle wall. Eosinophilic and fibrinous deposits are seen.
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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