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Question 1
Correct
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What is the primary mode of action of Enoxaparin?
Your Answer: Inhibits factor Xa
Explanation:Heparin acts as an anticoagulant by enhancing the inhibition rate of clotting proteases by antithrombin III impairing normal haemostasis and inhibition of factor Xa. Low molecular weight heparins have a small effect on the activated partial thromboplastin time and strongly inhibit factor Xa. Enoxaparin is derived from porcine heparin that undergoes benzylation followed by alkaline depolymerization.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 2
Incorrect
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You are reviewing a patient complaining of loss of vision. Previous images shows a lesion at the optic chiasm. What type of visual field defect are you most likely to see in a lesion at the optic chiasm:
Your Answer: Homonymous hemianopia with macular sparing
Correct Answer: Bitemporal hemianopia
Explanation:A lesion at the optic chiasm will result in a bitemporal hemianopia.
A lesion of the optic nerve will result in ipsilateral monocular visual loss.
A lesion of the optic tract will result in a contralateral homonymous hemianopia. -
This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 3
Correct
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Regarding cortical areas, which one is found in the posterior part of the inferior frontal gyrus?
Your Answer: Broca’s area
Explanation:Broca’s area is involved in the expressive aspects of spoken and written language (production of sentences constrained by the rules of grammar and syntax). It corresponds to the opercular and triangular parts of the inferior frontal gyrus (BA 44 and 45). These areas are defined by two rami (branches) of the lateral sulcus (one ascending, one horizontal) which ‘slice into’ the inferior frontal gyrus. In keeping with its role in speech and language, Broca’s area is immediately anterior to the motor and premotor representations of the face, tongue and larynx. A homologous area in the opposite hemisphere is involved in non-verbal communication such as facial expression, gesticulation and modulation of the rate, rhythm and intonation of speech.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 4
Incorrect
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Which of the following is most likely to cause a bitemporal hemianopia:
Your Answer: Stroke
Correct Answer: Pituitary adenoma
Explanation:A bitemporal hemianopia is most likely due to compression at the optic chiasm. This may be caused by pituitary tumour, craniopharyngioma, meningioma, optic glioma or aneurysm of the internal carotid artery. A posterior cerebral stroke will most likely result in a contralateral homonymous hemianopia with macular sparing.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 5
Correct
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At rest, the left dome of the diaphragm normally reaches as high as which of the following:
Your Answer: Fifth intercostal space
Explanation:At rest the right dome of the diaphragm lies slightly higher than the left; this is thought to be due to the position of the liver. In normal expiration, the normal upper limits of the superior margins are the fifth rib for the right dome, the fifth intercostal space for the left dome and the xiphoid process for the central tendon.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 6
Incorrect
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A 35-year-old lady has suffered a serious brain injury. Her uvula has deviated to the right, according to inspection. Which of the following nerves is likely to be affected?
Your Answer: Left hypoglossal nerve
Correct Answer: Left vagus nerve
Explanation:When the vagus nerve is damaged, the soft palate is paralyzed and the uvula is shifted away from the affected side. The vagus nerve innervates the uvulae muscle, which forms the uvula’s core. If only one side is innervated, contraction of the active muscle will draw the uvula towards it.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 7
Incorrect
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A range of one standard deviation above and below the mean includes what approximate percentage of the sample values:
Your Answer: 0.56
Correct Answer: 0.68
Explanation:A range of one SD above and below the mean (+/- 1 SD) includes 68.2% of the sample values.
A range of two SD above and below the mean (+/- 2 SD) includes 95.4% of the sample values.
A range of three SD above and below the mean (+/- 3 SD) includes 99.7% of the sample values. -
This question is part of the following fields:
- Evidence Based Medicine
- Statistics
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Question 8
Correct
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Which of the following is a clinical effect of hyperkalaemia:
Your Answer: Muscle weakness
Explanation:Clinical features of hyperkalaemia may include:
paraesthesia, muscle weakness or paralysis, cardiac conduction abnormalities and dysrhythmias.Clinical features of hypokalaemia may include:
muscle weakness, muscle cramps, rhabdomyolysis and myoglobinuria, ascending paralysis resulting in respiratory failure, constipation, gut ileus with distension, anorexia, nausea and vomiting, impaired ADH action with polyuria and polydipsia, ECG changes and cardiac arrhythmias. -
This question is part of the following fields:
- Physiology
- Renal
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Question 9
Correct
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A 5-year-old girl is brought into the Paediatric ER for acute seizures. She has been convulsing for the past 18 minutes now and was already two doses of lorazepam in the ambulance. Now, you prepare a phenytoin infusion to abolish the seizures.
According to the APLS algorithm, what dose of phenytoin is advised for a convulsing child at this stage?Your Answer: 20 mg/kg over 20 minutes
Explanation:Advanced paediatric life support (APLS) recommends phenytoin as the first choice for second-line anticonvulsant in a patient that continues to seize ten minutes after the second dose of the first-line anticonvulsant (benzodiazepine). (step 3 of the APLS algorithm)
The recommended dose of phenytoin infusion is up at 20 mg/kg over 20 minutes. If the patient has already taken phenytoin as maintenance therapy or is allergic to phenytoin, then a phenobarbitone infusion should be set up at 20 mg/kg over 30-60 minutes.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 10
Correct
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You examine a patient's blood tests and discover that her electrolyte levels are abnormal.
Which of the following is the major extracellular cation?Your Answer: Sodium
Explanation:Electrolytes are compounds that may conduct an electrical current and dissociate in solution. Extracellular and intracellular fluids contain these chemicals. The predominant cation in extracellular fluid is sodium, whereas the major anion is chloride. Potassium is the most abundant cation in the intracellular fluid, while phosphate is the most abundant anion. These electrolytes are necessary for homeostasis to be maintained.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 11
Correct
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Low levels of which of the following arterial blood gas parameters stimulate the peripheral chemoreceptors?
Your Answer: Arterial pO 2
Explanation:Chemoreceptors are activated when the chemical composition of their immediate surroundings changes.
Peripheral chemoreceptors, together with central chemoreceptors, regulate respiratory functions. They detect changes in arterial blood oxygen levels. Decreased arterial Po2 (partial pressure of oxygen) reflexly stimulates peripheral chemoreceptors.
When peripheral chemoreceptors detect changes in arterial blood oxygen, they will trigger cardiorespiratory changes such as an increase in breathing and blood pressure. These reflexes are important for maintaining homeostasis during hypoxemia.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 12
Correct
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What is the primary function of collagen in wound healing?
Your Answer: Strength and support
Explanation:Key elements of the maturation stage include collagen cross-linking, collagen remodelling, wound contraction, and repigmentation. The tensile strength of the wound is directly proportional to the amount of collagen present. Numerous types of collagen have been identified; types I and III predominate in the skin and aponeurotic layers. Initially, a triple helix (tropocollagen) is formed by three protein chains; two are identical alpha-1 protein chains, and the third is an alpha-2 protein.
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This question is part of the following fields:
- Pathology
- Wound Healing
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Question 13
Incorrect
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You are about to perform a blood test on a patient suspected of having systemic lupus erythematosus. Which antibodies will indicate a positive result of systemic lupus erythematosus?
Your Answer: Antiphospholipid antibodies
Correct Answer: Anti-nuclear antibodies
Explanation:Antinuclear antibodies (ANA) are autoantibodies to the cells’ nucleus.
The ANA test is the most sensitive diagnostic test for verifying the disease’s diagnosis.
Other autoantibodies that may be found in SLE patients include rheumatoid factor, antiphospholipid antibodies, and antimitochondrial antibodies.
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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Question 14
Incorrect
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Regarding likelihood ratios, which of the following statements is INCORRECT:
Your Answer: Positive likelihood ratio = sensitivity/(1 - specificity)
Correct Answer: Likelihood ratios, like predictive values, are affected by the prevalence of the disease in the population.
Explanation:A likelihood ratio is a measure of the diagnostic value of a test. Likelihood ratios show how many times more likely patients with a disease are to have a particular test result than patients without the disease. Likelihood ratios are more useful than predictive values because they are calculated from sensitivity and specificity and therefore remain constant even when the prevalence of the disorder changes.
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This question is part of the following fields:
- Evidence Based Medicine
- Statistics
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Question 15
Correct
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A 35 year old man presents with a deep laceration to the proximal part of the forearm. On further assessment, the patient is unable to flex the metacarpophalangeal joints and interphalangeal joints of the index, middle finger and the thumb.
The ring and little fingers are intact but there is weakness at the proximal interphalangeal joint.
There is also loss of sensation over the lateral palm and the palmar surface of the lateral three and a half fingers.
Which of these nerve(s) has most likely been affected?
Your Answer: Median nerve
Explanation:A median nerve injury affecting the extrinsic and intrinsic muscles of the hand will present with:
Loss of sensation to the lateral palm and the lateral three and a half fingers.
Weakness of flexion at the metacarpophalangeal joints of the index and middle finger. This is because of paralysis of the lateral two lumbricals.
Weakness of flexion of the proximal interphalangeal joints of all four fingers due to paralysis of the flexor digitorum superficialis
Weakness of flexion at the distal interphalangeal joints of the index and middle finger following paralysis of the lateral half of the flexor digitorum profundus.
Weakness of thumb flexion, abduction and opposition due to paralysis of the flexor pollicis longus and thenar muscles -
This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 16
Correct
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Severe vomiting and diarrhoea were reported by a 25-year-old man. He's dehydrated and needs intravenous fluids to rehydrate. You give him cyclizine as part of his treatment.
What is cyclizine's main mechanism of action?Your Answer: Antihistamine action
Explanation:Cyclizine is a piperazine derivative that functions as an antihistamine (H1-receptor antagonist). To prevent nausea and vomiting, it is thought to act on the chemoreceptor trigger zone (CTZ) and the labyrinthine apparatus. It has a lower antimuscarinic effect as well.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 17
Correct
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A 29-year-old female with a swollen red finger presents to your clinic and you suspect that the underlying process is of acute inflammation. You request for some bloods investigations.
Which statement about histamine as a chemical mediator of the acute inflammatory response is TRUE?Your Answer: It increases vascular permeability
Explanation:Histamine increases vascular permeability in the acute inflammatory response.
Histamine causes vasodilation.
It is released from Mast cells and basophils, eosinophils and platelets.
Mast cells and basophils are its primary source
Nitric oxide (not histamine) is a major factor in endotoxic shock
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 18
Correct
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Which of the following is the most common cause of megaloblastic anaemia:
Your Answer: Vitamin B12 deficiency
Explanation:Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress from the growth stage to the mitosis stage. This leads to continuing cell growth without division, which presents as macrocytosis, with an increase in mean corpuscular volume (MCV). The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically vitamin B12 deficiency or folate deficiency.
Folate is an essential vitamin found in most foods, especially liver, green vegetables and yeast. The normal daily diet contains 200 – 250 μg, of which about 50% is absorbed. Daily adult requirements are about 100 μg. Absorption of folate is principally from the duodenum and jejunum. Stores of folate are normally only adequate for 4 months and so features of deficiency may be apparent after this time. -
This question is part of the following fields:
- Haematology
- Pathology
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Question 19
Incorrect
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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: GABA receptor agonist
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 20
Correct
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A 33-year-old heavily muscled man presents with left-sided chest pain. After taking part in a powerlifting competition, he felt a painful snap at the front of his shoulder and chest. There is also the presence of bruising and swelling over the left side of his chest. A ruptured pectoralis major muscle was suspected upon examining the injured area.
Which of the following statements regarding the surface markings of the pectoralis major muscle is considered correct?Your Answer: It inserts into the lateral lip of the bicipital groove of the humerus
Explanation:The pectoralis major is the superior most and largest muscle of the anterior chest wall. It is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla.
Its origin lies anterior surface of the medial half of the clavicle, the anterior surface of the sternum, the first 7 costal cartilages, the sternal end of the sixth rib, and the aponeurosis of the external oblique of the anterior abdominal wall.
The insertion of the pectoralis major is at the lateral lip of the intertubercular sulcus of the humerus. There are 2 heads of the pectoralis major, the clavicular and the sternocostal, which reference their area of origin.
The function of the pectoralis major is 3-fold and dependent on which heads of muscles are involved:
– Flexion, adduction and medial rotation of the arm at the glenohumeral joint
– Clavicular head causes flexion of the extended arm
– Sternoclavicular head causes extension of the flexed armArterial supply of the pectoralis major, the pectoral artery, arises from the second branch of the axillary artery, the thoracoacromial trunk.
The 2 heads of the pectoralis major have different nervous supplies. The clavicular head derives its nerve supply from the lateral pectoral nerve. The medial pectoral nerve innervates the sternocostal head. The lateral pectoral nerve arises directly from the lateral cord of the brachial plexus, and the medial pectoral nerve arises from the medial cord.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 21
Correct
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A 23-year-old male is referred to your haematology clinic after an acute attack of haemolytic anaemia. He was diagnosed with glucose-6-phosphate dehydrogenase deficiency ten years ago.
Which ONE of the following options is FALSE with regards to this disorder?Your Answer: Acute haemolysis can be triggered by cephalosporin antibiotics
Explanation:Glucose-6-phosphate dehydrogenase deficiency is an X-linked recessive disorder in which there is a deficiency of the enzyme G6PD. This causes instability of red blood cell membranes under oxidative stress leading to haemolysis.
Triggers include:
1) Fava beans
2) Sulphonamides
3) Primaquine
4) Anti-TB drugs
5) InfectionsMost individuals will be asymptomatic until exposed to one of the triggers listed above. It is the commonest human enzyme defect and affects males more than females because of the X-linked inheritance pattern. The use of penicillins and cephalosporins is generally safe.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 22
Incorrect
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An 82 year old man has fever, left sided abdominal and back pain and presents to the emergency room. Imaging reveals a large perinephric abscess. Which of the following most likely describes the fluid location:
Your Answer: Within the paranephric fat
Correct Answer: Between the renal capsule and the renal fascia
Explanation:The perinephric fat is immediately external to the renal capsule and completely surrounds the kidney. The renal fascia surrounds the perinephric fat and the paranephric fat is external to the renal fascia. The location of a perinephric abscess is in the perinephric fat between the renal capsule and the renal fascia.
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This question is part of the following fields:
- Abdomen
- Anatomy
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Question 23
Incorrect
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Excessive gastric acid output is detected in a patient with a history of recurrent stomach ulcers. It's possible that the patient has Zollinger-Ellison syndrome.
Which of the following statements about stomach acid is correct?Your Answer: Secretion occurs via passive transport
Correct Answer: The proton pump located in the canalicular membrane is vital to its secretion
Explanation:The stomach produces gastric acid, which is a digesting fluid. The stomach secretes about 2-3 litres every day. It is involved in tissue breakdown, the conversion of pepsinogen to active pepsin, and the creation of soluble salts with calcium and iron, and has a pH range of 1.5-3.5. It also serves as an immune system by destroying microbes.
The following substances are found in gastric acid:
Water
Acid hydrochloride
Pepsinogen
mucous
Intrinsic factorThe parietal cells in the proximal 2/3 (body) of the stomach release gastric acid. The concentration of hydrogen ions in parietal cell secretions is 1-2 million times that of blood. Chloride is released against both a concentration and an electric gradient, and active transport is required for the parietal cell to produce acid.
The following is how stomach acid is secreted:
1. Gastric acid secretion is dependent on the H+/K+ ATPase (proton pump) situated in the canalicular membrane. The breakdown of water produces hydrogen ions within the parietal cell. The hydroxyl ions produced in this reaction mix quickly with carbon dioxide to generate bicarbonate ions. Carbonic anhydrase is the enzyme that catalyses this process.
2. In return for chloride, bicarbonate is carried out of the basolateral membrane. The ‘alkaline tide’ occurs when bicarbonate is released into the bloodstream, resulting in a modest rise in blood pH. The parietal cell’s intracellular pH is maintained by this procedure. Conductance channels carry chloride and potassium ions into the lumen of canaliculi.
3. Through the action of the proton pump, hydrogen ions are pushed out of the cell and into the lumen in exchange for potassium; potassium is thus efficiently recycled.
4. The canaliculi accumulate osmotically active hydrogen ions, which creates an osmotic gradient across the membrane, allowing water to diffuse outward.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 24
Incorrect
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The sensation produced by touching the arm with a vibrating tuning fork during a neurological examination is mediated by which of the following spinal tracts:
Your Answer: Anterior spinothalamic tract
Correct Answer: Posterior column
Explanation:Fine-touch, proprioception and vibration sensation are mediated by the posterior column-medial lemniscus pathway.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 25
Incorrect
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A 55-year-old woman was complaining of headaches. On examination, the patient is found to have weakness on the left side of her body and her eyes are deviated towards the right hand side. These are signs of damage to which of the following areas?
Your Answer: Parietal lobe
Correct Answer: Frontal lobe
Explanation:Some potential symptoms of frontal lobe damage can include loss of movement, either partial or complete, on the opposite side of the body.
In the patient’s case, it is a result of motor cortex damage on the right side since her left side of the body is affected. The conjugate eye deviation symptom towards the side of the lesion is a result of damage to the frontal eye field.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 26
Correct
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Which of the following is NOT a common effect of etomidate:
Your Answer: Significant hypotension
Explanation:Etomidate causes less hypotension than thiopental sodium and propofol during induction. However, it is associated with a high incidence of extraneous muscle movements, which can be minimised by an opioid analgesic or a short-acting benzodiazepine given prior to induction. Pain on injection is common and there is a high rate of thrombophlebitis in the postoperative period. Postoperative nausea and vomiting commonly occur. Etomidate suppresses adrenocortical function, particularly during continuous administration, and it should not be used for maintenance of anaesthesia. It should be used with caution in patients with underlying adrenal insufficiency, for example, those with sepsis.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 27
Correct
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A 70-year-old patient presents with a chronic digoxin overdose. She has vomited several times, is extremely tired, and her vision 'appears yellow,' according to her.
Which of the following is a reason for this patient's use of Digifab?Your Answer: Coexistent renal failure
Explanation:An antidote for digoxin overdose is digoxin-specific antibody (Digifab). It’s a lyophilized preparation of digoxin-immune ovine Fab immunoglobulin fragments that’s sterile, purified, and lyophilized. These fragments were extracted from the blood of healthy sheep that had been immunised with a digoxin derivative called digoxin-dicarboxymethoxylamine (DDMA), a digoxin analogue that contains the functionally important cyclopentaperhydrophenanthrene:lactone ring moiety coupled to keyhole limpet hemocyanin (KLH).
Digifab has a higher affinity for digoxin than digoxin does for its sodium pump receptor, which is thought to be the site of its therapeutic and toxic effects. When given to a patient who is intoxicated, Digifab binds to digoxin molecules, lowering free digoxin levels and shifting the equilibrium away from binding to receptors, reducing cardio-toxic effects. The kidney and reticuloendothelial system then clear the Fab-digoxin complexes.
The following summarises the indications for Digifab in acute and chronic digoxin toxicity:
Acute digoxin toxicity
Chronic digoxin toxicity
Cardiac arrest
Life-threatening arrhythmia
Potassium level > 5 mmol/l
>10 mg digoxin ingested (adult)
>4 mg digoxin ingested (child)
Digoxin level > 12 ng/ml
Cardiac arrest
Life-threatening arrhythmia
Significant gastrointestinal symptoms
Symptoms of digoxin toxicity -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 28
Correct
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Which of the following microbes is spread by a vector:
Your Answer: Plasmodium falciparum
Explanation:The female Anopheles mosquito is the vector for Plasmodium falciparum transmission. Treponema pallidum is transmitted through sexual transmission or direct skin contact. Clostridium perfringens is spread by direct skin contact or through oral-faecal route. The oral-faecal pathway is how Vibrio cholerae spreads. Mycoplasma tuberculosis is spread via the airborne route.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 29
Correct
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Which of the following best describes the therapeutic effect of calcium gluconate when used in treatment for hyperkalaemia:
Your Answer: Reduces cardiac cell membrane excitability
Explanation:Calcium resonium is an ion-exchange resin that exchanges sodium for potassium as it passes through the intestine, leading to excretion of potassium from the body. Salbutamol and insulin act to increase intracellular uptake of K+ via Na-K ATP pump. Sodium bicarbonate acts to correct acidosis and thus promotes intracellular uptake of K+. Calcium gluconate acts to protect the cardiac membrane and has no effect on serum K+ levels.
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This question is part of the following fields:
- Fluids And Electrolytes
- Pharmacology
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Question 30
Incorrect
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Which of the following nerves is most important for eversion of the foot:
Your Answer: Tibial nerve
Correct Answer: Superficial fibular nerve
Explanation:Eversion of the foot is primarily produced by the fibularis longus and fibularis brevis, both innervated by the superficial fibular nerve. The fibularis tertius, innervated by the deep fibular nerve, also assists in this action.
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This question is part of the following fields:
- Anatomy
- Lower Limb
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SESSION STATS - PERFORMANCE PER SPECIALTY
