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Question 1
Correct
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Which enzyme is deficient in the inborn error of metabolism called galactosemia?
Your Answer: Galactose-1-phosphate uridyl transferase
Explanation:Galactosaemia is a rare genetic autosomal recessive metabolic disorder. Lactose is broken down by the enzyme lactase into glucose and galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose (Galactose-1-phosphate uridyltransferase) are severely diminished or missing entirely, leading to toxic levels of galactose 1-phosphate in various tissues.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 2
Correct
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Which of the following results in the resting membrane potential of a myocyte?
Your Answer: Activation of outward K+ channels
Explanation:Phase 0 is caused by the sodium current. Voltage gated sodium channels open leading to the influx of sodium into the cardiac muscle cell. Phase 1 is the rapid transient repolarization phase which is caused by the inactivation of the voltage gated sodium channels and opening of the voltage gated potassium channels along with opening of the slow calcium channels. Phase 2 which is the plateau is caused by opening of the slow calcium channels. Phase 4 is caused by closing of the slow calcium channels and opening of the potassium channels leading to efflux of potassium leading to the establishment of the resting membrane potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 3
Incorrect
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Which cell secretes parathyroid hormone?
Your Answer: Parafollicular cells
Correct Answer: Chief cells
Explanation:Parathyroid chief cells, also known as parathyroid principal cells or parathyroid cells, are the most prevalent type of cell in the parathyroid gland and the only ones present at birth. They secrete parathyroid hormone (PTH).
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 4
Correct
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Question 5
Incorrect
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The ability of the SA node cells to allow ionic flow through channels activated in a hyperpolarized state is known as:
Your Answer: All of the above
Correct Answer: Pace maker potential
Explanation:Rhythmically discharging cells have a membrane potential that, after each impulse, declines to the firing level. Thus this prepotential or Pacemaker potential triggers the next impulse. The inherent leakiness of the sinus nodal fibers to Na+ and Ca2+ causes their self excitation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Correct
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Which statement describes endogenous transmission the best?
Your Answer: Commensal flora that gain access to an inappropriate area
Explanation:All answers A, B, C, and D are examples of exogenous infections. Endogenous infection is an infection by organisms that normally reside in the body but have previously been dormant.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 7
Incorrect
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The formation of superoxide is catalysed by which enzyme?
Your Answer:
Correct Answer: NADPH oxidase
Explanation:Superoxide is biologically toxic and is deployed by the immune system to kill invading microorganisms. In phagocytes, superoxide is produced in large quantities by the enzyme NADPH oxidase for use in oxygen-dependent killing mechanisms of invading pathogens.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 8
Incorrect
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Which of the following portocaval anastomoses can cause problems in preterm infants?
Your Answer:
Correct Answer: Patent ductus venosus.
Explanation:The ductus venosus is open at the time of the birth and closes during the first week of life in most full-term neonates; however, it may take much longer to close in pre-term neonates. After it closes, the remnant is known as ligamentum venosum. If the ductus venosus fails to occlude after birth, it remains patent (open), and the individual is said to have a patent ductus venosus and thus an intrahepatic portosystemic shunt (PSS).
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 9
Incorrect
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The consensual light reflex is co-ordinated mainly in the:
Your Answer:
Correct Answer: Edinger-Westphal nucleus
Explanation:The consensual light reflex occurs when an individual’s right eye is shielded and light shines into the left eye, constriction of the right pupil will occur, as well as the left. This is because the afferent signal sent through one optic nerve connects to the Edinger-Westphal nucleus, whose axons run to both the right and the left oculomotor nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 10
Incorrect
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Which cranial nerve is responsible for the parasympathetic nerve supply of the thorax and upper abdomen?
Your Answer:
Correct Answer: CN X
Explanation:Cranial nerve X supplies the structures of the thorax and abdomen. All the rest of the cranial nerves supply the structures in the head and neck
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This question is part of the following fields:
- Medicine
- Neurology
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Question 11
Incorrect
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The parasympathetic function of the facial nerve is:
Your Answer:
Correct Answer: Secretion of tears from lacrimal glands, secretion of saliva from the sublingual and submandibular salivary glands.
Explanation:Facial nerve (Cranial Nerve VII) has both sensory and motor components so it is a mixed nerve. It carries axons of:General somatic afferent – to skin and the posterior earGeneral visceral efferent – which innervate sublingual, submandibular and lacrimal glands and the mucosa of the nasal cavity.General visceral afferent – provide sensation to soft palate and parts of the nasal cavity.Special visceral efferent – innervate muscles of facial expression and stapedius, the posterior belly of the digastric and the stylohyoid musclesSpecial visceral afferent – provide taste to the anterior two-thirds of the tongue via chorda tympani.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 12
Incorrect
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A 74 year old man presents with 12 kg weight loss and persistent back pain that is unrelated to activity for the past several months. Laboratory findings show :WCC: 6.7 x 109/l (5.4 neutrophils, 1.2 lymphocytes and 0.2 monocytes)Haemoglobin: 11.2 g/dlhaematocrit: 33.3%MCV: 88 flPlatelet count: 89 x 109/l.The biochemistry shows:sodium 144 mmol/lpotassium 4.5 mmol/lchloride 100 mmol/lbicarbonate 26 mmol/lurea 14 mmol/lcreatinine 90 μmol/la glucose of 5.4 mmol/l.A CT scan of the spine reveals scattered 0.4 to 1.2 cm bright lesions in the vertebral bodies.Which of the following additional laboratory test findings is he most likely to have?
Your Answer:
Correct Answer: Serum prostate specific antigen of 35 microgram/l
Explanation:Old age, persistent backache, weight loss, and osteosclerotic lesions make prostatic adenocarcinoma the most likely diagnosis. The sequelae include severe pain, pathological fractures, hypercalcemia and cord compression. Prostatic adenocarcinoma is detected by elevated levels of prostate specific antigen. Positive serology for borrelia burgdorferi would hint at Lyme disease which does not cause osteosclerotic bone lesions, neither would Neisseria gonorrhoeae have such a presentation.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 13
Incorrect
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Regarding the surface anatomy of the orifices of the heart, where is the aortic valve located?
Your Answer:
Correct Answer: Opposite the left 3rd intercostal space to the left of the sternum
Explanation:The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 14
Incorrect
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Afferent fibers from the baroreceptors of the great arteries form branches of which cranial nerves?
Your Answer:
Correct Answer: Glossopharyngeal and vagus nerves
Explanation:The receptors of the carotid sinus are innervated by the carotid sinus nerve, a branch of the glossopharyngeal nerve. The aortic arch receptors located in the arch of the aorta are innervated by the aortic depressor nerve, a branch of the vagus nerve.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 15
Incorrect
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A 42 year old female with a history of SLE presents with an exacerbation of wrist pain. Which of the following markers would be the most suitable for monitoring disease activity?
Your Answer:
Correct Answer: Anti-dsDNA titres
Explanation:A high level of anti-dsDNA in the blood is strongly associated with lupus and is often significantly increased during or just prior to a flare-up. When the anti-dsDNA is positive and the person tested has other clinical signs and symptoms associated with lupus, it means that the person tested likely has lupus. This is especially true if an anti-Sm test is also positive.In the evaluation of someone with lupus nephritis, a high level (titre) of anti-dsDNA is generally associated with ongoing inflammation and damage to the kidneys.A very low level of anti-dsDNA is considered negative but does not exclude a diagnosis of lupus. Only about 65-85% of those with lupus will have anti-dsDNA.Low to moderate levels of the autoantibody may be seen with other autoimmune disorders, such as Sjögren syndrome and mixed connective tissue disease (MCTD).
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 16
Incorrect
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A 48-year-old male with a history of bipolar disorder presents with acute confusion. In-transit to hospital he had a generalized seizure which terminated spontaneously after around 30 seconds. On arrival to the emergency department, his GCS is 14/15 and he is noted to have a coarse tremor. Suspecting a diagnosis of lithium toxicity, intravenous access is obtained, a blood sample was drawn for investigations and a saline infusion is started. The blood investigations revealed:Lithium level: 4.2 mmol/lNa+: 136 mmol/lK+: 4.6 mmol/lUrea: 8.1 mmol/lCreatinine: 99 µmol/lBicarbonate: 18 mmol/lWhat is the most appropriate management for the patient?
Your Answer:
Correct Answer: Arrange haemodialysis
Explanation:The presentation of the patient is typical of chronic lithium toxicity (due to the presence of mainly neurological manifestations). Additional to the blood investigations mentioned, urine analysis, electrolyte levels, and renal function should also be performed. A low urine Anion gap and a low urine specific gravity are highly suggestive of lithium toxicity.ECG obtained in this patient is likely to show: nonspecific, diffuse ST segment depression with T wave inversion.Acute lithium toxicity presents with more GI manifestations while, the clinical features of chronic lithium toxicity are mainly neurological and can include:Coarse tremors (fine tremors are seen in therapeutic levels), hyperreflexia, acute confusion, seizures, and coma.The management of lithium toxicity is as follows:Immediate GI decontamination with gastric lavage (in case of acute intoxication)Saline Administrations: the goal of saline administration is to restore GFR, normalize urine output and enhance lithium clearance.Haemodialysis remains the mainstay treatment for lithium toxicity as lithium is readily dialyzed because of water solubility, low volume of distribution, and lack of protein binding.The Extracorporeal Treatments in Poisoning Workgroup (EXTRIP Workgroup) recommendations for dialysis (extracorporeal treatment) in lithium toxicity include:• Impaired kidney function and lithium levels > 4.0 mEq/L• Decreased consciousness, seizures, or life-threatening dysrhythmias, regardless of lithium levels• Levels are > 5.0 mEq/L, significant confusion is noted, or the expected time to reduce levels to < 1.0 mEq/L is more than 36 hoursAs post-dialysis rebound elevations in lithium levels have been documented, continuous veno-venous hemofiltration (CVVH) has been advocated.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 17
Incorrect
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The net effect of parathyroid hormone on calcium and phosphate homeostasis is?
Your Answer:
Correct Answer: Increase in Ca, decrease in phosphate
Explanation:Parathyroid hormone’s main target organs are the kidneys, bone, and intestine. In the kidney, it decreases reabsorption of phosphate and increases calcium reabsorption. It also promotes absorption of calcium from bone. PTH release results in a small drop in serum phosphate concentrations.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 18
Incorrect
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Into how many functional units can the cerebellum be divided?
Your Answer:
Correct Answer: 3
Explanation:The functional division of the cerebellum are the: Vestibulocerebellum (floculonodular lobe), Spinocerebellum (vermis and associated areas in the midline) and cerebrocerebellum (lateral hemispheres).
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This question is part of the following fields:
- Medicine
- Neurology
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Question 19
Incorrect
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With regards to the Na+/K+ ATPase, which one of the following is correct?
Your Answer:
Correct Answer: 3 Na+ released into the extracellular fluid
Explanation:Na+/K+ pump or sodium–potassium pump is an enzyme found in the plasma membrane. This pumping is active (i.e. it uses energy from ATP) and is important for cell physiology. Its simple function is to pump 3 sodium ions out for every 2 potassium ions taken in and since they both have equal ionic charges, this creates a electrochemical gradient between a cell and its exterior.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 20
Incorrect
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Protein digestion starts in the stomach by which enzyme?
Your Answer:
Correct Answer: Pepsin
Explanation:Pepsinogen is the inactive form of pepsin which is secreted by gastric chief cells and is converted to pepsin, in the presence of gastric HCL. Pepsin is a peptidase that breaks down proteins into smaller peptides.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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