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Question 1
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 2
Correct
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A 54 year old patient presents with vertigo, ipsilateral hemiataxia, dysarthria, ptosis and miosis.
Which of these blood vessels has most likely been occluded?
Your Answer: Posterior inferior cerebellar artery
Explanation:Posterior inferior cerebellar artery (PICA) occlusion is characterised by vertigo, ipsilateral hemiataxia, dysarthria, ptosis and miosis. PICA occlusion causes infarction of the posterior inferior cerebellum, inferior cerebellar vermis and lateral medulla.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 3
Correct
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Carbamazepine is indicated for all of the following EXCEPT for:
Your Answer: Myoclonic seizures
Explanation:Carbamazepine is a drug of choice for simple and complex focal seizures and is a first-line treatment option for generalised tonic-clonic seizures. It is also used in trigeminal neuralgia and diabetic neuropathy. Carbamazepine may exacerbate tonic, atonic, myoclonic and absence seizures and is therefore not recommended if these seizures are present.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 4
Correct
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A 32-year-old female is diagnosed case of bipolar disorder and is on medication. She presents to her psychiatric team with symptoms of severe depression. She is currently taking Lithium.
Out of the following, which is TRUE regarding lithium?Your Answer: It commonly causes a tremor
Explanation:Lithium is the drug of choice for bipolar disorders but is commonly associated with side effects and toxicity.
Fine hand tremor is very commonly seen and reported in as many as 50% of patients during the first week of therapy with Lithium. The tremor tends to reduce with time and is only present in around 5% of patients taking the medication two years or longer. Lithium tremors are more common with older age, presumably due to the additive effects of age-related essential tremors.
Option The normal therapeutic range is 2.0-2.5 mmol/l: Lithium should be carefully monitored as it has a very low therapeutic index. The normal therapeutic range is 0.4-0.8 mmol/l. Levels should be checked one week after starting therapy and one week after every change in dosage. (Option Levels should be checked one month after starting therapy)
Option It can induce hyperthyroidism: Lithium has a known effect on thyroid function. Lithium decreases the production of T4 and T3 and commonly causes hypothyroidism. More rarely, lithium causes hyperthyroidism due to thyroiditis.
Option It can induce diabetes mellitus: Lithium can induce nephrogenic diabetes insipidus but not diabetes mellitus.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 5
Incorrect
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Regarding gas exchange at the alveolar-capillary membrane, which of the following statements is CORRECT:
Your Answer: The rate of transfer of nitrous oxide is diffusion-limited.
Correct Answer: The rate of diffusion in lungs can be estimated by measuring the diffusing capacity of the lungs for carbon monoxide.
Explanation:Gas exchange between alveolar air and blood in the pulmonary capillaries takes place by diffusion across the alveolar-capillary membrane. Diffusion occurs from an area of high partial pressure to an area of low partial pressure, thus the driving force for diffusion is the alveolar-capillary partial pressure gradient. Diffusion occurs across a membrane and is therefore governed by Fick’s law. Although CO2is larger than O2, it is is much more soluble and diffuses 20 times more rapidly. The diffusing capacity for oxygen (DLO2) cannot be measured directly but the rate of diffusion in the lungs can be estimated by measuring the diffusing capacity of the lungs for carbon monoxide (DLCO).
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 6
Incorrect
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At rest, the left dome of the diaphragm normally reaches as high as which of the following:
Your Answer: Sixth intercostal space
Correct 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 7
Correct
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Antidiuretic hormone (ADH) levels are found to be increased in a young lady with unexplained hyponatraemia.
In a healthy patient under normal circumstances, in which of the following conditions would ADH not be released?Your Answer: Increased alcohol intake
Explanation:Antidiuretic hormone (ADH) is produced in the hypothalamus’s supraoptic nucleus and then released into the blood via axonal projections from the hypothalamus to the posterior pituitary.
It is carried down axonal extensions from the hypothalamus (the neurohypophysial capillaries) to the posterior pituitary, where it is kept until it is released, after being synthesized in the hypothalamus.
The secretion of ADH from the posterior pituitary is regulated by numerous mechanisms:
Increased plasma osmolality: Osmoreceptors in the hypothalamus detect an increase in osmolality and trigger ADH release.Hypovolaemia causes a drop in atrial pressure, which stretch receptors in the atrial walls and big veins detect (cardiopulmonary baroreceptors). ADH release is generally inhibited by atrial receptor firing, but when the atrial receptors are stretched, the firing reduces and ADH release is promoted.
Hypotension causes baroreceptor firing to diminish, resulting in increased sympathetic activity and ADH release.
An increase in angiotensin II stimulates angiotensin II receptors in the hypothalamus, causing ADH production to increase.Nicotine, Sleep, Fright, and Exercise are some of the other elements that might cause ADH to be released.
Alcohol (which partly explains the diuretic impact of alcohol) and elevated levels of ANP/BNP limit ADH release. -
This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 8
Correct
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A 66-year-old male is brought to your clinic by his wife with the complaint of increasing confusion and disorientation over the past three days, along with decreased urination. She reports that he has been complaining of increasing pain in his back and ribs over the past three months.
On examination, the patient looks anaemic, is not oriented in time, place and person and has tenderness on palpation of the lumbar spine and the 10th, 11th and 12th ribs.
Blood tests show anaemia which is normocytic, normochromic, raised urea and creatinine and hypercalcemia.
Which one of the following diagnoses is most likely in this case?Your Answer: Multiple myeloma
Explanation:Multiple myeloma is a clonal abnormality affecting plasma cells in which there is an overproduction of functionless immunoglobulins. The most common patient complaint is bone pain, especially in the back and ribs. Anaemia and renal failure are common, along with hypercalcemia. Hypercalcemia may lead to an altered mental status, as in this case.
Chronic lymphocytic leukaemia occurs due to the overproduction of lymphocytes, usually B cells. CLL may present with an asymptomatic elevation of B cells. Patients are generally more than 50 years old and present with non-specific fatigue and weight loss symptoms.
There is no history of alcohol abuse in this case. Furthermore, patients with a history of alcohol abuse may have signs of liver failure, which are not present here.
Metastatic prostate cancer would most often cause lower backache as it metastasises first to the lumbar spine via the vertebral venous plexus.
A patient with Vitamin B12 deficiency would have anaemia, megaloblastic, hypersegmented neutrophils, and signs of peripheral neuropathy.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 9
Correct
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A 30-year-old man suffers from an open femoral shaft fracture after being involved in a road traffic accident. As a consequence of his injury, the nerve that was damaged innervates the popliteus muscle.
In which of the following nerves is the popliteus muscle innervated by?Your Answer: Tibial nerve
Explanation:The popliteus muscle is innervated by the tibial nerve (L4, 5 and S1).
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 10
Correct
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Which of the following side effects is more common of etomidate than other intravenous induction agents:
Your Answer: Extraneous muscle movements
Explanation:Etomidate 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. Etomidate causes less hypotension than thiopental sodium and propofol during induction. Etomidate is associated with rapid recovery without a hangover effect. The rate of respiratory depression and tachycardia is not higher in etomidate.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 11
Correct
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A 34-year-old male presents to the Emergency Department with the complaint of palpitations and difficulty breathing, which started suddenly half an hour ago. His ECG shows findings of supraventricular tachycardia. You attempt vagal manoeuvres but cannot convert them back to sinus rhythm. Therefore, drug therapy is necessary to terminate the arrhythmia. Adenosine cannot be used in this patient because of a contra-indication listed in his medical record.
Which one of the conditions listed below would be a contraindication in this case?Your Answer: Asthma
Explanation:Entonox is a mixture of 50% Oxygen and 50% nitrous oxide and is given in an inhaled form as a quick form of analgesia. Entonox causes non-competitive inhibition of NMDA (N-methyl-D-aspartate) receptors, which are a subtype of the glutamate receptor.
It is stored in blue and white cylinders and administered via a pressure regulator and demand valve. The administration of this medicine reduces pain and anxiety in paediatric and dental procedures ands during labour.
Effects are apparent after 20 seconds, and peak action occurs after 3 to 5 minutes as it is a drug with a rapid onset and the patient will also recover rapidly from its effects. Entonox is widely used as it does not accumulate in the body and does not cause many side effects. However, a notable side effect is the inhibition of Vitamin B12 synthesis.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 12
Correct
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A 34-year-old man arrives at the department befuddled. He has a history of schizophrenia and is on an antipsychotic medication, but he can't recall what it's called.
Which of the following statements about antipsychotic drug side effects is correct?Your Answer: Haloperidol is the most common causative antipsychotic drug
Explanation:Extrapyramidal side effects are most common with piperazine phenothiazines (fluphenazine, prochlorperazine, and trifluoperazine) and butyrophenones (fluphenazine, prochlorperazine, and trifluoperazine) (benperidol and haloperidol). The most common causative antipsychotic drug is haloperidol.
Tardive dyskinesia (rhythmic, involuntary movements of the tongue, face, and jaw) is most commonly associated with long-term or high-dose treatment. It is the most serious form of extrapyramidal symptoms because withdrawal of the causative drug may make it irreversible, and treatment is usually ineffective.
Dystonia (abnormal facial and body movements) is more common in children and young adults, and it usually shows up after only a few doses. Procyclidine 5 mg IV or benzatropine 2 mg IV as a bolus can be used to treat acute dystonia.
An unpleasant feeling of restlessness characterises akathisia. The inability to initiate movement is known as akinesia.
Renal impairment causes increased cerebral sensitivity, so lower doses should be used.
In elderly patients with dementia-related psychosis who are treated with haloperidol, there is an increased risk of death. This appears to be due to a higher risk of heart attacks and infections like pneumonia.
The following are some of the antipsychotic drugs’ contraindications:
Reduced level of consciousness/coma
Depression of the central nervous system
Phaeochromocytoma -
This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 13
Incorrect
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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: Digoxin level of 3.5 ng/ml
Correct 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 14
Incorrect
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A 40-year-old woman was rushed to the Emergency Department due to an anaphylactic reaction after being stung by a bee. She responded well to initial treatment but developed anaphylactic symptoms after 6 hours. Her symptoms were resolved after a further dose of adrenaline. Her family threatened legal action as they thought she had not received adequate treatment but withdrew their accusation after the attending physician explained that the woman had suffered a biphasic reaction.
What is the approximate percentage of people who suffer this type of reaction?Your Answer: 10%
Correct Answer: 20%
Explanation:Anaphylactic reactions are Type 1 hypersensitivity reactions IgE-mediated and can be potentially life-threatening if not treated promptly. There are four well-recognized patterns of anaphylaxis:
1) Uniphasic
2) Biphasic
3) Protracted
4) RefractoryBiphasic reactions occur in 20% of the population, although their mechanism is poorly understood. The symptoms of anaphylaxis recur within 4-6 hours, although they may also recur up to 72 hours later. All patients discharged from the hospital after an anaphylactic shock must:
1) Be warned to return to the hospital immediately if symptoms recur
2) Have a treatment plan in place
3) Have a follow-up appointment
4) Be considered for an adrenaline auto-injector
5) Referred to an allergy clinic -
This question is part of the following fields:
- General Pathology
- Pathology
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Question 15
Incorrect
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Which of the following statements regarding the infectivity periods of these corresponding diseases is correct?
Your Answer: Hepatitis A is infectious from the onset of jaundice for 1 month
Correct Answer: Rubella is infectious until 5 days after the rash appears
Explanation:Rubella can be contagious from 7 days before to 7 days after the rash appears.
Patients with measles are contagious from 1-2 days before the onset of symptoms.
A person with chickenpox is considered contagious beginning 1 to 2 days before rash onset until all the chickenpox lesions have crusted (scabbed).
The infectious period of mumps is considered from 2 days before to 5 days after parotitis onset.
Hepatitis A is highly transmissible and has an average incubation period of 28 to 30 days (range 15–50 days). The maximum infectivity is during the second half of the incubation period (i.e. while asymptomatic) and most cases are considered non-infectious after the first week of jaundice.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 16
Incorrect
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A 35-year-old man, who was feeling unwell after his return from a business trip, was diagnosed with a disease that is known to be transmitted by a vector.
Among the following microorganisms, which of the following has a mode of transmission of being vector-borne?Your Answer: Bordatella pertussis
Correct Answer: Plasmodium falciparum
Explanation:Plasmodium falciparum is a parasite that is vector-borne which is transmitted by the female Anopheles mosquito.
Bordetella pertussis is transmitted through the respiratory tract, via respiratory droplets or direct contact with infectious secretions.
Mycobacterium tuberculosis is transmitted via inhalation of infected respiratory droplets.
HIV may be transmitted via sexual contact, vertical transmission from mothers to infants, and among injection drug users sharing infected needles, as well as through transfusion of infected blood products.
Treponema pallidum transmission normally occurs during direct sexual contact with an individual who has an active primary or secondary syphilitic lesion.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 17
Correct
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Regarding water and electrolyte absorption in the small intestine, which of the following statements is INCORRECT:
Your 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 18
Correct
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Which of the following is NOT a typical complication associated with mumps:
Your Answer: Subacute sclerosing panencephalitis
Explanation:Complications of mumps include meningitis, post meningitis deafness, encephalitis, pancreatitis, orchitis and oophoritis. Subacute sclerosing panencephalitis is a complication typically associated with measles infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
Incorrect
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You've been asked to visit a 20-year-old patient  who has been complaining of stomach pain, diarrhoea, and bloating. The GP recently saw the patient and is now looking into numerous possible reasons for stomach hypermotility.
Which of the following factors contributes to increased stomach motility?Your Answer: Ghrelin
Correct Answer: Gastrin
Explanation:Gastrin is a peptide hormone that aids in gastric motility by stimulating the generation of gastric acid by the parietal cells of the stomach. G-cells in the stomach’s pyloric antrum, the duodenum, and the pancreas release it.
The following stimuli cause the release of gastrin:
Stimulation of the vagus nerve
Hypercalcaemia
stomach bloating
Proteins that have been partially digested, particularly amino acids.
The presence of acid and somatostatin inhibits the release of gastrin.
Gastrin’s main actions are as follows:
Gastric parietal cells are stimulated to release hydrochloric acid.
ECL cells are stimulated to produce histamine.
Gastric parietal cell maturation and fundal growth stimulation
Causes the secretion of pepsinogen by the gastric chief cells.
Improves antral muscle mobility
stimulates gastric contractions
Increases gastric emptying rate and stimulates pancreatic secretion
Gallbladder emptying is induced. -
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 20
Correct
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Regarding pressures and airflow during the normal breathing cycle, which of the following statements is INCORRECT:
Your Answer: Negative intrapleural pressure causes dynamic compression of the airways.
Explanation:Dynamic compression occurs during forced expiration, when as the expiratory muscles contract, all the structures within the lungs, including the airways, are compressed by the positive intrapleural pressure. Consequently the smaller airways collapse before the alveoli empty completely and some air remains within the lungs (the residual volume).
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 21
Correct
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Regarding ciprofloxacin, which of the following statements is INCORRECT:
Your Answer: Ciprofloxacin decreases plasma concentrations of theophylline.
Explanation:Ciprofloxacin increases plasma concentrations of theophylline. There is an increased risk of convulsions when quinolones are given with NSAIDs or theophylline. There is an increased risk of tendon damage when quinolones are given with corticosteroids. Quinolones are known to increase the QT-interval and should not be taken with concomitantly with other drugs that are known to cause QT-interval prolongation. There is an increased risk of myopathy when erythromycin or clarithromycin are taken with simvastatin or atorvastatin.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 22
Correct
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Which of these cell types in the stomach releases pepsinogen?
Your 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 23
Correct
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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: 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 24
Correct
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An increased anion gap metabolic acidosis is typically caused by which of the following?
Your Answer: Propylene glycol overdose
Explanation:Causes of a raised anion gap acidosis can be remember using the mnemonic MUDPILES:
-Methanol
-Uraemia (in renal failure)
-Diabetic ketoacidosis
-Propylene glycol overdose
-Infection/Iron overdose/Isoniazid/Inborn errors of metabolism
-Lactic acidosis
-Ethylene glycol overdose
-Salicylate overdose -
This question is part of the following fields:
- Physiology
- Renal
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Question 25
Correct
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The fluid in contact with a tube is dragged by frictional forces to the tube's sidewalls. This creates a velocity gradient in which the fluid flow is greatest in the tube's centre.
Which of the following terms most accurately characterizes this flow pattern?Your Answer: Laminar flow
Explanation:The fluid in contact with a tube is dragged by frictional forces at the tube’s sidewalls. This creates a velocity gradient in which the fluid flow is greatest in the tube’s centre.
This is known as laminar flow, and it characterizes the flow in most circulatory and respiratory systems when they are at rest.The velocity of the fluid flow can fluctuate erratically at high velocities, particularly within big arteries and airways, disrupting laminar flow. As a result, resistance increases significantly.
This is known as turbulent flow, and symptoms include heart murmurs and asthmatic wheeze. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 26
Incorrect
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A patient presents with pain in the wrist and a tingling in the hand. On examination Tinel's test is positive and you diagnose carpal tunnel syndrome. Regarding the carpal tunnel, which of the following statements is INCORRECT:
Your Answer: The flexor retinaculum forms the roof of the carpal tunnel.
Correct Answer: The tendons of the flexor digitorum profundus, flexor digitorum superficialis and flexor pollicis longus lie within a single synovial sheath.
Explanation:Free movement of the tendons in the carpal tunnel is facilitated by synovial sheaths, which surround the tendons. All of the tendons of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) are contained within a single synovial sheath with a separate sheath enclosing the tendon of the flexor pollicis longus (FPL).
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 27
Correct
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Regarding carbon dioxide transport in the blood, which of the following statements is CORRECT:
Your Answer: Deoxygenated haemoglobin acts as a buffer for H+ ions.
Explanation:CO2generated in the tissues and water combine to form carbonic acid which readily dissociates to form HCO3-and H+. The first part of this reaction is very slow in plasma, but is accelerated dramatically by the enzyme carbonic anhydrase present in red blood cells. Bicarbonate is therefore formed preferentially in red cells, from which it freely diffuses down its concentration gradient into plasma where it is transported to the lungs. The red cell membrane is impermeable to H+ions which remain in the cell. To maintain electroneutrality, Cl-ions diffuse into the cell to replace HCO3-, an effect known as the chloride shift. Deoxygenated haemoglobin acts as a buffer for H+, allowing the reaction to continue.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 28
Correct
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Which of the following statements is correct with regards to insulin receptors?
Your Answer: Insulin has its intracellular effects via activation of tyrosine kinase.
Explanation:Most cells have insulin receptors present on them which can be sequestered into the cell to inactivate them. These receptors consist of two extracellular alpha subunits which contain the insulin-binding site and two transmembrane beta subunits. Because insulin is a polypeptide hormone, it must act via cell surface receptors as it is unable to readily cross the cell membrane. On binding to the receptor, the beta subunit of insulin autophosphorylation, which activates tyrosine kinase. As a result, there is an intracellular cascade of phosphorylation, causing a translocation of the glucose transporter GLUT4 and GLUT-1 to the plasma membrane of the affected cell. This facilitates glucose entry.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 29
Correct
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You are taking care of a 55-year-old male patient with a direct inguinal hernia. In explaining his hernia, which of the following layers was compromised and had resulted in his condition?
Your Answer: Transversalis fascia
Explanation:Direct inguinal hernias are most often caused by a weakness in the muscles of the abdominal wall that develops over time, or are due to straining or heavy lifting.
A direct inguinal hernia protrudes through the Transversalis fascia.
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This question is part of the following fields:
- Abdomen
- Anatomy
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Question 30
Correct
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The percentage of patients with hepatitis B that develop chronic infection is about:
Your Answer: 10%
Explanation:With hepatitis B, about 90% of people will develop lifelong immunity after clearing the infection. Chronic hepatitis develops in about 10% of patients and this may be complicated by cirrhosis or hepatocellular carcinoma. There is a very high risk of chronic infection and hepatocellular carcinoma when there is congenital infection. The risk of this in healthy adults is only about 5%.
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This question is part of the following fields:
- Microbiology
- Pathogens
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SESSION STATS - PERFORMANCE PER SPECIALTY
