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Question 1
Correct
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A 53 year old women presents to the emergency room with a chronic cough. The pulmonary receptors likely to be involved in causing her cough are:
Your Answer: Irritant receptors
Explanation:Throughout the airways, there are irritant receptors which are located between epithelial cells which are made of rapidly adapting afferent myelinated fibres in the vagus nerve. A cough is as a result of receptor stimulation located in the trachea, hyperpnoea is as a result of receptor stimulation in the lower airway. Stimulation may also result in reflex bronchial and laryngeal constriction. Many factors can stimulate irritant receptors. These include irritant gases, smoke and dust, airway deformation, pulmonary congestion, rapid inflation/deflation and inflammation. Deep augmented breaths or sighs seen every 5 – 20 minutes at rest are due to stimulation of these irritant receptors. This reverses the slow lung collapse that occurs in quiet breathing.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 2
Incorrect
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A 29-year-old volunteer returns from a recent trip to the middle east with profuse watery diarrhoea. You make a diagnosis of cholera and organize a hospital admission for rehydration with intravenous fluids.
What is the mechanism of action of cholera toxin?
Your Answer: Active absorption of NaCl
Correct Answer: ADP-ribosylation of the G regulatory protein
Explanation:Cholera is caused by Vibrio cholerae, a motile, Gram-negative, curved bacillus. It is transmitted through water and food (especially seafood) and is primarily a disease seen in developing countries where there is poor sanitation and lack of safe water supplies.
The cholera toxin leads to stimulation of adenyl cyclase, ADP-ribosylation of the G regulatory protein, inactivation of GTPase leading to active outpouring of NaCl.
The cholera toxin consists of an A (the toxin) and B subunit. The B subunit attaches to the gut mucosa and presents the A subunit to the cell. The toxin stimulates adenyl cyclase by irreversible ADP-ribosylation of the GTP binding domain of adenyl cyclase leading to the opening of chloride channels resulting in an outpouring of NaCl and water into the lumen of the gut and causing secretory diarrhoea.
Incubation period is between 2 and 5 days, but can be as short as just a few hours.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 3
Incorrect
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You're currently treating an infection in a patient and trying to figure out which antibiotic would be best.
Which of the following antimicrobial drugs inhibits the formation of cell walls?Your Answer: Gentamicin
Correct Answer: Cefuroxime
Explanation:Cefuroxime and other cephalosporin antibiotics are bactericidal ß-lactam antibiotics. They work similarly to penicillins in that they prevent cross-linking between the linear peptidoglycan polymer chains that make up the bacterial cell wall. As a result, they prevent the formation of cell walls.
The following is a summary of the various mechanisms of action of various types of antimicrobial agents:1) Inhibition of cell wall synthesis
Penicillins
Cephalosporins
Vancomycin2) Disruption of cell membrane function
Polymyxins
Nystatin
Amphotericin B3) Inhibition of protein synthesis
Macrolides
Aminoglycosides
Tetracyclines
Chloramphenicol4) Inhibition of nucleic acid synthesis
Quinolones
Trimethoprim
5-nitroimidazoles
Rifampicin5) Anti-metabolic activity
Sulphonamides
Isoniazid -
This question is part of the following fields:
- Infections
- Pharmacology
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Question 4
Incorrect
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You've been requested to give a discussion to a group of medical students about cardiovascular physiology. One of them inquires about cardiac output and asks if you can explain it.
Which of the following statements is correct?
Your Answer: An average resting cardiac output in a man is 6 L/min
Correct Answer: An average resting cardiac output in a woman is 5 L/min
Explanation:The terminology cardiac output refers to the amount of blood pumped by the heart in one minute. Women’s rates are around 5 L/min, whereas men’s rates are somewhat higher, around 5.5 L/min.
Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR):
CO = HR x SVAs a result, both stroke volume and heart rate are exactly proportional to cardiac output. There will be an increase in cardiac output if the stroke volume or heart rate increases, and a reduction in cardiac output if the stroke volume or heart rate lowers.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 5
Incorrect
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Among the following microorganisms, which is considered to be transmitted by invasion of intact skin?
Your Answer: Staphylococcus epidermidis
Correct Answer: Leptospira spp.
Explanation:Rodents and domestic animals are the primary reservoirs for the Leptospira spp, although other animals, including cows, horses, mongooses, and frogs, can also harbour the leptospires. Humans may be directly infected from animal urine or indirectly by contact with soil or water that is contaminated with urine from infected animals. Infected humans can shed leptospires in urine for up to 11 months, infected cows for 3.5 months, infected dogs for 4 years, and infected rodents possibly for their entire lifetime.
The organisms enter the host through mucous membranes or abraded skin. The incubation period ranges from 5 to 14 days.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 6
Incorrect
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Regarding inflammatory bowel disease, acute mild to moderate disease of the rectum or rectosigmoid should be treated initially with:
Your Answer: Oral aminosalicylate
Correct Answer: Local aminosalicylate
Explanation:Acute mild to moderate disease affecting the rectum (proctitis) or the rectosigmoid is treated initially with local application of an aminosalicylate; alternatively, a local corticosteroid can be used but it is less effective. A combination of a local aminosalicylate and a local corticosteroid can be used for proctitis that does not respond to a local aminosalicylate alone.
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This question is part of the following fields:
- Gastrointestinal
- Pharmacology
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Question 7
Incorrect
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A 6 year old boy is brought into the ED by his mom with a rash that is associated with Koplik's spots and a diagnosis of measles is made. What advice should be given about returning to school?
Your Answer:
Correct Answer: 4 days from the onset of the rash
Explanation:Prevention of spread of measles is extremely important and infected patients should be isolated. The infectious stage is from 3 days before the rash emerges and patients are advised to stay away from school/nursery/work for 4 days from onset of the rash.
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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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You examine a 48-year-old patient who has had proximal weakness, hypertension, and easy bruising in the past. She exhibits considerable face fullness and truncal obesity on examination. You diagnose her�with Cushing's syndrome.
When would her random cortisol level likely be abnormal?Your Answer:
Correct Answer: 2400 hrs
Explanation:Cortisol levels fluctuate throughout the day, with the greatest levels occurring around 0900 hours and the lowest occurring at 2400 hrs during sleep.
The diurnal swing of cortisol levels is lost in Cushing’s syndrome, and levels are greater throughout the 24-hour period. In the morning, levels may be normal, but they may be high at night-time, when they are generally repressed.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 9
Incorrect
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Swelling of the lips, tongue, and face is observed in a 59-year-old African-American woman. In the emergency room, she is given intramuscular adrenaline, but her symptoms do not improve. Her GP recently started her on a new medication.
Which of the following drugs is most likely to have caused her symptoms?Your Answer:
Correct Answer: Ramipril
Explanation:Angiotensin-converting enzyme (ACE) inhibitors are the most common cause of drug-induced angioedema in the United Kingdom and the United States, owing to their widespread use.
Angioedema is caused by ACE inhibitors in 0.1 to 0.7 percent of patients, with data indicating a persistent and relatively constant risk year after year. People of African descent have a five-fold higher chance of contracting the disease.
Swelling of the lips, tongue, or face is the most common symptom, but another symptom is episodic abdominal pain due to intestinal angioedema. Itching and urticaria are noticeably absent.
The mechanism appears to be activated complement or other pro-inflammatory cytokines like prostaglandins and histamine, which cause rapid vasodilation and oedema.
Other medications that are less frequently linked to angioedema include:
Angiotensin-receptor blockers (ARBs)
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Bupropion (e.g. Zyban and Wellbutrin)
Beta-lactam antibiotics
Statins
Proton pump inhibitorsThe majority of these reactions are minor and can be treated by stopping the drug and prescribing antihistamines.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 10
Incorrect
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At rest, saliva is produced predominantly by which of the following:
Your Answer:
Correct Answer: Submandibular gland
Explanation:At rest, most saliva is produced by the submandibular gland (65%). When stimulated by the autonomic nervous system, about 50% of saliva is produced by the parotid gland with only 30% produced by the submandibular gland.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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