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Question 1
Incorrect
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Pancreatic acinar digestive enzyme secretion is mainly stimulated by which of the following hormones:
Your Answer: Pancreatic polypeptide
Correct Answer: Cholecystokinin
Explanation:Exocrine pancreatic secretion is controlled by:
Parasympathetic stimulation which enhances secretion of both the enzyme and aqueous components
Sympathetic stimulation which inhibits pancreatic secretion
Secretin which stimulates secretion of the alkaline-rich fluid from ductal cells
Cholecystokinin which stimulates secretion of the enzyme-rich fluid from acinar cells
Somatostatin which inhibits secretion from both acinar and ductal cells
Gastrin which stimulates pancreatic acinar cells to secrete digestive enzymes -
This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 2
Incorrect
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A 29-year-old woman with a skin infection not responding to first-line antibiotics return for a review clinic appointment. The result of her culture shows growth of methicillin-resistant Staphylococcus aureus (MRSA).
Which among the following antibiotics is methicillin-resistant Staphylococcus aureus usually sensitive to?Your Answer: Imipenem
Correct Answer: Linezolid
Explanation:Historically, MRSA has been treated successfully with outpatient oral sulphonamides, clindamycin, rifampin, doxycycline, or a combination of these agents. With the development of increasing drug resistance of MRSA to these traditional antimicrobials, there has been a search for more effective antibiotics. One recent study demonstrated that vancomycin, linezolid, and quinupristin-dalfopristin were the most effective antibiotics against multiple strains of MRSA.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 3
Correct
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A 67-year-old man with chronic breathlessness is sent for a lung function test.
Which statement concerning lung function testing is true?Your Answer: In restrictive lung disease, the FEV 1 /FVC ratio is usually >0.7
Explanation:In restrictive lung disease, the FEV1/FVC ratio is usually >0.7%.
In obstructive lung disease, FEV1 is reduced to <80% of normal and FVC is usually reduced. The FEV1/FVC ratio is reduced to <0.7. Airflow obstruction is defined in the NICE guidelines as:
Mild airflow obstruction = an FEV 1 of >80% in the presence of symptoms
Moderate airflow obstruction = FEV 1 of 50-79%
Severe airflow obstruction = FEV 1 of 30-49%
Very severe airflow obstruction = FEV1<30%. Spirometry is a poor predictor of quality of life in COPD. However, it can be used as part of the assessment of severity of COPD. -
This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 4
Correct
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Regarding Clostridium species, which of the following statements is INCORRECT:
Your Answer: They are facultative anaerobes.
Explanation:Clostridium spp. are obligatory anaerobic spore-forming Gram-positive bacilli. Toxin production is the main pathogenicity mechanism.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 5
Correct
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A 67-year-old female presents with a history of morning stiffness and arthritis of her hand joints. She is being investigated for rheumatoid arthritis.
Which test is most sensitive and specific for this diagnosis?
Your Answer: Anti-CCP
Explanation:Anti-cyclic citrullinated peptide (anti-CCP) is an antibody present in 60-80% of rheumatoid arthritis patients. It is measured by enzyme-linked immunosorbent assay (ELISA). It may be present years before the onset of the disease and is associated with a more severe disease course.
While most patients with anti-CCP antibodies are also positive for rheumatoid factor (RF), RF antibody is not specific for rheumatoid arthritis as it can occur in patients with other conditions such as infections and other autoimmune conditions.
ESR, antinuclear antibodies(ANA) and Synovial fluid examination are not specific for rheumatoid arthritis.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 6
Correct
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Which of the following is most true of the sinoatrial node:
Your Answer: Frequency of depolarisation is increased by sympathetic stimulation.
Explanation:Cardiac myocyte contraction is not dependent on an external nerve supply but instead the heart generates its own rhythm, demonstrating inherent rhythmicity. The heartbeat is initiated by spontaneous depolarisation of the sinoatrial node (SAN), a region of specialised myocytes in the right atrium close to the coronary sinus, at a rate of 100-110 beats/min. This intrinsic rhythm is primarily influenced by autonomic nerves, with vagal influences being dominant over sympathetic influences at rest. This vagal tone reduces the resting heart rate down to 60-80 beats/min. To increase heart rate, the autonomic nervous system increases sympathetic outflow to the SAN, with concurrent inhibition of vagal tone. These changes mean the pacemaker potential more rapidly reaches the threshold for action potential generation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 7
Incorrect
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You examine a 79-year-old woman who has had hypertension and atrial fibrillation in the past. Her most recent blood tests show that she has severe renal impairment.
Which medication adjustments should you make in this patient's case?Your Answer: No medication changes are required
Correct Answer: Reduce dose of digoxin
Explanation:Digoxin is excreted through the kidneys, and impaired renal function can lead to elevated digoxin levels and toxicity.
The patient’s digoxin dose should be reduced in this case, and their digoxin level and electrolytes should be closely monitored. -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 8
Correct
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A 25-year-old guy who has had a knee-high plaster cast on his left leg for the past 5 weeks arrives at the emergency department complaining of numbness on the dorsum of his left foot and an inability to dorsiflex or evert his foot. You know that his symptoms are due to fibular nerve compression. Where is the fibular nerve located?
Your Answer: Neck of fibula
Explanation:Dorsiflexion and eversion of the foot are innervated by the deep fibular nerve and the superficial fibular nerve, respectively.
The common fibular nerve runs obliquely downward along the lateral border of the popliteal fossa (medial to the biceps femoris) before branching at the neck of the fibula.
Thus, it is prone to being affected during an impact injury or fracture to the bone or leg. Casts that are placed too high can also compress the fibular nerve.
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 9
Correct
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Regarding the intervertebral disc, which of the following statements is CORRECT:
Your Answer: In L4 - L5 disc herniation, the L5 spinal nerve root is the most commonly affected.
Explanation:A posterolateral herniation of the disc at the L4 – L5 level would be most likely to damage the fifth lumbar nerve root, not the fourth lumbar nerve root, due to more oblique descending of the fifth lumbar nerve root within the subarachnoid space.
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This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 10
Correct
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Which of the following nerves supplies the abductor pollicis brevis?
Your Answer: The recurrent branch of the median nerve
Explanation:Abductor pollicis brevis is innervated by the recurrent (thenar) branch of median nerve (root value C8 and T1).
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 11
Incorrect
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A 19-year-old woman presents with dysuria and vaginal discharge. A swab was taken for culture. Culture results showed the presence of Neisseria gonorrhoeae infection. Treatment of azithromycin and doxycycline was started.
Which of the following statements is considered correct regarding Neisseria gonorrhoeae?Your Answer: Vaginal discharge is present in around 90% of infected women
Correct Answer: Throat swabs can be used for diagnosis
Explanation:Neisseria gonorrhoeae is a Gram-negative diplococcus that causes gonorrhoea. Gonorrhoea is an acute pyogenic infection of nonciliated columnar and transitional epithelium; infection can be established at any site where these cells are found. Gonococcal infections are primarily acquired by sexual contact and occur primarily in the urethra, endocervix, anal canal, pharynx, and conjunctiva.
In men, acute urethritis, usually resulting in purulent discharge and dysuria (painful urination), is the most common manifestation. The endocervix is the most common site of infection in women. Symptoms of infection, when present, include dysuria, cervical discharge, and lower abdominal pain. Some cases in women may be asymptomatic leading to complications such as pelvic inflammatory disease. Blood-borne dissemination occurs in less than 1% of all infections, resulting in purulent arthritis and rarely septicaemia. Fever and a rash on the extremities can also be present. Other conditions associated with N. gonorrhoeae include anorectal and oropharyngeal infections. Infections in these sites are more common in men who have sex with men but can also occur in women.
Pharyngitis is the chief complaint in symptomatic oropharyngeal infections, whereas discharge, rectal pain, or bloody stools may be seen in rectal gonorrhoea. Approximately 30% to 60% of women with genital gonorrhoea have concurrent rectal infection. Newborns can acquire ophthalmia neonatorum, a gonococcal eye infection, during vaginal delivery through an infected birth canal.
Specimens collected for the recovery of N. gonorrhoeae may come from genital sources or from other sites, such as the rectum, pharynx, and joint
fluid. According to the 2010 STD Treatment guidelines, cephalosporins (e.g., ceftriaxone, cefixime) are currently recommended treatments. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 12
Correct
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A patient has a diagnosis of acute osteomyelitis. They have no joint prosthesis on indwelling metal work and no known drug allergies. He has had a recent skin swab that has cultured MRSA and MRSA infection is suspected.
Which of the following antibacterial agents would be most appropriate to prescribe in this case? Select ONE answer only.Your Answer: Vancomycin
Explanation:In the majority of patients the commonest causative organism for osteomyelitis isStaphylococcus aureus.Salmonella spp. are the commonest cause in patients with sickle cell disease.
Other bacteria that can cause osteomyelitis include:
Enterobacter spp.
Group A and B streptococcus
Haemophilus influenzae
The current recommendations by NICE and the BNF on the treatment of osteomyelitis are:
Flucloxacillin first-line
Consider adding fusidic acid or rifampicin for initial 2 weeks
If penicillin allergic use clindamycin
If MRSA is suspected use vancomycin
Suggested duration of treatment is 6 weeks for acute infection -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 13
Correct
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A 33 year old lady with a known nut allergy was having dinner at a Thai restaurant. She suddenly complained of lip and tongue swelling and difficulty breathing and is brought to ED by ambulance with suspected anaphylaxis. She received intramuscular adrenaline in the ambulance.
The most appropriate doses of the second line treatments for anaphylaxis are which of the following?Your Answer: 10 mg chlorphenamine and 200 mg hydrocortisone
Explanation:Second line drugs to reduce the severity and duration of anaphylactic symptoms are intravenous or intramuscular chlorpheniramine and hydrocortisone. The recommended dose is 10 mg chlorpheniramine and 200 mg hydrocortisone in adults.
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This question is part of the following fields:
- Pharmacology
- Respiratory
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Question 14
Correct
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A 29-year-old man has been complaining about his recent headaches. Detailed history was taken and a neurological examination was performed.
Which of the following cranial nerves is correctly paired with its lesion?Your Answer: The oculomotor nerve: the eye appears to look ‘down and out’
Explanation:The following are the lesions of the cranial nerves:
1. Olfactory nerve (I)
Reduced taste and smell, but not to ammonia which stimulates the pain fibres carried in the trigeminal nerve2. Optic nerve (II)
Manifested by visual field defects, pupillary abnormalities, optic neuritis, optic atrophy, papilledema3. Oculomotor nerve (III)
A fixed, dilated pupil which doesn’t accommodate, ptosis, complete internal ophthalmoplegia (masked by ptosis), unopposed lateral rectus causes outward deviation of the eye. If the ocular sympathetic fibres are also affected behind the orbit, the pupil will be fixed but not dilated.4. Trochlear nerve (IV)
Diplopia due to weakness of downward and inward eye movement. The most common cause of a pure vertical diplopia. The patient tends to compensate by tilting the head away from the affected side.5. Trigeminal nerve (V)
Reduced sensation or dysesthesia over the affected area. Weakness of jaw clenching and side-to-side movement. If there is a lower motor neuron (LMN) lesion, the jaw deviates to the weak side when the mouth is opened. There may be fasciculation of temporalis and masseter.6. Abducens nerve (VI)
Inability to look laterally. The eye is deviated medially because of unopposed action of the medial rectus muscle.7. Facial nerve (VII)
Facial weakness. In an LMN lesion the forehead is paralysed – the final common pathway to the muscles is destroyed; whereas the upper facial muscles are partially spared in an upper motor neurone (UMN) lesion because of alternative pathways in the brainstem. There appear to be different pathways for voluntary and emotional movement. CVAs usually weaken voluntary movement, often sparing involuntary movements (e.g., spontaneous smiling). The much rarer selective loss of emotional movement is called mimic paralysis and is usually due to a frontal or thalamic lesion.8. Vestibulocochlear nerve (VIII)
Unilateral sensorineural deafness, tinnitus. Slow-growing lesions seldom present with vestibular symptoms as compensation has time to occur.9. Glossopharyngeal nerve (IX)
Unilateral lesions do not cause any deficit because of bilateral corticobulbar connections. Bilateral lesions result in pseudobulbar palsy. These nerves are closely interlinked.10. Vagus nerve (X)
Palatal weakness can cause ‘nasal speech’ and nasal regurgitation of food. The palate moves asymmetrically when the patient says ‘ahh’. Recurrent nerve palsy results in hoarseness, loss of volume and ‘bovine cough’.11. Accessory nerve (XI)
Weakness and wasting of sternocleidomastoid and trapezius muscles12.Hypoglossal nerve (XII)
An LMN lesion produces wasting of the ipsilateral side of the tongue, with fasciculation; and on attempted protrusion the tongue deviates towards the affected side, but the tongue deviates away from the side of a central lesion. -
This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 15
Correct
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Needle thoracentesis in a patient with a tension pneumothorax is performed at which anatomical landmark?
Your Answer: 4th or 5th intercostal space mid-axillary line
Explanation:Tension pneumothorax is a fatal disease causing acute and severe compromise of patients’ ventilation and circulation, in which case immediate decompression is necessary for better prognosis [6]. A previous study has shown that the incidence of tension pneumothorax varies from 0.2% to 1.7% in patients with prehospital trauma. Several trauma guidelines recommend needle thoracostomy as a life-saving intervention, with placement in the second intercostal space at the midclavicular line (second ICS-MCL), the fourth intercostal space at the anterior axillary line (fourth ICS-AAL), or the fifth intercostal space at the midaxillary line (fifth ICS-MAL) for tension pneumothorax in a prehospital environment.
In 2018, according to newly issued the Advanced Trauma Life Support (ATLS) guidelines, the fifth ICS-MAL was suggested as the preferred place, and an 8 cm needle rather than the common 5 cm needle was proved to increase success rate of adults’ decompression.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 16
Correct
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A 65-year-old man complains of severe vertigo, nausea, and tinnitus. Upon presenting himself to the emergency room, it was observed that he is exhibiting ataxia, right-sided loss of pain and temperature sense on the face, and left-sided sensory loss to the body. An MRI and CT scan was ordered and the results showed that he is suffering from a right-sided stroke.
Branches of which of the following arteries are most likely implicated in the case?Your Answer: Basilar artery
Explanation:The lateral pontine syndrome occurs due to occlusion of perforating branches of the basilar and anterior inferior cerebellar (AICA) arteries. It is also known as Marie-Foix syndrome or Marie-Foix-Alajouanine syndrome. It is considered one of the brainstem stroke syndromes of the lateral aspect of the pons.
It is characterized by ipsilateral limb ataxia, loss of pain and temperature sensation of the face, facial weakness, hearing loss, vertigo and nystagmus, hemiplegia/hemiparesis, and loss of pain and temperature sensation.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 17
Correct
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Question 18
Correct
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The ECG of a patient presenting with a history of intermittent palpitations has a prolonged QT interval.
Which of these can cause prolongation of the QT interval on the ECG?Your Answer: Hypomagnesaemia
Explanation:The causes of a prolonged QT interval include:
Hypomagnesaemia
Hypothermia
Hypokalaemia
Hypocalcaemia
Hypothyroidism
Jervell-Lange-Nielsen syndrome (autosomal dominant)
Romano Ward syndrome (autosomal recessive)
Ischaemic heart disease
Mitral valve prolapse
Rheumatic carditis
Erythromycin
Amiodarone
Quinidine
Tricyclic antidepressants
Terfenadine
Methadone
Procainamide
Sotalol -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 19
Incorrect
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Which of the following is characterised by passive carrier-mediated transport down a chemical concentration gradient:
Your Answer: Osmosis
Correct Answer: Facilitated diffusion
Explanation:Facilitated diffusion is the process of spontaneous passive transport of molecules or ions down their concentration gradient across a cell membrane via specific transmembrane transporter (carrier) proteins. The energy required for conformational changes in the transporter protein is provided by the concentration gradient rather than by metabolic activity.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 20
Correct
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Regarding platelets, which of the following statements is CORRECT:
Your Answer: Platelets are produced in the bone marrow by fragmentation of the cytoplasm of megakaryocytes.
Explanation:Platelets are produced in the bone marrow by fragmentation of the cytoplasm of megakaryocytes, derived from the common myeloid progenitor cell. The time interval from differentiation of the human stem cell to the production of platelets averages 10 days. Thrombopoietin is the major regulator of platelet formation and 95% of this is produced by the liver. The normal platelet count is approximately 150 – 450 x 109/L and the normal platelet lifespan is 10 days. Under normal circumstances, about one-third of the marrow output of platelets may be trapped at any one time in the normal spleen.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 21
Incorrect
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A 38-year-old man returns from an overseas business trip with a fever and a headache. Following investigations a diagnosis of Plasmodium falciparum malaria is made.
Which of the following statements regarding Plasmodium falciparum malaria is true? Select ONE answer only.Your Answer: Sporozoites invade the red blood cells of the host.
Correct Answer: There may be a continuous fever
Explanation:Plasmodium falciparum malaria is transmitted by female of the Anopheles genus of mosquito. The Aedes genus is responsible for transmitting diseases such as dengue fever and yellow fever.
Plasmodium falciparumis found globally but is mainly found in sub-Saharan Africa.
The incubation period of Plasmodium falciparum malaria is 7-14 days.
Sporozoites invade hepatocytes. Within the hepatocyte asexual reproduction occurs producing merozoites, which are released into the blood stream and invade the red blood cells of the host.
Artesunate is the drug treatment of choice for Plasmodium falciparum malaria. Quinine can still be used where artesunate is not available. Often combination therapy with drugs such as doxycycline or fansidar is also required.
The classic symptom of malaria is the malarial paroxysm, a cyclical occurrence of a cold phase, where the patient experiences intense chills, a hot stage, where the patient feels extremely hot and finally a sweating stage, where the fever declines and the patient sweats profusely. There may also, however, be a continuous fever. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 22
Incorrect
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A patient with profuse watery diarrhoea was found to have C. difficile cytotoxin. Which of the following complications is NOT a typical complication of pseudomembranous colitis:
Your Answer: Acute kidney injury
Correct Answer: Volvulus
Explanation:Dehydration, electrolyte imbalance, acute kidney injury secondary to diarrhoea, toxic megacolon, bowel perforation, and sepsis secondary to intestinal infection are all possible complications of pseudomembranous colitis.
When the intestine twists around itself and the mesentery that supports it, an obstruction is created. This condition is known as a volvulus. Volvulus is caused by malrotation and other anatomical factors, as well as postoperative abdominal adhesions, and not by Clostridium difficile infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 23
Correct
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An analytical cohort study is done to compare the relationship between omega 3 intake and occurrence of myocardial infarction (MI) among males aged over 65 years. The following are the data from the study:
No. of subjects taking placebo: 100 men
No. of subjects taking placebo who suffered an MI: 15 men
No. of subjects taking omega 3: 100 men
No. of subjects taking omega 3 who suffered an MI: 5 men
Compute for the relative risk of the study.Your Answer: 0.33
Explanation:Relative risk (RR) is a ratio of the probability of an event occurring in the exposed group versus the probability of the event occurring in the non-exposed group.
RR can be computed as the absolute risk of events in the treatment group (ART), divided by the absolute risk of events in the control group (ARC).
RR = ART/ARC
RR = (5/100) / (15/100)
RR = 0.33 -
This question is part of the following fields:
- Evidence Based Medicine
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Question 24
Incorrect
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A patient is diagnosed with a Klebsiella infection.
Which SINGLE statement regarding Klebsiella infections is true?Your Answer: Klebsiella spp. are usually sensitive to penicillin
Correct Answer: Klebsiella spp are an important cause of ventilator-associated pneumonia
Explanation:Klebsiellais a genus of non-motile,Gram-negative, rod-shaped bacteriawith a prominent polysaccharide-based capsule. They are routinely found in the nose, mouth and gastrointestinal tract as normal flora, however, they can also behave as opportunistic pathogens.
Infections with Klebsiella spp. areusually nosocomial. They are an important cause of ventilator-associated pneumonia (VAP), urinary tract infection, wound infection and bacteraemia. Outbreaks of infections with Klebsiellaspp. in high-dependency units have been described and are associated with septicaemia and high mortality rates. Length of hospital stay and performance of invasive procedures are risk factors forKlebsiellainfections.
Primary pneumonia withKlebsiella pneumoniaeis a rare,severe, community-acquired infection associated with a poor outcome.
Klebsiella rhinoscleromatis causes a progressive granulomatous infection of the nasal passages and surrounding mucous membranes. This infection is mainly seen in the tropics.
Klebsiella ozanae is a recognised cause of chronic bronchiectasis.
Klebsiella organisms are resistant to multiple antibiotics including penicillins. This is thought to be a plasmid-mediated property. Agents with high intrinsic activity againstKlebsiellapneumoniaeshould be selected for severely ill patients. Examples of such agents include third-generation cephalosporins (e.g cefotaxime), carbapenems (e.g. imipenem), aminoglycosides (e.g. gentamicin), and quinolones (e.g. ciprofloxacin). These agents may be used as monotherapy or combination therapy. Aztreonam may be used in patients who are allergic to beta-lactam antibiotics.
Species with ESBLs (Extended spectrum beta-lactamase) are resistant to penicillins and also cephalosporins such as cefotaxime and ceftriaxone
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 25
Correct
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Where in the nephron is most K+reabsorbed:
Your Answer: Proximal tubule
Explanation:Approximately 65 – 70% of filtered K+is reabsorbed in the proximal tubule. Potassium reabsorption is tightly linked to that of sodium and water. The reabsorption of sodium drives that of water, which may carry some potassium with it. The potassium gradient resulting from the reabsorption of water from the tubular lumen drives the paracellular reabsorption of potassium and may be enhanced by the removal of potassium from the paracellular space via the Na+/K+ATPase pump. In the later proximal tubule, the positive potential in the lumen also drives the potassium reabsorption through the paracellular route.
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This question is part of the following fields:
- Physiology
- Renal
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Question 26
Correct
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Which of the following cell types in the stomach secretes histamine?
Your Answer: Enterochromaffin-like cells
Explanation:The parietal cells operate in close association with another type of cell called enterochromaffin-like cells (ECL cells), the primary function of which is to secrete histamine. The ECL cells lie in the deep recesses of the oxyntic glands and therefore release histamine indirect contact with the parietal cells of the glands.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 27
Correct
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A patient with a stab wound to the axilla arrives to the emergency department. You notice weakness in elbow flexion and forearm supination during your assessment. Which of these nerves has been affected:
Your Answer: Musculocutaneous nerve
Explanation:The musculocutaneous nerve is relatively protected in the axilla, hence injury to it is uncommon. A stab wound in the axilla is the most prevalent source of damage. Because of the activities of the pectoralis major and deltoid, the brachioradialis, and the supinator muscles, arm flexion and forearm flexion and supination are diminished but not completely lost. Over the lateral part of the forearm, there is a lack of sensation.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 28
Correct
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Water is reabsorbed in which portion of the Henle loop:
Your Answer: Thin descending limb
Explanation:The loop of Henle consists of three functionally distinct segments: the thin descending segment, the thin ascending segment, and the thick ascending segment. About 20 percent of the filtered water is reabsorbed in the loop of Henle and almost all of this occurs in the thin descending limb. Na+ and Cl-ions are actively reabsorbed from the tubular fluid in the thick ascending limb via the Na+/K+/2Cl-symporter on the apical membrane. Because the thick ascending limb is water-impermeable, ion reabsorption lowers tubular fluid osmolality while raising interstitial fluid osmolality, resulting in an osmotic difference. Water moves passively out of the thin descending limb as the interstitial fluid osmolality rises, concentrating the tubular fluid. This concentrated fluid descends in the opposite direction of fluid returning from the deep medulla still higher osmolality areas.
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This question is part of the following fields:
- Physiology
- Renal
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Question 29
Correct
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You review a 46-year-old woman who has recently been prescribed antibiotics for a urinary tract infection. She suffers from COPD and is currently prescribed salbutamol and Seretide inhalers, and Phyllocontin continus. Since starting the antibiotics, she has been experiencing nausea, vomiting and abdominal pain.
Which of the following antibiotics is she MOST LIKELY to have been prescribed for her UTI? Select ONE answer only .Your Answer: Ciprofloxacin
Explanation:Phyllocontin continus contains aminophylline (a mixture of theophylline and ethylenediamine), a bronchodilator used in the management of COPD and asthma.
This patient is exhibiting symptoms of theophylline toxicity, which may have been triggered by the prescription of the antibiotic. Quinolone antibiotics, such as ciprofloxacin and levofloxacin, and macrolide antibiotics, such as erythromycin, increase the plasma concentration of theophyllines and can lead to toxicity.
The drugs that commonly affect the half-life and the plasma concentration of theophylline are summarised in the table below:
Drugs increasing plasma concentration of theophylline
Drugs decreasing plasma concentration of theophylline
Calcium channel blockers, e.g. Verapamil
Cimetidine
Fluconazole
Macrolides, e.g. erythromycin
Quinolones, e.g. ciprofloxacin
Methotrexate
Barbiturates
Carbamazepine
Phenobarbitol
Phenytoin (and fosphenytoin)
Rifampicin
St. John’s wort -
This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 30
Correct
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A 46-year-old male who is suffering from a chest infection. You decide to start giving the patient antibiotics, however he is allergic to penicillin. You consult with one of your co-workers about the best choice of antibiotic to give.
From the following choices, which is considered an example of bacteriostatic antibiotic?
Your Answer: Trimethoprim
Explanation:Antibiotics that are bactericidal kill bacteria, while antibiotics that are bacteriostatic limit their growth or reproduction. The antibiotics grouped into these two classes are summarized in the table below:
Bactericidal antibiotics
Bacteriostatic antibioticsVancomycin
Metronidazole
Fluoroquinolone, such as ciprofloxacin
Penicillins, such as benzylpenicillin
Cephalosporin, such as ceftriaxone
Co-trimoxazole
Tetracyclines, such as doxycycline
Macrolides, such as erythromycin
Sulphonamides, such as sulfamethoxazole
Clindamycin
Trimethoprim
Chloramphenicol -
This question is part of the following fields:
- Infections
- Pharmacology
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Question 31
Correct
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On which of the following is preload primarily dependent?
Your Answer: End-diastolic volume
Explanation:Preload refers to the initial stretching of the cardiac myocytes before contraction. It is therefore related to muscle sarcomere length. The sarcomere length cannot be determined in the intact heart, and so, other indices of preload are used, like ventricular end-diastolic volume or pressure. The end-diastolic pressure and volume of the ventricles increase when venous return to the heart is increased, and this stretches the sarcomeres, which increase their preload.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 32
Incorrect
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Which of the following is NOT a heritable risk factor for venous thrombosis:
Your Answer: Factor V Leiden
Correct Answer: Von Willebrand disease
Explanation:Approximately one-third of patients who suffer DVT or PE have an identifiable heritable risk factor, although additional risk factors are usually present when they develop the thrombosis. The history of a spontaneous DVT in a close relative increases an individual’s risk of DVT even if no known genetic predisposition can be identified.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 33
Incorrect
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Loop diuretics primarily act on which Na+ transporter?
Your Answer: Na + /Cl - symporter
Correct Answer: Na + /K + /2Cl - symporter
Explanation:The most potent diuretics are loop diuretics e.g. furosemide. They work by inhibiting the Na+/K+/2Cl-symporter in the thick ascending limb of the loop of Henle, which inhibits sodium, potassium, and chloride reabsorption. As a result, there is diuresis with loss of these electrolytes. There is a reduction in transcellular voltage difference, paracellular calcium and magnesium reabsorption.
The medullary interstitium becomes more concentrated by salt reabsorption in the ascending limb. Loop diuretics block this process and reduce the ability of the kidney to concentrate urine. In the collecting duct, there is increased sodium delivery to the principal cells, which increases potassium secretion in return for sodium reabsorption. -
This question is part of the following fields:
- Physiology
- Renal
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Question 34
Correct
-
Intrinsic factor is secreted by which of the following cell types in the stomach:
Your Answer: Parietal cells
Explanation:Intrinsic factor is essential for the absorption of the small amounts of vitamin B12 normally present in the diet from the terminal ileum. The parietal cells of the stomach produce intrinsic factor, and following a gastrectomy, the absorption of vitamin B12 will be markedly reduced, and a deficiency state will exist.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 35
Correct
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A 67-year-old man complains of chest pain and goes to the emergency room. He takes several medications, including amiodarone.
Which of the following is amiodarone mechanism of action?Your Answer: Blocks Na + and K + channels and beta-adrenoreceptors in the heart
Explanation:Amiodarone is an anti-arrhythmic medication that can be used to treat both ventricular and atrial arrhythmias. It’s a class III anti-arrhythmic that works by blocking a variety of channels, including Na+ and K+ channels, as well as beta-adrenoreceptors. As a result, it slows conduction through the SA and AV nodes and prolongs phase 3 of the cardiac action potential (slowing repolarisation).
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 36
Correct
-
Regarding hypernatraemia, which of the following statements is INCORRECT:
Your Answer: In acute severe hypernatraemia, seizures and intracranial vascular haemorrhage can occur as a result of brain cell lysis.
Explanation:Acute severe hypernatraemia is a medical emergency and requires inpatient management in a high dependency setting. Seizures and intracranial vascular haemorrhage as a result of brain cell crenation can occur. The cause is most commonly excessive water loss and the key aspect of treatment is aggressive fluid replacement (typically with normal saline as this is relatively hypotonic). If urine osmolality is low, diabetes insipidus (DI )should be considered and a trial of synthetic ADH given. In patients with known DI, it is essential to ensure synthetic ADH is given parenterally and that close fluid balance is observed.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 37
Incorrect
-
Which of the following is NOT a typical clinical feature of beta-thalassaemia major:
Your Answer: Osteoporosis
Correct Answer: Increased bleeding tendency
Explanation:Features include:
– severe anaemia (becoming apparent at 3 – 6 months when the switch from gamma-chain to beta-chain production takes place)
– failure to thrive
– hepatosplenomegaly (due to excessive red cell destruction, extramedullary haemopoiesis and later due to transfusion related iron overload)
– expansion of bones (due to marrow hyperplasia, resulting in bossing of the skull and cortical thinning with tendency to fracture)
– increased susceptibility to infections (due to anaemia, iron overload, transfusion and splenectomy)
– osteoporosis
– hyperbilirubinaemia and gallstones
– hyperuricaemia and gout
– other features of haemolytic anaemia
– liver damage and other features of iron overload -
This question is part of the following fields:
- Haematology
- Pathology
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Question 38
Correct
-
A patient suffers a stab wound to the neck. The entry point of the blade is situated within the anterior triangle of the neck.
Which of the following muscles is most likely to be involved? Select ONE answer only.Your Answer: Sternothyroid
Explanation:The anterior triangle is the triangular area of the neck found anteriorly to the sternocleidomastoid muscle. It is formed by the anterior border of sternocleidomastoid laterally, the median line of the neck medially and by the inferior border of the mandible superiorly. The apex of the anterior triangle extends towards the manubrium sterni. The anterior triangle contains:
Muscles: thyrohyoid, sternothyroid, sternohyoid muscles
Organs: thyroid gland, parathyroid glands, larynx, trachea, esophagus, submandibular gland, caudal part of the parotid gland
Arteries: superior and inferior thyroid, common carotid, external carotid, internal carotid artery (and sinus), facial, submental, lingual arteries
Veins: anterior jugular veins, internal jugular, common facial, lingual, superior thyroid, middle thyroid veins, facial vein, submental vein, lingual veins
Nerves: vagus nerve (CN X), hypoglossal nerve (CN XII), part of sympathetic trunk, mylohyoid nerveThe posterior triangle is a triangular area found posteriorly to the sternocleidomastoid muscle. It has three borders; anterior, posterior and inferior borders. The anterior border is the posterior margin of the sternocleidomastoid muscle. The posterior border is the anterior margin of the trapezius muscle, while the inferior border is the middle one-third of the clavicle. The investing layer of deep cervical fascia and integument forms the roof of the space, while the floor is covered with the prevertebral fascia along with levator scapulae, splenius capitis and the scalene muscles. The inferior belly of omohyoid subdivides the posterior triangle into a small supraclavicular, and a large occipital, triangle.
Contents:
Vessels: the third part of the subclavian artery, suprascapular and transverse cervical branches of the thyrocervical trunk, external jugular vein, lymph nodes
Nerves: accessory nerve (CN XI), the trunks of the brachial plexus, fibers of the cervical plexus -
This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 39
Incorrect
-
Which of the following is NOT a typical clinical feature of osteomalacia:
Your Answer: Pseudofractures on x-ray
Correct Answer: Hypercalcaemia
Explanation:Features of osteomalacia include:
Bone pain (particularly bone, pelvis, ribs)
Neuromuscular dysfunction (particularly in the gluteal muscles, leading to waddling gait
Pseudofractures on x-ray (looser zones)
Elevated alkaline phosphatase, hypocalcaemia and low phosphate due to secondary hyperparathyroidism -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 40
Correct
-
Liquefactive necrosis is most commonly seen in which of the following conditions:
Your Answer: Ischaemic stroke
Explanation:Liquefactive necrosis results in the loss of all cellular structure and the formation of a soft, semi-solid mass. This is commonly seen in the brain after a cerebral infarction.
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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Question 41
Correct
-
A 70-year-old man has a resting tremor, rigidity, bradykinesia, and a shuffling gait. Parkinson's disease is caused by one of the following mechanisms:
Your Answer: Loss of dopaminergic neurons in the substantia nigra
Explanation:Parkinson’s disease (PD) is one of the most common neurologic disorders, affecting approximately 1% of individuals older than 60 years and causing progressive disability that can be slowed but not halted, by treatment. The 2 major neuropathologic findings in Parkinson’s disease are loss of pigmented dopaminergic neurons of the substantia nigra pars compacta and the presence of Lewy bodies and Lewy neurites. See the images below.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 42
Incorrect
-
Regarding the varicella zoster virus, which of the following statements is CORRECT:
Your Answer: Childhood chickenpox should be treated with oral antiviral medication.
Correct Answer: Contracting chickenpox infection while pregnant is associated with a higher risk of developing varicella pneumonitis.
Explanation:Chickenpox infection in neonates, adults/adolescents and pregnant women is associated with more severe disease. Varicella zoster pneumonitis typically occurs in pregnant women or immunocompromised individuals and is associated with a high mortality. A live attenuated-virus vaccine is available and recommended for non-immune healthcare workers but is not part of the routine childhood immunisation schedule. Antiviral treatment is not typically recommended in childhood chickenpox but is indicated for shingles.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 43
Incorrect
-
The most important Complement protein for antigen opsonization is:
Your Answer: C3a
Correct Answer: C3b
Explanation:Phagocytosis is largely responsible for depletion of cells coated with antibodies. Cells opsonized by IgG antibodies are recognized by phagocyte Fc receptors, which are specific for the Fc portions of some IgG subclasses. In addition, when IgM or IgG antibodies are deposited on the surfaces of cells, they may activate the complement system by the classical pathway. Complement activation generates by-products, mainly C3b and C4b, which are deposited on the surfaces of the cells and recognized by phagocytes that express receptors for these proteins. The net result is phagocytosis of the opsonized cells and their destruction.
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 44
Correct
-
A patient with a high potassium level is at risk of going into cardiac arrest. What changes in the ECG may indicate the incident of cardiac arrest in this patient?
Your Answer: Peaked T waves and broad QRS complex
Explanation:Severe hyperkalaemia can result in a heart attack or a life-threatening arrhythmia.
T waves become narrow-based, pointed, and tall if hyperkalaemia is not treated.
The QRS complex widens and eventually merges with the T wave, resulting in a classic sine-wave electrocardiogram. Ventricular fibrillation and asystole are likely to follow.
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This question is part of the following fields:
- Physiology
- Renal
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Question 45
Incorrect
-
A 20-year-old male patient lives in a travelling community and has never received any vaccinations. He presents to you with fever.
Which of these statements concerning indications and contraindications for vaccination is FALSE?
Your Answer: Live vaccines are contraindicated in pregnancy
Correct Answer: Premature infants should have the their immunisation schedule adjusted for gestational age
Explanation:All vaccines are contraindicated in individuals with:
A confirmed anaphylactic reaction to a previous dose of the vaccine or a vaccine containing the same antigens.
A confirmed anaphylactic reaction to a component in the vaccine e.g. neomycinLive attenuated vaccines are contraindicated in pregnancy except in cases where risk of infection is more than the risks of vaccination.
During times of acute febrile illness, vaccination should be avoided.
12 weeks should elapse after a dose of human immunoglobulin before a live vaccine is administered.
The normal times recommended for immunization of full-term babies should also be applied to premature infants and correction for gestational age should NOT be implemented.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 46
Incorrect
-
Which of the following statements is correct with regards to immunoglobulin?
Your Answer: Only the heavy chain has a variable region, the light chain is constant.
Correct Answer: The isotype of immunoglobulin is determined by the heavy chain.
Explanation:The composition of immunoglobulin molecules is two identical heavy and two identical light chains. These chains are linked by disulphide bridges and are each have highly variable regions which give the immunoglobulin its specificity. In addition, they have constant regions and there is virtual complete correspondence in amino acid sequence in all antibodies of a given isotype.
Five isotypes of immunoglobulin exist – these are IgG, IgA, IgM, IgE and IgD. They are determined by the heavy chain (gamma, alpha, mu, epsilon or delta respectively). The light chains are either kappa or lambda. -
This question is part of the following fields:
- Immune Responses
- Pathology
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Question 47
Correct
-
A 57-year-old male presents to the orthopaedic clinic complaining of pain and swelling in the left knee joint. On examination, the left knee is swollen, tender and erythematous. The patient is booked for joint aspiration, and a diagnosis of pseudogout is made following the aspiration.
Which types of crystals would be seen in the joint aspirate to lead to this diagnosis?Your Answer: Positively birefringent brick-shaped crystals
Explanation:Gout and pseudogout are both characterised by crystal deposition in the affected joints. The deposition of urate crystals causes gout, while calcium pyrophosphate crystals cause pseudogout. The crystals can be distinguished microscopically because urate crystals are negatively birefringent needle-shaped crystals, whilst calcium pyrophosphate crystals are positively birefringent brick-shaped crystals.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 48
Correct
-
A 32-year old male patient has been diagnosed with meningococcal meningitis and was given appropriate treatments. Because he is a family man, he fears that he might transmit the infection to the rest of his family members.
The causative agent of meningococcal meningitis is spread via what mode of transmission?Your Answer: Respiratory droplet route
Explanation:N. meningitidis, the causative agent of meningococcal meningitis, is considered both a commensal and a pathogen. It can be found in the surfaces of mucous membranes such as the nasopharynx and oropharynx. With this, it can be transmitted from a carrier to a new host via respiratory droplet secretions.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 49
Correct
-
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 50
Incorrect
-
An analytical study is conducted to compare the risk of stroke between Ticagrelor therapy and Warfarin therapy among patients with atrial fibrillation. The following is obtained from the study:
No. of patients who took Ticagrelor: 300
No. of patients who took Ticagrelor and suffered a stroke: 30
No. of patients who took Warfarin: 500
No. of patients who took Warfarin and suffered a stroke: 20
Compute for the absolute risk reduction of a stroke, with Warfarin as the standard of treatment.Your Answer: 0.04
Correct Answer: -0.06
Explanation:Absolute risk reduction (ARR) is computed as the difference between the absolute risk in the control group (ARC) and the absolute risk in the treatment group (ART).
Since Warfarin is the standard of treatment, Warfarin is considered as the control group.
ARR = ARC-ART
ARR = (20/500) – (30/300)
ARR = -0.06This means that there is increased risk of stroke in the treatment group, which is the Ticagrelor group.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 51
Correct
-
A 36-year-old woman is 22-weeks pregnant and is investigated for a possible thyroid disorder. When her total thyroid hormone levels does not correlate with her thyrometabolic status, her thyroid-binding globulin levels are checked.
What percentage of circulating thyroid hormones is bound to thyroid-binding globulin?Your Answer: 70%
Explanation:Only a very small fraction of the thyroid hormones circulating in the blood are free. The majority is bound to transport proteins. Only the free thyroid hormones are biologically active, and measurement of total thyroid hormone levels can be misleading.
The relative percentages of bound and unbound thyroid hormones are:
Bound to thyroid-binding globulin -70%
Bound to albumin -15-20%
Bound to transthyretin -10-15%
Free T3 -0.3%
Free T4 -0.03% -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 52
Correct
-
Which of the following best describes the popliteal artery's course?
Your Answer: After exiting the popliteal fossa terminates at the lower border of the popliteus muscle
Explanation:The popliteal artery divides into the anterior and posterior tibial arteries at the lower border of the popliteus after exiting the popliteal fossa between the gastrocnemius and popliteus muscles.
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 53
Correct
-
The most important nerve for plantar flexion of the foot at the ankle joint is:
Your Answer: Tibial nerve
Explanation:Muscles of the posterior compartment of the leg, innervated by the tibial nerve, perform plantar flexion of the foot at the ankle joint. The fibularis longus (innervated by the superficial fibular nerve) assists in plantar flexion but is not the most important.
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 54
Correct
-
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 55
Correct
-
A patient presents with an acute severe asthma attack. Following a poor response to his initial salbutamol nebuliser, you administer a further nebuliser that this time also contains ipratropium bromide.
After what time period would you expect the maximum effect of the ipratropium bromide to occur? Select ONE answer only.Your Answer: 30 -60 minutes
Explanation:Ipratropium bromide is an antimuscarinic drug used in the management of acute asthma and COPD. It can provide short-term relief in chronic asthma, but short-acting β2agonists act more quickly and are preferred.
The BTS guidelines recommend that nebulised ipratropium bromide (0.5 mg 4-6 hourly) can be added to β2agonist treatment for patients with acute severe or life-threatening asthma or those with a poor initial response to β2 agonist therapy.
The aerosol inhalation of ipratropium can be used for short-term relief in mild chronic obstructive pulmonary disease in patients who are not already using a long-acting antimuscarinic drug (e.g. tiotropium).Its maximum effect occurs 30-60 minutes after use; its duration of action is 3-6 hours, and bronchodilation can usually be maintained with treatment three times per day.
The commonest side effect of ipratropium bromide is dry mouth. It can also trigger acute closed-angle glaucoma in susceptible patients. Tremor is commonly seen with β2agonists but not with antimuscarinics. Ipratropium bromide should be used with caution in: Men with prostatic hyperplasia and bladder-outflow obstruction (worsened urinary retention has been reported in elderly men), People with chronic kidney disease (CKD) stages 3 and above (because of the risk of drug toxicity), People with angle-closure glaucoma (nebulised mist of antimuscarinic drugs can precipitate or worsen acute angle-closure glaucoma) -
This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 56
Correct
-
A 14-year-old female is brought to the Emergency Room by her mother after a fall from a tree in which she injured her elbow. An elbow fracture is suspected based on the examination findings, and she is given Entonox for analgesia as her elbow is set in a cast.
Which one of the following statements regarding this drug is true?Your Answer: It can cause inhibition of vitamin B12 synthesis
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:
- Anaesthesia
- Pharmacology
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Question 57
Correct
-
The pelvic bone is formed by which of the following:
Your Answer: Ilium, ischium and pubis
Explanation:Each pelvic bone is formed by three elements: the ilium (superiorly), the pubis (anteroinferiorly) and the ischium (posteroinferiorly).
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This question is part of the following fields:
- Abdomen
- Anatomy
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Question 58
Correct
-
You are calculating the anion gap on a patient with an acid-base disturbance and you find the anion gap to be low. Which of the following is the most likely cause for the low anion gap:
Your Answer: Hypoalbuminaemia
Explanation:A low anion gap is frequently caused by hypoalbuminemia. Albumin is a negatively charged protein and its loss from the serum results in the retention of other negatively charged ions such as chloride and bicarbonate. As bicarbonate and chloride anions are used to calculate the anion gap, there is a subsequent decrease in the gap. The anion gap is sometimes reduced in multiple myeloma, where there is an increase in plasma IgG (paraproteinaemia).
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This question is part of the following fields:
- Physiology
- Renal
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Question 59
Correct
-
In the extrinsic pathway of the coagulation cascade, the tenase complex is:
Your Answer: Factor VIIa-tissue factor complex
Explanation:The extrinsic pathway for initiating the formation of prothrombin activator begins with a traumatized vascular wall or traumatized extravascular tissues that come in contact with the blood. Exposed and activated by vascular injury, with plasma factor VII. The extrinsic tenase complex, factor VIIa-tissue factor complex, activates factor X to factor Xa.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 60
Correct
-
At the start of the cardiac cycle, towards the end of diastole, all of the following statements are true EXCEPT for:
Your Answer: The semilunar valves are open.
Explanation:At the start of the cardiac cycle, towards the end of diastole, the whole of the heart is relaxed. The atrioventricular (AV) valves are open because the atrial pressure is still slightly greater than the ventricular pressure. The semilunar valves are closed, as the pressure in the pulmonary artery and aorta is greater than the ventricular pressures. The cycle starts when the sinoatrial node (SAN) initiates atrial systole.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 61
Incorrect
-
Which of the following microbes adheres to the genital mucosa using fimbriae:
Your Answer: Chlamydia trachomatis
Correct Answer: Neisseria gonorrhoeae
Explanation:Infection of the genital mucosa by Neisseria gonorrhoeae involves attachment to and invasion of epithelial cells. Initial adherence of gonococci to columnar epithelial cells is mediated by type IV pili assembled from pilin subunit PilE proteins and pilus tip-associated PilC proteins, it then invades the epithelial layer, triggering a local acute inflammatory response.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 62
Correct
-
You evaluate a 80-year-old man who has a history of persistent heart failure and discover that he has generalised oedema.
Which of the following claims regarding capillary hydrostatic pressure (P c) is false?Your Answer: P c increases along the length of the capillary, from arteriole to venule
Explanation:The capillary hydrostatic pressure (Pc) is normally between 15 and 30 millimetres of mercury. Pc Decreases along the capillary’s length, mirroring the arteriolar and venule pressures proximally and distally.
Pc is determined by the ratio of arteriolar resistance (RA) to venular resistance (RV).When the RA/RV ratio is high, the pressure drop across the capillary is modest, and Pcis is close to venule pressure.
When the ratio of RA/RV is low, the pressure drop across the capillary is considerable, and Pcis is close to arteriolar pressure.
Pcis closer to the venule pressure and thus more responsive to changes in venous pressure than arteriolar pressure when RA/RV is high.
Pcis the major force behind fluid pushing out of the capillary bed and into the interstitium.
It is also the most variable of the forces affecting fluid transport at the capillary, partly because sympathetic-mediated arteriolar vasoconstriction varies. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 63
Incorrect
-
A 26-year-old woman is currently 9 weeks pregnant. Upon interview and history taking, she mentioned that she visited a friend whose child had just been diagnosed with slapped cheek disease.
If the mother contracts an illness during pregnancy, which among the following is not known to cause fetal abnormalities?Your Answer: Cytomegalovirus
Correct Answer: Hepatitis A
Explanation:Hepatitis A usually doesn’t pose a special risk to a pregnant woman or her baby. Maternal infection doesn’t result in birth defects, and a mother typically doesn’t transmit the infection to her baby. HAV is almost always transmitted by the faecal-oral route and is usually acquired through close personal contact or via contaminated food.
When a woman has chickenpox in the first 20 weeks of pregnancy, there is a 1 in 50 chance for the baby to develop a set of birth defects. This is called the congenital varicella syndrome. It includes scars, defects of muscle and bone, malformed and paralyzed limbs, small head size, blindness, seizures, and intellectual disability.
TORCH Syndrome refers to infection of a developing foetus or newborn by any of a group of infectious agents. “TORCH” is an acronym meaning (T)toxoplasmosis, (O)ther Agents, (R)ubella (also known as German Measles), (C)ytomegalovirus, and (H)erpes Simplex.
Infection with any of these agents may cause a constellation of similar symptoms in affected newborns. These may include fever; difficulties feeding; small areas of bleeding under the skin, causing the appearance of small reddish or purplish spots; enlargement of the liver and spleen (hepatosplenomegaly); yellowish discoloration of the skin, whites of the eyes, and mucous membranes (jaundice); hearing impairment; abnormalities of the eyes; and other symptoms and findings. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 64
Correct
-
You review a 56-year-old man who has recently been prescribed antibiotics for a chest infection. He suffers from COPD and is currently prescribed salbutamol and Seretide inhalers, and Phyllocontin continus. Since starting the antibiotics, he has been experiencing nausea, vomiting and abdominal pain.
Which of the following antibiotics is he MOST LIKELY to have been prescribed for his chest infection? Select ONE answer only .Your Answer: Levofloxacin
Explanation:Phyllocontin continus contains aminophylline (a mixture of theophylline and ethylenediamine), a bronchodilator used in the management of COPD and asthma.
This patient is exhibiting symptoms of theophylline toxicity, which may have been triggered by the prescription of the antibiotic. Quinolone antibiotics, such as ciprofloxacin and levofloxacin, and macrolide antibiotics, such as erythromycin, increase the plasma concentration of theophyllines and can lead to toxicity.
The drugs that commonly affect the half-life and the plasma concentration of theophylline are summarised in the table below:
Drugs increasing plasma concentration of theophylline
Drugs decreasing plasma concentration of theophylline
Calcium channel blockers, e.g. Verapamil
Cimetidine
Fluconazole
Macrolides, e.g. erythromycin
Quinolones, e.g. ciprofloxacin
Methotrexate
Barbiturates
Carbamazepine
Phenobarbitol
Phenytoin (and fosphenytoin)
Rifampicin
St. John’s wort -
This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 65
Correct
-
An 82-year-old woman was brought in an ambulance to the Emergency Department with a 1-hour history of left-sided weakness and dysphasia.
A CT scan is performed, and primary intracerebral haemorrhage is excluded as a possible cause. She is prepared for thrombolysis when her blood pressure is recorded at 200/115 mmHg.
Out of the following, which step would be the most appropriate as the next step in her management?Your Answer: Labetalol 10 mg IV
Explanation:A patient suffering from acute ischemic stroke can commonly present with hypertensive emergencies. Thrombolytic therapy is contraindicated in a patient with:
1. Systolic blood pressure greater than 185 mmHg
2. Diastolic blood pressure greater than 110 mmHgBut delaying thrombolytic therapy is associated with increased morbidity in patients with acute ischemic stroke.
Managing high blood pressure in acute ischemic stroke requires a slower and more controlled reduction in BP. In the presence of an ischaemic stroke, rapid reduction of MAP can compromise blood flow, causing further ischemia and worsening of the neurological deficit.
Intravenous labetalol is the agent of choice. The dose is 10 mg IV over 1-2 minutes. This dose can be repeated, or an infusion can be set up that runs at 2-8 mg/minute. Thrombolysis can be performed once the blood pressure is brought down to less than 180/105 mmHg.
A nitrate infusion (for example, Isoket) can be used as an alternative in patients with contraindications to the use of beta-blockers (e.g., asthma, heart block, cardiac failure).
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 66
Correct
-
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 67
Incorrect
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A 30-year-old woman with type 1 diabetes mellitus is brought in drowsy and confused. Her BM is 2.2 mmol/l and a dose of IM glucagon is administered.
What is the principal stimulus for the secretion of glucagon?Your Answer: Cholecystokinin
Correct Answer: Hypoglycaemia
Explanation:Glucagon, a peptide hormone, is produced and secreted by alpha cells of the islets of Langerhans, located in the endocrine portion of the pancreas.
Its main physiological role is stimulation of hepatic glucose output leading to increase in blood glucose. It is the major counter-regulatory hormone to insulin in maintaining glucose homeostasis.
The principal stimulus for the secretion of glucagon is hypoglycaemia. Hypoglycaemia then stimulates:
Glycogenolysis
Gluconeogenesis
Lipolysis in adipose tissue leading to increased glycaemia.Secretion of glucagon is also stimulated by arginine, alanine, adrenaline, acetylcholine and cholecystokinin
Secretion of glucagon is inhibited by:
Insulin
Somatostatin
Increased free fatty acids
Increased urea production -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 68
Incorrect
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A 33-year-old woman who is investigated for recurrent renal stones is discovered to have a markedly elevated parathyroid hormone (PTH) level.
Which of the following would stimulate PTH release under normal circumstances? Select ONE answer only.Your Answer: Increased plasma calcium concentration
Correct Answer: Decreased plasma calcium concentration
Explanation:Parathyroid hormone (PTH) is a polypeptide containing 84 amino acids. It is the principal controller of free calcium in the body.
PTH is synthesised by and released from the chief cells of the four parathyroid glands that are located immediately behind the thyroid gland.
PTH is released in response to the following stimuli:
Decreased plasma calcium concentration
Increased plasma phosphate concentration (indirectly by binding to plasma calcium and reducing the calcium concentration)
PTH release is inhibited by the following factors:
Normal/increased plasma calcium concentration
Hypomagnesaemia
The main actions of PTH are:
Increases plasma calcium concentration
Decreases plasma phosphate concentration
Increases osteoclastic activity (increasing calcium and phosphate resorption from bone)
Increases renal tubular reabsorption of calcium
Decreases renal phosphate reabsorption
Increases renal conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (via stimulation of 1-alpha hydroxylase)
Increases calcium and phosphate absorption in the small intestine (indirectly via increased 1,25-dihydroxycholecalciferol) -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 69
Correct
-
One of your patients is in resuscitation and is suffering from kidney failure. The intensive care outreach team arrives to assess them and determines that a dopamine infusion is necessary.
Dopamine primarily acts on which of the following receptors at low doses?Your Answer: Dopamine receptors
Explanation:Dopamine is a catecholamine that occurs naturally and is used to treat low cardiac output, septic shock, and renal failure. It is both adrenaline and noradrenaline’s immediate precursor.
Dopamine acts on D1 and D2 dopamine receptors in the renal, mesenteric, and coronary beds at low doses (1-5 g/kg/min). Dopamine causes a significant decrease in renal vascular resistance and an increase in renal blood flow at these doses. Within this dose range, it is also involved in central modulation of behaviour and movement.
Dopamine stimulates beta- and alpha-adrenergic receptors directly and indirectly at higher doses. Beta-stimulation predominates at a rate of 5-10 g/kg/min, resulting in a positive inotropic effect that increases cardiac output and coronary blood flow. Alpha-stimulation predominates at infusion rates greater than 15 g/kg/min, resulting in peripheral vasoconstriction and an increase in venous return and systolic blood pressure.
Below is a summary of the mechanisms and effects of various inotropic agents:
Inotrope
Mechanism
Effects
Adrenaline (epinephrine)
Beta-1 and -2 agonist at increasing doses;
Alpha-agonist at high doses
Increased cardiac output;
Vasoconstriction at higher doses
Noradrenaline (norepinephrine)
Mainly alpha-agonist;
Beta-1 and -2 agonist at increasing doses
Vasoconstriction;
Some increased cardiac output
Dopamine
Dopamine agonist at low doses;
Beta-1 and -2 agonist at increasing doses;
Alpha-agonist at high doses
Increased cardiac output;
Vasoconstriction at higher doses
Dobutamine
Mainly beta-1 agonist
Increased cardiac output -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 70
Correct
-
In adult basic life support, chest compressions should be performed at which of the following rates:
Your Answer: 100 - 120 per minute
Explanation:Chest compressions should be performed at a rate of 100 – 120 per minute.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 71
Correct
-
A 43-year old male is taken to the Emergency Room for a lacerated wound on the abdomen, situated above the umbilicus. A short segment of the small bowel has herniated through the wound.
Which of these anatomic structures is the deepest structure injured in the case above?Your Answer: Transversalis fascia
Explanation:The following structures are the layers of the anterior abdominal wall from the most superficial to the deepest layer:
Skin
Fatty layer of the superficial fascia (Camper’s fascia)
Membranous layer of the superficial fascia (Scarpa’s fascia)
Aponeurosis of the external and internal oblique muscles
Rectus abdominis muscle
Aponeurosis of the internal oblique and transversus abdominis
Fascia transversalis
Extraperitoneal fat
Parietal peritoneum -
This question is part of the following fields:
- Abdomen And Pelvis
- Anatomy
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Question 72
Correct
-
Regarding the heart sounds in the cardiac cycle, which of the following statements is INCORRECT:
Your Answer: The third heart sound is caused by filling of an abnormally stiff ventricle in atrial systole.
Explanation:Heart Sound – Phase of Cardiac Cycle – Mechanical Event:
First heart sound – Start of systole – Caused by closure of the atrioventricular (mitral & tricuspid) valves
Second heart sound – End of systole – Caused by closure of the semilunar (aortic and pulmonary) valves
Third heart sound – Early diastole – Caused by rapid flow of blood from the atria into the ventricles during the ventricular filling phase
Fourth heart sound – Late diastole – Caused by filling of an abnormally stiff ventricle in atrial systole -
This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 73
Correct
-
Following a phone call from the microbiology consultant, you evaluate a patient who has been diagnosed with urinary sepsis. Following the results of the blood cultures, he recommends that you add gentamicin to the patient's antibiotic treatment.
Gentamicin produces its pharmacological effect by binding to which of the following?Your Answer: The 30S subunit of the bacterial ribosome
Explanation:Antibiotics with aminoglycosides, such as gentamicin, bind to the 30S subunit of the bacterial ribosome and prevent aminoacyl-tRNA from binding, preventing protein synthesis.
They also cause mRNA misreading, resulting in the production of non-functional proteins. This last mechanism is unique to aminoglycosides, and it may explain why they are bactericidal rather than bacteriostatic, as other protein synthesis inhibitors are.
Patients with myasthenia gravis should avoid aminoglycosides since they can disrupt neuromuscular transmission. They cross the placenta and are linked to poisoning of the 8th cranial nerve in the foetus, as well as permanent bilateral deafness.
It is possible that they will cause deafness, although this is not a contraindication. In individuals with renal impairment, serum aminoglycoside concentrations should be closely monitored, but this is still not considered a contraindication.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 74
Correct
-
A patient suffers an injury to the nerve that innervates piriformis.
The piriformis muscle is innervated by which of the following nerves? Select ONE answer only.Your Answer: Nerve to piriformis
Explanation:Piriformis is innervated by the nerve to piriformis, which is a direct branch from the sacral plexus (S1 and S2).
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 75
Correct
-
Aplastic crises in sickle cell anaemia is classically precipitated by which of the following infections:
Your Answer: Parvovirus B19
Explanation:A serious complication in sickle cell disease (SCD) is the aplastic crisis. This may be caused by infection with Parvovirus B-19 (B19V). This virus causes fifth disease, a normally benign childhood disorder associated with fever, malaise, and a mild rash. This virus infects RBC progenitors in bone marrow, resulting in impaired cell division for a few days.
Healthy people experience, at most, a slight drop in hematocrit, since the half-life of normal erythrocytes in the circulation is 40-60 days. In people with SCD, however, the RBC lifespan is greatly shortened (usually 10-20 days), and a very rapid drop in Hb occurs. The condition is self-limited, with bone marrow recovery occurring in 7-10 days, followed by brisk reticulocytosis. -
This question is part of the following fields:
- Haematology
- Pathology
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Question 76
Correct
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Question 77
Correct
-
A 28-year-old female patient with a history of hypothyroidism arrives at the Emergency Department after taking 30 of her 200 mcg levothyroxine tablets. She tells you she's 'tired of life' and 'can't take it any longer.' She is currently asymptomatic, and her findings are all within normal limits.
What is the minimum amount of levothyroxine that must be taken before thyrotoxicosis symptoms appear?Your Answer: >10 mg
Explanation:An overdose of levothyroxine can happen by accident or on purpose. Intentional overdosing is sometimes done to lose weight, but it can also happen in patients who are suicidal. The development of thyrotoxicosis, which can lead to excited sympathetic activity and high metabolism syndrome, is the main source of concern. The time between ingestion and the emergence of clinical features associated with an overdose is often quite long.
After a levothyroxine overdose, the majority of patients are asymptomatic. Symptoms and signs are usually only seen in patients who have taken more than 10 mg of levothyroxine in total.
The following are the most commonly seen clinical features in patients developing clinical features:
Tremor
Agitation
Sweating
Insomnia
Headache
Increased body temperature
Increased blood pressure
Diarrhoea and vomiting
Less common clinical features associated with levothyroxine overdose include:
Seizures
Acute psychosis
Thyroid storm
Tachycardia
Arrhythmias
ComaThe continued absorption of the ingested levothyroxine causes a progressive rise in both total serum T4 and total serum T3 levels in the first 24 hours after an overdose. However, in some cases, the biochemical picture is completely normal. Thyroid function tests are not always recommended after a thyroxine overdose. Although elevated thyroxine levels are common, they have little clinical significance and have no impact on treatment. Following a levothyroxine overdose, the following biochemical features are common:
T4 and T3 levels in the blood are elevated.
Free T4 and Free T3 levels are higher.
TSH levels in the blood are low.
If the patient is cooperative and more than 10 mg of levothyroxine has been consumed, activated charcoal can be given (i.e., likely to become symptomatic)
Within an hour of ingestion, the patient presents.The treatment is mostly supportive and aimed at managing the sympathomimetic symptoms that come with levothyroxine overdose. If beta blockers aren’t an option, try propranolol 10-40 mg PO 6 hours or diltiazem 60-180 mg 8 hours.
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This question is part of the following fields:
- Endocrine Pharmacology
- Pharmacology
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Question 78
Correct
-
Approximately how long is the duration of a lidocaine block (when given with adrenaline):
Your Answer: 90 minutes
Explanation:Lidocaine is a tertiary amine that is primarily used as a local anaesthetic but can also be used intravenously in the treatment of ventricular dysrhythmias.
Lidocaine works as a local anaesthetic by diffusing in its uncharged base form through neural sheaths and the axonal membrane to the internal surface of the cell membrane sodium channels. Here it alters signal conduction by blocking the fast voltage-gated sodium channels. With sufficient blockage, the membrane of the postsynaptic neuron will not depolarise and will be unable to transmit an action potential, thereby preventing the transmission of pain signals.
Each 1 ml of plain 1% lidocaine solution contains 10 mg of lidocaine hydrochloride. The maximum safe dose of plain lidocaine is 3 mg/kg. When administered with adrenaline 1:200,000, the maximum safe dose is 7 mg/kg. Because of the risk of vasoconstriction and tissue necrosis, lidocaine should not be used in combination with adrenaline in extremities such as fingers, toes, and the nose.
The half-life of lidocaine is 1.5-2 hours. Its onset of action is rapid within a few minutes, and it has a duration of action of 30-60 minutes when used alone. Its duration of action is prolonged by co-administration with adrenaline (about 90 minutes).
Lidocaine tends to cause vasodilatation when used locally. This is believed to be due mainly to the inhibition of action potentials via sodium channel blocking in vasoconstrictor sympathetic nerves. -
This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 79
Correct
-
Since the fluid that enters the loop of Henle is isotonic, what is its estimated osmolality?
Your Answer: 300 mOsm
Explanation:The loop of Henle connects the proximal tubule to the distal convoluted tubule and lies parallel to the collecting ducts. It is consists of three major segments, the thin descending limb, the thin ascending limb, and the thick ascending limb.
The segments are differentiated based on structure, anatomic location, and function. The main action of the loop of Henle is to recover water and sodium chloride from urine. The liquid entering the loop of Henle is a solution of salt, urea, and other substances traversed along by the proximal convoluted tubule, from which most of the dissolved components are needed by the body, particularly glucose, amino acids, and sodium bicarbonate that have been reabsorbed into the blood.
This fluid is isotonic. Isotonic fluids generally have an osmolality ranging from 270 to 310 mOsm/L. With the fluid that enters the loop of Henle, it is estimated to be 300 mOsm/L. However, after passing the loop, fluid entering the distal tubule is hypotonic to plasma since it has been diluted during its passage.
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This question is part of the following fields:
- Physiology
- Renal Physiology
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Question 80
Correct
-
Which of the following is the most abundant immunoglobulin in plasma:
Your Answer: IgG
Explanation:IgA is the major Ig in secretions, particularly from the gastrointestinal tract (but also in saliva, tears, sweat and breast milk).
IgE is important for mast cell degranulation in allergic and antiparasitic response. In the allergic response, the plasma cell produces IgE-antibodies, which, like antibodies of other immunoglobulin isotypes, are capable of binding a specific allergen via its Fab portion.
IgG is the most abundant in plasma (comprising 80% of normal serum immunoglobulin) and the main circulatory Ig for the secondary immune response. -
This question is part of the following fields:
- Immune Responses
- Pathology
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Question 81
Correct
-
Streptococcus pyogenes is commonly implicated in all of the following infective diseases EXCEPT for:
Your Answer: Gas gangrene
Explanation:Gas gangrene is a life-threatening infection caused by toxin-producing Clostridium species, primarily Clostridium perfringens, and characterised by rapidly progressive muscle necrosis, gas production and sepsis.
Gas gangrene is not a notifiable disease. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 82
Incorrect
-
Which of the following globin chains makes up haemoglobin A2 (HbA2)?
Your Answer: Two alpha and two beta chains
Correct Answer: Two alpha chains and two delta chains
Explanation:Haemoglobin is a 64.4 kd tetramer consisting of two pairs of globin polypeptide chains: one pair of alpha-like chains, and one pair of non-alpha chains. The chains are designated by Greek letters, which are used to describe the particular haemoglobin (e.g., Hb A is alpha2/beta2).
Two copies of the alpha-globin gene (HBA2, HBA1) are located on chromosome 16 along with the embryonic zeta genes (HBZ). There is no substitute for alpha globin in the formation of any of the normal haemoglobins (Hb) following birth (e.g., Hb A, Hb A2, and Hb F). Thus, absence any alpha globin, as seen when all 4 alpha-globin genes are inactive or deleted is incompatible with extrauterine life, except when extraordinary measures are taken.
A homotetramer of only alpha-globin chains is not thought to occur, but in the absence of alpha chains, beta and gamma homotetramers (HbH and Bart’s haemoglobin, respectively) can be found, although they lack cooperativity and function poorly in oxygen transport. The single beta-globin gene (HBB) resides on chromosome 11, within a gene cluster consisting of an embryonic beta-like gene, the epsilon gene (HBE1), the duplicated and nearly identical fetal, or gamma globin genes (HBG2, HBG1), and the poorly expressed delta-globin gene (HBD). A heme group, consisting of a single molecule of protoporphyrin IX co-ordinately bound to a single ferrous (Fe2+) ion, is linked covalently at a specific site to each globin chain. If the iron is oxidized to the ferric state (Fe3+), the protein is called methaemoglobin.
Alpha globin chains contain 141 amino acids (residues) while the beta-like chains contain 146 amino acids. Approximately 75 percent of haemoglobin is in the form of an alpha helix. The non helical stretches permit folding of the polypeptide upon itself. Individual residues can be assigned to one of eight helices (A-H) or to adjacent non helical stretches.
Heme iron is linked covalently to a histidine at the eighth residue of the F helix (His F8), at residue 87 of the alpha chain and residue 92 of the beta chain. Residues that have charged side groups, such as lysine, arginine, and glutamic acid, lie on the surface of the molecule in contact with the surrounding water solvent. Exposure of the hydrophilic (charged) amino acids to the aqueous milieu is an important determinant of the solubility of haemoglobin within the red blood cell and of the prevention of precipitation.
The haemoglobin tetramer is a globular molecule (5.0 x 5.4 x 6.4 nm) with a single axis of symmetry. The polypeptide chains are folded such that the four heme groups lie in clefts on the surface of the molecule equidistant from one another.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 83
Correct
-
A 25-year-old man suffers from a shoulder injury that damaged the nerve that innervates the infraspinatus muscle.
Which of the following nerves may most likely be affected?Your Answer: The suprascapular nerve
Explanation:The suprascapular nerve (C5-C6) innervates the infraspinatus. It originates at the superior trunk of the brachial plexus. It runs laterally across the lateral cervical region to supply the infraspinatus and also the supraspinatus.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 84
Correct
-
A 43-year old male is taken to the Emergency Room for a lacerated wound on the abdomen, situated above the umbilicus. A short segment of the small bowel has herniated through the wound.
Which of these anatomic structures is the most superficial structure injured in the case above?Your Answer: Camper’s fascia
Explanation:The following structures are the layers of the anterior abdominal wall from the most superficial to the deepest layer:
Skin
Fatty layer of the superficial fascia (Camper’s fascia)
Membranous layer of the superficial fascia (Scarpa’s fascia)
Aponeurosis of the external and internal oblique muscles
Rectus abdominis muscle
Aponeurosis of the internal oblique and transversus abdominis
Fascia transversalis
Extraperitoneal fat
Parietal peritoneum -
This question is part of the following fields:
- Abdomen And Pelvis
- Anatomy
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Question 85
Correct
-
Which of these structures is the smallest and deepest component of muscle connective tissue?
Your Answer: Endomysium
Explanation:There are three types of muscle:
Skeletal muscle
Cardiac muscle
Smooth muscleIndividual muscle is enveloped in a layer of dense irregular connective tissue called the epimysium. The epimysium protects the muscles from friction against bones and other muscles.
Skeletal muscle is composed of muscle fibres, referred to as myofibers which is ensheathed by a wispy layer of areolar connective tissue called the endomysium. The endomysium is the smallest and deepest component of muscle connective tissue.
Myofibers grouped together in bundles form fascicles, or fasciculi. These are surrounded by a type of connective tissue called the perimysium.
Beneath the endomysium lies the sarcolemma, an elastic sheath with infoldings that invaginate the interior of the myofibers, particularly at the motor endplate of the neuromuscular junction.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 86
Correct
-
The enzyme protein gastric lipase is responsible for the breakdown of lipids in the stomach.
Which of the following cell types secretes gastric lipase?Your Answer: Chief cells
Explanation:Gastric lipase, commonly known as LIPF, is an acidic lipase released by gastric chief cells, which are found deep within the stomach lining’s mucosal layer. It’s an enzymatic protein that’s in charge of fat digestion in the stomach.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 87
Correct
-
A 36 year old man who is overweight with a history of gout, presents to emergency room with an acutely painful big toe which is red, hot and swollen. However, he is apyrexic and otherwise systemically well. He has been diagnosed with acute gout. The most appropriate first line treatment for him is which of the following?
Your Answer: NSAIDs
Explanation:The first line treatment for acute gout includes NSAIDs like diclofenac, indomethacin or naproxen. In patients in whom NSAIDs are contraindicated, not tolerated or ineffective, colchicine is an alternative. In those who cannot tolerate or who are resistant to NSAIDs and colchicine, oral or parenteral corticosteroids are an effective alternative. In acute monoarticular gout, intra-articular injection of a corticosteroid can be used occasionally. In acute gout. allopurinol is not used in the actual treatment, but its use should be continued during an acute attack if the patient is already established on long term therapy.
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This question is part of the following fields:
- Musculoskeletal
- Pharmacology
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Question 88
Correct
-
Which of the following is the most likely causative organism of acute epiglottitis in a 6 year old?
Your Answer: Streptococcus pneumoniae
Explanation:Since the introduction of the HIB vaccine, most cases of acute epiglottitis are now caused by Streptococcus spp. The condition is now rare in children.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 89
Incorrect
-
Regarding likelihood ratios, which of the following statements is INCORRECT:
Your Answer: Negative likelihood ratio = (1 - sensitivity)/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 90
Incorrect
-
What is the interquartile range of the following data set: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70
Your Answer: 50
Correct Answer: 30
Explanation:5, 10, 15 /20, 25, 30 /35, 40, 45 /50, 60, 70
Sample size (n) = 12
Median = [(n+1)/2]th value
= (12+1)/2 = 6.5
= halfway between 6th and 7th value
= (30 +35)/2 = 32.5
The lower (first) quartile = halfway between 15 and 20
= 17.5
The upper (third) quartile = halfway between 45 and 50
= 47.5
The interquartile range is the difference between the upper quartile and lower quartile
= 47.5 – 17.5 = 30 -
This question is part of the following fields:
- Evidence Based Medicine
- Statistics
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Question 91
Incorrect
-
Which of the following microbes is spread by a vector:
Your Answer: Treponema pallidum
Correct 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 92
Correct
-
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 93
Correct
-
Nifedipine commonly causes which of the following adverse effects?
Your Answer: Ankle oedema
Explanation:Most common adverse effects of Nifedipine include:
Peripheral oedema (10-30%)
Dizziness (23-27%)
Flushing (23-27%)
Headache (10-23%)
Heartburn (11%)
Nausea (11%) -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 94
Correct
-
The term cardiac output refers to the amount of blood pumped by the heart in one minute. The rate in women is around 5 L/min, whereas in men is somewhat higher, around 5.5 L/min.
Which of the equations below best describes cardiac output?
Your Answer: Stroke volume x heart rate
Explanation: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 95
Incorrect
-
An 18-year-old student presents with a 1-week history of sore throat, low grade fever, and malaise. Upon history taking, she noted that she had a fine rash over her body a week ago that quickly fades. Further examination and observation was done and the presence of mild splenomegaly was noted. Her test shows positive for heterophile antibody test, suspecting a diagnosis of infectious mononucleosis.
Which of the following characteristics is mostly associated with the diagnosis of infectious mononucleosis?Your Answer: Pruritic maculopapular rash
Correct Answer: Atypical lymphocytes
Explanation:Epstein-Barr virus causes infectious mononucleosis which is a clinical entity characterized by sore throat, cervical lymph node enlargement, fatigue and fever.
It is accompanied by atypical large peripheral blood lymphocytes. These atypical lymphocytes, also known as Downey cells, are actually activated CD8 T lymphocytes, most of which are responding to EBV-infected cells.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 96
Incorrect
-
A patient is diagnosed as having a glucagonoma. Her blood serum glucagon concentration is 1246 pg/mL.
Glucagon is produced in which of the following cells? Select ONE answer only.Your Answer: G-cells in the stomach
Correct Answer: Alpha-cells in the pancreas
Explanation:Glucagon is a peptide hormone that is produced and secreted by alpha cells of the islets of Langerhans, which are located in the endocrine portion of the pancreas. The main physiological role of glucagon is to stimulate hepatic glucose output, thereby leading to increases in glycaemia. It provides the major counter-regulatory mechanism to insulin in maintaining glucose homeostasis.
Hypoglycaemia is the principal stimulus for the secretion of glucagon but may also be used as an antidote in beta-blocker overdose and in anaphylaxis in patients on beta-blockers that fail to respond to adrenaline.
Glucagon then causes:
Glycogenolysis
Gluconeogenesis
Lipolysis in adipose tissue
The secretion of glucagon is also stimulated by:
Adrenaline
Cholecystokinin
Arginine
Alanine
Acetylcholine
The secretion of glucagon is inhibited by:
Insulin
Somatostatin
Increased free fatty acids
Increased urea productionGlycolysis is the metabolic pathway that converts glucose into pyruvate. The free energy released by this process is used to form ATP and NADH. Glycolysis is inhibited by glucagon, and glycolysis and gluconeogenesis are reciprocally regulated so that when one cell pathway is activated, the other is inactive and vice versa.
Glucagon has a minor effect of enhancing lipolysis in adipose tissue. Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into glycerol and free fatty acids. It makes fatty acids available for oxidation.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 97
Correct
-
A 62-year-old man complains of chest pain and goes to the emergency room. You diagnose him with an acute coronary syndrome and prescribe enoxaparin as part of his treatment plan.
Enoxaparin inactivates which of the following?Your Answer: Thrombin
Explanation:Enoxaparin is a low molecular weight heparin (LMWH) that works in the same way as heparin by binding to and activating the enzyme inhibitor antithrombin III. Antithrombin III inactivates thrombin by forming a 1:1 complex with it. Factor Xa and a few other clotting proteases are also inhibited by the heparin-antithrombin III complex.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 98
Correct
-
A 22-year-old woman comes in with an asthmatic flare. Salbutamol is her only regular medication.
What is the dosage per inhalation of a standard metered dose salbutamol inhaler?Your Answer: 100 micrograms
Explanation:The dose of a conventional metered dose inhaler is 100 micrograms per metered inhalation.
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This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 99
Correct
-
Which of the following statements is correct with regards to heparin-induced thrombocytopaenia (HIT)?
Your Answer: HIT typically develops 5-10 days after starting heparin.
Explanation:Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 (PF4) and heparin. HIT is frequently considered in the differential diagnosis of thrombocytopenia occurring in patients on heparin therapy. HIT is a challenging diagnosis because of routine heparin use in hospitalized patients, the common occurrence of thrombocytopenia. The process of heparin dependent IgG antibodies binding to heparin/platelet factor 4 complexes activates platelets and produces a hypercoagulable state. This syndrome typically develops 5-10 days (range 4-15 days) after heparin is commenced. It can occur with unfractionated heparin, low molecular weight heparin, or, rarely, fondaparinux. The diagnosis of HIT requires the combination of a compatible clinical picture and laboratory confirmation of the presence of heparin dependent platelet activating HIT antibodies. Discontinuation of heparin alone or initiation of a vitamin K antagonist alone like warfarin, is not sufficient to stop the development of thrombosis in patients with acute HIT. If there is moderate clinical suspicion for HIT, all sources of heparin must be discontinued and there must be consideration of anticoagulant treatment with a non-heparin drug.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 100
Correct
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Thiopental sodium is contraindicated in which of the following:
Your Answer: Acute intermittent porphyrias
Explanation:Barbiturates induce hepatic enzymes. The enzyme gamma aminolevulinic acid synthetase, which produces porphyrins, can be induced and in susceptible patients an attack of acute intermittent porphyria can occur. Thiopental is absolutely contraindicated in these patients.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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