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Question 1
Correct
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A 23-year-old has a known diagnosis of HIV. Blood is sent to the laboratory for tests.
AIDS be diagnosed at a CD4 counts below?Your Answer: 200 cells/mm 3
Explanation:A normal CD4 count ranges from 500-1000 cells/mm3.
At CD4 count of less than 350 cells/mm3 treatment with anti-retroviral therapy should be considered.
At a CD4 count of >200 cells/mm3 AIDS is diagnosed.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 2
Correct
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Which statement regarding skeletal muscle is true?
Your Answer: Myosin is the major constituent of the thick filament
Explanation:Myosin is the major constituent of the thick filament.
Actin is the major constituent of the THIN filament.
Thin filaments consist of actin, tropomyosin and troponin in the ratio 7:1:1.
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This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 3
Incorrect
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You've been asked to give a discussion to a group of medical students about skeletal muscle physiology and its use in clinical medicine. They pose a series of difficult questions to you.
Which of the following definitions for the A-band of the sarcomere is correct?
Your Answer: The segment between two neighbouring Z-lines
Correct Answer: A band that contains the entire length of a single thick filament (myosin)
Explanation:Myofibrils, which are around 1 m in diameter, make up each myofiber. The cytoplasm separates them and arranges them in a parallel pattern along the cell’s long axis. These myofibrils are made up of actin and myosin filaments that are repeated in sarcomeres, which are the myofiber’s basic functional units.
Myofilaments are the filaments that make up myofibrils, and they’re made mostly of proteins. Myofilaments are divided into three categories:
Myosin filaments are thick filaments made up mostly of the protein myosin.
Actin filaments are thin filaments made up mostly of the protein actin.
Elastic filaments are mostly made up of the protein titin.
The sarcomere is a Z-line segment that connects two adjacent Z-lines.
The I-bands are thin filament zones that run from either side of the Z-lines to the thick filament’s beginning.
Between the I-bands is the A-band, which spans the length of a single thick filament.
The H-zone is a zone of thick filaments that is not overlaid by thin filaments in the sarcomere’s centre. The H-zone keeps the myosin filaments in place by surrounding them with six actin filaments each.
The M-band (or M-line) is a disc of cross-connecting cytoskeleton elements in the centre of the H-zone.
The thick filament is primarily made up of myosin. The thin filament is primarily made up of actin. Actin, tropomyosin, and troponin are found in a 7:1:1 ratio in thin filaments. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 4
Incorrect
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Which of the following body location is the appropriate site to apply pressure when performing a carotid sinus massage?
Your Answer: Thyrohyoid membrane
Correct Answer: Thyroid cartilage
Explanation:The common carotid artery runs through the neck and divides into internal and external carotid arteries on both sides near the upper thyroid cartilage. In emergency situations, carotid sinus massage is also used to diagnose or treat paroxysmal supraventricular tachycardia.
During the procedure, to maximize access to the carotid artery, the patient is put in a supine position with the neck extended (i.e. elevating the chin away from the chest). The carotid sinus is normally positioned inferior to the angle of the jaw, near the arterial impulse, at the level of the thyroid cartilage. For 5 to 10 seconds, pressure is administered to one carotid sinus.
Although pulsatile pressure applied in a vigorous circular motion may be more effective, continuous pressure is preferred since it is more reproducible. If the predicted reaction is not obtained, the operation is repeated on the opposite side after a one- to two-minute wait.
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This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 5
Correct
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Which of the following nerves provides cutaneous innervation to the posterior surface of the scrotum?
Your Answer: Branch of the perineal nerve
Explanation:The following nerves provide cutaneous innervation to the scrotum, and other anatomic structures:
The perineal nerve supplies the muscles in the urogenital triangle, and the skin on the posterior surface of the scrotum (or labia majora).
The genital branch of the genitofemoral nerve supplies the cremaster muscle, the skin over the anterior surface of the thigh, and the anterolateral surface of the scrotum.
The ilioinguinal nerve supplies the external oblique, internal oblique, transversus abdominis, skin of the upper medial aspect of thigh, the root of the penis and the anterior surface of the scrotum in the male, and the mons pubis and labia majora in the female.
The posterior cutaneous nerve of the thigh, or posterior femoral cutaneous nerve, supplies the skin over the lower medial quadrant of the buttock, the inferior skin of the scrotum or labium majus, and the back of the thigh and the upper part of the leg.
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This question is part of the following fields:
- Abdomen And Pelvis
- Anatomy
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Question 6
Correct
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In which of the following would you NOT typically see a neutropaenia:
Your Answer: Asplenism
Explanation:Causes of neutropaenia:
Drug-induced (e.g. chemotherapy, chloramphenicol, co-trimoxazole, phenytoin, carbamazepine, carbimazole, furosemide, chloroquine, clozapine, some DMARDs)
Benign (racial or familial)
Cyclical
Immune (e.g. SLE, Felty’s syndrome, hypersensitivity and anaphylaxis)
Leukaemia
Infections (e.g. HIV, hepatitis, fulminant bacterial infection)
General Pancytopaenia
Hypersplenism, aplastic anaemia, malignant infiltration of bone marrow, megaloblastic anaemia, chemotherapy, myelodysplasia -
This question is part of the following fields:
- Immune Responses
- Pathology
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Question 7
Correct
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Which of the following statements accurately describes the number needed to harm?
Your Answer: The NNH is the number of patients that need to be treated for one to experience the side effect
Explanation:Number needed to harm (NNH) corresponds to the number of individuals that must be treated, so that one of them presents an adverse reaction accountable to the treatment.
Hence, a NNH of 100 means that 100 individuals need to be treated in order to produce an adverse effect of the treatment in one individual.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 8
Incorrect
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After a work-related accident, a 33-year old male is taken to the emergency room with difficulty in adduction and flexion of his left arm at the glenohumeral joint. The attending physician is suspects involvement of the coracobrachialis muscle.
The nerve injured in the case above is?Your Answer: The upper and lower subscapular nerves
Correct Answer: The musculocutaneous nerve
Explanation:The coracobrachialis muscle is innervated by the musculocutaneous nerve (C5-C7) a branch of the lateral cord of the brachial plexus.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 9
Incorrect
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All of the following are indications for beta-blockers EXCEPT for:
Your Answer: Pheochromocytoma
Correct Answer: Raynaud's disease
Explanation:Beta-blockers are contraindicated in Raynaud’s syndrome.
Beta-blockers may be indicated in:
Hypertension
Pheochromocytoma (only with an alpha-blocker)
Angina
Secondary prevention after ACS
Arrhythmias including atrial fibrillation
Heart failure
Thyrotoxicosis
Anxiety
Prophylaxis of migraine
Essential tremor
Glaucoma -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 10
Incorrect
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Regarding the foetal oxygen-haemoglobin dissociation curve, which of the following statements is CORRECT:
Your Answer: The double Bohr effect means that the oxygen dissociation curves for maternal HbA and foetal HbF move closer together.
Correct Answer: The HbF dissociation curve lies to the left of that for HbA.
Explanation:Foetal haemoglobin (HbF) has a higher affinity for oxygen than adult haemoglobin (HbA) because it’s gamma chains bind 2,3-DPG less avidly than beta chains of HbA. The HbF dissociation curve lies to the left of that for HbA. In the placenta PCO2moves from the foetal to the maternal circulation, shifting the maternal curve further right and the foetal curve further left (the double Bohr effect). The higher affinity of HbF relative to HbA helps transfer oxygen from mother to foetus. Therefore even through blood returning from the placenta to the foetus in the umbilical vein has a PO2of only about 4 kPa, its saturation is 70%. Oxygen transport in the foetus is also helped by a high Hb of about 170 – 180 g/L.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 11
Incorrect
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Regarding water and electrolyte absorption in the small intestine, which of the following statements is INCORRECT:
Your Answer: Na+/K+ ATPase located on the basolateral membrane of the epithelial cells pumps three Na+ ions from the cell in exchange for two K+ ions in.
Correct Answer: Na+ enters the cell across the apical membrane against its concentration gradient by both membrane channels and transporter protein mechanisms.
Explanation:As the contents of the intestine are isotonic with body fluids and mostly have the same concentration of the major electrolytes, their absorption is active. Water cannot be moved directly, but follows osmotic gradients set up by the transport of ions, primarily mediated by the sodium pump.Na+/K+ ATPase located on the basolateral membrane of the epithelial cells pumps three Na+ ions from the cell in exchange for two K+ ions, against their respective concentration gradients. This leads to a low intracellular concentration of Na+ and a high intracellular concentration of K+. The low intracellular concentration of Na+ ensures a movement of Na+ from the intestinal contents into the cell down its concentration gradient by both membrane channels and transporter protein mechanisms. Na+ is then rapidly pumped again by the basolateral sodium pump. K+ leaves the cell across the basolateral membrane down its concentration gradient linked to an outward movement of Cl- against its concentration gradient (Cl- having entered the cell across the luminal membrane down its concentration gradient).
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 12
Incorrect
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Identify the type of graph described below:
A graph that is a useful summary of a set of bivariate data (two variables), usually drawn before working out a linear correlation coefficient or fitting a regression line.Your Answer: Histogram
Correct Answer: Scatterplot
Explanation:A scatterplot is a useful summary of a set of bivariate data (two variables), usually drawn before working out a linear correlation coefficient or fitting a regression line. It gives a good visual picture of the relationship between the two variables, and aids the interpretation of the correlation coefficient or regression model. Each unit contributes one point to the scatterplot, on which points are plotted but not joined. The resulting pattern indicates the type and strength of the relationship between the two variables.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 13
Incorrect
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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: >2 mg
Correct 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 14
Incorrect
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Which of the following statements is correct regarding homeostasis?
Your Answer: Most systems in the body are controlled by positive feedback mechanisms.
Correct Answer: In negative feedback mechanisms, effectors always act to move the variable in the opposite direction to the change that was originally detected.
Explanation:The vast majority of systems within the body work by negative feedback mechanisms. This negative feedback refers to the way that effectors act to move the variable in the opposite direction to the change that was originally detected. Because there is an inherent time delay between detecting a change in a variable and effecting a response, the negative feedback mechanisms cause oscillations in the variable they control. There is a narrow range of values within which a normal physiological function occurs and this is called the ‘set point’. The release of oxytocin in childbirth is an example of positive feedback.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 15
Correct
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The patient is a 61-year-old man with severe central chest pain. An acute myocardial infarction is revealed by his ECG. Clopidogrel is one of the medications he takes as part of his treatment.
Clopidogrel's direct mechanism of action is which of the following?Your Answer: Inhibition of platelet ADP receptors
Explanation:Clopidogrel, a thienopyridine derivative, prevents platelet aggregation and cross-linking by the protein fibrin by inhibiting the ADP receptor on platelet cell membranes (inhibits binding of ADP to its platelet receptor (P2Y12 ADP-receptor).
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 16
Correct
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A 20-year-old asthmatic patient's symptoms is deteriorating and patient is moved to the resuscitation area of the Emergency Department. A loading dose of IV aminophylline is administered and her symptoms begin to improve. You are asked to check her theophylline levels after an appropriate time period.
How long should you wait before taking her blood sample be taken?
Your Answer: 4-6 hours
Explanation:Plasma theophylline concentration is usually measured five days after starting oral treatment and three days after each dose adjustment.
A blood sample to check theophylline concentration should usually be taken after 4-6 hours if an IV dose of aminophylline was given.
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This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 17
Incorrect
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Which of the following pathogens is most commonly implicated in croup:
Your Answer: Respiratory syncytial virus
Correct Answer: Parainfluenza
Explanation:Parainfluenza virus is the most commonly implicated infectious agent in croup.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 18
Incorrect
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Which patients are particularly susceptible to infection with herpes simplex, those with:
Your Answer: Neutropaenia
Correct Answer: T-cell deficiency
Explanation:Cell-mediated immunity, especially the action of cytotoxic T-cells, is essential in the control of herpesvirus infections and patients with T-cell deficiency are at particular risk of reactivation and severe infection. T-cell deficiency may follow HIV infection, chemotherapy, corticosteroid therapy or organ transplantation.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
Correct
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Which of the following is a contraindication to using nitrous oxide:
Your Answer: Raised intracranial pressure
Explanation:Nitrous oxide should not be utilized in patients with an air-containing confined area because it diffuses into these spaces, causing a rise in pressure. This includes circumstances like pneumothorax, intracranial air after a head injury, imprisoned air from a recent undersea dive, a recent intraocular gas injection, or intestinal blockage. Nitrous oxide increases cerebral blood flow and should be avoided in individuals who have or are at risk of having high intracranial pressure.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 20
Correct
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Which of the following diseases is caused by a build-up of lymphoblasts in the bone marrow?
Your Answer: Acute lymphoblastic leukaemia
Explanation:Acute lymphoblastic leukaemia (ALL) is a clonal (malignant) bone marrow disorder in which early lymphoid precursors multiply and replace the marrow’s normal hematopoietic cells. ALL is most common between the ages of 3 and 7, with 75 percent of cases occurring before the age of 6.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 21
Correct
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The 'bucket handle' movement of the thoracic wall describes which of the following movements:
Your Answer: The middles of the shafts of the ribs moving upwards and laterally
Explanation:Because the middles of the shafts of the ribs are lower than either the anterior or posterior end, elevation of the ribs also moves the middles of the shafts laterally. This ‘bucket handle’ upwards and lateral movement increases the lateral dimensions of the thorax.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 22
Correct
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Clostridium difficile primarily causes which of the following infectious diseases:
Your Answer: Pseudomembranous colitis
Explanation:Clostridium difficile causes pseudomembranous colitis, an acute inflammatory diarrhoeal disease and an important cause of morbidity and mortality in hospitals. Gas gangrene is primarily caused by Clostridium perfringens. Tetanus is caused by Clostridium tetani. Toxic shock syndrome may be caused by Staphylococcus aureus or Streptococcus pyogenes. Necrotising fasciitis is most commonly caused by Streptococcus pyogenes but has a multitude of causes.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 23
Incorrect
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Which of the following is true about the extensor carpi radialis longus?
Your Answer: It arises from the medial epicondyle of the humerus
Correct Answer: It assists with abduction of the hand at the wrist
Explanation:The majority of extensor carpi radialis longus originates from the lateral supracondylar ridge of humerus (distal third) and anterior aspect of the lateral intermuscular septum of the arm. A small portion of its fibres originate from the common extensor tendon attached to the lateral epicondyle of humerus. The fibres unite into a muscle belly which extends approximately to the middle of the forearm. The muscle belly is then replaced by a flat tendon that travels distally along the lateral surface of the radius, together with the tendon of extensor carpi radialis brevis. Both tendons course towards the radial styloid process, deep to the tendons of abductor pollicis longus and extensor pollicis brevis muscles. Proximal to the wrist, the tendons of extensor carpi radialis longus and brevis pass behind the radial styloid process within a common synovial sheath and continue along the radial groove deep to the extensor retinaculum of the wrist. At this level, the tendon of extensor carpi radialis longus is crossed by the tendon of extensor pollicis longus, after which it inserts on the posterior aspect of the base of the second metacarpal bone. Some tendon slips can insert into the first and third metacarpal bones.
Extensor carpi radialis longus receives innervation from the radial nerve, with contributions mainly from spinal nerves C5-C8. The radial nerve is a branch of the brachial plexus.
Extensor carpi radialis longus receives blood supply mainly from the radial artery. It directly supplies the distal part of the muscle, while the rest of the muscle receives blood from one of its radial recurrent branches. The brachial artery also supplies a small portion of the muscle via the radial collateral artery.
Extensor carpi radialis longus primarily acts on the wrist joint to produce two major actions: (1) wrist extension by working synergistically with extensor carpi radialis brevis and extensor carpi ulnaris, and (2) hand abduction (radial deviation), with the help of flexor carpi radialis.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 24
Incorrect
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A 24-year-old athlete drinks a 500 ml hypertonic sports drink before an endurance event he participates in.
Which of the following effects will this cause?Your Answer: The intracellular fluid becomes more dilute
Correct Answer: The interstitial fluid becomes more concentrated
Explanation:Osmosis is the passive movement of water across a semipermeable membrane from a region of low solute concentration to a region of higher solute concentration.
When hypertonic fluid is ingested:
The plasma becomes CONCENTRATED.The cells lose water and shrink
The intracellular fluid becomes more concentrated.
Water and ions move freely from the plasma into the interstitial fluid and the interstitial fluid becomes more concentrated.
The increased osmotic potential draws water out of the cells. -
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
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Question 25
Incorrect
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Regarding ciprofloxacin, which of the following statements is INCORRECT:
Your Answer: Ciprofloxacin is particularly active against Gram-negative bacteria.
Correct Answer: Ciprofloxacin decreases plasma concentrations of theophylline.
Explanation:Ciprofloxacin increases plasma concentrations of theophylline. There is an increased risk of convulsions when quinolones are given with NSAIDs or theophylline. There is an increased risk of tendon damage when quinolones are given with corticosteroids. Quinolones are known to increase the QT-interval and should not be taken with concomitantly with other drugs that are known to cause QT-interval prolongation. There is an increased risk of myopathy when erythromycin or clarithromycin are taken with simvastatin or atorvastatin.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 26
Incorrect
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Which of the following is NOT a heritable risk factor for venous thrombosis:
Your Answer: Antithrombin Deficiency
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 27
Incorrect
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Regarding renal clearance, which of the following statements is CORRECT:
Your Answer: Clearance is defined as the volume of urine that is cleared of a substance per unit time.
Correct Answer: The MDRD equation uses plasma creatinine to estimate the GFR making an adjustment for age, sex and race.
Explanation:Clearance is defined as the volume of plasma that is cleared of a substance per unit time. Inulin clearance is the gold standard for measurement of GFR but creatinine clearance is typically used instead. Creatinine is freely filtered and not reabsorbed, but there is a little creatinine tubular secretion. In practice, GFR is usually estimated from the plasma creatinine using a formula e.g. the MDRD equation making an adjustment for age, sex and race.
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This question is part of the following fields:
- Physiology
- Renal
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Question 28
Incorrect
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Which of the following statements is considered correct regarding Klebsiella infections?
Your Answer: Klebsiella pneumoniae is most commonly associated with chronic bronchiectasis
Correct Answer: Klebsiella spp. are non-motile
Explanation:Klebsiella is a Gram-negative, rod-shaped, non-motile bacteria. The absence of motility distinguishes Klebsiella spp. from most other members of the family Enterobacteriaceae.
K. pneumoniae is the most commonly isolated species and has the distinct feature of possessing a large polysaccharide capsule. The capsule offers the organism protection against phagocytosis and antimicrobial absorption,
contributing to its virulence.Colonization of gram-negative bacilli in the respiratory tracts of hospitalized patients, particularly by K. pneumoniae, increases with the length of hospital stay. It is a frequent cause of lower respiratory tract infections among hospitalized patients and in immunocompromised hosts such as newborns,
elderly patients, and seriously ill patients on respirators. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 29
Correct
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Which of the following medications can block the effect of adrenaline?
Your Answer: Beta-blockers
Explanation:Beta-blockers may reduce the response to adrenaline in the treatment of anaphylactic reactions.
Noncardioselective beta-blockers in particular can antagonize the broncho dilating and cardio stimulatory effects of adrenaline by blocking beta-2 adrenergic receptors in the smooth muscles of the bronchial tree and in the heart muscles.
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This question is part of the following fields:
- Pharmacology
- Respiratory
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Question 30
Correct
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A thyroid function test is done for a 55-year-old woman with non-specific symptoms, the results are shown below:
TSH = 5.2
Free T4 is normal
Free T3 is normal
The most likely diagnosis in this patient is?
Your Answer: Subclinical hypothyroidism
Explanation:Hypothyroidism is diagnosed using the results of thyroid function tests (TFTs).
In the early stages of the disease, the earliest biochemical change noticed is a rise in thyroid-stimulating hormone (TSH) levels. Free triiodothyronine (T3) and thyroxine (T4) levels are usually normal.
In primary hypothyroidism, the serum TSH level is usually greater than 10 mU/L, and free T4 levels are below the reference range.
Subclinical hypothyroidism is diagnosed when the serum TSH level is above the reference range, and the free T4 levels are within the reference range. The test should, however, be repeated after 3-6 months to exclude transient causes of raised TSH.
In summary, how to interpret TFTs in cases of suspected hypothyroidism is shown below:
Subclinical hypothyroidism
TSH is raised
Free T4 is normal
Free T3 is normalPrimary hypothyroidism
TSH is raised
Free T4 is lowered
Free T3 is lowered or normalSecondary hypothyroidism
TSH is lowered or normal
Free T4 is lowered
Free T3 is lowered or normal -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 31
Correct
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A patient has a cardiac output of 4.8 L/min and a heart rate of 80 bpm, therefore their stroke volume is:
Your Answer: 60 mL
Explanation:Cardiac output (CO) = Stroke volume (SV) x Heart rate (HR).
Therefore SV = CO/HR
= 4.8/80
= 0.06 L = 60 mL. -
This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 32
Correct
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Thyroid cancer has spread to the regional lymph nodes of a patient as seen in a staging CT scan.
The lymph from the thyroid gland will drain directly to which of the following nodes?Your Answer: Deep lateral cervical lymph nodes
Explanation:Lymphatic drainage of the thyroid gland involves the lower deep cervical, prelaryngeal, pretracheal, and paratracheal nodes. The paratracheal and lower deep cervical nodes, specifically, receive lymphatic drainage from the isthmus and the inferior lateral lobes. The superior portions of the thyroid gland drain into the superior pretracheal and cervical nodes.
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This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 33
Correct
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A patient presents with a rash for a dermatological examination. A flat circumscribed area of discoloured skin measuring 0.7 cm in diameter is seen on examination.
What is the best description of this rash that you have found on examination?
Your Answer: Macule
Explanation:A macule is a flat, well circumscribed area of discoloured skin less than 1 cm in diameter with no changes in the thickness or texture of the skin.
A vesicle is a visible collection of clear fluid measuring less than 0.5 cm in diameter.
A papule is a solid, well circumscribed, skin elevation measuring less than 0.5 cm in diameter.
A nodule is a solid, well circumscribed, raised area that lies in or under the skin and measures greater than 0.5 cm in diameter. They are usually painless.
A plaque is a palpable skin lesion that is elevated and measures >1cm in diameter.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 34
Incorrect
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A man working as a waiter cuts his arm on a glass while he was working. The palmaris longus muscle was damaged as a consequence of his injury.
Which of the following statements regarding the palmaris longus muscle is considered correct?Your Answer: It arises from the lateral epicondyle of the humerus
Correct Answer: It receives its blood supply from the ulnar artery
Explanation:The palmaris longus is a small, fusiform-shaped muscle located on the anterior forearm of the human upper extremity. The palmaris longus muscle is commonly present but may be absent in a small percentage of the population, ranging from 2.5% to 26% of individuals, depending on the studied population.
The palmaris longus belongs to the anterior forearm flexor group in the human upper extremity. The muscle attaches proximally to the medial humeral epicondyle and distally to the palmar aponeurosis and flexor retinaculum. The blood supply to the palmaris longus muscle is via the ulnar artery, a branch of the brachial artery in the human upper extremity.
The palmaris longus muscle receives its innervation via branches of the median nerve containing nerve roots C5-T1. Median nerve injury at or above the elbow joint (including brachial plexus and nerve root injury) can lead to deficits in the palmaris longus and other forearm flexor muscles, leading to weakened elbow flexion, wrist flexion, radial deviation, finger flexion, thumb opposition, flexion, and abduction, in addition to the loss of sensory function in the distribution of the median nerve.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 35
Correct
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A 28-year-old woman in her second trimester is diagnosed with a psychiatric illness. She is started on treatment with a drug. The treatment results in her baby being born with poor tone, feeding problems, hypothyroidism, and a goitre
Out of the following, which drug is most likely responsible for the baby's condition?Your Answer: Lithium
Explanation:In pregnancy and postpartum, lithium is an effective treatment for relapse prevention in bipolar disorder. However, lithium has also been associated with risks during pregnancy for both the mother and the unborn child. Recent large studies have confirmed the association between first-trimester lithium exposure and an increased risk of congenital malformations.
Lithium levels need to be monitored more frequently throughout pregnancy and the postnatal period.
If given in the 1st-trimester, lithium is associated with a risk of fetal cardiac malformations, such as Ebstein’s anomaly.
If given in the 2nd and 3rd-trimesters, there is a risk of the following:
1. hypotonia
2. lethargy
3. feeding problems
4. hypothyroidism
5. goitre
6. nephrogenic diabetes insipidus in the neonate -
This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 36
Correct
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A 50-year-old woman has an anaphylactic reaction following accidental ingestion peanuts at a restaurant. She is a known hypertensive on atenolol 50 mg daily and BP is well controlled. She is also on amlodipine 5 mg daily. Two doses of IM adrenaline has been given without improvement.
Which medication may prove helpful in this patient?
Your Answer: IM Glucagon
Explanation:Resistant to the effects of adrenaline in anaphylaxis is seen in patients taking beta-blockers.
Glucagon can be used to overcome the effects of the beta-blockade if initial doses of adrenaline are unsuccessful in patients taking beta-blockers.
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This question is part of the following fields:
- Pharmacology
- Respiratory Pharmacology
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Question 37
Correct
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A patient who has a nerve injury has sparing of the upper half of the orbicularis oculi muscle but not the lower half. Which branch of the facial nerve supplies the lower half of the orbicularis oculi?
Your Answer: Zygomatic branch
Explanation:The facial nerve divides into five terminal branches once in the parotid gland.
1. The temporal branch innervates muscles in the temple, forehead and supraorbital areas.
2. The zygomatic branch innervates muscles in the infraorbital area, the lateral nasal area and the upper lip.
3. The buccal branch innervates muscles in the cheek, the upper lip and the corner of the mouth.
4. The marginal mandibular branch innervates muscles of the lower lip and chin.
5. The cervical branch innervates the platysma muscle. -
This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 38
Incorrect
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The following are all examples of type II hypersensitivity EXCEPT for:
Your Answer: Rheumatic heart disease
Correct Answer: Post-streptococcal glomerulonephritis
Explanation:Examples of type II reactions include:
Incompatible blood transfusions
Haemolytic disease of the newborn
Autoimmune haemolytic anaemias
Goodpasture’s syndrome
Rheumatic heart disease
Bullous pemphigoid -
This question is part of the following fields:
- Immune Responses
- Pathology
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Question 39
Incorrect
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Regarding fat digestion, which of the following statements is CORRECT:
Your Answer: Bilirubin in bile emulsifies fat to increase surface area for enzymatic digestion by pancreatic lipase.
Correct Answer: Chylomicrons consist of a cholesterol and triglyceride core with a phospholipid coat studded with apolipoproteins.
Explanation:Dietary fat is chiefly composed of triglycerides. In the duodenum fat is emulsified by bile acids, a process where larger lipid droplets are broken down into much smaller droplets providing a greater surface area for enzymatic digestion. Once inside the epithelial cell, lipid is taken into the smooth endoplasmic reticulum where much of it is re esterified. Dietary and synthesised lipids are then incorporated into chylomicrons in the Golgi body, which are exocytosed from the basolateral membrane to enter lacteals. Chylomicrons consist mainly of triglyceride with small amounts of cholesterol and cholesteryl esters in the centre with a phospholipid coat studded with apolipoproteins. Fat-soluble are absorbed into enterocytes from micelles by simple diffusion together with the products of fat digestion.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 40
Incorrect
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Depolarisation of a neuron begins with which of the following:
Your Answer: Closing of ligand-gated Na + channels
Correct Answer: Opening of ligand-gated Na + channels
Explanation:Action potentials are initiated in nerves by activation of ligand-gated Na+channels by neurotransmitters. Opening of these Na+channels results in a small influx of sodium and depolarisation of the negative resting membrane potential (-70 mV). If the stimulus is sufficiently strong, the resting membrane depolarises enough to reach threshold potential (generally around -55 mV), at which point an action potential can occur. Voltage-gated Na+channels open, causing further depolarisation and activating more voltage-gated Na+channels and there is a sudden and massive sodium influx, driving the cell membrane potential to about +40 mV.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 41
Correct
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Which of the following is a contraindication for aspirin?
Your Answer: Children under 16 years
Explanation:Aspirin contraindications include: hypersensitivity to NSAIDs; asthma, rhinitis, and nasal polyps; and usage in children or teens.
There is little evidence of allergic cross-reactivity for salicylates. However, due to similarities in chemical structure and/or pharmacologic activities, the possibility of cross-sensitivity cannot be completely ruled out. -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 42
Correct
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Regarding the accessory nerve, which of the following statements is INCORRECT:
Your Answer: Accessory nerve palsy results in the inability to nod the head
Explanation:Accessory nerve palsy results in inability to shrug the shoulders and to rotate the head to look at the opposite side to the lesion.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 43
Correct
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The QRS duration of a broad-complex tachyarrhythmia is:
Your Answer: Greater than or equal to 0.12 s
Explanation:It’s a broad-complex tachycardia if the QRS duration is 0.12 seconds or more. It’s a narrow-complex tachycardia if the QRS complex is shorter than 0.12 seconds. The QRS duration should be examined if the patient with tachyarrhythmia is stable.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 44
Correct
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A 29-year-old male presents with a 3-day history of bloody diarrhoea and abdominal pain.
All the following are causes of infectious bloody diarrhoea EXCEPT?
Your Answer: Enterotoxigenic Escherichia coli
Explanation:Infective causes of bloody diarrhoea include:
Salmonella spp
Campylobacter spp
Schistosomiasis
Entamoeba histolytica (Amoebiasis )
Shigella spp
Clostridium difficile
Yersinia spp
Enteroinvasive Escherichia coliEnterotoxigenic Escherichia coli is non-invasive and does not cause inflammation of the gut and bloody diarrhoea. It presents with copious watery diarrhoea and usually are not associated with abdominal cramping.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 45
Correct
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Which of the following statements is not true regarding ion channels?
Your Answer: Ion channels provide a charged, hydrophobic pore through which ions can diffuse across the lipid bilayer.
Explanation:Ion channels are pore-forming protein complexes that facilitate the flow of ions across the hydrophobic core of cell membranes. They are present in the plasma membrane and membranes of intracellular organelles of all cells, and perform essential physiological functions. They provide a charged, hydrophilic pore through which ions can move across the lipid bilayer. They are selective for particular ions and their pores may be opened or closed. Because of this ability to open and close, ion channels allow the cell to have the ability to closely control the movement of ions across the membrane. Gating refers to the transition between an open and closed ion channel state, and is brought about by a conformationational change in the protein subunits that open or close the ion-permeable pore.
Ion channels can be:
1. voltage-gated these are regulated according to the potential difference across the cell membrane or
2. ligand-gated – these are regulated by the presence of a specific signal molecule. -
This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 46
Correct
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You are teaching a group of medical students about cardiovascular examination. You are discussing heart sounds and the cardiac cycle. Which of the following stages of the cardiac cycle occurs immediately after the aortic valve closes:
Your Answer: Isovolumetric relaxation
Explanation:Immediately after the closure of the semilunar valves, the ventricles rapidly relax and ventricular pressure decreases rapidly but the AV valves remain closed as initially the ventricular pressure is still greater than atrial pressure. This is isovolumetric relaxation. Atrial pressure continues to rise because of venous return, with the v wave of the JVP waveform peaking during this phase. Rapid flow of blood from the atria into the ventricles during the ventricular filling phase causes thethird heart sound, which is normal in children but, in adults, is associated with disease such as ventricular dilation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 47
Correct
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Identify the type of graph described below:
A graph wherein the frequency distribution is represented by adjoining vertical bars and cases are stacked in adjoining columns. It can be used for continuous quantitative data, such as to analyse outbreak data to show an epidemic curve.Your Answer: Histogram
Explanation:A histogram is used to demonstrate the distribution of continuous quantitative data. It is a very familiar graphical display device for representing the distribution of a single batch of data. The range of the data is divided into class intervals or bins, and the number of values falling into each interval is counted. The histogram then consists of a series of rectangles whose widths are defined by the class limits implied by the binwidths, and whose heights depend on the number of values in each bin. Histograms quickly reveal such attributes of the data distribution as location, spread, and symmetry. If the data are multimodal (i.e., more than one “hump” in the distribution of the data), this is quickly evident as well.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 48
Correct
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Antidiuretic hormone (ADH) is synthesised by which of the following:
Your Answer: Hypothalamus
Explanation:Antidiuretic hormone is synthesised in the hypothalamus and transported to the posterior pituitary within nerve fibres where it is stored in secretory granules. ADH binds V2 receptors on renal principal cells in the late distal tubule and collecting ducts, raising cAMP levels and causing intracellular vesicles to fuse with the apical membrane. In their membrane these vesicles have water channels called aquaporins, which increase the water permeability allowing greater water reabsorption and concentration of urine. Excess levels of ADH results in syndrome of inappropriate ADH secretion (SIADH) characterised by hyponatremia with concomitant hypo-osmolality and high urine osmolality.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 49
Correct
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Campylobacter jejuni is primarily spread via which of the following routes:
Your Answer: Faecal-oral route
Explanation:Campylobacter spp. are a common cause of acute infective gastroenteritis, particularly in children, with Campylobacter jejuni responsible for 90% of Campylobacter gastroenteritis. Infection typically follows ingestion of contaminated meat (most frequently undercooked poultry), unpasteurised milk or contaminated water, following which the microorganism invades and colonises the mucosa of the small intestine.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 50
Incorrect
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An 80-year-old woman with history of hypertension, diabetes, and ischemic stroke, presents with left-sided hemiplegia of the face, tongue, and limbs and right-sided deficits in motor eye activity. A CT scan was ordered and showed a right-sided stroke.
Branches of which of the following arteries are most likely implicated in the case?Your Answer: Vertebral artery
Correct Answer: Basilar artery
Explanation:Weber syndrome is a midbrain stroke characterized by crossed hemiplegia along with oculomotor nerve deficits and it occurs with the occlusion of the median and/or paramedian perforating branches of the basilar artery.
Typical clinical findings include ipsilateral CN III palsy, ptosis, and mydriasis (such as damage to parasympathetic fibres of CN III) with contralateral hemiplegia.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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SESSION STATS - PERFORMANCE PER SPECIALTY
