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Question 1
Correct
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Which of the following best describes the mechanism of action of aspirin:
Your Answer: Cyclo-oxygenase (COX) inhibitor
Explanation:Aspirin is a non-steroidal anti-inflammatory drug (NSAID). Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes and the resulting inhibition of prostaglandin synthesis results in analgesic, antipyretic and to a lesser extent anti-inflammatory actions.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 2
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 3
Correct
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A blood transfusion is given to a 52-year-old woman. She develops chills and rigours shortly after the transfusion begins.
The following are her observations: Temperature 40°C, HR 116 bpm, BP 80/48, SaO 2 97 percent on air.
Which of the following treatments is the most appropriate?Your Answer: Stop the transfusion and administer antibiotics
Explanation:Bacterial infections are common in the following situations:
Platelet transfusions are associated with a higher risk of bacterial infection (as platelets are stored at room temperature)
Immersion in a water bath thawed previously frozen components.
Components of red blood cells that have been stored for several weeks
Gram-positive and Gram-negative bacteria have both been linked to transfusion-transmitted bacterial infection, but Gram-negative bacteria are linked to a higher rate of morbidity and mortality.
Yersinia enterocolitica is the most common bacterial organism linked to transfusion-transmitted bacterial infection. This organism can multiply at low temperatures while also utilising iron as a nutrient. As a result, it’s well-suited to proliferating in blood banks.The following are some of the most common clinical signs and symptoms of a bacterial infection transmitted through a blood transfusion. These symptoms usually appear shortly after the transfusion begins:
Fever is very high.
Rigours and chills
Vomiting and nausea
Tachycardia
Hypotension
Collapse of the circulatory systemIf a bacterial infection from a transfusion is suspected, the transfusion should be stopped right away. Blood cultures and a Gram stain should be requested, as well as broad-spectrum antibiotics. In addition, the blood pack should be returned to the blood bank for an urgent culture and Gram-stain.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 4
Incorrect
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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: No significant abnormality detected
Correct 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 5
Incorrect
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What is the interquartile range of the following data set: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70
Your Answer: 20
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 =Â 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 6
Correct
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Which of the following comprises a negative feedback mechanism?
Your Answer: Detectors, comparators, a variable set point and effectors
Explanation:Negative feedback loops, also known as inhibitory loops, play a crucial role in controlling human health. It is a self-regulating mechanism of some sort.
A negative feedback system is made up of three main components: a detector (often neural receptor cells) that measures the variable in question and provides input to the comparator; a comparator (usually a neural assembly in the central nervous system) that receives input from the detector, compares the variable to the variable set point, and determines whether or not a response is required.
The comparator activates an effector (typically muscular or glandular tissue) to conduct the appropriate reaction to return the variable to its set point.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 7
Incorrect
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Fusidic acid is primarily indicated for infections caused by which of the following microorganisms:
Your Answer: Pneumococcal infections
Correct Answer: Staphylococcal infections
Explanation:Fusidic acid is a narrow spectrum antibiotic used for staphylococcal infections, primarily topically for minor staphylococcal skin (impetigo) or eye infection. It is sometimes used orally for penicillin-resistant staphylococcal infection, including osteomyelitis or endocarditis, in combination with other antibacterials.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 8
Correct
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A 49-year-old man known sickle cell disease patient received a blood transfusion and developed a mild fever and dark urine 6 days after transfusion. His investigations show raised bilirubin, raised LDH, and a positive Direct Antiglobulin Test (DAT).
Which transfusion reaction is most likely occurred?Your Answer: Delayed haemolytic reaction
Explanation:Delayed haemolytic transfusion reactions (DHTRs) commonly occurs 4-8 days after blood transfusion, but can occur up to a month after. Signs and symptoms include jaundice, fever, an inadequate rise in PCV, reticulocytosis, a positive antibody screen and a positive Direct Antiglobulin Test (Coombs test). DHTRs usually have a benign course and require no treatment but sometimes, life-threatening haemolysis with severe anaemia and renal failure can occur so haemoglobin levels and renal function should be monitored.
Acute haemolytic reaction aka immediate haemolytic transfusion reaction presents with fever, chills, pain at transfusion site, nausea, vomiting, dark urine and feeling of ‘impending doom’. Often, it occurs due to ABO incompatibility.
Febrile transfusion reaction presents with a 1 degree rise in temperature from baseline during transfusion. Patient may have chills and malaise. It is the most common transfusion reaction (1 in 8 transfusions) and is usually caused by cytokines released from leukocytes in transfused red cell or platelet components.
Transfusion-associated circulatory overload (TACO) presents as acute or worsening respiratory distress within 6 hours of transfusion of a large volume of blood. It is common in patients with diminished cardiac reserve or chronic anaemia. Elderly patients, infants and severely anaemic patients are particularly susceptible. Clinical features of TACO include: Acute respiratory distress, Tachycardia, Hypertension, Acute/worsening pulmonary oedema on chest X-ray. The BNP is usually raised to at least 1.5 times the pre-transfusion baseline.
Graft versus host disease(GVHD) is an immune mediated condition that arises from a complex interaction between donor and recipients adaptive immunity. It presents as dermatitis, hepatitis and enteritis developing within 100 days after stem cell or bone marrow transplant.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 9
Correct
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A 78-year-old woman visits the emergency room with dizziness and nausea. She claims that her doctor gave her cinnarizine two days prior, but that it didn't seem to help.
Cinnarizine's mechanism of action is which of the following?Your Answer: Antihistamine action
Explanation:Cinnarizine is a piperazine derivative with an antihistamine effect that makes it anti-emetic. Motion sickness and vestibular disorders, such as Méniéres disease, are the most common conditions for which it is prescribed.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 10
Correct
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By what mechanism does Vibrio cholerae causes diarrhoea?
Your Answer: Increases Cl- secretory channels in crypt cells
Explanation:Cholera is a severe diarrheal illness caused by the Vibrio cholerae bacteria infecting the bowel. Ingesting cholera-infected food or drink is the a way to contract the disease. In the intestinal crypt cells, the toxigenic bacterium Vibrio cholera activates adenylate cyclase and raises cyclic adenosine monophosphate (cAMP).
cAMP stimulates the Cl-secretory channels in crypt cells, resulting in the secretion of chloride with sodium ions and water. The toxin it produces causes the body to secrete massive amounts of water, resulting in diarrhoea and significant fluid and electrolyte loss.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 11
Incorrect
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A patient is sent in to ED by her GP with hyponatraemia and hyperkalaemia. There is most likely to be a deficiency in which of the following hormones:
Your Answer: Antidiuretic hormone
Correct Answer: Aldosterone
Explanation:A deficiency of aldosterone, as seen in adrenal insufficiency, can result in hyponatraemia and hyperkalaemia.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 12
Incorrect
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A young female was diagnosed with a urinary tract infection and was sent home with medications. However, after 48 hours of discharge, she returned to the hospital because there had been no relief from her symptoms. She is pregnant in her second trimester.
The urine sensitivity test report is still unavailable. Fresh blood tests were sent, and her estimated GFR is calculated to be >60 ml/minute.
She was prescribed nitrofurantoin 100 mg modified-release orally twice a day for two days.
Out of the following, which antibiotic is most appropriate to be prescribed to this patient?Your Answer: Ciprofloxacin
Correct Answer: Cefalexin
Explanation:The NICE guidelines for pregnant women with lower UTIs are:
1. Prescribe an antibiotic immediately, taking into account the previous urine culture and susceptibility results or avoiding past antibiotics that may have caused resistance
2. Obtain a midstream urine sample before starting antibiotics and send for urine culture and susceptibility
– Review the choice of antibiotic when the results are available
– change the antibiotic according to susceptibility results if the bacteria are resistant, using a narrow-spectrum antibiotic wherever possibleThe first choice of antibiotics for pregnant women aged 12 years and over is:
1. Nitrofurantoin
100 mg modified-release PO BD for 3 days – if eGFR >45 ml/minuteThe second-choice (no improvement in lower UTI symptoms on first-choice for at least 48 hours, or when first-choice is not suitable) are:
1. Amoxicillin
500 mg PO TDS for seven days (ONLY if culture results available and susceptible)
2. Cefalexin
500 mg BD for seven days
Alternative second-choices – consult local microbiologist, choose antibiotics based on culture and sensitivity results -
This question is part of the following fields:
- Infections
- Pharmacology
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Question 13
Correct
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Insulin is produced by which of the following pancreatic cells:
Your Answer: β cells
Explanation:Insulin is produced by beta cells, located centrally within the islets of Langerhans, in the endocrine tissues of the pancreas. Insulin is a polypeptide hormone consisting of two short chains (A and B) linked by disulphide bonds. Proinsulin is synthesised as a single-chain peptide. Within storage granules, a connecting peptide (C peptide) is removed by proteases to yield insulin. Insulin release is stimulated initially during eating by the parasympathetic nervous system and gut hormones such as secretin, but most output is driven by the rise in plasma glucose concentration that occurs after a meal. The effects of insulin are mediated by the receptor tyrosine kinase.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 14
Incorrect
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Which of the following statements is correct with regards to immunoglobulin?
Your Answer: Each immunoglobulin molecule has one kappa light chain and one delta light chain.
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 15
Incorrect
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You contact the intensive care outreach team to inquire about a severely hypotensive resuscitated patient. They make the decision to start a dopamine infusion.
Dopamine primarily has which of the following effects at high doses (>15 g/kg/min)?Your Answer: Increases renal blood flow
Correct Answer: Alpha-adrenergic stimulation
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.
Because clearance varies greatly in critically ill patients, plasma concentrations cannot be predicted reliably from infusion rates.
Dopamine is given as an intravenous infusion, and because extravasation can cause tissue necrosis and sloughing, a central line is usually used (especially at higher doses >240 g/min). In an emergency, however, dopamine can be administered through a large vein (cephalic or basilic) while a central line is being prepared. Alkaline intravenous solutions inactivate it, so sodium bicarbonate should not be infused with it.The following are the most common dopamine side effects:
Nausea and vomiting
Tachycardia
Dysrhythmias
Angina
Hypertension -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 16
Correct
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Regarding Gaussian sample distribution, which of the following statements is false?
Your Answer: It can be skewed left or right
Explanation:Gaussian distribution, also known as normal distribution, is the most important probability distribution in statistics because it fits many natural phenomena. The normal distribution is a probability function that describes how the values of a variable are distributed. Below are its characteristics:
(1) Bell-shaped and symmetrical about the mean
(2) The mean, median, mode are all equal
(3) The total area under the curve and above the x-axis is equal to 1
(4) It has long tapering tails extending infinitely but never touching the x-axis
(5) It is determined by its parameters: its mean and standard deviation
(6) The standard deviation becomes a more meaningful quality than merely being a measure of dispersionThe mean is the most common measure of central tendency. It is the sum of all observed values divided by the number of observation, and is also known as the ‘average’.
The median is the value that falls in the middle position when the observations are ranked in order from the smallest to the largest. If the number of observations is odd, the median is the middle number. If it is even, the median is the average of the two middle numbers.
The mode is the value that occurs with the greatest frequency in a set of observations, and is commonly used in public health statistics, such as the top 10 causes of mortality.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 17
Correct
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Gallstones are commonly found lodged in which of the following parts of the gallbladder?
Your Answer: Neck
Explanation:There is a significant association between the presence of Hartmann’s pouch and gallbladder stones. It is the most common location for gallstones to become lodged and cause cholestasis.
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This question is part of the following fields:
- Abdomen And Pelvis
- Anatomy
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Question 18
Incorrect
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You examine a patient who is experiencing a worsening of his chronic heart failure. You discuss his care with the on-call cardiology registrar, who recommends switching him from furosemide to bumetanide at an equivalent dose. He's on 80 mg of furosemide once a day right now.
What is the recommended dose of bumetanide?Your Answer: 20 mg
Correct Answer: 2 mg
Explanation:Bumetanide is 40 times more powerful than furosemide, and one milligram is roughly equivalent to 40 milligrams of furosemide. This patient is currently taking 80 mg of furosemide and should be switched to a 2 mg bumetanide once daily.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 19
Incorrect
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Among the following infectious diseases, which is typically considered to have an incubation period of 3 weeks and longer?
Your Answer: Mumps
Correct Answer: Infectious mononucleosis
Explanation:Infectious mononucleosis is caused by Epstein-Barr virus (EBV). The incubation period for EBV varies from 2 weeks to 2 months.
The usual incubation period for rubella is 14 days; with a range of 12 to 23 days.
Gonorrhoea has a short incubation period of approximately 2 to 7 days.
The mumps virus can be isolated from infected saliva and swabs rubbed over the Stensen’s duct from 9 days before onset of symptoms until 8 days after parotitis appears.
Scarlet fever, which appears within 1 to 2 days after bacterial infection, is characterized by a diffuse red rash that appears on the upper chest and spreads to the trunk and extremities. The rash disappears over the next 5 to
7 days and is followed by desquamation. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 20
Incorrect
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Which of the following statements regarding forest plots is true? Select ONE answer only.
Which of the following statements regarding forest plots is true? Select ONE answer only.Your Answer: The length of the horizontal lines emerging from the squares represents the standard deviation
Correct Answer: Larger studies are associated with smaller horizontal lines
Explanation:Forest plots are graphical displays designed to illustrate the relative strength of treatment effects in multiple individual studies addressing the same question.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 21
Incorrect
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Which of the following is NOT an effect of cytokine activity:
Your Answer: Fever
Correct Answer: Opsonisation of bacteria for phagocytosis
Explanation:Cytokines are a family of chemical messengers, secreted by leucocytes, that act over short distances by binding specific receptors on target cell surfaces. They include: interleukins (act between leucocytes), interferons (inhibit replication of viruses within cells and activate macrophages and natural killer cells), growth factors, and tumour necrosis factors (kill tumour cells). Effects include: induction of fever and acute phase response, stimulation of leucocyte differentiation and maturation, leucocyte recruitment and activation and increased antibody production.
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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Question 22
Incorrect
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Regarding fat digestion, which of the following statements is CORRECT:
Your Answer: Fatty acids and monoglycerides in the duodenum stimulate gastric emptying.
Correct Answer: Lipids are reesterified in the smooth endoplasmic reticulum of the enterocyte.
Explanation:Fats are digested almost entirely in the small intestine and are only released from the stomach into the duodenum at the rate at which they can be digested (the presence of fatty acids and monoglycerides in the duodenum inhibits gastric emptying). 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. Pancreatic lipase digests triglyceride into monoglycerides and free fatty acids. The products of fat digestion (fatty acids and monoglycerides), cholesterol and fat-soluble vitamins diffuse passively into the enterocytes. 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.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 23
Incorrect
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Regarding the foetal oxygen-haemoglobin dissociation curve, which of the following statements is CORRECT:
Your Answer: Blood travelling from the placenta to the foetus in the umbilical vein has a PO 2 of about 10 kPa.
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 24
Incorrect
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Disease specific immunoglobulin is available for all of the following infectious diseases EXCEPT for:
Your Answer: Hepatitis B
Correct Answer: Hepatitis A
Explanation:Disease specific immunoglobulins are available for:
hepatitis B
rabies
tetanus
varicella-zoster
Normal immunoglobulin can be used to confer protection against hepatitis A. -
This question is part of the following fields:
- Immunoglobulins And Vaccines
- Pharmacology
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Question 25
Incorrect
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A 20-year-old female presents with painful wrist following a fall while skating. X-rays shows fracture of the ulna.
The initial phase of bone healing is?
Your Answer: Lamellar bone formation
Correct Answer: Haematoma at the fracture site
Explanation:Haemorrhage occurs into the fracture site from the ruptured vessels in the bone marrow and those supplying the periosteum immediately after fracture. This hematoma formation is the first phase of bone healing.
The 4 stages of bone healing are:
Haematoma at the fracture site (provides a framework for healing)
Callus formation
Lamellar bone formation
Remodelling -
This question is part of the following fields:
- General Pathology
- Pathology
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Question 26
Incorrect
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Pancreatic ductal alkaline fluid secretion is mainly stimulated by which of the following hormones:
Your Answer: Pancreatic polypeptide
Correct Answer: Secretin
Explanation:Pancreatic exocrine 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 cellsSomatostatin 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 27
Incorrect
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Diabetic ketoacidosis is characterised by which of the following:
Your Answer: Hypovolaemia, hyperglycaemia and raised plasma osmolality
Correct Answer: Hyperglycaemia, ketonaemia and acidosis
Explanation:DKA is characterised by the biochemical triad:
1. Hyperglycaemia (> 11 mmol/L)
2. Ketonaemia (> 3 mmol/L)
3. Acidosis (pH < 7.3 +/- HCO3 < 15 mmol/L) -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 28
Incorrect
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A 21-year-old student presents with fever, headache, malaise, fatigue, and muscle aches after returning from a trip to India. A diagnosis of malaria was suspected.
Which of the following statements is considered correct regarding malaria?Your Answer: Plasmodium falciparum has the longest incubation period
Correct Answer: Haemoglobinuria and renal failure following treatment is suggestive of Plasmodium falciparum
Explanation:Malaria results from infection with single-celled parasites belonging to the Plasmodium genus. Five species of Plasmodium are known to cause disease in humans: P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi.
Chloroquine remains the mainstay of treatment for uncomplicated vivax malaria.
The female Anopheles mosquito serves as the biologic vector and definitive host.
A complication of infection with P. falciparum is blackwater fever, a condition characterized by haemoglobinuria.
Plasmodium ovale has the longest incubation period, which can be up to 40 days. Plasmodium falciparum has a shorter incubation period of 7-14 days.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 29
Incorrect
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The correct statement about the glomerular filtration barrier is which of the following?
Your Answer: The glomerular capillaries are continuous, with cells connected by tight junctions.
Correct Answer: The basement membrane is negatively charged, restricting filtration of negatively charged molecules.
Explanation:The main factor in determining whether a substance is filtered or not is molecular weight. Molecules < 7 kDa in molecular weight e.g. glucose, amino acids, urea, ions are filtered freely, but larger molecules are increasingly restricted up to 70 kDa, and there is very little filtration for anything above this.
There is further restriction of negatively charged molecules because they are repelled by negative charges, particularly in the basement membrane. Albumin, which has a molecular weight of 69 kDa and is negatively charged, is filtered but only in very small amounts. All of the filtered albumin is reabsorbed in the proximal tubule. Small molecules such as ions, glucose, amino acids and urea pass the filter without hindrance. Other than the ultrafiltrate being essentially protein free, it has an otherwise identical composition of plasma. Bowman’s capsule consists of:
– an epithelial lining which consists of a single layer of cells called podocytes
– endothelium which is perforated by pores or fenestrations – this allows plasma components with a molecular weight of < 70 kDa to pass freely. -
This question is part of the following fields:
- Physiology
- Renal
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Question 30
Incorrect
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The blood test reports of a 56-year-old female are sent for your review. She seems acutely sick and has had multiple infections over the past few months. Her complete blood count report shows neutropenia.
Which one of the following options is true with regards to neutropenia?Your Answer: It is caused by hyposplenism
Correct Answer: It can be caused by both radiotherapy and chemotherapy
Explanation:A total neutrophil count of less than 2 x 109/L is defined as neutropenia. It can be caused by the following:
1. viral infections
2. SLE
3. RA
4. hypersplenism
5. chemo- and radiotherapy
6. vitamin B12 and folate deficiency
7. drug reactions -
This question is part of the following fields:
- Haematology
- Pathology
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SESSION STATS - PERFORMANCE PER SPECIALTY
