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Question 1
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A 57-year-old man with chronic pancreatitis is experiencing difficulty in absorbing fat-soluble nutrients from his diet. Can you identify the fat-soluble vitamin that acts as an antioxidant during immune function and safeguarding cell membranes?
Your Answer: Vitamin E
Explanation:Vitamin E is the correct answer as it helps strengthen the body’s immune system and acts as an anti-oxidant. Vitamin B12, Vitamin K, and Vitamin C are not the most appropriate answers as they have different functions and properties.
Understanding Vitamin E and its Deficiency
Vitamin E is a type of fat-soluble vitamin that functions as an antioxidant. Its primary role is to protect cells from damage caused by free radicals, which are unstable molecules that can harm cells and contribute to the development of chronic diseases. However, when there is a deficiency of vitamin E in the body, it can lead to erythrocyte membrane fragility. This means that the red blood cells become more susceptible to breaking down, which can result in a condition called haemolytic anaemia. It is important to maintain adequate levels of vitamin E in the body to prevent such health complications.
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This question is part of the following fields:
- General Principles
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Question 2
Correct
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In the realm of evidence based medicine, what is the purpose of utilizing the GRADE approach?
Your Answer: Assessing the quality of evidence
Explanation:Levels and Grades of Evidence in Evidence-Based Medicine
In order to evaluate the quality of evidence in evidence-based medicine, levels or grades are often used to organize the evidence. Traditional hierarchies placed systematic reviews or randomized control trials at the top and case-series/report at the bottom. However, this approach is overly simplistic as certain research questions cannot be answered using RCTs. To address this, the Oxford Centre for Evidence-Based Medicine introduced their 2011 Levels of Evidence system which separates the type of study questions and gives a hierarchy for each. On the other hand, the GRADE system is a grading approach that classifies the quality of evidence as high, moderate, low, or very low. The process begins by formulating a study question and identifying specific outcomes. Outcomes are then graded as critical or important, and the evidence is gathered and criteria are used to grade the evidence. Evidence can be promoted or downgraded based on certain circumstances. The use of levels and grades of evidence helps to evaluate the quality of evidence and make informed decisions in evidence-based medicine.
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This question is part of the following fields:
- General Principles
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Question 3
Incorrect
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A 57-year-old man comes to the emergency department following an unobserved fall. He has a medical history of atrial fibrillation.
During his lying and standing blood pressure test, there is a 30mmHg decrease, indicating postural hypotension.
To increase his blood pressure, the emergency department administers an anti-hypotensive medication.
Which receptor does the drug act on?Your Answer: β2 adrenergic receptors
Correct Answer: α1 adrenergic receptors
Explanation:The contraction of smooth muscle in blood vessels is controlled by α1 adrenergic receptors, which are responsible for vasoconstriction in peripheral blood vessels. α2 receptors, located on presynaptic nerves, regulate the release of neurotransmitters. β1 receptors in the heart increase inotropy and chronotropy, while β2 receptors in smooth muscle promote bronchodilation and vasodilation. β3 receptors in fat tissue stimulate lipolysis and thermogenesis.
Adrenergic receptors are a type of G protein-coupled receptors that respond to the catecholamines epinephrine and norepinephrine. These receptors are primarily involved in the sympathetic nervous system. There are four types of adrenergic receptors: α1, α2, β1, and β2. Each receptor has a different potency order and primary action. The α1 receptor responds equally to norepinephrine and epinephrine, causing smooth muscle contraction. The α2 receptor has mixed effects and responds equally to both catecholamines. The β1 receptor responds equally to epinephrine and norepinephrine, causing cardiac muscle contraction. The β2 receptor responds much more strongly to epinephrine than norepinephrine, causing smooth muscle relaxation.
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This question is part of the following fields:
- General Principles
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Question 4
Incorrect
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A 54-year-old woman arrived at the emergency department with a sudden chest pain that started an hour ago. She experienced sweating, nausea, and vomiting. An electrocardiogram showed a non-ST segment elevation myocardial infarction in the anterior leads, and a blood test revealed elevated levels of troponin. The woman was admitted to the coronary care unit for treatment. After a few days, the interventional cardiologist discussed with the woman the possibility of inserting a stent to prevent future myocardial infarctions. A new type of drug-eluting stent was recently tested in a small group of patients at a hospital. The researchers discovered that the new stent was not more effective than the currently available stents in reducing future myocardial infarctions. What type of error or bias is more likely in this trial?
Your Answer: Type I error
Correct Answer: Type II error
Explanation:1: A study is considered to be statistically significant when the probability of obtaining the observed results by chance is very low. This means that the observed results are likely to be due to the intervention or treatment being studied.
2: A p-value is a measure of the probability that any observed difference is due to chance. A lower p-value indicates a lower probability of chance and a higher likelihood that the observed difference is due to the intervention or treatment being studied.
3: Lead-time bias occurs when a disease is detected earlier, leading to an apparent increase in survival time. This is not a true increase in survival time, but rather a result of earlier detection.
4: Type II errors occur when a study’s sample size is too small to detect a difference. To prevent type II errors, a larger sample size should be recruited.
5: Confounding bias occurs when a variable interacts with both the outcome and predictor variables. If not controlled for, the effect of the predictor variable cannot be accurately determined.
Significance tests are used to determine the likelihood of a null hypothesis being true. The null hypothesis states that two treatments are equally effective, while the alternative hypothesis suggests that there is a difference between the two treatments. The p value is the probability of obtaining a result by chance that is at least as extreme as the observed result, assuming the null hypothesis is true. Two types of errors can occur during significance testing: type I, where the null hypothesis is rejected when it is true, and type II, where the null hypothesis is accepted when it is false. The power of a study is the probability of correctly rejecting the null hypothesis when it is false, and it can be increased by increasing the sample size.
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This question is part of the following fields:
- General Principles
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Question 5
Incorrect
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A 42-year-old woman comes to you with a complaint of increasing fatigue and shortness of breath over the past 4 months. She has a history of HIV but no other medical problems. On examination, her chest X-ray shows enlarged pulmonary arteries and clear lung fields, while her ECG reveals right ventricular hypertrophy. You decide to perform a right heart catheterization, which reveals a pulmonary arterial pressure of 25 mmHg (normal is 8-20 mmHg at rest). What is the arachidonic acid metabolite that can be used to treat this condition?
Your Answer:
Correct Answer: Prostaglandin I2
Explanation:PGI2 causes vasodilation.
Arachidonic Acid Metabolism: The Role of Leukotrienes and Endoperoxides
Arachidonic acid is a fatty acid that plays a crucial role in the body’s inflammatory response. The metabolism of arachidonic acid involves the production of various compounds, including leukotrienes and endoperoxides. Leukotrienes are produced by leukocytes and can cause constriction of the lungs. LTB4 is produced before leukocytes arrive, while the rest of the leukotrienes (A, C, D, and E) cause lung constriction.
Endoperoxides, on the other hand, are produced by the cyclooxygenase enzyme and can lead to the formation of thromboxane and prostacyclin. Thromboxane is associated with platelet aggregation and vasoconstriction, which can lead to thrombosis. Prostacyclin, on the other hand, has the opposite effect and can cause vasodilation and inhibit platelet aggregation.
Understanding the metabolism of arachidonic acid and the role of these compounds can help in the development of treatments for inflammatory conditions and cardiovascular diseases.
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This question is part of the following fields:
- General Principles
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Question 6
Incorrect
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A 35-year-old male patient visits his doctor complaining of red, itchy skin around his nose and mouth. He has a medical history of portal hypertension, macrocytic anemia, and alcoholic liver disease. Upon examination, the doctor suspects a deficiency in vitamin B6. If left untreated, what other symptom may this patient experience?
Your Answer:
Correct Answer: Seizures
Explanation:Insufficient levels of Vitamin B6 can lead to seizures as it reduces the production of GABA, which is the primary inhibitory neurotransmitter in the central nervous system.
Other deficiencies may result in specific symptoms such as muscle weakness and lack of energy for Vitamin B1 (thiamine), bleeding gums and slow wound healing for Vitamin C, hair loss and skin inflammation for Vitamin B7 (biotin), diarrhea and skin inflammation for Vitamin B3 (niacin), and seizures, peripheral neuropathy, and sideroblastic anemia for Vitamin B6 (pyridoxine).
The Importance of Vitamin B6 in the Body
Vitamin B6 is a type of water-soluble vitamin that belongs to the B complex group. Once it enters the body, it is converted into pyridoxal phosphate (PLP), which acts as a cofactor for various biochemical reactions such as transamination, deamination, and decarboxylation. These reactions are essential for the proper functioning of the body.
However, a deficiency in vitamin B6 can lead to various health problems such as peripheral neuropathy and sideroblastic anemia. One of the common causes of vitamin B6 deficiency is isoniazid therapy, which is used to treat tuberculosis. Therefore, it is important to ensure that the body receives an adequate amount of vitamin B6 to maintain optimal health.
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This question is part of the following fields:
- General Principles
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Question 7
Incorrect
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A general practitioner is involved in a charity project to build a hospital in Uganda and holds a weekly clinic. A 50-year-old farmer comes to the clinic with swollen legs and an enlarged scrotum. He is experiencing tenderness in his scrotum and is worried about being ostracised by his family if he does not receive treatment. On examination, there is evidence of hydrocele and the scrotal skin is swollen, leading to a suspected diagnosis of lymphatic filariasis (elephantiasis). What is the most likely pathogen responsible for this patient's condition?
Your Answer:
Correct Answer: Wuchereria bancrofti
Explanation:African farmer experiences significant swelling in his legs and scrotum.
Helminths are a group of parasitic worms that can infect humans and cause various diseases. Nematodes, also known as roundworms, are one type of helminth. Strongyloides stercoralis is a type of roundworm that enters the body through the skin and can cause symptoms such as diarrhea, abdominal pain, and skin lesions. Treatment for this infection typically involves the use of ivermectin or benzimidazoles. Enterobius vermicularis, also known as pinworm, is another type of roundworm that can cause perianal itching and other symptoms. Diagnosis is made by examining sticky tape applied to the perianal area. Treatment typically involves benzimidazoles.
Hookworms, such as Ancylostoma duodenale and Necator americanus, are another type of roundworm that can cause gastrointestinal infections and anemia. Treatment typically involves benzimidazoles. Loa loa is a type of roundworm that is transmitted by deer fly and mango fly and can cause red, itchy swellings called Calabar swellings. Treatment involves the use of diethylcarbamazine. Trichinella spiralis is a type of roundworm that can develop after eating raw pork and can cause fever, periorbital edema, and myositis. Treatment typically involves benzimidazoles.
Onchocerca volvulus is a type of roundworm that causes river blindness and is spread by female blackflies. Treatment involves the use of ivermectin. Wuchereria bancrofti is another type of roundworm that is transmitted by female mosquitoes and can cause blockage of lymphatics and elephantiasis. Treatment involves the use of diethylcarbamazine. Toxocara canis, also known as dog roundworm, is transmitted through ingestion of infective eggs and can cause visceral larva migrans and retinal granulomas. Treatment involves the use of diethylcarbamazine. Ascaris lumbricoides, also known as giant roundworm, can cause intestinal obstruction and occasionally migrate to the lung. Treatment typically involves benzimidazoles.
Cestodes, also known as tapeworms, are another type of helminth. Echinococcus granulosus is a tapeworm that is transmitted through ingestion of eggs in dog feces and can cause liver cysts and anaphylaxis if the cyst ruptures
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This question is part of the following fields:
- General Principles
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Question 8
Incorrect
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A 28-year-old man visits his GP complaining of weight loss, fevers, and night sweats that have persisted for several months. Upon examination, he has non-tender lymphadenopathy. He is referred to a specialist and eventually diagnosed with Hodgkin's lymphoma. At the haematological cancer multidisciplinary team meeting, it is decided to initiate vincristine treatment.
At what stage of the cell cycle does this medication take effect?Your Answer:
Correct Answer: Metaphase
Explanation:Vincristine disrupts the metaphase stage of the cell cycle. This is when chromosomes align in the middle of the cell and begin to separate. By binding to the tubulin protein, Vincristine prevents the formation of microtubules, which stops the initiation of chromosome separation. As a result, the cell undergoes apoptosis. Vincristine does not act during anaphase, cytokinesis, or prophase.
Mitosis: The Process of Somatic Cell Division
Mitosis is a type of cell division that occurs in somatic cells during the M phase of the cell cycle. This process allows for the replication and growth of tissues by producing genetically identical diploid daughter cells. Before mitosis begins, the cell prepares itself during the S phase by duplicating its chromosomes. The phases of mitosis include prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. During prophase, the chromatin in the nucleus condenses, and during prometaphase, the nuclear membrane breaks down, allowing microtubules to attach to the chromosomes. In metaphase, the chromosomes align at the middle of the cell, and in anaphase, the paired chromosomes separate at the kinetochores and move to opposite sides of the cell. Telophase occurs when chromatids arrive at opposite poles of the cell, and cytokinesis is the final stage where an actin-myosin complex in the center of the cell contacts, resulting in it being pinched into two daughter cells.
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This question is part of the following fields:
- General Principles
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Question 9
Incorrect
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Where does spironolactone act in the kidney?
Your Answer:
Correct Answer: Distal convoluted tubule
Explanation:Potassium-sparing diuretics are classified into two types: epithelial sodium channel blockers (such as amiloride and triamterene) and aldosterone antagonists (such as spironolactone and eplerenone). However, caution should be exercised when using these drugs in patients taking ACE inhibitors as they can cause hyperkalaemia. Amiloride is a weak diuretic that blocks the epithelial sodium channel in the distal convoluted tubule. It is usually given with thiazides or loop diuretics as an alternative to potassium supplementation since these drugs often cause hypokalaemia. On the other hand, aldosterone antagonists like spironolactone act in the cortical collecting duct and are used to treat conditions such as ascites, heart failure, nephrotic syndrome, and Conn’s syndrome. In patients with cirrhosis, relatively large doses of spironolactone (100 or 200 mg) are often used to manage secondary hyperaldosteronism.
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This question is part of the following fields:
- General Principles
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Question 10
Incorrect
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Which drug is the least likely to trigger an episode of acute intermittent porphyria?
Your Answer:
Correct Answer: Penicillin
Explanation:Drugs to Avoid and Use in Acute Intermittent Porphyria
Acute intermittent porphyria (AIP) is a genetic disorder that affects the production of haem. It is characterized by abdominal and neuropsychiatric symptoms and is more common in females. AIP is caused by a defect in the porphobilinogen deaminase enzyme. Certain drugs can trigger an attack in individuals with AIP, including barbiturates, halothane, benzodiazepines, alcohol, oral contraceptive pills, and sulphonamides. Therefore, it is important to avoid these drugs in individuals with AIP. However, there are some drugs that are considered safe to use, such as paracetamol, aspirin, codeine, morphine, chlorpromazine, beta-blockers, penicillin, and metformin.
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This question is part of the following fields:
- General Principles
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