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Question 1
Incorrect
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A 43-year-old man is seeking information about the COVID-19 vaccine. He has heard that the vaccine may not provide complete protection and wants to know how effective it is. As his healthcare provider, you provide him with the following data for this specific vaccine:
Vaccinated Not vaccinated Total
COVID-19 occurred 10 90 100
COVID-19 did not occur 90 10 100
Column totals 100 100 200
What is the most appropriate response to this patient's inquiry?Your Answer: 90/100 - 10/100 = 80%
Correct Answer: (10/100 - 90/100) / 90/100 = -90%
Explanation:Understanding Relative Risk in Clinical Trials
Relative risk (RR) is a measure used in clinical trials to compare the risk of an event occurring in the experimental group to the risk in the control group. It is calculated by dividing the experimental event rate (EER) by the control event rate (CER). If the resulting ratio is greater than 1, it means that the event is more likely to occur in the experimental group than in the control group. Conversely, if the ratio is less than 1, the event is less likely to occur in the experimental group.
To calculate the relative risk reduction (RRR) or relative risk increase (RRI), the absolute risk change is divided by the control event rate. This provides a percentage that indicates the magnitude of the difference between the two groups. Understanding relative risk is important in evaluating the effectiveness of interventions and treatments in clinical trials. By comparing the risk of an event in the experimental group to the control group, researchers can determine whether the intervention is beneficial or not.
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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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A 67-year-old man with a stable angina history for two years visits his cardiologist for a regular check-up. During the review, the cardiologist observes that the patient's heart rate is low at 46 bpm. As a result, the cardiologist decides to replace his beta-blocker with a new anti-anginal drug called nicorandil.
What is the mode of action of the patient's new medication?Your Answer: Potassium channel activator through activation of guanylyl cyclase
Explanation:Nicorandil activates potassium channels, leading to vasodilation. This activation triggers guanylyl cyclase, which increases the production of cyclic GMP (cGMP) and activates protein kinase G (PKG). PKG phosphorylates and inhibits GTPase RhoA, reducing Rho-kinase activity and increasing myosin phosphatase activity. As a result, the smooth muscle becomes less sensitive to calcium, leading to dilation of the large coronary arteries and improved perfusion. Nicorandil does not significantly affect calcium or sodium channels. This mechanism helps alleviate anginal symptoms.
Nicorandil is a medication that is commonly used to treat angina. It works by activating potassium channels, which leads to vasodilation. This process is achieved through the activation of guanylyl cyclase, which results in an increase in cGMP. However, there are some adverse effects associated with the use of nicorandil, including headaches, flushing, and the development of ulcers on the skin, mucous membranes, and eyes. Additionally, gastrointestinal ulcers, including anal ulceration, may also occur. It is important to note that nicorandil should not be used in patients with left ventricular failure.
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This question is part of the following fields:
- Cardiovascular System
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Question 3
Correct
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An 80-year-old white woman visits her GP with complaints of stiffness, pain, and swelling in her hands. The symptoms are more severe in the morning and gradually improve throughout the day. She has a medical history of hypertension and gout. She admits to taking her husband's prednisolone tablets occasionally to manage her symptoms.
What risk factors does this patient have for the probable diagnosis?Your Answer: Female sex
Explanation:Rheumatoid arthritis is more prevalent in female patients, with a 3-fold higher incidence compared to males. It is characterized by symmetrical pain and stiffness, particularly in the morning. Rheumatoid arthritis can affect individuals of any age and is treated with medications such as prednisolone. Contrary to popular belief, gout does not increase the likelihood of developing rheumatoid arthritis. Additionally, ethnicity, specifically being of white descent, is not considered a risk factor for this condition.
Understanding the Epidemiology of Rheumatoid Arthritis
Rheumatoid arthritis is a chronic autoimmune disease that affects people of all ages, but it typically peaks between the ages of 30 and 50. The condition is more common in women, with a female-to-male ratio of 3:1. The prevalence of rheumatoid arthritis is estimated to be around 1% of the population. However, there are some ethnic differences in the incidence of the disease, with Native Americans having a higher prevalence than other groups.
Researchers have identified a genetic link to rheumatoid arthritis, with the HLA-DR4 gene being associated with the development of the condition. This gene is particularly linked to a subtype of rheumatoid arthritis known as Felty’s syndrome. Understanding the epidemiology of rheumatoid arthritis is important for healthcare professionals to provide appropriate care and support to those affected by the disease. By identifying risk factors and understanding the prevalence of the condition, healthcare providers can better tailor their treatment plans to meet the needs of their patients.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 4
Incorrect
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What is the endocrine condition that is linked to low blood sugar levels?
Your Answer: Glucagon excess
Correct Answer: Hypoadrenalism
Explanation:Hypoglycaemia in Adults
Hypoglycaemia is a condition where the blood glucose level falls below the typical fasting level, which is around <4 mmol/L for adults. This condition can be caused by various endocrine factors such as hypoadrenalism, growth hormone deficiency, glucagon deficiency, and hypothyroidism. However, the most common cause of hypoglycaemia in adults is medication for diabetes, particularly insulin or sulphonylureas. Symptoms of hypoglycaemia are caused by sympathetic activity and disrupted central nervous system function due to inadequate glucose. These symptoms include tremors, sweating, nausea, lightheadedness, hunger, and disorientation. Severe hypoglycaemia can cause confusion, aggressive behaviour, and reduced consciousness. Mild hypoglycaemia is common during fasting, pregnancy, and minor illness. Apart from medication and endocrine factors, other causes of hypoglycaemia in adults include non-diabetic drugs, alcohol, hepatic failure, critical illness, hormone deficiency, malignancy, insulinoma, non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS), and bariatric surgery. It is important to identify the underlying cause of hypoglycaemia to provide appropriate treatment. In summary, hypoglycaemia is a condition where the blood glucose level falls below the typical fasting level. It can be caused by various factors, including medication, endocrine factors, and other medical conditions. Recognizing the symptoms and identifying the underlying cause is crucial in managing hypoglycaemia.
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This question is part of the following fields:
- Clinical Sciences
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Question 5
Incorrect
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A 25-year-old man comes to the clinic with a concern of small red bumps that are itchy on his abdomen and thighs for the past three days. He noticed yesterday that the rash has become tender. Additionally, he feels fatigued. He went to a water park with his friends five days ago, and no one he knows has had this rash recently.
What is the most probable organism responsible for this rash?Your Answer: Staphylococcus aureus
Correct Answer: Pseudomonas aeruginosa
Explanation:Hot tub folliculitis is primarily caused by Pseudomonas aeruginosa.
Diarrhoea, often seen in individuals who have been treated with antibiotics, can be caused by Clostridium difficile infection of the bowel.
Granulomatous diseases are typically caused by Mycobacterium tuberculosis.
Boils are commonly caused by Staphylococcus aureus.
Pseudomonas aeruginosa: A Gram-negative Rod Causing Various Infections
Pseudomonas aeruginosa is a type of bacteria that is commonly found in the environment. It is a Gram-negative rod that can cause a range of infections in humans. Some of the infections it causes include chest infections, skin infections such as burns and wound infections, otitis externa, and urinary tract infections.
In the laboratory, Pseudomonas aeruginosa is identified as a Gram-negative rod that does not ferment lactose and is oxidase positive. The bacteria produce both an endotoxin and exotoxin A. The endotoxin causes fever and shock, while exotoxin A inhibits protein synthesis by catalyzing ADP-ribosylation of elongation factor EF-2.
Overall, Pseudomonas aeruginosa is a pathogenic bacteria that can cause a variety of infections in humans. Its ability to produce toxins makes it particularly dangerous and difficult to treat. Proper hygiene and infection control measures can help prevent the spread of this bacteria.
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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 13-year-old boy presents at the emergency room with wrist joint pain. He reports a persistent dull ache for three days and mild swelling. Upon examination, there is no misalignment or bruising. The doctor evaluates active and passive movement, including flexion, extension, abduction, and adduction.
Which synovial joint is impacted in this case?Your Answer: Hinge
Correct Answer: Condyloid
Explanation:The wrist joint is classified as a synovial condyloid joint, which allows movement along two axes. Unlike a synovial ball and socket joint, the wrist joint cannot rotate. It also differs from a hinge joint, which only allows movement in one plane, and a pivot joint, which only allows axial rotation. Additionally, the wrist joint is not a synovial saddle joint. While the wrist joint has less freedom of movement than the shoulder joint, it is still capable of flexion, extension, abduction, and adduction.
Carpal Bones: The Wrist’s Building Blocks
The wrist is composed of eight carpal bones, which are arranged in two rows of four. These bones are convex from side to side posteriorly and concave anteriorly. The trapezium is located at the base of the first metacarpal bone, which is the base of the thumb. The scaphoid, lunate, and triquetrum bones do not have any tendons attached to them, but they are stabilized by ligaments.
In summary, the carpal bones are the building blocks of the wrist, and they play a crucial role in the wrist’s movement and stability. The trapezium bone is located at the base of the thumb, while the scaphoid, lunate, and triquetrum bones are stabilized by ligaments. Understanding the anatomy of the wrist is essential for diagnosing and treating wrist injuries and conditions.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 7
Correct
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A 63-year-old woman is referred to dermatology for evaluation of a concerning lesion on her arm. She reports that it was previously a uniform shape and approximately 5 mm in size, but has since grown and become irregular in shape with multiple colors. A biopsy confirms advanced melanoma and she is started on ipilimumab. What is the mechanism of action for this medication?
Your Answer: Blockage of Cytotoxic T Lymphocyte-associated Protein 4 (CTLA-4)
Explanation:Ipilimumab is a type of immune checkpoint inhibitor that is used to treat melanoma by blocking CTLA-4. Other immune checkpoint inhibitors, such as nivolumab and pembrolizumab, block PD-1 and can be used to treat various cancers including melanoma, Hodgkin’s lymphoma, and non-small cell lung cancer. Atezolizumab and durvalumab are examples of immune checkpoint inhibitors that block PD-L1 and can be used to treat lung and urothelial cancer. Alkylating agents like cyclophosphamide exert their effect by cross-linking DNA, while medications like vincristine and vinblastine inhibit the formation of microtubules.
Understanding Immune Checkpoint Inhibitors
Immune checkpoint inhibitors are a type of immunotherapy that is becoming increasingly popular in the treatment of certain types of cancer. Unlike traditional therapies such as chemotherapy, these targeted treatments work by harnessing the body’s natural anti-cancer immune response. They boost the immune system’s ability to attack and destroy cancer cells, rather than directly affecting their growth and proliferation.
T-cells are an essential part of our immune system that helps destroy cancer cells. However, some cancer cells produce high levels of proteins that turn T-cells off. Checkpoint inhibitors block this process and reactivate and increase the body’s T-cell population, enhancing the immune system’s ability to recognize and fight cancer cells.
There are different types of immune checkpoint inhibitors, including Ipilimumab, Nivolumab, Pembrolizumab, Atezolizumab, Avelumab, and Durvalumab. These drugs block specific proteins found on T-cells and cancer cells, such as CTLA-4, PD-1, and PD-L1. They are administered by injection or intravenous infusion and can be given as a single-agent treatment or combined with chemotherapy or each other.
However, the mechanism of action of these drugs can result in side effects termed ‘Immune-related adverse events’ that are inflammatory and autoimmune in nature. This is because all immune cells are boosted by these drugs, not just the ones that target cancer. The overactive T-cells can produce side effects such as dry, itchy skin and rashes, nausea and vomiting, decreased appetite, diarrhea, tiredness and fatigue, shortness of breath, and a dry cough. Management of such side effects reflects the inflammatory nature, often involving corticosteroids. It is important to monitor liver, kidney, and thyroid function as these drugs can affect these organs.
In conclusion, the early success of immune checkpoint inhibitors in solid tumors has generated tremendous interest in further developing and exploring these strategies across the oncology disease spectrum. Ongoing testing in clinical trials creates new hope for patients affected by other types of disease.
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This question is part of the following fields:
- Haematology And Oncology
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Question 8
Incorrect
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A 32-year-old man comes to you complaining of persistent diarrhoea for the past 10 days. He describes his diarrhoea as watery and foul-smelling, but denies any blood. He feels exhausted and asks for a prescription for an antidiarrhoeal medication. He has no notable medical history.
The stool cultures come back negative, and you contemplate starting the patient on diphenoxylate. Can you explain the mechanism of action of this drug?Your Answer: Inhibits peristalsis by acting on delta-opioid in the GI tract
Correct Answer: Inhibits peristalsis by acting on μ-opioid in the GI tract
Explanation:Diphenoxylate slows down peristalsis in the GI tract by acting on μ-opioid receptors.
Increased gut motility can be achieved through the positive cholinergic effect of muscarinic receptor activation.
All other options are inaccurate.
Antidiarrhoeal Agents: Opioid Agonists
Antidiarrhoeal agents are medications used to treat diarrhoea. Opioid agonists are a type of antidiarrhoeal agent that work by slowing down the movement of the intestines, which reduces the frequency and urgency of bowel movements. Two common opioid agonists used for this purpose are loperamide and diphenoxylate.
Loperamide is available over-the-counter and is often used to treat acute diarrhoea. It works by binding to opioid receptors in the intestines, which reduces the contractions of the muscles in the intestinal wall. This slows down the movement of food and waste through the intestines, allowing more time for water to be absorbed and resulting in firmer stools.
Diphenoxylate is a prescription medication that is often used to treat chronic diarrhoea. It works in a similar way to loperamide, but is often combined with atropine to discourage abuse and overdose.
Overall, opioid agonists are effective at treating diarrhoea, but should be used with caution and under the guidance of a healthcare professional. They can cause side effects such as constipation, dizziness, and nausea, and may interact with other medications.
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This question is part of the following fields:
- Gastrointestinal System
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Question 9
Incorrect
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A 50-year-old man is having a left hemicolectomy. During the procedure, the surgeons come across a tubular structure located at the inferior aspect of psoas major. What is the most probable identity of this structure?
Your Answer:
Correct Answer: Left ureter
Explanation:The left colon is positioned anterior to the left ureter. The iliac vessels are usually in closer proximity to the sigmoid colon and upper rectum, which are not typically located above the L4 vertebrae.
Anatomy of the Ureter
The ureter is a muscular tube that measures 25-35 cm in length and is lined by transitional epithelium. It is surrounded by a thick muscular coat that becomes three muscular layers as it crosses the bony pelvis. This retroperitoneal structure overlies the transverse processes L2-L5 and lies anterior to the bifurcation of iliac vessels. The blood supply to the ureter is segmental and includes the renal artery, aortic branches, gonadal branches, common iliac, and internal iliac. It is important to note that the ureter lies beneath the uterine artery.
In summary, the ureter is a vital structure in the urinary system that plays a crucial role in transporting urine from the kidneys to the bladder. Its unique anatomy and blood supply make it a complex structure that requires careful consideration in any surgical or medical intervention.
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This question is part of the following fields:
- Gastrointestinal System
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Question 10
Incorrect
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During a routine ophthalmology appointment, a 5-year-old child is diagnosed with a cataract in their left eye. The child's medical history reveals that they have galactokinase deficiency. The parents are concerned about what caused the cataract and how to prevent it from happening again.
The ophthalmologist explains that the cataract is a result of an excess of a particular chemical produced due to galactokinase deficiency. What could have caused the formation of the cataract in this child?Your Answer:
Correct Answer: Accumulation of galactitol
Explanation:Galactokinase deficiency causes an accumulation of galactitol, which can be deposited in the lenses and lead to the formation of cataracts.
Reduced metabolism of branched chain amino acids can result in an excess of valine, leucine, and isoleucine in patients with maple syrup urine disease.
Phenylketonuria is characterized by an excess of phenylalanine.
Disorders of Galactose Metabolism
Galactose metabolism is a complex process that involves the breakdown of galactose, a type of sugar found in milk and dairy products. There are two main disorders associated with galactose metabolism: classic galactosemia and galactokinase deficiency. Both of these disorders are inherited in an autosomal recessive manner.
Classic galactosemia is caused by a deficiency in the enzyme galactose-1-phosphate uridyltransferase, which leads to the accumulation of galactose-1-phosphate. This disorder is characterized by symptoms such as failure to thrive, infantile cataracts, and hepatomegaly.
On the other hand, galactokinase deficiency is caused by a deficiency in the enzyme galactokinase, which results in the accumulation of galactitol. This disorder is characterized by infantile cataracts, as galactitol accumulates in the lens. Unlike classic galactosemia, there is no hepatic involvement in galactokinase deficiency.
In summary, disorders of galactose metabolism can have serious consequences and require careful management. Early diagnosis and treatment are essential for improving outcomes and preventing complications.
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This question is part of the following fields:
- General Principles
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Question 11
Incorrect
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A 20-year-old man comes to the emergency department complaining of abdominal pain, vomiting, polyuria, polydipsia, and confusion that have been present for the past 12 hours. During the examination, he shows mild generalized abdominal tenderness without guarding. His breathing is observed to be deep and rapid.
The patient has a medical history of type 1 diabetes, but he confesses to being non-compliant with his insulin regimen.
What is the probable pathophysiology behind his symptoms?Your Answer:
Correct Answer: Uncontrolled lipolysis which results in an excess of free fatty acids
Explanation:The cause of DKA is uncontrolled lipolysis, leading to an excess of free fatty acids that are converted to ketone bodies. This results in high levels of ketones in the urine. Hypoglycemia activates the sympathetic nervous system. Lactic acidosis is similar to DKA but lacks the presence of ketones in urine. Appendicitis can cause abdominal pain, vomiting, and urinary symptoms, but the presence of ketones in urine suggests DKA. Urinary tract infections are rare in men under 50 and typically occur with abnormal anatomy or catheterization.
Diabetic ketoacidosis (DKA) is a serious complication of type 1 diabetes mellitus, accounting for around 6% of cases. It can also occur in rare cases of extreme stress in patients with type 2 diabetes mellitus. DKA is caused by uncontrolled lipolysis, resulting in an excess of free fatty acids that are converted to ketone bodies. The most common precipitating factors of DKA are infection, missed insulin doses, and myocardial infarction. Symptoms include abdominal pain, polyuria, polydipsia, dehydration, Kussmaul respiration, and breath that smells like acetone. Diagnostic criteria include glucose levels above 11 mmol/l or known diabetes mellitus, pH below 7.3, bicarbonate below 15 mmol/l, and ketones above 3 mmol/l or urine ketones ++ on dipstick.
Management of DKA involves fluid replacement, insulin, and correction of electrolyte disturbance. Fluid replacement is necessary as most patients with DKA are deplete around 5-8 litres. Isotonic saline is used initially, even if the patient is severely acidotic. Insulin is administered through an intravenous infusion, and correction of electrolyte disturbance is necessary. Long-acting insulin should be continued, while short-acting insulin should be stopped. Complications may occur from DKA itself or the treatment, such as gastric stasis, thromboembolism, arrhythmias, acute respiratory distress syndrome, acute kidney injury, and cerebral edema. Children and young adults are particularly vulnerable to cerebral edema following fluid resuscitation in DKA and often need 1:1 nursing to monitor neuro-observations, headache, irritability, visual disturbance, focal neurology, etc.
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This question is part of the following fields:
- Endocrine System
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Question 12
Incorrect
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A study examines the effectiveness of adding a new antiplatelet drug to aspirin for patients over the age of 60 who have had a stroke. One hundred and fifty patients over the age of 60 are recruited for the study, with 100 receiving the new drug in addition to aspirin and the remaining 50 receiving only aspirin. After 5 years, 12 patients who received the new drug had a further stroke compared to 8 patients who just received aspirin. What is the number needed to treat?
Your Answer:
Correct Answer: 20
Explanation:Numbers needed to treat (NNT) is a measure that determines how many patients need to receive a particular intervention to reduce the expected number of outcomes by one. To calculate NNT, you divide 1 by the absolute risk reduction (ARR) and round up to the nearest whole number. ARR can be calculated by finding the absolute difference between the control event rate (CER) and the experimental event rate (EER). There are two ways to calculate ARR, depending on whether the outcome of the study is desirable or undesirable. If the outcome is undesirable, then ARR equals CER minus EER. If the outcome is desirable, then ARR is equal to EER minus CER. It is important to note that ARR may also be referred to as absolute benefit increase.
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This question is part of the following fields:
- General Principles
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Question 13
Incorrect
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A 60-year-old man complains of excessive urination and increased thirst. You want to examine for diabetes insipidus.
What is the most suitable test to conduct?Your Answer:
Correct Answer: Water deprivation test
Explanation:The water deprivation test is a diagnostic tool for investigating diabetes insipidus. The Short Synacthen test is utilized to diagnose Addison’s disease. Cranial diabetes insipidus can be treated with Desmopressin, while nephrogenic diabetes insipidus can be treated with thiazide diuretics.
Diabetes insipidus is a medical condition that can be caused by either a decreased secretion of antidiuretic hormone (ADH) from the pituitary gland (cranial DI) or an insensitivity to ADH (nephrogenic DI). Cranial DI can be caused by various factors such as head injury, pituitary surgery, and infiltrative diseases like sarcoidosis. On the other hand, nephrogenic DI can be caused by genetic factors, electrolyte imbalances, and certain medications like lithium and demeclocycline. The common symptoms of DI are excessive urination and thirst. Diagnosis is made through a water deprivation test and checking the osmolality of the urine. Treatment options include thiazides and a low salt/protein diet for nephrogenic DI, while central DI can be treated with desmopressin.
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This question is part of the following fields:
- Renal System
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Question 14
Incorrect
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A 25-year-old man slips and falls at a nightclub, resulting in a shard of glass penetrating his skin at the level of the medial epicondyle. Which of the following outcomes is the least probable?
Your Answer:
Correct Answer: Claw like appearance of the hand
Explanation:When the ulnar nerve is injured in the mid to distal forearm, it can result in a claw hand. This means that the 4th and 5th interphalangeal joints will flex while the metacarpophalangeal joints will extend. The severity of the clawing can be increased if the flexor digitorum profundus is not affected. However, if the ulnar nerve lesion is more proximal, the clinical picture will be milder due to the simultaneous paralysis of the ulnar half of the flexor digitorum profundus. This is known as the ‘ulnar paradox’. In this case, the hand may not have a claw-like appearance that is typically seen in more distal injuries. The ulnar nerve also supplies the first dorsal interosseous muscle, which will be affected by the injury.
The ulnar nerve originates from the medial cord of the brachial plexus, specifically from the C8 and T1 nerve roots. It provides motor innervation to various muscles in the hand, including the medial two lumbricals, adductor pollicis, interossei, hypothenar muscles (abductor digiti minimi, flexor digiti minimi), and flexor carpi ulnaris. Sensory innervation is also provided to the medial 1 1/2 fingers on both the palmar and dorsal aspects. The nerve travels through the posteromedial aspect of the upper arm and enters the palm of the hand via Guyon’s canal, which is located superficial to the flexor retinaculum and lateral to the pisiform bone.
The ulnar nerve has several branches that supply different muscles and areas of the hand. The muscular branch provides innervation to the flexor carpi ulnaris and the medial half of the flexor digitorum profundus. The palmar cutaneous branch arises near the middle of the forearm and supplies the skin on the medial part of the palm, while the dorsal cutaneous branch supplies the dorsal surface of the medial part of the hand. The superficial branch provides cutaneous fibers to the anterior surfaces of the medial one and one-half digits, and the deep branch supplies the hypothenar muscles, all the interosseous muscles, the third and fourth lumbricals, the adductor pollicis, and the medial head of the flexor pollicis brevis.
Damage to the ulnar nerve at the wrist can result in a claw hand deformity, where there is hyperextension of the metacarpophalangeal joints and flexion at the distal and proximal interphalangeal joints of the 4th and 5th digits. There may also be wasting and paralysis of intrinsic hand muscles (except for the lateral two lumbricals), hypothenar muscles, and sensory loss to the medial 1 1/2 fingers on both the palmar and dorsal aspects. Damage to the nerve at the elbow can result in similar symptoms, but with the addition of radial deviation of the wrist. It is important to diagnose and treat ulnar nerve damage promptly to prevent long-term complications.
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This question is part of the following fields:
- Neurological System
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Question 15
Incorrect
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During a tricuspid valve repair, the right atrium is opened after establishing cardiopulmonary bypass. Which of the following structures is not located within the right atrium?
Your Answer:
Correct Answer: Trabeculae carnae
Explanation:The walls of each cardiac chamber are made up of the epicardium, myocardium, and endocardium. The heart and roots of the great vessels are related anteriorly to the sternum and the left ribs. The coronary sinus receives blood from the cardiac veins, and the aortic sinus gives rise to the right and left coronary arteries. The left ventricle has a thicker wall and more numerous trabeculae carnae than the right ventricle. The heart is innervated by autonomic nerve fibers from the cardiac plexus, and the parasympathetic supply comes from the vagus nerves. The heart has four valves: the mitral, aortic, pulmonary, and tricuspid valves.
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This question is part of the following fields:
- Cardiovascular System
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Question 16
Incorrect
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You are present during the colonoscopy of a middle-aged patient who is being investigated by gastroenterology due to experiencing severe abdominal pain and passing bloody stools multiple times a day for several weeks. Although the symptoms have subsided, the patient also complains of significant joint pain and has had episodes of painful, red left eye with blurry vision. The consultant suspects ulcerative colitis as the probable diagnosis and performs a biopsy during the procedure to confirm it. What feature would most likely confirm the consultant's suspicions?
Your Answer:
Correct Answer: Crypt abscesses
Explanation:Ulcerative colitis is a chronic inflammatory bowel disease that can cause various symptoms, including ocular manifestations such as anterior uveitis. A biopsy of affected tissue is crucial in diagnosing ulcerative colitis and distinguishing it from other similar conditions, particularly Crohn’s disease. The characteristic microscopic features of ulcerative colitis include crypt abscesses and pseudopolyps. Partial villous atrophy is not typically associated with ulcerative colitis but may be seen in tropical sprue. Crypt hyperplasia and complete villous atrophy are more commonly seen in coeliac disease. Non-caseating granulomas and transmural inflammation are typical histological features of Crohn’s disease, which is the primary differential diagnosis for ulcerative colitis.
Inflammatory bowel disease (IBD) is a condition that includes two main types: Crohn’s disease and ulcerative colitis. Although they share many similarities in terms of symptoms, diagnosis, and treatment, there are some key differences between the two. Crohn’s disease is characterized by non-bloody diarrhea, weight loss, upper gastrointestinal symptoms, mouth ulcers, perianal disease, and a palpable abdominal mass in the right iliac fossa. On the other hand, ulcerative colitis is characterized by bloody diarrhea, abdominal pain in the left lower quadrant, tenesmus, gallstones, and primary sclerosing cholangitis. Complications of Crohn’s disease include obstruction, fistula, and colorectal cancer, while ulcerative colitis has a higher risk of colorectal cancer than Crohn’s disease. Pathologically, Crohn’s disease lesions can be seen anywhere from the mouth to anus, while ulcerative colitis inflammation always starts at the rectum and never spreads beyond the ileocaecal valve. Endoscopy and radiology can help diagnose and differentiate between the two types of IBD.
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This question is part of the following fields:
- Gastrointestinal System
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Question 17
Incorrect
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A person experiences a haemorrhage in a specific area of their brain. As a result, they are no longer able to control their body temperature. Which region of the brain has been affected?
Your Answer:
Correct Answer: Hypothalamus
Explanation:The hypothalamus plays a crucial role in regulating body temperature. Specifically, the anterior portion of the hypothalamus helps to lower body temperature by activating the parasympathetic nervous system, while the posterior nucleus helps to raise body temperature by activating the sympathetic nervous system. In contrast, the thalamus serves as a relay center in the brain, the pituitary gland secretes hormones, the midbrain is the uppermost part of the brainstem, and the medulla is the lowermost part of the brainstem. Lesions to these areas would not have a significant impact on body temperature regulation.
The hypothalamus is a part of the brain that plays a crucial role in maintaining the body’s internal balance, or homeostasis. It is located in the diencephalon and is responsible for regulating various bodily functions. The hypothalamus is composed of several nuclei, each with its own specific function. The anterior nucleus, for example, is involved in cooling the body by stimulating the parasympathetic nervous system. The lateral nucleus, on the other hand, is responsible for stimulating appetite, while lesions in this area can lead to anorexia. The posterior nucleus is involved in heating the body and stimulating the sympathetic nervous system, and damage to this area can result in poikilothermia. Other nuclei include the septal nucleus, which regulates sexual desire, the suprachiasmatic nucleus, which regulates circadian rhythm, and the ventromedial nucleus, which is responsible for satiety. Lesions in the paraventricular nucleus can lead to diabetes insipidus, while lesions in the dorsomedial nucleus can result in savage behavior.
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This question is part of the following fields:
- Neurological System
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Question 18
Incorrect
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Which of the following structures separates the intervertebral disks from the spinal cord?
Your Answer:
Correct Answer: Posterior longitudinal ligament
Explanation:The posterior longitudinal ligament covers both the posterior surface of the vertebral bodies and the intervertebral disks.
Intervertebral Discs
Intervertebral discs are composed of two main parts: the outer annulus fibrosus and the inner nucleus pulposus. The annulus fibrosus is made up of multiple layers of fibrocartilage, while the nucleus pulposus contains loose fibers suspended in a mucoprotein gel with a jelly-like consistency. The nucleus of the disc acts as a shock absorber, and pressure on the disc can cause the posterior protrusion of the nucleus pulposus. This is most commonly seen in the lumbrosacral and lower cervical areas.
The discs are separated by hyaline cartilage, and there is one disc between each pair of vertebrae, except for C1/2 and the sacrococcygeal vertebrae. Understanding the structure and function of intervertebral discs is important in the diagnosis and treatment of spinal conditions. By providing support and cushioning to the spine, these discs play a crucial role in maintaining spinal health and mobility.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 19
Incorrect
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A 65-year-old woman presents to the emergency department with central chest pain and is diagnosed with a new left bundle branch block on ECG. If a histological analysis of her heart is conducted within the first 24 hours following the MI, what are the probable findings?
Your Answer:
Correct Answer: Coagulative necrosis
Explanation:In the first 24 hours following a myocardial infarction (MI), histological findings typically show early coagulative necrosis, neutrophils, wavy fibres, and hypercontraction of myofibrils. This is a critical time period as there is a high risk of ventricular arrhythmia, heart failure, and cardiogenic shock. The necrosis occurs due to the lack of blood flow to the myocardium, and within the next few days, macrophages will begin to clear away dead tissue and granulation tissue will form to aid in the healing process. It is important to recognize the early signs of MI in order to provide prompt treatment and prevent further damage to the heart.
Myocardial infarction (MI) can lead to various complications, which can occur immediately, early, or late after the event. Cardiac arrest is the most common cause of death following MI, usually due to ventricular fibrillation. Cardiogenic shock may occur if a large part of the ventricular myocardium is damaged, and it is difficult to treat. Chronic heart failure may result from ventricular myocardium dysfunction, which can be managed with loop diuretics, ACE-inhibitors, and beta-blockers. Tachyarrhythmias, such as ventricular fibrillation and ventricular tachycardia, are common complications. Bradyarrhythmias, such as atrioventricular block, are more common following inferior MI. Pericarditis is common in the first 48 hours after a transmural MI, while Dressler’s syndrome may occur 2-6 weeks later. Left ventricular aneurysm and free wall rupture, ventricular septal defect, and acute mitral regurgitation are other complications that may require urgent medical attention.
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This question is part of the following fields:
- Cardiovascular System
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Question 20
Incorrect
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Which of the following medications can lead to hyperkalemia?
Your Answer:
Correct Answer: Heparin
Explanation:Hyperkalaemia can be caused by both unfractionated and low-molecular weight heparin due to their ability to inhibit aldosterone secretion. Salbutamol is a known remedy for hyperkalaemia.
Hyperkalaemia is a condition where there is an excess of potassium in the blood. The levels of potassium in the plasma are regulated by various factors such as aldosterone, insulin levels, and acid-base balance. When there is metabolic acidosis, hyperkalaemia can occur as hydrogen and potassium ions compete with each other for exchange with sodium ions across cell membranes and in the distal tubule. The ECG changes that can be seen in hyperkalaemia include tall-tented T waves, small P waves, widened QRS leading to a sinusoidal pattern, and asystole.
There are several causes of hyperkalaemia, including acute kidney injury, drugs such as potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, and heparin, metabolic acidosis, Addison’s disease, rhabdomyolysis, and massive blood transfusion. Foods that are high in potassium include salt substitutes, bananas, oranges, kiwi fruit, avocado, spinach, and tomatoes.
It is important to note that beta-blockers can interfere with potassium transport into cells and potentially cause hyperkalaemia in renal failure patients. In contrast, beta-agonists such as Salbutamol are sometimes used as emergency treatment. Additionally, both unfractionated and low-molecular weight heparin can cause hyperkalaemia by inhibiting aldosterone secretion.
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This question is part of the following fields:
- Renal System
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