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Question 1
Incorrect
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Which one of the following is not a branch of the posterior cord of the brachial plexus?
Your Answer: Axillary nerve
Correct Answer: Musculocutaneous nerve
Explanation:The posterior cord gives rise to mnemonic branches, including the subscapular (upper and lower), thoracodorsal, axillary, and radial nerves. On the other hand, the musculocutaneous nerve is a branch originating from the lateral cord.
Understanding the Brachial Plexus and Cutaneous Sensation of the Upper Limb
The brachial plexus is a network of nerves that originates from the anterior rami of C5 to T1. It is divided into five sections: roots, trunks, divisions, cords, and branches. To remember these sections, a common mnemonic used is Real Teenagers Drink Cold Beer.
The roots of the brachial plexus are located in the posterior triangle and pass between the scalenus anterior and medius muscles. The trunks are located posterior to the middle third of the clavicle, with the upper and middle trunks related superiorly to the subclavian artery. The lower trunk passes over the first rib posterior to the subclavian artery. The divisions of the brachial plexus are located at the apex of the axilla, while the cords are related to the axillary artery.
The branches of the brachial plexus provide cutaneous sensation to the upper limb. This includes the radial nerve, which provides sensation to the posterior arm, forearm, and hand; the median nerve, which provides sensation to the palmar aspect of the thumb, index, middle, and half of the ring finger; and the ulnar nerve, which provides sensation to the palmar and dorsal aspects of the fifth finger and half of the ring finger.
Understanding the brachial plexus and its branches is important in diagnosing and treating conditions that affect the upper limb, such as nerve injuries and neuropathies. It also helps in understanding the cutaneous sensation of the upper limb and how it relates to the different nerves of the brachial plexus.
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This question is part of the following fields:
- Neurological System
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Question 2
Correct
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A 70-year-old man is receiving treatment for pneumonia and is currently experiencing delirium. He has been catheterized and is receiving IV antibiotics. The nurse has observed that he has not urinated overnight, despite attempts to flush the catheter.
The patient has a medical history of hypertension, chronic back pain, and type 2 diabetes, for which he takes ramipril, furosemide, naproxen, and gliclazide. His daily blood tests are pending, and the morning medication round has begun.
What is the appropriate course of action regarding his medications?Your Answer: Withhold furosemide, naproxen, and ramipril, continue gliclazide and IV antibiotics
Explanation:When a patient is suspected to have acute kidney injury (AKI), it is important to stop nephrotoxic medications such as ACE inhibitors, ARBs, diuretics, and NSAIDs. In this case, the patient is on ramipril, furosemide, and naproxen, which should be withheld. Gliclazide and IV antibiotics can be continued, but blood sugar levels should be monitored closely due to the increased risk of hypoglycemia in renal impairment. It is incorrect to give morning medication and wait for blood test results, increase furosemide, withhold all regular medications, or withhold only furosemide and gliclazide while continuing everything else. The appropriate action is to withhold all nephrotoxic medications and continue necessary treatments while monitoring the patient’s condition closely.
Acute kidney injury (AKI) is a condition where there is a reduction in renal function following an insult to the kidneys. It was previously known as acute renal failure and can result in long-term impaired kidney function or even death. AKI can be caused by prerenal, intrinsic, or postrenal factors. Patients with chronic kidney disease, other organ failure/chronic disease, a history of AKI, or who have used drugs with nephrotoxic potential are at an increased risk of developing AKI. To prevent AKI, patients at risk may be given IV fluids or have certain medications temporarily stopped.
The kidneys are responsible for maintaining fluid balance and homeostasis, so a reduced urine output or fluid overload may indicate AKI. Symptoms may not be present in early stages, but as renal failure progresses, patients may experience arrhythmias, pulmonary and peripheral edema, or features of uraemia. Blood tests such as urea and electrolytes can be used to detect AKI, and urinalysis and imaging may also be necessary.
Management of AKI is largely supportive, with careful fluid balance and medication review. Loop diuretics and low-dose dopamine are not recommended, but hyperkalaemia needs prompt treatment to avoid life-threatening arrhythmias. Renal replacement therapy may be necessary in severe cases. Patients with suspected AKI secondary to urinary obstruction require prompt review by a urologist, and specialist input from a nephrologist is required for cases where the cause is unknown or the AKI is severe.
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This question is part of the following fields:
- Renal System
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Question 3
Incorrect
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A 35-year-old woman delivers a baby at term through spontaneous delivery. The newborn weighs 1500 g and appears to be struggling. Upon blood tests, hyperglycemia is detected and the baby is diagnosed with neonatal diabetes after a senior consultant evaluation. The consultant informs the mother that neonatal diabetes may result from the absence of an enzyme called glucokinase, which is essential for what function in carbohydrate metabolism?
Your Answer: Converts glucose-6-phosphate to fructose-6-phosphate
Correct Answer: Phosphorylates glucose to glucose-6-phosphate
Explanation:Glucose is phosphorylated to glucose-6-phosphate by the enzyme glucokinase. The resulting glucose-6-phosphate is then converted to fructose-6-phosphate by glucose-6-phosphate isomerase. Phosphofructokinase-1 then phosphorylates fructose-6-phosphate to form fructose-1,6-bisphosphate. Finally, pyruvate kinase converts phosphoenol pyruvate to pyruvate.
Glucokinase: An Enzyme Involved in Carbohydrate Metabolism
Glucokinase is an enzyme that can be found in various parts of the body such as the liver, pancreas, small intestine, and brain. Its primary function is to convert glucose into glucose-6-phosphate through a process called phosphorylation. This enzyme plays a crucial role in carbohydrate metabolism, which is the process of breaking down carbohydrates into energy that the body can use. Without glucokinase, the body would not be able to properly regulate its blood sugar levels, which can lead to various health problems such as diabetes. Overall, glucokinase is an essential enzyme that helps the body maintain its energy balance and overall health.
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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 50-year-old man has been diagnosed with early onset Alzheimer's disease and has a significant family history of the condition. Which gene is the most probable to be mutated?
Your Answer: APOE e4
Correct Answer: Presenilin 1 gene (PSEN1)
Explanation:Mutations in the amyloid precursor protein gene (APP), presenilin 1 gene (PSEN1), or presenilin 2 gene (PSEN2) are responsible for early onset familial Alzheimer’s disease, which is inherited in an autosomal dominant manner. Sporadic Alzheimer’s disease is strongly linked to APOE e4 mutations. Familial Parkinson’s disease is associated with PARK7 mutations, while hereditary motor neuron disease is linked to SOD1 mutations. Trinucleotide repeat mutations are also implicated in certain genetic disorders.
Alzheimer’s disease is a type of dementia that gradually worsens over time and is caused by the degeneration of the brain. There are several risk factors associated with Alzheimer’s disease, including increasing age, family history, and certain genetic mutations. The disease is also more common in individuals of Caucasian ethnicity and those with Down’s syndrome.
The pathological changes associated with Alzheimer’s disease include widespread cerebral atrophy, particularly in the cortex and hippocampus. Microscopically, there are cortical plaques caused by the deposition of type A-Beta-amyloid protein and intraneuronal neurofibrillary tangles caused by abnormal aggregation of the tau protein. The hyperphosphorylation of the tau protein has been linked to Alzheimer’s disease. Additionally, there is a deficit of acetylcholine due to damage to an ascending forebrain projection.
Neurofibrillary tangles are a hallmark of Alzheimer’s disease and are partly made from a protein called tau. Tau is a protein that interacts with tubulin to stabilize microtubules and promote tubulin assembly into microtubules. In Alzheimer’s disease, tau proteins are excessively phosphorylated, impairing their function.
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This question is part of the following fields:
- Neurological System
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Question 5
Correct
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What is the full form of ATP and how is it used during exercise?
Your Answer: Adenosine triphosphate
Explanation:ATP Generation During Exercise
During exercise, the process of muscle contraction requires the generation of ATP, which stands for adenosine triphosphate. ATP is a small molecule composed of adenine and a sugar group attached to three phosphate groups. When ATP loses a phosphate group, it becomes ADP and releases energy.
To sustain prolonged exercise, ATP must be regenerated quickly. This is achieved through the creatine phosphate – ATP system. Creatine phosphate releases a phosphate group, which allows for the rapid regeneration of ATP from ADP. This system ensures that the muscles have a constant supply of ATP to support muscle contraction during exercise. Proper ATP generation is crucial for athletes and individuals engaging in physical activity to perform at their best.
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This question is part of the following fields:
- Clinical Sciences
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Question 6
Correct
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A 9-year-old girl is taken to her doctor by her father with intense throat discomfort and is diagnosed with a probable bacterial throat infection. The doctor prescribes an antibiotic that specifically targets bacterial protein synthesis.
What is the name of the prescribed antibiotic?Your Answer: Erythromycin
Explanation:Bacterial protein synthesis is the target of erythromycin.
Bacterial division is inhibited by ciprofloxacin through targeting DNA gyrase.
The production of bacterial cell wall is inhibited by penicillin through targeting the beta-lactam ring.
The activation of folic acid in susceptible organisms is inhibited by trimethoprim.
The mechanism of action of antibiotics can be categorized into inhibiting cell wall formation, protein synthesis, DNA synthesis, and RNA synthesis. Beta-lactams such as penicillins and cephalosporins inhibit cell wall formation by blocking cross-linking of peptidoglycan cell walls. Antibiotics that inhibit protein synthesis include aminoglycosides, chloramphenicol, macrolides, tetracyclines, and fusidic acid. Quinolones, metronidazole, sulphonamides, and trimethoprim inhibit DNA synthesis, while rifampicin inhibits RNA synthesis.
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This question is part of the following fields:
- General Principles
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Question 7
Correct
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A 20-year-old male with sickle cell disease arrives at the hospital exhibiting symptoms of dehydration, infection, and acute kidney injury. What is the direct activator of the renin-angiotensin system in this case?
Your Answer: Low blood pressure
Explanation:The RAS is a hormone system that regulates plasma sodium concentration and arterial blood pressure. When plasma sodium concentration is low or renal blood flow is reduced due to low blood pressure, juxtaglomerular cells in the kidneys convert prorenin to renin, which is secreted into circulation. Renin acts on angiotensinogen to form angiotensin I, which is then converted to angiotensin II by ACE found in the lungs and epithelial cells of the kidneys. Angiotensin II is a potent vasoactive peptide that constricts arterioles, increasing arterial blood pressure and stimulating aldosterone secretion from the adrenal cortex. Aldosterone causes the kidneys to reabsorb sodium ions from tubular fluid back into the blood while excreting potassium ions in urine.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 8
Correct
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A 79-year-old woman comes to the emergency department complaining of abdominal pain that has been present for 2 days. The pain started gradually and has been constant without radiation. She denies any history of blood in her stool.
Upon assessment, her blood pressure is 124/78 mmHg, heart rate 80 beats per minute, respiratory rate 18 breaths per minute, temperature 38.1ºC, and spO2 98%.
During the physical examination, the patient experiences pain when the left iliac fossa is superficially palpated.
What is the most probable diagnosis?Your Answer: Diverticulitis
Explanation:The most likely cause of left lower quadrant pain and low-grade fever in an elderly patient is diverticulitis. Treatment for mild cases may include oral antibiotics, a liquid diet, and pain relief. Acute mesenteric ischemia, appendicitis, and ischemic colitis are less likely causes of these symptoms in an elderly patient.
Understanding Diverticulitis
Diverticulitis is a condition where an out-pouching of the intestinal mucosa becomes infected. This out-pouching is called a diverticulum and the presence of these pouches is known as diverticulosis. Diverticula are common and are thought to be caused by increased pressure in the colon. They usually occur in the sigmoid colon and are more prevalent in Westerners over the age of 60. While only a quarter of people with diverticulosis experience symptoms, 75% of those who do will have an episode of diverticulitis.
Risk factors for diverticulitis include age, lack of dietary fiber, obesity (especially in younger patients), and a sedentary lifestyle. Patients with diverticular disease may experience intermittent abdominal pain, bloating, and changes in bowel habits. Those with acute diverticulitis may experience severe abdominal pain, nausea and vomiting, changes in bowel habits, and urinary symptoms. Complications may include colovesical or colovaginal fistulas.
Signs of diverticulitis include low-grade fever, tachycardia, tender lower left quadrant of the abdomen, and possibly a palpable mass. Imaging tests such as an erect chest X-ray, abdominal X-ray, and CT scan may be used to diagnose diverticulitis. Treatment may involve oral antibiotics, a liquid diet, and analgesia for mild cases. More severe cases may require hospitalization for intravenous antibiotics. Colonoscopy should be avoided initially due to the risk of perforation.
In summary, diverticulitis is a common condition that can cause significant discomfort and complications. Understanding the risk factors, symptoms, and signs of diverticulitis can help with early diagnosis and treatment.
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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 6-year-old girl is brought to the physician by her mother due to fatigue and lethargy for the past 9 months. Previously, she was very active and was at the 80th percentile for height and weight. Currently, she is also unable to concentrate and lagging academically in school. The family moved to an old house 3 years back. During physical examination, conjunctival pallor and a blue line on her gingiva are observed.
Blood tests reveal:
Hb 100 g/L Male: (119-150)
Female: (119-150)
Platelets 340 * 109/L (150 - 400)
WBC 4 * 109/L (4.0 - 11.0)
Mean corpuscular volume (MCV) 70 fL (80 - 100)
A skeletal survey shows dense opacity at the junction of metaphysis and epiphysis of the long bones.
What is the most probable diagnosis?Your Answer: Iron deficiency anemia
Correct Answer: Lead poisoning
Explanation:Lead poisoning can cause the accumulation of lead in the metaphysis of bones, which can be seen as bands of increased density on x-rays. In this case, the child’s recent deterioration in academic and physical performance, along with the history of moving to an old house, suggests the possibility of lead-based paint exposure. The presence of a lead line on the gums further supports this suspicion. While normocytic anemia can have many causes, the addition of radiodense lines in the metaphysis of long bones increases the likelihood of lead poisoning. Cretinism, caused by maternal hypothyroidism, typically presents earlier and has different symptoms. Osteomyelitis, an infection of the bone, has different x-ray findings. Sickle cell anemia and iron deficiency are not associated with the symptoms and x-ray findings in this case.
Lead poisoning is a condition that should be considered when a patient presents with abdominal pain and neurological symptoms, along with acute intermittent porphyria. This condition is caused by defective ferrochelatase and ALA dehydratase function. Symptoms of lead poisoning include abdominal pain, peripheral neuropathy (mainly motor), neuropsychiatric features, fatigue, constipation, and blue lines on the gum margin (which is rare in children and only present in 20% of adult patients).
To diagnose lead poisoning, doctors typically measure the patient’s blood lead level, with levels greater than 10 mcg/dl considered significant. A full blood count may also be performed, which can reveal microcytic anemia and red cell abnormalities such as basophilic stippling and clover-leaf morphology. Additionally, raised serum and urine levels of delta aminolaevulinic acid may be seen, which can sometimes make it difficult to differentiate from acute intermittent porphyria. Urinary coproporphyrin is also increased, while urinary porphobilinogen and uroporphyrin levels are normal to slightly increased. In children, lead can accumulate in the metaphysis of the bones, although x-rays are not typically part of the standard work-up.
Various chelating agents are currently used to manage lead poisoning, including dimercaptosuccinic acid (DMSA), D-penicillamine, EDTA, and dimercaprol. These agents work to remove the lead from the body and can help alleviate symptoms.
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This question is part of the following fields:
- Haematology And Oncology
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Question 10
Correct
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A 55-year-old man with a smoking history of over 30 years presented to the emergency department with acute confusion and disorientation. He was unable to recognize his family members and relatives. He had been experiencing unexplained weight loss, loss of appetite, and occasional episodes of haemoptysis for the past few months. Urgent blood tests were performed, revealing abnormal levels of electrolytes and renal function.
Based on the likely diagnosis, what is the mechanism of action of the hormone that is being secreted excessively in this case?Your Answer: Insertion of aquaporin-2 channels
Explanation:Antidiuretic hormone (ADH) plays a crucial role in promoting water reabsorption by inserting aquaporin-2 channels in principal cells. In small-cell lung cancer patients, decreased serum sodium levels are commonly caused by the paraneoplastic syndrome of inadequate ADH secretion (SIADH) or ADH released during the initial lysis of tumour cells after chemotherapy. It is important to note that arteriolar vasodilation, promoting water excretion, decreased urine osmolarity, and increased portal blood flow are not functions of ADH.
Understanding Antidiuretic Hormone (ADH)
Antidiuretic hormone (ADH) is a hormone that is produced in the supraoptic nuclei of the hypothalamus and released by the posterior pituitary gland. Its primary function is to conserve body water by promoting water reabsorption in the collecting ducts of the kidneys through the insertion of aquaporin-2 channels.
ADH secretion is regulated by various factors. An increase in extracellular fluid osmolality, a decrease in volume or pressure, and the presence of angiotensin II can all increase ADH secretion. Conversely, a decrease in extracellular fluid osmolality, an increase in volume, a decrease in temperature, or the absence of ADH can decrease its secretion.
Diabetes insipidus (DI) is a condition that occurs when there is either a deficiency of ADH (cranial DI) or an insensitivity to ADH (nephrogenic DI). Cranial DI can be treated with desmopressin, which is an analog of ADH.
Overall, understanding the role of ADH in regulating water balance in the body is crucial for maintaining proper hydration and preventing conditions like DI.
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This question is part of the following fields:
- Endocrine System
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Question 11
Correct
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A 75-year-old man visits his GP complaining of trouble eating and a lump on the right side of his mandible. His blood work reveals elevated alkaline phosphatase levels and nothing else. Upon examination, doctors diagnose him with Paget's disease of the bone, which is causing his symptoms. The patient is experiencing numbness in his chin, a missing jaw jerk reflex, and muscle wasting in his mastication muscles. Through which part of the skull does the affected cranial nerve pass?
Your Answer: Foramen ovale
Explanation:The mandibular nerve travels through the foramen ovale in the skull.
This is because the foramen ovale is the exit point for CN V3 (mandibular nerve) from the trigeminal nerve, which provides sensation to the lower face. The mandibular branch also serves the muscles of mastication, the tensor veli palatini, and tensor veli tympani.
The cribriform plate is not correct as it is where the olfactory nerve innervates for the sense of smell.
The foramen rotundum is also incorrect as it is where the sensory afferents of CN V1 and V2 (ophthalmic and maxillary nerves) exit the skull.
The jugular foramen is not the answer as it is where the accessory (CN XI) nerve passes through to innervate the motor supply of the sternocleidomastoid and trapezius muscles.
Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.
In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 12
Correct
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Sarah is a 12-year-old girl who has been experiencing recurrent infections. She has been diagnosed with multiple episodes of pneumonia and sinusitis. Her sputum cultures have grown Streptococcus pneumonia in the past. Additionally, she had two episodes of meningitis caused by Neisseria meningitidis.
Sarah is currently experiencing another chest infection, and her sputum cultures have grown Pseudomonas aeruginosa.
Her blood tests are as follows:
- Hb 150 g/L (Female: 115-160)
- Platelets 320 * 109/L (150-400)
- WBC 7.5 * 109/L (4.0-11.0)
- Neuts 4.5 * 109/L (2.0-7.0)
- Lymphs 2.0 * 109/L (1.0-3.5)
- Mono 0.6 * 109/L (0.2-0.8)
- Eosin 0.4 * 109/L (0.0-0.4)
An isolated IgG level was measured and has returned normal. However, you are concerned that Sarah may have an underlying immunoglobulin deficiency based on her pattern of infections. Which immunoglobulin is likely affected?Your Answer: IgM
Explanation:Immunoglobulins, also known as antibodies, are proteins produced by the immune system to help fight off infections and diseases. There are five types of immunoglobulins found in the body, each with their own unique characteristics.
IgG is the most abundant type of immunoglobulin in blood serum and plays a crucial role in enhancing phagocytosis of bacteria and viruses. It also fixes complement and can be passed to the fetal circulation.
IgA is the most commonly produced immunoglobulin in the body and is found in the secretions of digestive, respiratory, and urogenital tracts and systems. It provides localized protection on mucous membranes and is transported across the interior of the cell via transcytosis.
IgM is the first immunoglobulin to be secreted in response to an infection and fixes complement, but does not pass to the fetal circulation. It is also responsible for producing anti-A, B blood antibodies.
IgD’s role in the immune system is largely unknown, but it is involved in the activation of B cells.
IgE is the least abundant type of immunoglobulin in blood serum and is responsible for mediating type 1 hypersensitivity reactions. It provides immunity to parasites such as helminths and binds to Fc receptors found on the surface of mast cells and basophils.
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This question is part of the following fields:
- General Principles
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Question 13
Correct
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What is the primary function of riboflavin (vitamin B2) in the human body?
Your Answer: Energy production
Explanation:The Importance of Riboflavin in the Body
Riboflavin, also known as vitamin B2, is a vital nutrient in the body. Its structure consists of a sugar molecule attached to a flavin ring structure, which gives it a yellow color. One of the main roles of riboflavin is to aid in energy production and cellular metabolism of fuels. This is achieved by the creation of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are essential for generating ATP from carbohydrates and other fuel sources. Additionally, riboflavin has antioxidant properties that help protect cells from damage caused by free radicals.
Riboflavin can be found in a variety of foods, including yeast and yeast extract, liver and kidney, wheat germ, milk and cheese, eggs, and some breakfast cereals and drinks that are fortified with riboflavin. It is important to ensure that you are getting enough riboflavin in your diet to support your body’s energy production and antioxidant functions.
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This question is part of the following fields:
- Clinical Sciences
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Question 14
Incorrect
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An Emergency Department receives a 75-year-old male patient with an intracranial haemorrhage. The patient has been undergoing heparin therapy for a deep vein thrombosis. What medication is used as a heparin antagonist to treat major bleeds associated with heparin therapy?
Your Answer: Vitamin K
Correct Answer: Protamine
Explanation:Protamine sulphate can reverse an overdose of heparin.
Heparin is a type of anticoagulant medication that comes in two main forms: unfractionated heparin and low molecular weight heparin (LMWH). Both types work by activating antithrombin III, but unfractionated heparin forms a complex that inhibits thrombin, factors Xa, IXa, XIa, and XIIa, while LMWH only increases the action of antithrombin III on factor Xa. Adverse effects of heparins include bleeding, thrombocytopenia, osteoporosis, and hyperkalemia. LMWH has a lower risk of causing heparin-induced thrombocytopenia (HIT) and osteoporosis compared to unfractionated heparin. HIT is an immune-mediated condition where antibodies form against complexes of platelet factor 4 (PF4) and heparin, leading to platelet activation and a prothrombotic state. Treatment for HIT includes direct thrombin inhibitors or danaparoid. Heparin overdose can be partially reversed by protamine sulfate.
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This question is part of the following fields:
- General Principles
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Question 15
Incorrect
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As a junior doctor at a general practice, you have an appointment with a 58-year-old man who has been diagnosed with atrial fibrillation. Upon reviewing his notes, you see that he has been prescribed a class three antiarrhythmic medication that blocks potassium channels. Which of the following drugs functions via this mechanism?
Your Answer: Flecainide
Correct Answer: Sotalol
Explanation:Sotalol is classified as a beta-blocker, but it also blocks potassium channels, which slows down the heart rate by delaying ventricular relaxation. This makes it a class three antiarrhythmic agent, along with amiodarone. However, it can also cause a life-threatening type of ventricular tachycardia called torsades de pointes due to its effects on potassium channels.
Digoxin, on the other hand, is a cardiac glycoside that works by reducing conduction through the atrioventricular node, slowing down the ventricular rate in atrial fibrillation and flutter. It also has positive inotropic effects, meaning it can increase the heart’s contractility. It does not fit into the Vaughan Williams classification.
Flecainide is a class one antiarrhythmic agent that blocks fast inward sodium channels and prolongs the refractory period of the heart during diastole.
Propranolol is a beta-blocker and falls under category two of the Vaughan-Williams classification. It is non-selective and used to treat various conditions such as hypertension, thyrotoxicosis, pheochromocytoma, anxiety, angina, essential tremor, and migraine prophylaxis. However, caution should be exercised when using it in patients with asthma as it can cause bronchospasm.
The Vaughan Williams Classification of Antiarrhythmics
The Vaughan Williams classification is a widely used system for categorizing antiarrhythmic drugs based on their mechanism of action. The classification system is divided into four classes, each with a different mechanism of action. Class I drugs block sodium channels, Class II drugs are beta-adrenoceptor antagonists, Class III drugs block potassium channels, and Class IV drugs are calcium channel blockers.
Class Ia drugs, such as quinidine and procainamide, increase the duration of the action potential by blocking sodium channels. However, quinidine toxicity can cause cinchonism, which is characterized by symptoms such as headache, tinnitus, and thrombocytopenia. Procainamide may also cause drug-induced lupus.
Class Ib drugs, such as lidocaine and mexiletine, decrease the duration of the action potential by blocking sodium channels. Class Ic drugs, such as flecainide and propafenone, have no effect on the duration of the action potential but still block sodium channels.
Class II drugs, such as propranolol and metoprolol, are beta-adrenoceptor antagonists that decrease the heart rate and contractility of the heart.
Class III drugs, such as amiodarone and sotalol, block potassium channels, which prolongs the duration of the action potential.
Class IV drugs, such as verapamil and diltiazem, are calcium channel blockers that decrease the influx of calcium ions into the heart, which slows down the heart rate and reduces contractility.
It should be noted that some common antiarrhythmic drugs, such as adenosine, atropine, digoxin, and magnesium, are not included in the Vaughan Williams classification.
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This question is part of the following fields:
- General Principles
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Question 16
Incorrect
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A 9-year-old girl has come to your clinic complaining of fatigue and widespread aches. She describes the pain as 'burning'. During the examination, you notice small, painless bumps on her abdomen, and she also has proteinuria. Based on these symptoms, you suspect that she may have Fabry disease.
What is the mode of inheritance for this condition?Your Answer: Autosomal recessive
Correct Answer: X-linked recessive
Explanation:Understanding Fabry Disease
Fabry disease is a genetic disorder that is inherited in an X-linked recessive manner. It is caused by a deficiency of alpha-galactosidase A, an enzyme that breaks down a type of fat called globotriaosylceramide. This leads to the accumulation of this fat in various organs and tissues, causing a range of symptoms.
One of the earliest symptoms of Fabry disease is burning pain or paraesthesia in childhood, particularly in the hands and feet. Other common features include angiokeratomas, which are small red or purple spots on the skin, and lens opacities, which can cause vision problems. Proteinuria, or the presence of excess protein in the urine, is also a common finding in people with Fabry disease.
Perhaps the most serious complication of Fabry disease is early cardiovascular disease, which can lead to heart attacks and strokes. This is thought to be due to the accumulation of globotriaosylceramide in the walls of blood vessels, causing them to become stiff and narrow.
Overall, Fabry disease is a complex condition that can affect many different parts of the body. Early diagnosis and treatment are important for managing symptoms and preventing complications.
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This question is part of the following fields:
- General Principles
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Question 17
Correct
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You are working in the palliative care unit. A 67-year-old male has severe neuropathic pain secondary to spinal cord metastasis. It has been unresponsive to titration of opioid and neuropathic agents. Your consultant decides to use ketamine.
What is the mechanism of action of ketamine?Your Answer: NMDA receptor antagonist
Explanation:Ketamine works by blocking NMDA receptors. It can be used to treat neuropathic pain that does not respond well to opioids and other oral pain medications, especially when there is abnormal pain sensitivity such as allodynia, hyperalgesia, or hyperpathia.
Gabapentin works by changing the way voltage-gated calcium channels function.
Pregabalin is similar to the neurotransmitter GABA.
Benzodiazepines activate GABA receptors.
Local anesthetics like lidocaine block sodium channels.
Overview of Commonly Used IV Induction Agents
Propofol, sodium thiopentone, ketamine, and etomidate are some of the commonly used IV induction agents in anesthesia. Propofol is a GABA receptor agonist that has a rapid onset of anesthesia but may cause pain on IV injection. It is widely used for maintaining sedation on ITU, total IV anesthesia, and day case surgery. Sodium thiopentone has an extremely rapid onset of action, making it the agent of choice for rapid sequence induction. However, it may cause marked myocardial depression and metabolites build up quickly, making it unsuitable for maintenance infusion. Ketamine, an NMDA receptor antagonist, has moderate to strong analgesic properties and produces little myocardial depression, making it a suitable agent for anesthesia in those who are hemodynamically unstable. However, it may induce a state of dissociative anesthesia resulting in nightmares. Etomidate has a favorable cardiac safety profile with very little hemodynamic instability but has no analgesic properties and is unsuitable for maintaining sedation as prolonged use may result in adrenal suppression. Postoperative vomiting is common with etomidate.
Overall, each of these IV induction agents has specific features that make them suitable for different situations. Anesthesiologists must carefully consider the patient’s medical history, current condition, and the type of surgery being performed when selecting an appropriate induction agent.
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This question is part of the following fields:
- General Principles
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Question 18
Incorrect
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A 78-year-old man is diagnosed with a vitamin B1 deficiency. What food is known to be a rich source of thiamine?
Your Answer: White bread
Correct Answer: Wheat germ
Explanation:Thiamine Deficiency and Dietary Sources
Thiamine, also known as vitamin B1, is an essential nutrient that the body cannot store in large amounts and must be obtained through the diet. Wholegrain cereals, oatmeal, yeast, pork, sunflower seeds, and certain vegetables such as potatoes, asparagus, and cauliflower are good dietary sources of thiamine. However, refined cereals and white flour typically contain low levels of thiamine, and processing, boiling, and overcooking vegetables can remove a significant amount of the vitamin.
Thiamine plays a crucial role in energy production, nervous transmission, and collagen synthesis. A deficiency in thiamine can lead to impairment of these processes, resulting in various signs and symptoms such as muscle tenderness, weakness, and reduced reflexes, confusion, memory impairment, impaired wound healing, poor balance, falls, constipation, and reduced appetite. Therefore, it is important to ensure adequate intake of thiamine through a balanced diet to prevent deficiency and maintain optimal health.
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This question is part of the following fields:
- Clinical Sciences
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Question 19
Incorrect
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Which of the following anatomical planes separates the prostate from the rectum?
Your Answer: None of the above
Correct Answer: Denonvilliers fascia
Explanation:The rectum is separated from the prostate by the Denonvilliers fascia, while the sacrum is separated from the rectum by Waldeyer’s fascia.
Anatomy of the Prostate Gland
The prostate gland is a small, walnut-shaped gland located below the bladder and separated from the rectum by Denonvilliers fascia. It receives its blood supply from the internal iliac vessels, specifically the inferior vesical artery. The gland has an internal sphincter at its apex, which can be damaged during surgery and result in retrograde ejaculation.
The prostate gland has four lobes: the posterior lobe, median lobe, and two lateral lobes. It also has an isthmus and three zones: the peripheral zone, central zone, and transition zone. The peripheral zone, which is the subcapsular portion of the posterior prostate, is where most prostate cancers occur.
The gland is surrounded by various structures, including the pubic symphysis, prostatic venous plexus, Denonvilliers fascia, rectum, ejaculatory ducts, lateral venous plexus, and levator ani. Its lymphatic drainage is to the internal iliac nodes, and its innervation comes from the inferior hypogastric plexus.
In summary, the prostate gland is a small but important gland in the male reproductive system. Its anatomy includes lobes, zones, and various surrounding structures, and it plays a crucial role in ejaculation and prostate health.
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This question is part of the following fields:
- Gastrointestinal System
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Question 20
Incorrect
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An 80-year-old man visits the GP clinic for a routine hearing examination. He reports a decline in hearing ability in his left ear for the past few months. After conducting Rinne and Weber tests, you determine that he has conductive hearing loss in the left ear. Upon otoscopy, you observe cerumen impaction.
What are the test findings for this patient?Your Answer: Rinne: bone conduction > air conduction in left ear; Weber: lateralising to left ear
Correct Answer: Rinne: bone conduction > air conduction in right ear; Weber: lateralising to right ear
Explanation:Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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