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Question 1
Incorrect
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A 4-day old neonate with Down's syndrome is experiencing excessive vomiting during their stay in the ward. The mother had an uncomplicated full-term pregnancy. The baby has not yet had their first bowel movement, causing increased concern for the parents. Upon examination, there is slight abdominal distension. Where is the site of pathology within the colon?
Your Answer: Serosa
Correct Answer: Muscularis propria externa
Explanation:The myenteric nerve plexus, also known as Auerbach’s plexus, is located within the muscularis externa, which is one of the four layers of the bowel. In neonates with Hirschsprung disease, there is a lack of ganglion cells in the myenteric plexus, resulting in a lack of peristalsis and symptoms such as nausea, vomiting, bloating, and delayed passage of meconium. This condition is more common in males and children with Down’s syndrome.
The four layers of the bowel, from deep to superficial, are the mucosa, submucosa, muscularis propria (externa), and serosa. The muscularis externa contains two layers of smooth muscle, the inner circular layer and the outer longitudinal layer, with the myenteric plexus located between them. The mucosa also contains a thin layer of connective tissue called the lamina propria.
Layers of the Gastrointestinal Tract and Their Functions
The gastrointestinal (GI) tract is composed of four layers, each with its own unique function. The innermost layer is the mucosa, which can be further divided into three sublayers: the epithelium, lamina propria, and muscularis mucosae. The epithelium is responsible for absorbing nutrients and secreting mucus, while the lamina propria contains blood vessels and immune cells. The muscularis mucosae helps to move food along the GI tract.
The submucosa is the layer that lies beneath the mucosa and contains Meissner’s plexus, which is responsible for regulating secretion and blood flow. The muscularis externa is the layer that lies beneath the submucosa and contains Auerbach’s plexus, which controls the motility of GI smooth muscle. Finally, the outermost layer of the GI tract is either the serosa or adventitia, depending on whether the organ is intraperitoneal or retroperitoneal. The serosa is responsible for secreting fluid to lubricate the organs, while the adventitia provides support and protection. Understanding the functions of each layer is important for understanding the overall function of the GI tract.
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This question is part of the following fields:
- Gastrointestinal System
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Question 2
Correct
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A 28-year-old man is found on his bathroom floor next to needles and syringes and is brought into the hospital. He has a Glasgow coma score of 10 and a bedside oxygen saturation of 88%. On physical examination, he has pinpoint pupils and needle track marks on his left arm. His arterial blood gases are as follows: PaO2 7.4 kPa (11.3-12.6), PaCO2 9.6 kPa (4.7-6.0), pH 7.32 (7.36-7.44), and HCO3 25 mmol/L (20-28). What do these results indicate?
Your Answer: Acute type II respiratory failure
Explanation:Opiate Overdose
Opiate overdose is a common occurrence that can lead to slowed breathing, inadequate oxygen saturation, and CO2 retention. This classic picture of opiate overdose can be reversed with the use of naloxone. The condition is often caused by the use of illicit drugs and can have serious consequences if left untreated.
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This question is part of the following fields:
- Respiratory System
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Question 3
Correct
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A 67-year-old patient is being evaluated after being admitted for treatment of a persistent Clostridium difficile infection. The patient had received treatment for a previous infection three weeks ago, but the symptoms did not subside, and she continued to experience diarrhoea. The patient was hospitalized three days ago due to a life-threatening Clostridium difficile infection.
The patient has been receiving oral vancomycin and IV metronidazole for the past few days, but there has been no improvement in her symptoms. What would be the venous blood gas results in this case?Your Answer: Metabolic acidosis + hypokalaemia
Explanation:If a patient experiences prolonged diarrhoea, they may develop metabolic acidosis and hypokalaemia. This is likely the case for a patient with a history of prolonged Clostridium difficile infection, as the loss of bicarbonate ions from the GI tract during diarrhoea can lead to metabolic acidosis. Prolonged diarrhoea can also result in hypokalaemia due to the direct loss of potassium from the GI tract, which the body may be unable to compensate for. Therefore, metabolic acidosis and hypokalaemia are the expected outcomes in this scenario.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 4
Correct
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As a medical student in general practice, a 45-year-old male patient complains of fatigue and is diagnosed with anemia. What is the recommended daily intake of iron for an average person?
Your Answer: 8-14mg
Explanation:According to the NHS, the recommended daily intake of iron is 8.7mg for men (aged 19-64) and 14.8mg for women (aged 19-50). Women aged 50-64 require 8.7mg per day. It is possible to obtain sufficient iron from a balanced diet.
Iron Metabolism: Absorption, Distribution, Transport, Storage, and Excretion
Iron is an essential mineral that plays a crucial role in various physiological processes. The absorption of iron occurs mainly in the upper small intestine, particularly the duodenum. Only about 10% of dietary iron is absorbed, and ferrous iron (Fe2+) is much better absorbed than ferric iron (Fe3+). The absorption of iron is regulated according to the body’s need and can be increased by vitamin C and gastric acid. However, it can be decreased by proton pump inhibitors, tetracycline, gastric achlorhydria, and tannin found in tea.
The total body iron is approximately 4g, with 70% of it being present in hemoglobin, 25% in ferritin and haemosiderin, 4% in myoglobin, and 0.1% in plasma iron. Iron is transported in the plasma as Fe3+ bound to transferrin. It is stored in tissues as ferritin, and the lost iron is excreted via the intestinal tract following desquamation.
In summary, iron metabolism involves the absorption, distribution, transport, storage, and excretion of iron in the body. Understanding these processes is crucial in maintaining iron homeostasis and preventing iron-related disorders.
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This question is part of the following fields:
- General Principles
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Question 5
Correct
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A woman in her 30s experiences dehydration from diarrhoea and vomiting, leading to activation of the renin-angiotensin-aldosterone system by her kidneys. This increases the pressure across the glomerulus and maintains glomerular filtration rate. What is the normal passage of blood through this area?
Your Answer: afferent arteriole- glomerular capillary bed- efferent arteriole- peritubular capillaries and medullary vasa recta
Explanation:The journey of blood to a nephron begins with the afferent arteriole, followed by the glomerular capillary bed, efferent arteriole, and finally the peritubular capillaries and medullary vasa recta.
The afferent arteriole is the first stage, where blood enters the nephron. From there, it flows through the glomerulus and exits through the efferent arteriole.
If the efferent arteriole is constricted, it can increase pressure across the glomerulus, leading to a higher filtration fraction and maintaining eGFR.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 6
Incorrect
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A 28-year-old man with Crohn's disease is prescribed azathioprine. His doctor orders a blood test to evaluate TPMT activity. What is the doctor's primary concern?
Your Answer: Low enzyme activity leading to accumulation of azathioprine
Correct Answer: Low enzyme activity leading to accumulation of 6-mercaptopurine
Explanation:Enzyme Deficiencies and Drug Toxicity
Enzyme deficiencies can lead to drug toxicity and adverse effects in patients. One example is TPMT deficiency, which can cause accumulation of 6-mercaptopurine, the active metabolite of azathioprine. This can result in bone marrow suppression and other serious complications. Approximately 10% of individuals have low TPMT activity, while 0.3% have very low activity, putting them at high risk for azathioprine-related toxicity.
Another example of enzyme deficiency is phenylalanine hydroxylase deficiency, which leads to the accumulation of phenylalanine. This condition, known as phenylketonuria, can be detected through neonatal screening using a blood spot taken from the heel several days after birth.
In clinical practice, many gastroenterologists will start patients on azathioprine and send for TPMT enzyme activity testing. Patients are advised to stop the drug if they experience symptoms, but to continue taking it while waiting for the results if they do not. Early detection of enzyme deficiencies can help prevent drug toxicity and improve patient outcomes.
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This question is part of the following fields:
- Clinical Sciences
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Question 7
Incorrect
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A 32-year-old man has come in for a follow-up appointment after being diagnosed with irritable bowel syndrome. However, his faecal calprotectin was slightly elevated, but not high enough to raise suspicion of inflammatory bowel disease.
He had initially presented with abdominal pain and diarrhoea, along with feelings of discomfort and bloating that were relieved upon defecation. He denied any presence of blood in his stool. You prescribed psyllium husk and scheduled a review in four weeks. He has a medical history of low back pain, migraine, and depression.
Today, his faecal calprotectin has returned to normal levels. What is the most likely cause of the initial abnormal test result?Your Answer: Ulcerative colitis
Correct Answer: Use of NSAIDs
Explanation:Mallory-Weiss syndrome (MWS) is characterized by a rupture in the mucous membrane at the junction of the stomach and oesophagus.
Faecal Calprotectin: A Screening Tool for Intestinal Inflammation
Faecal calprotectin is a recommended screening tool for inflammatory bowel disease (IBD) by NICE. It is a test that detects intestinal inflammation and can also be used to monitor the response to treatment in IBD patients. The test has a high sensitivity of 93% and specificity of 96% for IBD in adults. However, in children, the specificity falls to around 75%.
Apart from IBD, other conditions that can cause a raised faecal calprotectin include bowel malignancy, coeliac disease, infectious colitis, and the use of NSAIDs. Therefore, faecal calprotectin is a useful diagnostic tool for detecting intestinal inflammation and can aid in the diagnosis and management of various gastrointestinal conditions.
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This question is part of the following fields:
- Gastrointestinal System
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Question 8
Incorrect
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These thyroid function tests were obtained on a 55-year-old female who has recently been treated for hypertension:
Free T4 28.5 pmol/L (9.8-23.1)
TSH <0.02 mU/L (0.35-5.5)
Free T3 10.8 pmol/L (3.5-6.5)
She now presents with typical symptoms of hyperthyroidism.
Which medication is likely to have caused this?Your Answer: Disopyramide
Correct Answer: Amiodarone
Explanation:Amiodarone and its Effects on Thyroid Function
Amiodarone is a medication that can have an impact on thyroid function, resulting in both hypo- and hyperthyroidism. This is due to the high iodine content in the drug, which contributes to its antiarrhythmic effects. Atenolol, on the other hand, is a beta blocker that is commonly used to treat thyrotoxicosis. Warfarin is another medication that is used to treat atrial fibrillation.
There are two types of thyrotoxicosis that can be caused by amiodarone. Type 1 results in excess thyroxine synthesis, while type 2 leads to the release of excess thyroxine but normal levels of synthesis. It is important for healthcare professionals to monitor thyroid function in patients taking amiodarone and adjust treatment as necessary to prevent complications.
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This question is part of the following fields:
- Pharmacology
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Question 9
Correct
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A 70-year-old man is undergoing an elective total knee replacement surgery for chronic osteoarthritis. The surgical team aims to minimize the risk of damage to the common peroneal nerve and tibial nerve during the procedure. Can you identify the anatomical landmark where the sciatic nerve divides into these two nerves?
Your Answer: Apex of the popliteal fossa
Explanation:The sciatic nerve is derived from the lumbosacral plexus and consists of nerve roots L4-S3. It enters the gluteal region through the greater sciatic foramen and emerges inferiorly to the piriformis muscle, traveling inferolaterally. The nerve enters the posterior thigh by passing deep to the long head of biceps femoris and eventually splits into the tibial and common fibular nerves at the apex of the popliteal fossa. The sciatic nerve primarily innervates the muscles of the posterior thigh and the hamstring portion of the adductor magnus, but it has no direct sensory function.
Understanding the Sciatic Nerve
The sciatic nerve is the largest nerve in the body, formed from the sacral plexus and arising from spinal nerves L4 to S3. It passes through the greater sciatic foramen and emerges beneath the piriformis muscle, running under the cover of the gluteus maximus muscle. The nerve provides cutaneous sensation to the skin of the foot and leg, as well as innervating the posterior thigh muscles and lower leg and foot muscles. Approximately halfway down the posterior thigh, the nerve splits into the tibial and common peroneal nerves. The tibial nerve supplies the flexor muscles, while the common peroneal nerve supplies the extensor and abductor muscles.
The sciatic nerve also has articular branches for the hip joint and muscular branches in the upper leg, including the semitendinosus, semimembranosus, biceps femoris, and part of the adductor magnus. Cutaneous sensation is provided to the posterior aspect of the thigh via cutaneous nerves, as well as the gluteal region and entire lower leg (except the medial aspect). The nerve terminates at the upper part of the popliteal fossa by dividing into the tibial and peroneal nerves. The nerve to the short head of the biceps femoris comes from the common peroneal part of the sciatic, while the other muscular branches arise from the tibial portion. The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis, which is innervated by the common peroneal nerve.
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This question is part of the following fields:
- Neurological System
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Question 10
Correct
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A 35-year-old woman came in with a 7-month history of upper abdominal pain and nausea. She reported no weight loss. An upper GI endoscopy showed mild gastritis, but her symptoms persisted even after a 3-month course of proton pump inhibitors. A CT scan was done and revealed a probable gastrinoma. Which type of cell does the hormone produced by this tumor target to stimulate acid secretion?
Your Answer: Parietal cell
Explanation:The secretion of H+ by gastric parietal cells is increased by gastrin.
Overview of Gastrointestinal Hormones
Gastrointestinal hormones play a crucial role in the digestion and absorption of food. These hormones are secreted by various cells in the stomach and small intestine in response to different stimuli such as the presence of food, pH changes, and neural signals.
One of the major hormones involved in food digestion is gastrin, which is secreted by G cells in the antrum of the stomach. Gastrin increases acid secretion by gastric parietal cells, stimulates the secretion of pepsinogen and intrinsic factor, and increases gastric motility. Another hormone, cholecystokinin (CCK), is secreted by I cells in the upper small intestine in response to partially digested proteins and triglycerides. CCK increases the secretion of enzyme-rich fluid from the pancreas, contraction of the gallbladder, and relaxation of the sphincter of Oddi. It also decreases gastric emptying and induces satiety.
Secretin is another hormone secreted by S cells in the upper small intestine in response to acidic chyme and fatty acids. Secretin increases the secretion of bicarbonate-rich fluid from the pancreas and hepatic duct cells, decreases gastric acid secretion, and has a trophic effect on pancreatic acinar cells. Vasoactive intestinal peptide (VIP) is a neural hormone that stimulates secretion by the pancreas and intestines and inhibits acid secretion.
Finally, somatostatin is secreted by D cells in the pancreas and stomach in response to fat, bile salts, and glucose in the intestinal lumen. Somatostatin decreases acid and pepsin secretion, decreases gastrin secretion, decreases pancreatic enzyme secretion, and decreases insulin and glucagon secretion. It also inhibits the trophic effects of gastrin and stimulates gastric mucous production.
In summary, gastrointestinal hormones play a crucial role in regulating the digestive process and maintaining homeostasis in the gastrointestinal tract.
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This question is part of the following fields:
- Gastrointestinal System
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Question 11
Incorrect
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A 47-year-old woman, who is notably tall, visits the surgical clinic due to bilateral inguinal hernias. During her evaluation, she experiences chest discomfort and faints. A chest x-ray reveals indications of mediastinal widening. What is the probable underlying condition?
Your Answer: Tietze syndrome
Correct Answer: Aortic dissection
Explanation:Individuals with Marfan syndrome may exhibit various connective tissue disorders, including bilateral inguinal hernia. They are particularly susceptible to aortic dissection, as demonstrated in this instance.
Aortic dissection is a serious condition that can cause chest pain. It occurs when there is a tear in the inner layer of the aorta’s wall. Hypertension is the most significant risk factor, but it can also be associated with trauma, bicuspid aortic valve, and certain genetic disorders. Symptoms of aortic dissection include severe and sharp chest or back pain, weak or absent pulses, hypertension, and aortic regurgitation. Specific arteries’ involvement can cause other symptoms such as angina, paraplegia, or limb ischemia. The Stanford classification divides aortic dissection into type A, which affects the ascending aorta, and type B, which affects the descending aorta. The DeBakey classification further divides type A into type I, which extends to the aortic arch and beyond, and type II, which is confined to the ascending aorta. Type III originates in the descending aorta and rarely extends proximally.
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This question is part of the following fields:
- Cardiovascular System
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Question 12
Incorrect
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A 68-year-old male comes to the emergency department with a sudden onset of numbness in his right arm and leg. During the examination, you observe that he has left-sided facial numbness. There are no alterations in his speech or hearing, and he has no weakness in any of his limbs.
What is the probable diagnosis?Your Answer: Lateral pontine syndrome
Correct Answer: Lateral medullary syndrome
Explanation:Understanding Lateral Medullary Syndrome
Lateral medullary syndrome, also referred to as Wallenberg’s syndrome, is a condition that arises when the posterior inferior cerebellar artery becomes blocked. This condition is characterized by a range of symptoms that affect both the cerebellum and brainstem. Cerebellar features of the syndrome include ataxia and nystagmus, while brainstem features include dysphagia, facial numbness, and cranial nerve palsy such as Horner’s. Additionally, patients may experience contralateral limb sensory loss. Understanding the symptoms of lateral medullary syndrome is crucial for prompt diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 13
Correct
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A middle-aged male patient with a history of schizophrenia and non-compliance with medication presents with delusions of alien possession. How would you characterize his delusions?
Your Answer: Delusions of control
Explanation:Schizophrenia Symptoms: Delusion of Control, Depersonalisation, and Delusions of Misidentification
Delusion of control, also known as passivity experience, is a primary symptom of schizophrenia identified by Schneider. This symptom is characterized by the belief that one’s body, mind, volition, or emotion is being controlled by another entity, being, or force. On the other hand, depersonalisation is the feeling of being disconnected from reality, often accompanied by derealisation.
Delusions of misidentification, another symptom of schizophrenia, can be divided into two types: Fregoli Syndrome and Capgras Syndrome. Fregoli Syndrome is the belief that someone whose appearance is unfamiliar is actually someone you know, while Capgras Syndrome is the belief that someone who looks familiar is an imposter.
Overall, these symptoms can significantly impact an individual’s perception of reality and their ability to function in daily life. It is important to seek professional help if experiencing any of these symptoms or suspecting someone else may be experiencing them.
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This question is part of the following fields:
- Psychiatry
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Question 14
Correct
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A 16-year-old patient presents to his GP with concerns about his physical development. The patient reports feeling self-conscious about his body shape and experiencing bullying at school. On examination, the patient is noted to have gynaecomastia and microorchidism. The patient is referred to a paediatrician, who subsequently refers the patient to the genetics team. As part of their assessment, the genetics team orders a karyotype.
What karyotype results would be expected for this patient, given the likely diagnosis?Your Answer: Klinefelter syndrome (47,XXY)
Explanation:Understanding Klinefelter’s Syndrome
Klinefelter’s syndrome is a genetic condition that is characterized by an extra X chromosome, resulting in a karyotype of 47, XXY. Individuals with this syndrome often have a taller than average stature, but lack secondary sexual characteristics. They may also have small, firm testes and be infertile. Gynaecomastia, or the development of breast tissue, is also common in individuals with Klinefelter’s syndrome, and there is an increased risk of breast cancer. Despite elevated levels of gonadotrophins, testosterone levels are typically low.
Diagnosis of Klinefelter’s syndrome is made through karyotyping, which involves analyzing an individual’s chromosomes. It is important for individuals with this condition to receive appropriate medical care and support, as well as genetic counseling for family planning.
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This question is part of the following fields:
- Endocrine System
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Question 15
Incorrect
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A university conducts a study to test for the effectiveness of a new teaching method. It turns out that in 20% of the cases, the results are not statistically significant. In other words, 20% of the time there is no difference found.
What is the statistical power given the information above?Your Answer: 0.80
Correct Answer: 0.85
Explanation:Understanding the Concept of Power in Research Studies
Power is a statistical concept that refers to the probability of correctly rejecting the null hypothesis when it is false. In other words, it is the ability of a study to detect a clinically meaningful difference or effect. The value of power ranges from 0 to 1, with 0 indicating 0% and 1 indicating 100%. It is often expressed as 1 – beta, where beta is the probability of a Type II error. A power of 0.80 is generally considered the minimum acceptable level.
Several factors influence the power of a study, including sample size, meaningful effect size, and significance level. Larger sample sizes lead to more accurate parameter estimations and increase the study’s ability to detect a significant effect. The meaningful effect size is determined at the beginning of the study and represents the size of the difference between two means that would lead to the rejection of the null hypothesis. Finally, the significance level, also known as the alpha level, is the probability of a Type I error. Understanding the concept of power is crucial in determining the appropriate sample size and designing a study that can accurately detect meaningful differences or effects.
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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 68-year-old man visits the clinic with a complaint of persistent hiccups that have been ongoing for 5 days. During the consultation, he mentions feeling increasingly fatigued over the past 7 months. Apart from these issues, he reports no other health concerns. After conducting some blood tests, you discover that he is experiencing renal failure, and his potassium levels are at 6.2 (normal range is 3.5-5 mmol/l). You urgently advise him to go to the hospital, and upon arrival, the medical team requests an ECG to check for signs of hyperkalaemia. What is an ECG indication of hyperkalaemia?
Your Answer:
Correct Answer: Wide QRS complexes
Explanation:Hyperkalaemia can be identified on an ECG by the presence of broad QRS complexes, which may appear bizarre and form a sinusoidal waveform. Other signs include tall-tented T waves and small or absent P waves. Asystole can also occur as a result of hyperkalaemia.
On the other hand, hypokalaemia can be identified by ECG signs such as small or inverted T waves, ST segment depression, and prominent U waves. A prolonged PR interval and long QT interval may also be present, although a short PR interval may suggest pre-excitation or an AV nodal rhythm.
In the case of a patient presenting with hiccups, persistent hiccups may indicate uraemia, which can be caused by renal failure. Fatigue is another common symptom of renal failure, which is also a common cause of 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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Question 17
Incorrect
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These results were obtained on a 30-year-old male who has presented with tiredness:
Free T4 9.3 pmol/L (9.8-23.1)
TSH 49.31 mU/L (0.35-5.50)
What signs might be expected in this case?Your Answer:
Correct Answer: Slow relaxation of biceps reflex
Explanation:Diagnosis and Symptoms of Hypothyroidism
Hypothyroidism is diagnosed through blood tests that show low levels of T4 and elevated levels of TSH. Physical examination may reveal slow relaxation of tendon jerks, bradycardia, and goitre. A bruit over a goitre is associated with Graves’ thyrotoxicosis, while palmar erythema and fine tremor occur in thyrotoxicosis. In addition to these common symptoms, hypothyroidism may also present with rarer features such as cerebellar features, compression neuropathies, hypothermia, and macrocytic anaemia. It is important to diagnose and treat hypothyroidism promptly to prevent further complications.
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This question is part of the following fields:
- Endocrine System
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Question 18
Incorrect
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A 27-year-old man, who has a history of epilepsy, attends a follow-up appointment at neurology outpatients. He reports experiencing a prodrome of aura before having floaters in his vision and unusual flashes of color during the ictal phase. The patient has no other notable symptoms or medical history. Which region of the brain is linked to the symptoms described by this patient?
Your Answer:
Correct Answer: Occipital lobe
Explanation:Occipital lobe seizures are associated with visual disturbances such as floaters and flashes. The cerebellum is not typically associated with epilepsy, although recent research has potentially implicated this area in refractory epilepsy. Seizures in the frontal lobe can cause random hand and leg movements and abnormal posturing, while seizures in the parietal lobe can cause sensory disturbances such as paraesthesia.
Localising Features of Focal Seizures in Epilepsy
Focal seizures in epilepsy can be localised based on the specific location of the brain where they occur. Temporal lobe seizures are common and may occur with or without impairment of consciousness or awareness. Most patients experience an aura, which is typically a rising epigastric sensation, along with psychic or experiential phenomena such as déjà vu or jamais vu. Less commonly, hallucinations may occur, such as auditory, gustatory, or olfactory hallucinations. These seizures typically last around one minute and are often accompanied by automatisms, such as lip smacking, grabbing, or plucking.
On the other hand, frontal lobe seizures are characterised by motor symptoms such as head or leg movements, posturing, postictal weakness, and Jacksonian march. Parietal lobe seizures, on the other hand, are sensory in nature and may cause paraesthesia. Finally, occipital lobe seizures may cause visual symptoms such as floaters or flashes. By identifying the specific location and type of seizure, doctors can better diagnose and treat epilepsy in patients.
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This question is part of the following fields:
- Neurological System
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Question 19
Incorrect
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A 30-year-old man visits the GP complaining of weakness in his right foot muscles. The GP observes difficulty with inversion and suspects weakness in the posterior leg muscles.
Which muscle is responsible for this movement?Your Answer:
Correct Answer: Tibialis posterior
Explanation:The muscles located in the deep posterior compartment are:
Muscular Compartments of the Lower Limb
The lower limb is composed of different muscular compartments that perform various actions. The anterior compartment includes the tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus muscles. These muscles are innervated by the deep peroneal nerve and are responsible for dorsiflexing the ankle joint, inverting and evert the foot, and extending the toes.
The peroneal compartment, on the other hand, consists of the peroneus longus and peroneus brevis muscles, which are innervated by the superficial peroneal nerve. These muscles are responsible for eversion of the foot and plantar flexion of the ankle joint.
The superficial posterior compartment includes the gastrocnemius and soleus muscles, which are innervated by the tibial nerve. These muscles are responsible for plantar flexion of the foot and may also flex the knee.
Lastly, the deep posterior compartment includes the flexor digitorum longus, flexor hallucis longus, and tibialis posterior muscles, which are innervated by the tibial nerve. These muscles are responsible for flexing the toes, flexing the great toe, and plantar flexion and inversion of the foot, respectively.
Understanding the muscular compartments of the lower limb is important in diagnosing and treating injuries and conditions that affect these muscles. Proper identification and management of these conditions can help improve mobility and function of the lower limb.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 20
Incorrect
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A 65-year-old man arrives at the emergency department exhibiting confusion, agitation, anterograde and retrograde amnesia, and confabulation. He also has an ataxic gait. His medical history includes chronic alcohol abuse and malnutrition, and he does not regularly take any medications or vitamin supplements. What vitamin deficiency could be causing his symptoms?
Your Answer:
Correct Answer: B1
Explanation:The Importance of Vitamin B1 (Thiamine) in the Body
Vitamin B1, also known as thiamine, is a water-soluble vitamin that belongs to the B complex group. It plays a crucial role in the body as one of its phosphate derivatives, thiamine pyrophosphate (TPP), acts as a coenzyme in various enzymatic reactions. These reactions include the catabolism of sugars and amino acids, such as pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex, and branched-chain amino acid dehydrogenase complex.
Thiamine deficiency can lead to clinical consequences, particularly in highly aerobic tissues like the brain and heart. The brain can develop Wernicke-Korsakoff syndrome, which presents symptoms such as nystagmus, ophthalmoplegia, and ataxia. Meanwhile, the heart can develop wet beriberi, which causes dilated cardiomyopathy. Other conditions associated with thiamine deficiency include dry beriberi, which leads to peripheral neuropathy, and Korsakoff’s syndrome, which causes amnesia and confabulation.
The primary causes of thiamine deficiency are alcohol excess and malnutrition. Alcoholics are routinely recommended to take thiamine supplements to prevent deficiency. Overall, thiamine is an essential vitamin that plays a vital role in the body’s metabolic processes.
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This question is part of the following fields:
- General Principles
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Question 21
Incorrect
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A 35-year-old woman visits her doctor for a routine cervical smear. She has a history of generalised anxiety disorder and is concerned about the possibility of having an undiagnosed malignancy due to her family's history of cervical cancer. She wants to know the likelihood of not having cervical cancer if the cervical screening test is negative.
Which statistical measure would be most appropriate to address this patient's worries?Your Answer:
Correct Answer: Test negative predictive value
Explanation:Precision refers to the consistency of a test in producing the same results when repeated multiple times. It is an important aspect of test reliability and can impact the accuracy of the results. In order to assess precision, multiple tests are performed on the same sample and the results are compared. A test with high precision will produce similar results each time it is performed, while a test with low precision will produce inconsistent results. It is important to consider precision when interpreting test results and making clinical decisions.
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This question is part of the following fields:
- General Principles
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Question 22
Incorrect
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A 20-year-old woman presents to your GP surgery with recurrent nose bleeds. She reports that she sometimes experiences prolonged bleeding after accidental cuts. She is in good health and takes the oral combined contraceptive pill. Her father had mentioned years ago that he also experienced slow wound healing.
Based on the history provided, what is the most probable diagnosis?Your Answer:
Correct Answer: Von Willebrand's disease
Explanation:Von Willebrand’s disease is a genetic cause of coagulation disorders that can result in prolonged bleeding time and nosebleeds. On the other hand, disseminated intravascular coagulation is an acquired condition that does not typically cause increased bleeding time but may occur in patients with sepsis. Acquired hemophilia is also an acquired condition that is not associated with a family history of bleeding disorders. Vitamin K deficiency can lead to increased bleeding time, bruising, and nosebleeds. Reduced liver function can also result in decreased production of clotting factors and an increased risk of bleeding, but this is unlikely to be the cause of the patient’s symptoms based on their medical history.
Understanding Coagulation Disorders
Coagulation disorders refer to conditions that affect the body’s ability to form blood clots. These disorders can be hereditary or acquired. Hereditary coagulation disorders include haemophilia A, haemophilia B, and von Willebrand’s disease. These conditions are caused by genetic mutations that affect the production or function of certain clotting factors in the blood.
On the other hand, acquired coagulation disorders are caused by external factors that affect the body’s ability to form blood clots. These factors include vitamin K deficiency, liver disease, and disseminated intravascular coagulation (DIC). DIC can also cause thrombocytopenia, which is a condition characterized by low platelet counts in the blood. Another acquired coagulation disorder is acquired haemophilia, which is a rare autoimmune disorder that causes the body to produce antibodies that attack clotting factors in the blood.
It is important to understand coagulation disorders as they can lead to serious health complications such as excessive bleeding or blood clots. Treatment for coagulation disorders varies depending on the underlying cause and severity of the condition. It may include medication, blood transfusions, or surgery. Regular monitoring and management of these conditions can help prevent complications and improve quality of life.
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This question is part of the following fields:
- Haematology And Oncology
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Question 23
Incorrect
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A 25-year-old female presents to her GP with concerns about her acne. Despite trying topical benzoyl peroxide and isotretinoin, she has not seen any improvement. The GP decides to prescribe a prolonged course of doxycycline. What is a potential side effect of this medication?
Your Answer:
Correct Answer: Photosensitivity
Explanation:Photosensitivity can be caused by tetracyclines, including doxycycline. Co-amoxiclav and flucloxacillin can lead to cholestatic jaundice, while aminoglycosides like gentamicin can cause ototoxicity. Vancomycin is associated with ‘red man syndrome’ and both aminoglycosides and glycopeptides (such as vancomycin) can be nephrotoxic.
Understanding Tetracyclines: Antibiotics Used in Clinical Practice
Tetracyclines are a group of antibiotics that are commonly used in clinical practice. They work by inhibiting protein synthesis, specifically by binding to the 30S subunit and blocking the binding of aminoacyl-tRNA. However, bacteria can develop resistance to tetracyclines through increased efflux by plasmid-encoded transport pumps or ribosomal protection.
Tetracyclines are used to treat a variety of conditions such as acne vulgaris, Lyme disease, Chlamydia, and Mycoplasma pneumoniae. However, they should not be given to children under 12 years of age or to pregnant or breastfeeding women due to the risk of discolouration of the infant’s teeth.
While tetracyclines are generally well-tolerated, they can cause adverse effects such as photosensitivity, angioedema, and black hairy tongue. It is important to be aware of these potential side effects and to use tetracyclines only as prescribed by a healthcare professional.
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This question is part of the following fields:
- General Principles
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Question 24
Incorrect
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A 29-year-old woman is currently under investigation by her GP for chronic diarrhoea due to repeated occurrences of loose, bloody stools. As per the WHO guidelines, what is the definition of chronic diarrhoea?
Your Answer:
Correct Answer: Diarrhoea for >14 days
Explanation:Chronic diarrhoea is defined by the WHO as lasting for more than 14 days. The leading causes of this condition are irritable bowel syndrome, ulcerative colitis and Crohn’s disease, coeliac disease, hyperthyroidism, and infection. The remaining options provided are incorrect and do not align with the WHO’s definition.
Understanding Diarrhoea: Causes and Characteristics
Diarrhoea is defined as having more than three loose or watery stools per day. It can be classified as acute if it lasts for less than 14 days and chronic if it persists for more than 14 days. Gastroenteritis, diverticulitis, and antibiotic therapy are common causes of acute diarrhoea. On the other hand, irritable bowel syndrome, ulcerative colitis, Crohn’s disease, colorectal cancer, and coeliac disease are some of the conditions that can cause chronic diarrhoea.
Symptoms of gastroenteritis may include abdominal pain, nausea, and vomiting. Diverticulitis is characterized by left lower quadrant pain, diarrhoea, and fever. Antibiotic therapy, especially with broad-spectrum antibiotics, can also cause diarrhoea, including Clostridium difficile infection. Chronic diarrhoea may be caused by irritable bowel syndrome, which is characterized by abdominal pain, bloating, and changes in bowel habits. Ulcerative colitis may cause bloody diarrhoea, crampy abdominal pain, and weight loss. Crohn’s disease may cause crampy abdominal pain, diarrhoea, and malabsorption. Colorectal cancer may cause diarrhoea, rectal bleeding, anaemia, and weight loss. Coeliac disease may cause diarrhoea, abdominal distension, lethargy, and weight loss.
Other conditions associated with diarrhoea include thyrotoxicosis, laxative abuse, appendicitis, and radiation enteritis. It is important to seek medical attention if diarrhoea persists for more than a few days or is accompanied by other symptoms such as fever, severe abdominal pain, or blood in the stool.
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This question is part of the following fields:
- Gastrointestinal System
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Question 25
Incorrect
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An 82-year-old man comes to your clinic complaining of stiffness and swelling in the joints of his right hand. Upon examination, you notice uniform swellings mainly affecting the distal interphalangeal (DIP) joints, which are firm to the touch and not painful. The patient is in good overall health, and no other joints appear to be affected. There is no significant medical history to report.
What is the most probable clinical sign observed in this case?Your Answer:
Correct Answer: Heberden's nodes
Explanation:Heberden’s nodes are bony growths that occur on the distal interphalangeal (DIP) joints and are associated with osteoarthritis. In contrast, Bouchard’s nodes are bony growths that occur on the proximal interphalangeal (PIP) joints. The Boutonniere deformity, on the other hand, is characterized by PIP joint flexion and DIP extension, and is caused by damage to the extensor tendon slip, often due to rheumatoid arthritis or trauma. Rheumatoid nodules are subcutaneous lumps that occur on areas of pressure and are associated with active rheumatoid arthritis disease. However, in this case, the asymmetrical presentation and lack of other joint involvement or systemic symptoms suggest that the correct answer is Heberden’s nodes.
Hand Diseases and Lumps
Dupuytren’s contracture is a hand disease that causes the fingers to bend towards the palm and cannot be fully extended. It is caused by contractures of the palmar aponeurosis and is more common in males over 40 years of age. Treatment is surgical, but the condition may recur and surgical therapies carry risks.
Carpal tunnel syndrome is a common hand disease that affects the median nerve at the carpal tunnel. It is more common in females and may be associated with other connective tissue disorders. Symptoms occur mainly at night and treatment is by surgical decompression or non-surgical options such as splinting.
There are also various hand lumps that can occur. Osler’s nodes are painful, red, raised lesions caused by immune complexes. Bouchard’s nodes are hard, bony outgrowths on the middle joints of fingers or toes and are a sign of osteoarthritis. Heberden’s nodes develop in middle age and cause a permanent bony outgrowth that skews the fingertip sideways. Ganglion is a fluid-filled swelling near a joint that is usually asymptomatic and may be excised if troublesome.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 26
Incorrect
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During your 3rd-year neurology placement, you visit a nursing home where you conduct an interview with a 93-year-old male who has advanced dementia. Upon assessment, you observe that he has an intact short-term memory but impaired long-term memory. Which specific brain region is responsible for the conversion of short-term memory into long-term memory?
Your Answer:
Correct Answer: Hippocampus
Explanation:The Role of the Hippocampus in Long-Term Memory
Long-term memories are stored in the brain through permanent changes in neural connections that are widely distributed throughout the brain. The hippocampus plays a crucial role in the consolidation of information from short-term to long-term memories. However, it does not store information itself. Instead, it acts as a gateway for new memories to be transferred from short-term to long-term memory storage.
Without the hippocampus, new memories cannot be stored in long-term memory. This is because the hippocampus is responsible for encoding and consolidating new information into a form that can be stored in long-term memory. Once the information has been consolidated, it is distributed throughout the brain, where it is stored in various regions.
In summary, the hippocampus is essential for the formation of long-term memories. It acts as a gateway for new memories to be transferred from short-term to long-term memory storage. Without the hippocampus, new memories cannot be stored in long-term memory, and the ability to form new memories is severely impaired.
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This question is part of the following fields:
- General Principles
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Question 27
Incorrect
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You are giving a lecture to a group of nursing students on aspirin overdose and its characteristics.
As you discuss the pathophysiology of the metabolic acidosis observed in patients with aspirin overdose, you address the root cause of the metabolic acidosis in these individuals.Your Answer:
Correct Answer: Uncoupling of the electron transport chain in the mitochondria leading to reduced ATP production
Explanation:Inhibiting the electron transport chain in mitochondria, aspirin overdose leads to a decline in ATP production. This decrease in ATP is counterbalanced by an upsurge in anaerobic respiration, which generates lactate – an acidic byproduct. The accumulation of lactate leads to a decrease in pH, resulting in metabolic acidosis.
Salicylate overdose can cause a combination of respiratory alkalosis and metabolic acidosis. The respiratory center is initially stimulated, leading to hyperventilation and respiratory alkalosis. However, the direct acid effects of salicylates, combined with acute renal failure, can later cause metabolic acidosis. In children, metabolic acidosis tends to be more prominent. Other symptoms of salicylate overdose include tinnitus, lethargy, sweating, pyrexia, nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.
The treatment for salicylate overdose involves general measures such as airway, breathing, and circulation support, as well as administering activated charcoal. Urinary alkalinization with intravenous sodium bicarbonate can help eliminate aspirin in the urine. In severe cases, hemodialysis may be necessary. Indications for hemodialysis include a serum concentration of over 700 mg/L, metabolic acidosis that is resistant to treatment, acute renal failure, pulmonary edema, seizures, and coma.
Salicylates can also cause the uncoupling of oxidative phosphorylation, which leads to decreased adenosine triphosphate production, increased oxygen consumption, and increased carbon dioxide and heat production. It is important to recognize the symptoms of salicylate overdose and seek prompt medical attention to prevent serious complications.
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This question is part of the following fields:
- General Principles
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Question 28
Incorrect
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Samantha is a 75-year-old woman who is currently recovering in hospital following a stroke. Her MRI scan report says there is evidence of ischaemic damage to the superior optic radiation within the right temporal lobe.
What type of visual impairment is Samantha likely experiencing?Your Answer:
Correct Answer: Right superior homonymous quadrantanopia
Explanation:Lesions in the temporal lobe inferior optic radiations are responsible for superior homonymous quadrantanopias.
If the left temporal lobe is damaged, the resulting visual field defect would be in the right side. Specific damage to the inferior optic radiation would cause a superior homonymous quadrantanopia.
Damage to the right inferior optic radiation would lead to a left superior homonymous quadrantanopia.
A right inferior homonymous quadrantanopia would occur if the left superior optic radiation is damaged.
If the left occipital lobe is damaged, a right homonymous hemianopia would result.
Understanding Visual Field Defects
Visual field defects can occur due to various reasons, including lesions in the optic tract, optic radiation, or occipital cortex. A left homonymous hemianopia indicates a visual field defect to the left, which is caused by a lesion in the right optic tract. On the other hand, homonymous quadrantanopias can be categorized into PITS (Parietal-Inferior, Temporal-Superior) and can be caused by lesions in the inferior or superior optic radiations in the temporal or parietal lobes.
When it comes to congruous and incongruous defects, the former refers to complete or symmetrical visual field loss, while the latter indicates incomplete or asymmetric visual field loss. Incongruous defects are caused by optic tract lesions, while congruous defects are caused by optic radiation or occipital cortex lesions. In cases where there is macula sparing, it is indicative of a lesion in the occipital cortex.
Bitemporal hemianopia, on the other hand, is caused by a lesion in the optic chiasm. The type of defect can indicate the location of the compression, with an upper quadrant defect being more common in inferior chiasmal compression, such as a pituitary tumor, and a lower quadrant defect being more common in superior chiasmal compression, such as a craniopharyngioma.
Understanding visual field defects is crucial in diagnosing and treating various neurological conditions. By identifying the type and location of the defect, healthcare professionals can provide appropriate interventions to improve the patient’s quality of life.
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This question is part of the following fields:
- Neurological System
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Question 29
Incorrect
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A 48-hour-old boy who was born by vaginal delivery has not passed meconium.
A patent anal orifice can be seen, but an abdominal x-ray reveals dilatation of the bowel proximal to the sigmoid colon. A rectal mucosa biopsy confirms the diagnosis.
What is the probable condition affecting this infant?Your Answer:
Correct Answer: Hirschsprung's disease
Explanation:Hirschsprung’s Disease and Other Causes of Failure to Pass Meconium in Neonates
There are various reasons why a newborn may fail to pass meconium within the first 24 hours of life. One of these is Hirschsprung’s disease, which is caused by a loss of function mutation in the RET oncogene resulting in the absence of ganglion cells. This condition is always present in the rectum and extends proximally for a varying distance. The affected area is immotile, and proximal to it is a dilated section of the colon known as megacolon. Diagnosis is made through a rectal biopsy that confirms the absence of ganglion cells.
Chagas’ disease, on the other hand, is caused by infection with Trypanosoma cruzi and can also cause immotile megacolon, but it is not a condition that presents in newborns. Crohn’s disease, which usually presents with diarrhea rather than constipation, does not occur in neonates. Cystic fibrosis can cause meconium ileus, where thick meconium becomes lodged at the ileocecal valve, but the anatomical location is not correct in this case, and biopsy is not required. Congenital hypothyroidism may cause constipation, but it does not result in megacolon, and biopsy is not necessary.
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This question is part of the following fields:
- Paediatrics
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Question 30
Incorrect
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During your placement on a urology ward, you receive a call from microbiology regarding the bacteria found in a urine sample from an older male patient you are managing for urosepsis. What is the most frequent bacteria that causes a urinary tract infection?
Your Answer:
Correct Answer: Escherichia coli
Explanation:Urinary tract infections (UTIs) are common in adults and can affect different parts of the urinary tract. Lower UTIs are more common and can be managed with antibiotics. For non-pregnant women, local antibiotic guidelines should be followed, and a urine culture should be sent if they are aged over 65 years or have visible or non-visible haematuria. Trimethoprim or nitrofurantoin for three days are recommended by NICE Clinical Knowledge Summaries. Pregnant women with symptoms should have a urine culture sent, and first-line treatment is nitrofurantoin, while amoxicillin or cefalexin can be used as second-line treatment. Asymptomatic bacteriuria in pregnant women should also be treated with antibiotics. Men with UTIs should be offered antibiotics for seven days, and a urine culture should be sent before starting treatment. Catheterised patients should not be treated for asymptomatic bacteria, but if they are symptomatic, a seven-day course of antibiotics should be given, and the catheter should be removed or changed if it has been in place for more than seven days. For patients with signs of acute pyelonephritis, hospital admission should be considered, and local antibiotic guidelines should be followed. The BNF recommends a broad-spectrum cephalosporin or a quinolone for 10-14 days for non-pregnant women.
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This question is part of the following fields:
- General Principles
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Question 31
Incorrect
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As a medical student observing a parathyroidectomy in the short-stay surgical theatre, you witness the ligation of blood vessels supplying the parathyroid glands. The ENT consultant requests you to identify the arteries responsible for supplying oxygenated blood to the parathyroid gland. Can you correctly name these arteries?
Your Answer:
Correct Answer: Superior and inferior thyroid arteries
Explanation:The superior and inferior thyroid arteries provide oxygenated blood supply to the parathyroid glands. The existence of inferior parathyroid arteries and superior parathyroid arteries is not supported by anatomical evidence. While a middle thyroid artery may exist in some individuals, it is a rare variation that is not relevant to the question at hand.
Anatomy and Development of the Parathyroid Glands
The parathyroid glands are four small glands located posterior to the thyroid gland within the pretracheal fascia. They develop from the third and fourth pharyngeal pouches, with those derived from the fourth pouch located more superiorly and associated with the thyroid gland, while those from the third pouch lie more inferiorly and may become associated with the thymus.
The blood supply to the parathyroid glands is derived from the inferior and superior thyroid arteries, with a rich anastomosis between the two vessels. Venous drainage is into the thyroid veins. The parathyroid glands are surrounded by various structures, with the common carotid laterally, the recurrent laryngeal nerve and trachea medially, and the thyroid anteriorly. Understanding the anatomy and development of the parathyroid glands is important for their proper identification and preservation during surgical procedures.
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This question is part of the following fields:
- Cardiovascular System
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Question 32
Incorrect
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Which one of the following drugs exhibits saturation pharmacokinetics?
Your Answer:
Correct Answer: Phenytoin
Explanation:Phenytoin exhibits zero-order kinetics.
Understanding Drug Metabolism: Phase I and Phase II Reactions
Drug metabolism involves two types of biochemical reactions, namely phase I and phase II reactions. Phase I reactions include oxidation, reduction, and hydrolysis, which are mainly performed by P450 enzymes. However, some drugs are metabolized by specific enzymes such as alcohol dehydrogenase and xanthine oxidase. The products of phase I reactions are typically more active and potentially toxic. On the other hand, phase II reactions involve conjugation, where glucuronyl, acetyl, methyl, sulphate, and other groups are typically involved. The products of phase II reactions are typically inactive and excreted in urine or bile. The majority of phase I and phase II reactions take place in the liver.
First-Pass Metabolism and Drugs Affected by Zero-Order Kinetics and Acetylator Status
First-pass metabolism is a phenomenon where the concentration of a drug is greatly reduced before it reaches the systemic circulation due to hepatic metabolism. This effect is seen in many drugs, including aspirin, isosorbide dinitrate, glyceryl trinitrate, lignocaine, propranolol, verapamil, isoprenaline, testosterone, and hydrocortisone.
Zero-order kinetics describe metabolism that is independent of the concentration of the reactant. This is due to metabolic pathways becoming saturated, resulting in a constant amount of drug being eliminated per unit time. Drugs exhibiting zero-order kinetics include phenytoin, salicylates (e.g. high-dose aspirin), heparin, and ethanol.
Acetylator status is also an important consideration in drug metabolism. Approximately 50% of the UK population are deficient in hepatic N-acetyltransferase. Drugs affected by acetylator status include isoniazid, procainamide, hydralazine, dapsone, and sulfasalazine. Understanding these concepts is important in predicting drug efficacy and toxicity, as well as in optimizing drug dosing.
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This question is part of the following fields:
- General Principles
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Question 33
Incorrect
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A 54-year-old man comes to the emergency department complaining of difficulty breathing. The results of his pulmonary function tests are as follows:
Reference Range
FVC (% predicted) 102 80-120
FEV1 (% predicted) 62 80-120
FEV1/FVC (%) 60.1 >70
TCLO (% predicted) 140 60-120
What is the probable reason for his symptoms?Your Answer:
Correct Answer: Asthma exacerbation
Explanation:The raised transfer factor suggests that the patient is experiencing an exacerbation of asthma. This condition can cause obstructive patterns on pulmonary function tests, leading to reduced FEV1 and FEV1/FVC, as well as hypoxia and wheezing. However, other conditions such as COPD exacerbation, idiopathic pulmonary fibrosis, and pulmonary embolism would result in a low transfer factor, and are therefore unlikely explanations for the patient’s symptoms.
Understanding Transfer Factor in Lung Function Testing
The transfer factor is a measure of how quickly a gas diffuses from the alveoli into the bloodstream. This is typically tested using carbon monoxide, and the results can be given as either the total gas transfer (TLCO) or the transfer coefficient corrected for lung volume (KCO). A raised TLCO may be caused by conditions such as asthma, pulmonary haemorrhage, left-to-right cardiac shunts, polycythaemia, hyperkinetic states, male gender, or exercise. On the other hand, a lower TLCO may be indicative of pulmonary fibrosis, pneumonia, pulmonary emboli, pulmonary oedema, emphysema, anaemia, or low cardiac output.
KCO tends to increase with age, and certain conditions may cause an increased KCO with a normal or reduced TLCO. These conditions include pneumonectomy/lobectomy, scoliosis/kyphosis, neuromuscular weakness, and ankylosis of costovertebral joints (such as in ankylosing spondylitis). Understanding transfer factor is important in lung function testing, as it can provide valuable information about a patient’s respiratory health and help guide treatment decisions.
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This question is part of the following fields:
- Respiratory System
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Question 34
Incorrect
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A 43-year-old man comes to the clinic complaining of a painful rash on his left anterior chest wall that extends to his back and under his armpit, but does not cross the midline. The rash has been present for one day, and he has been feeling lethargic for three days. Based on these symptoms, what virus do you suspect is causing his condition?
Your Answer:
Correct Answer: Varicella zoster virus
Explanation:The Varicella zoster virus (VZV) is the correct answer. Shingles is a painful rash that typically appears in a dermatomal distribution and does not usually cross the mid-line. VZV is the virus responsible for causing chickenpox, and after the initial infection, it can remain dormant in nerve cells for many years. Shingles occurs when VZV reactivates. Additional information on shingles can be found below.
Epstein-Barr virus is primarily linked to infectious mononucleosis (glandular fever).
Human papillomavirus (HPV) is associated with viral warts, and some strains are linked to gynecological malignancies. Due to their potential to cause cancer, some types of HPV are now vaccinated against.
Herpes simplex virus is associated with oral or genital herpes infections.
Shingles is a painful blistering rash caused by reactivation of the varicella-zoster virus. It is more common in older individuals and those with immunosuppressive conditions. The diagnosis is usually clinical and management includes analgesia, antivirals, and reminding patients they are potentially infectious. Complications include post-herpetic neuralgia, herpes zoster ophthalmicus, and herpes zoster oticus. Antivirals should be used within 72 hours to reduce the incidence of post-herpetic neuralgia.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 35
Incorrect
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A 50-year-old male presents for an elective cholecystectomy. The anaesthetist administers the necessary medications, including an antiemetic, before the surgery. However, after 10 minutes, the patient experiences upward eye deviation and muscle spasms in the neck and arms. An IV injection of procyclidine is given.
What is the mechanism of action of procyclidine?Your Answer:
Correct Answer: Muscarinic antagonist
Explanation:Procyclidine is capable of crossing the blood-brain barrier and acts as a muscarinic antagonist. It is commonly used to alleviate oculogyric crisis, which is caused by an excess of cholinergic activity at the neuromuscular junction due to dopamine deficiency resulting from the administration of dopamine D2 antagonists like metoclopramide. Procyclidine works by reducing cholinergic transmission in such cases.
Understanding Oculogyric Crisis: Symptoms, Causes, and Management
Oculogyric crisis is a medical condition characterized by involuntary upward deviation of the eyes, often accompanied by restlessness and agitation. This condition is usually triggered by certain drugs or medical conditions, such as antipsychotics, metoclopramide, and postencephalitic Parkinson’s disease.
The symptoms of oculogyric crisis can be distressing and uncomfortable for the patient. They may experience a sudden and uncontrollable movement of their eyes, which can cause discomfort and disorientation. In some cases, the patient may also feel restless and agitated, making it difficult for them to focus or relax.
To manage oculogyric crisis, doctors may prescribe intravenous antimuscarinic medications such as benztropine or procyclidine. These drugs work by blocking the action of acetylcholine, a neurotransmitter that is involved in muscle movement. By reducing the activity of acetylcholine, these medications can help to alleviate the symptoms of oculogyric crisis and restore normal eye movement.
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This question is part of the following fields:
- General Principles
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Question 36
Incorrect
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Which statement accurately reflects the findings of the double-blind, randomised, placebo-controlled trial of drug A for hypercholesterolaemia treatment?
Your Answer:
Correct Answer: The null hypothesis is that drug A is as effective as placebo
Explanation:The Null Hypothesis in Testing for Differences between Variables
In testing for differences between variables, the null hypothesis always assumes that there is no difference between the variables being tested. This means that the null hypothesis assumes that the variables are either equally effective or equally ineffective.
For instance, in testing the cholesterol-reducing effect of drug A and placebo, the null hypothesis would assume that there is no difference between the two in terms of their effectiveness. Therefore, the null hypothesis would state that drug A and placebo are equally effective or equally ineffective in reducing cholesterol levels.
It is important to establish the null hypothesis before conducting any statistical analysis because it provides a baseline for comparison. If the results of the analysis show that there is a significant difference between the variables, then the null hypothesis can be rejected, and it can be concluded that there is indeed a difference between the variables being tested. On the other hand, if the results do not show a significant difference, then the null hypothesis cannot be rejected, and it can be concluded that there is no difference between the variables being tested.
In summary, the null hypothesis assumes that there is no difference between the variables being tested, and it serves as a baseline for comparison in statistical analysis.
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This question is part of the following fields:
- Clinical Sciences
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Question 37
Incorrect
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Samantha is a 55-year-old woman who has presented to her doctor with a persistent pain in her neck over the past 6 months. She has also noticed a lump on the anterolateral aspect of her neck and has been experiencing a persistent cough. Upon conducting blood tests, her doctor has found that she has hypocalcaemia and hypophosphataemia. Following an ultrasound and biopsy, Samantha has been diagnosed with medullary thyroid carcinoma. The tumour studies have shown that there has been no spread to local lymph nodes. Can you explain the reason for Samantha's abnormal blood results?
Your Answer:
Correct Answer: Inhibition of osteoclasts by calcitonin
Explanation:Calcitonin inhibits osteoclasts, leading to a decrease in plasma calcium and phosphate levels.
Understanding Calcitonin and Its Role in Regulating Calcium Levels
Calcitonin is a hormone that is produced by the parafollicular cells or C cells of the thyroid gland. It is released in response to high levels of calcium in the blood, which can occur due to various factors such as bone resorption, vitamin D toxicity, or certain cancers. The main function of calcitonin is to decrease the levels of calcium and phosphate in the blood by inhibiting the activity of osteoclasts, which are cells that break down bone tissue and release calcium into the bloodstream.
Calcitonin works by binding to specific receptors on the surface of osteoclasts, which reduces their ability to resorb bone. This leads to a decrease in the release of calcium and phosphate into the bloodstream, which helps to restore normal levels of these minerals. In addition to its effects on bone metabolism, calcitonin also has other physiological functions such as regulating kidney function and modulating the immune system.
Overall, calcitonin plays an important role in maintaining calcium homeostasis in the body and preventing the development of conditions such as hypercalcemia, which can have serious health consequences. By inhibiting osteoclast activity and promoting bone formation, calcitonin helps to maintain the structural integrity of bones and prevent fractures. Understanding the mechanisms of calcitonin action can provide insights into the pathophysiology of bone diseases and inform the development of new treatments for these conditions.
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This question is part of the following fields:
- General Principles
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Question 38
Incorrect
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A 16-year-old male presents to the emergency department after falling onto outstretched hands. An x-ray confirms a fracture in one of the bones in his forearm. Based on the mechanism of injury, which bone is most likely affected by this fracture?
Your Answer:
Correct Answer: Distal shaft of the radius
Explanation:The forearm has two weight-bearing bones, the scaphoid at the wrist and the radius within the forearm. If someone falls onto outstretched hands, there is a risk of fracturing both of these bones. The shaft of the radius is particularly vulnerable as it carries the weight and takes the full compression of the fall. The ulna is more likely to fracture from stress applied to the side of the arm rather than down its length. The lunate bone at the wrist is not involved in weight-bearing.
Anatomy of the Radius Bone
The radius bone is one of the two long bones in the forearm that extends from the lateral side of the elbow to the thumb side of the wrist. It has two expanded ends, with the distal end being the larger one. The upper end of the radius bone has articular cartilage that covers the medial to lateral side and articulates with the radial notch of the ulna by the annular ligament. The biceps brachii muscle attaches to the tuberosity of the upper end.
The shaft of the radius bone has several muscle attachments. The upper third of the body has the supinator, flexor digitorum superficialis, and flexor pollicis longus muscles. The middle third of the body has the pronator teres muscle, while the lower quarter of the body has the pronator quadratus muscle and the tendon of supinator longus.
The lower end of the radius bone is quadrilateral in shape. The anterior surface is covered by the capsule of the wrist joint, while the medial surface has the head of the ulna. The lateral surface ends in the styloid process, and the posterior surface has three grooves that contain the tendons of extensor carpi radialis longus and brevis, extensor pollicis longus, and extensor indicis. Understanding the anatomy of the radius bone is crucial in diagnosing and treating injuries and conditions that affect this bone.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 39
Incorrect
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A 45-year-old woman presents with a lesion in the cerebellopontine angle. Which cranial nerve is expected to be affected initially?
Your Answer:
Correct Answer: CN V
Explanation:An acoustic neuroma is the most probable type of lesion to develop in the cerebellopontine angle. The trigeminal nerve is typically affected first, with a wide base of involvement. The initial symptoms may be subtle, such as the loss of the corneal reflex on the same side. Additionally, hearing loss on the same side is likely to occur. If left untreated, the lesion may progress and eventually impact multiple cranial nerve roots in the area.
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 40
Incorrect
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A 31-year-old arrives at the Emergency Department by ambulance after being involved in a car accident. During the ABCDE assessment, it is discovered that the patient has suffered a penetrating injury at the T9 level.
Following an MRI of the spine and consultation with a neurologist, the patient is diagnosed with Brown-Sequard syndrome on the left side.
What symptoms can be expected from this patient's condition?Your Answer:
Correct Answer: Left-sided loss of motor, vibration and proprioception, with right-sided loss of pain and temperature sensation
Explanation:The spinothalamic tract crosses over at the same level where the nerve root enters the spinal cord, while the corticospinal tract, dorsal column medial lemniscus, and spinocerebellar tracts cross over at the medulla.
Brown-Sequard syndrome affects one entire side of the spinal cord, resulting in the loss of motor function, vibration, and proprioception on the left side, and loss of pain and temperature sensation on the right side.
In Brown-Sequard syndrome, the loss of motor function, vibration, and proprioception occurs on the same side due to the corticospinal tract and dorsal column medial meniscus crossing over at the medulla. The loss of pain and temperature sensation occurs on the opposite side due to the crossing over of the tract at the nerve root.
Anterior cord syndrome affects the descending corticospinal tract and ascending spinothalamic tract, leading to the loss of motor function, pain, and temperature sensation below the injury site. However, proprioception and vibration sensation remain unaffected as the dorsal columns are spared.
Central cord syndrome results in the loss of motor function on both sides, as well as some loss of vibration and proprioception.
Posterior cord syndrome affects the dorsal column medial lemniscus, leading to the loss of proprioception and vibration sensation on the same side. This condition can be caused by neck hyperflexion, disc compression, ischaemia, vitamin B12 deficiency, or multiple sclerosis.
The spinal cord is a central structure located within the vertebral column that provides it with structural support. It extends rostrally to the medulla oblongata of the brain and tapers caudally at the L1-2 level, where it is anchored to the first coccygeal vertebrae by the filum terminale. The cord is characterised by cervico-lumbar enlargements that correspond to the brachial and lumbar plexuses. It is incompletely divided into two symmetrical halves by a dorsal median sulcus and ventral median fissure, with grey matter surrounding a central canal that is continuous with the ventricular system of the CNS. Afferent fibres entering through the dorsal roots usually terminate near their point of entry but may travel for varying distances in Lissauer’s tract. The key point to remember is that the anatomy of the cord will dictate the clinical presentation in cases of injury, which can be caused by trauma, neoplasia, inflammatory diseases, vascular issues, or infection.
One important condition to remember is Brown-Sequard syndrome, which is caused by hemisection of the cord and produces ipsilateral loss of proprioception and upper motor neuron signs, as well as contralateral loss of pain and temperature sensation. Lesions below L1 tend to present with lower motor neuron signs. It is important to keep a clinical perspective in mind when revising CNS anatomy and to understand the ways in which the spinal cord can become injured, as this will help in diagnosing and treating patients with spinal cord injuries.
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This question is part of the following fields:
- Neurological System
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Question 41
Incorrect
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A 55-year-old man presents to the clinic with a one-month history of progressive burning and tingling sensations in his hands and feet. He enjoys restoring antique cars as a hobby. The patient has no known medical conditions and is not taking any medications. He does not smoke or drink alcohol. His blood pressure is 110/75 mmHg, and his pulse is 72/min. The palms and soles of his feet have hyperkeratosis and scaling. There is weakness in ankle plantarflexion and dorsiflexion, as well as in the interossei and wrist flexors and extensors.
The following are the patient's laboratory results:
Hb 100 g/L Male: (135-180)
Female: (115 - 160)
Platelets 1.2 * 109/L (150 - 400)
WBC 4.1 * 109/L (4.0 - 11.0)
What is the most likely diagnosis for this patient?Your Answer:
Correct Answer: Arsenic poisoning
Explanation:If a patient presents with painful sensorimotor polyneuropathy, skin lesions (including hypo- and hyperpigmented and hyperkeratotic lesions), pancytopenia, and mild transaminase elevation, it is important to consider the possibility of arsenic toxicity. This is especially true if the patient has a history of exposure to antique wood. Chronic exposure to arsenic can cause a specific type of neuropathy that affects the hands and feet, causing burning, pain, hypersensitivity, weakness, and reduced reflexes. Later on, patients may develop hyperkeratosis and scaling on the palms and soles.
It is important to differentiate arsenic toxicity from other conditions that can cause similar symptoms. Chronic lead poisoning can also cause neuropathy, but it typically presents with microcytic anemia and does not cause skin changes. Vitamin A deficiency can cause xerophthalmia, night blindness, and follicular hyperkeratosis, but it is not associated with polyneuropathy. Vitamin D deficiency can cause bone pain, myopathy, and an increased risk of fractures.
Heavy metal poisoning is the accumulation of heavy metals in the soft tissues of the body, which can be caused by ingestion, inhalation, or absorption through the skin or mucous membranes. The most commonly linked metals to poisoning are lead, mercury, arsenic, and cadmium, but other metals like iron, thallium, and bismuth may also be implicated. Heavy metal poisoning is rare in the UK, and the incidence of lead poisoning has decreased in affluent countries due to the removal of lead paint. The symptoms and signs of heavy metal poisoning depend on the metal involved, but fatigue, nausea, and vomiting are common. Arsenic, lead, mercury, and cadmium poisoning are the most commonly encountered, and each has its own set of symptoms and signs. Investigations may include a full history, examination, blood and urine levels, and X-rays.
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This question is part of the following fields:
- General Principles
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Question 42
Incorrect
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A 68-year-old male comes to the emergency department with hemiparesis. During your conversation with him, you discover that his speech is fluent but his repetition is poor. He is conscious of his inability to repeat words accurately but persists in trying. You suspect that a stroke may be the cause of this condition.
Which region of the brain has been impacted by the stroke?Your Answer:
Correct Answer: Arcuate fasciculus
Explanation:The patient is exhibiting symptoms of conduction aphasia, which is typically caused by a stroke that affects the arcuate fasciculus.
If the lesion is in the parietal lobe, the patient may experience sensory inattention and inferior homonymous quadrantanopia.
Lesions in the inferior frontal gyrus can cause speech to become non-fluent, labored, and halting.
Occipital lobe lesions can result in visual changes.
If the lesion is in the superior temporal gyrus, the patient may produce sentences that don’t make sense, use word substitution, and create neologisms, but their speech will still be fluent.
Types of Aphasia: Understanding the Different Forms of Language Impairment
Aphasia is a language disorder that affects a person’s ability to communicate effectively. There are different types of aphasia, each with its own set of symptoms and underlying causes. Wernicke’s aphasia, also known as receptive aphasia, is caused by a lesion in the superior temporal gyrus. This area is responsible for forming speech before sending it to Broca’s area. People with Wernicke’s aphasia may speak fluently, but their sentences often make no sense, and they may use word substitutions and neologisms. Comprehension is impaired.
Broca’s aphasia, also known as expressive aphasia, is caused by a lesion in the inferior frontal gyrus. This area is responsible for speech production. People with Broca’s aphasia may speak in a non-fluent, labored, and halting manner. Repetition is impaired, but comprehension is normal.
Conduction aphasia is caused by a stroke affecting the arcuate fasciculus, the connection between Wernicke’s and Broca’s area. People with conduction aphasia may speak fluently, but their repetition is poor. They are aware of the errors they are making, but comprehension is normal.
Global aphasia is caused by a large lesion affecting all three areas mentioned above, resulting in severe expressive and receptive aphasia. People with global aphasia may still be able to communicate using gestures. Understanding the different types of aphasia is important for proper diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 43
Incorrect
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You are working on a pediatric ward. The mother of a young patient has recently had some blood tests performed in hospital. She says that her child was referred to a pediatrician by their general practitioner. She is anxious to find out the results.
Whilst you are sitting at the nurses' station doing some paperwork she asks if you would mind looking up the results for her on the hospital reporting system.
What should you do next?Your Answer:
Correct Answer: Apologise that you cannot look up the results as you are not involved in her care and do not have the information and knowledge needed to interpret the results
Explanation:Why Checking a Colleague’s Medical Test Results Could Do More Harm Than Good
Whilst it may seem helpful to check a colleague’s medical test results and reassure them that everything is normal, there are several potential risks involved. Firstly, without specialist knowledge and access to the patient’s medical history, it may be difficult to accurately interpret the results. Additionally, if the results are reported as normal, there may still be pending results that you are not aware of, which could falsely reassure the patient.
Furthermore, checking a colleague’s medical test results without a legitimate interest in their care could breach their confidentiality. This could result in inadvertently learning more about their medical history than they were willing to disclose.
Therefore, the best course of action would be to politely decline the request and encourage the colleague to liaise with their consultant about the results. It is important to prioritize patient confidentiality and avoid potentially causing more harm than good.
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This question is part of the following fields:
- Ethics And Law
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Question 44
Incorrect
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Samantha is a 58-year-old woman who has been experiencing symptoms of urinary urgency and frequency. She is curious about the accuracy of the PSA test and would like to know what percentage of patients with an elevated PSA level (for their age) do not actually have prostate cancer.
Approximately what percentage of patients with a raised PSA level (relative to their age) do not have prostate cancer?Your Answer:
Correct Answer: 75%
Explanation:PSA Testing for Prostate Cancer
Prostate specific antigen (PSA) is an enzyme produced by the prostate gland, and it is used as a tumour marker for prostate cancer. However, there is still much debate about its usefulness as a screening tool. The NHS Prostate Cancer Risk Management Programme (PCRMP) has published guidelines on how to handle requests for PSA testing in asymptomatic men. The National Screening Committee has decided not to introduce a prostate cancer screening programme yet, but rather allow men to make an informed choice.
The PCRMP has recommended age-adjusted upper limits for PSA, while NICE Clinical Knowledge Summaries suggest a lower threshold for referral. However, PSA levels may also be raised by other conditions such as benign prostatic hyperplasia, prostatitis, urinary tract infection, ejaculation, vigorous exercise, urinary retention, and instrumentation of the urinary tract.
PSA testing has poor specificity and sensitivity, and various methods are used to try and add greater meaning to a PSA level, including age-adjusted upper limits and monitoring change in PSA level with time. It is important to note that digital rectal examination may or may not cause a rise in PSA levels, which is a matter of debate.
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This question is part of the following fields:
- Renal System
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Question 45
Incorrect
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A 33-year-old female patient has a confirmed pregnancy. One of the significant changes that occur during pregnancy is the relaxation of the myometrium, which is facilitated by several hormones, including progesterone. What is the arachidonic acid metabolite that is primarily linked to this process?
Your Answer:
Correct Answer: Prostacyclin (PGI2)
Explanation:The correct answer is Prostacyclin (PGI2). PGI2 is a metabolite of arachidonic acid that is known for its ability to relax smooth muscles, including the myometrium, which leads to decreased uterine tone.
Oxytocin is an incorrect answer. It is a hormone that stimulates uterine contractions and is not related to arachidonic acid metabolism.
Leukotriene C4 is also an incorrect answer. Although it is an arachidonic acid metabolite, it is not involved in controlling uterine tone but rather in bronchoconstriction.
Prostaglandin (PGE2) is another incorrect answer. PGE2 is associated with increased uterine tone and is actually used to induce labor by stimulating the cervix and uterus. It can be administered as a gel, tablet, or pessary.
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 46
Incorrect
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A 50-year-old woman visits the rheumatology clinic due to worsening joint pain caused by her longstanding rheumatoid arthritis. Her symptoms have progressed to the point where she can no longer perform her daily activities. She is interested in trying infliximab after hearing about it from a friend and reading about it online. She wants to know how the drug works and how it can potentially alleviate her symptoms.
What is the mechanism of action of infliximab?Your Answer:
Correct Answer: Anti-TNF
Explanation:Infliximab targets TNF through its monoclonal antibody action, while rituximab targets CD20, cetuximab acts as an antagonist to epidermal growth factor receptor, alemtuzumab targets CD52, and OKT3 targets CD3.
Understanding Tumour Necrosis Factor and its Inhibitors
Tumour necrosis factor (TNF) is a cytokine that plays a crucial role in the immune system. It is mainly secreted by macrophages and has various effects on the immune system, such as activating macrophages and neutrophils, acting as a costimulator for T cell activation, and mediating the body’s response to Gram-negative septicaemia. TNF also has anti-tumour effects and binds to both the p55 and p75 receptor, inducing apoptosis and activating NFkB.
TNF has endothelial effects, including increased expression of selectins and production of platelet activating factor, IL-1, and prostaglandins. It also promotes the proliferation of fibroblasts and their production of protease and collagenase. TNF inhibitors are used to treat inflammatory conditions such as rheumatoid arthritis and Crohn’s disease. Examples of TNF inhibitors include infliximab, etanercept, adalimumab, and golimumab.
Infliximab is also used to treat active Crohn’s disease unresponsive to steroids. However, TNF blockers can have adverse effects such as reactivation of latent tuberculosis and demyelination. Understanding TNF and its inhibitors is crucial in the treatment of various inflammatory conditions.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 47
Incorrect
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A baby girl is born at 38 weeks gestation. She is healthy at birth with no issues noted and no concerns from the obstetrics team.
Fifteen days later, the mother notices that the baby's eye is stuck closed with discharge, along with a reddening of the sclera and swelling of the eyelids. The baby is taken to the Pediatrician's office. A diagnosis of ophthalmia neonatorum is suspected and tests are done to confirm this.
What are the two bacteria that are most likely to be identified by the tests?Your Answer:
Correct Answer: Chlamydia trachomatis and Neisseria gonorrhoeae
Explanation:The most frequent culprits behind ophthalmia neonatorum are Chlamydia trachomatis and Neisseria gonorrhoeae, with the former being more prevalent. Typically, these two organisms manifest at different stages and necessitate distinct antibiotic treatments. Although less frequent, mixed infections can also occur. While the remaining choices may cause ophthalmia neonatorum, they are not as commonly observed.
Understanding Ophthalmia Neonatorum
Ophthalmia neonatorum is a term used to describe an infection that affects the eyes of newborn babies. This condition is caused by two main organisms, namely Chlamydia trachomatis and Neisseria gonorrhoeae. It is important to note that suspected cases of ophthalmia neonatorum should be referred for immediate ophthalmology or paediatric assessment.
To prevent complications, it is crucial to identify and treat ophthalmia neonatorum as soon as possible. This condition can cause severe damage to the eyes and even lead to blindness if left untreated. Therefore, parents and healthcare providers should be vigilant and seek medical attention if they notice any signs of eye infection in newborns. With prompt diagnosis and treatment, the prognosis for ophthalmia neonatorum is generally good.
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This question is part of the following fields:
- General Principles
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Question 48
Incorrect
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Whilst in general practice, you review John, a 50-year-old patient with hypertension. Despite taking lisinopril, his blood pressure remains clinically elevated. Based on current guidelines you consider add-on therapy with a thiazide-like diuretic.
Which of the following electrolyte imbalances may arise with this new treatment?Your Answer:
Correct Answer: Hypokalaemia
Explanation:Hypokalaemia may be caused by thiazides
Thiazide diuretics can lead to hypokalaemia by stimulating aldosterone production and inhibiting the Na-Cl symporter. This inhibition results in more sodium being available to activate the Na/K-ATPase channel, leading to increased potassium loss in the urine and hypokalaemia.
Thiazide diuretics may also cause other side effects such as hypocalciuria, hypomagnesemia, and hyperlipidemia. The other options that describe the opposite of these disturbances are incorrect.
Thiazide diuretics are medications that work by blocking the thiazide-sensitive Na+-Cl− symporter, which inhibits sodium reabsorption at the beginning of the distal convoluted tubule (DCT). This results in the loss of potassium as more sodium reaches the collecting ducts. While thiazide diuretics are useful in treating mild heart failure, loop diuretics are more effective in reducing overload. Bendroflumethiazide was previously used to manage hypertension, but recent NICE guidelines recommend other thiazide-like diuretics such as indapamide and chlorthalidone.
Common side effects of thiazide diuretics include dehydration, postural hypotension, and electrolyte imbalances such as hyponatremia, hypokalemia, and hypercalcemia. Other potential adverse effects include gout, impaired glucose tolerance, and impotence. Rare side effects may include thrombocytopenia, agranulocytosis, photosensitivity rash, and pancreatitis.
It is worth noting that while thiazide diuretics may cause hypercalcemia, they can also reduce the incidence of renal stones by decreasing urinary calcium excretion. According to current NICE guidelines, the management of hypertension involves the use of thiazide-like diuretics, along with other medications and lifestyle changes, to achieve optimal blood pressure control and reduce the risk of cardiovascular disease.
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This question is part of the following fields:
- Cardiovascular System
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Question 49
Incorrect
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A 31-year-old man visits an ophthalmology clinic with a complaint of experiencing double vision while descending stairs. He reports a recent mountain biking accident that required him to seek emergency medical attention. Although he has recuperated, he mentions that he sustained a severe frontal head injury after colliding with a tree.
During the examination, his left eye is raised and deviated medially, and he experiences vertical diplopia when looking up and down.
Which cranial nerve is most likely affected in this individual?Your Answer:
Correct Answer: Trochlear nerve
Explanation: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 50
Incorrect
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Sarah is a 63-year-old woman who has been experiencing gradual visual changes for the past 2 years. Recently, she has noticed a decline in her peripheral vision and has been running into objects.
During the examination, her eyes do not appear red. Ophthalmoscopy reveals bilateral cupping with a cup to disc ratio of 0.8. Tonometry shows a pressure of 26mmHg in her left eye and 28mmHg in her right eye.
After trying brinzolamide, latanoprost, and brimonidine, which were not well tolerated due to side effects, what is the mechanism of action of the best alternative medication?Your Answer:
Correct Answer: Decrease aqueous humour production
Explanation:Timolol, a beta blocker, is an effective treatment for primary open-angle glaucoma as it reduces the production of aqueous humor in the eye. This condition is caused by a gradual increase in intraocular pressure due to poor drainage within the trabecular meshwork, resulting in gradual vision loss. The first-line treatments for primary open-angle glaucoma include beta blockers, prostaglandin analogues, carbonic anhydrase inhibitors, and alpha-2-agonists. However, if a patient is unable to tolerate carbonic anhydrase inhibitors, prostaglandin analogues, or alpha-2-agonists, beta blockers like timolol are the remaining option. Carbonic anhydrase inhibitors reduce aqueous humor production, prostaglandin analogues increase uveoscleral outflow, and alpha-2-agonists have a dual action of reducing humor production and increasing outflow. It is important to note that increasing aqueous humor production and reducing uveoscleral outflow are not effective treatments for glaucoma.
Primary open-angle glaucoma is a type of optic neuropathy that is associated with increased intraocular pressure (IOP). It is classified based on whether the peripheral iris is covering the trabecular meshwork, which is important in the drainage of aqueous humour from the anterior chamber of the eye. In open-angle glaucoma, the iris is clear of the meshwork, but the trabecular network offers increased resistance to aqueous outflow, causing increased IOP. This condition affects 0.5% of people over the age of 40 and its prevalence increases with age up to 10% over the age of 80 years. Both males and females are equally affected. The main causes of primary open-angle glaucoma are increasing age and genetics, with first-degree relatives of an open-angle glaucoma patient having a 16% chance of developing the disease.
Primary open-angle glaucoma is characterised by a slow rise in intraocular pressure, which is symptomless for a long period. It is typically detected following an ocular pressure measurement during a routine examination by an optometrist. Signs of the condition include increased intraocular pressure, visual field defect, and pathological cupping of the optic disc. Case finding and provisional diagnosis are done by an optometrist, and referral to an ophthalmologist is done via the GP. Final diagnosis is made through investigations such as automated perimetry to assess visual field, slit lamp examination with pupil dilatation to assess optic nerve and fundus for a baseline, applanation tonometry to measure IOP, central corneal thickness measurement, and gonioscopy to assess peripheral anterior chamber configuration and depth. The risk of future visual impairment is assessed using risk factors such as IOP, central corneal thickness (CCT), family history, and life expectancy.
The majority of patients with primary open-angle glaucoma are managed with eye drops that aim to lower intraocular pressure and prevent progressive loss of visual field. According to NICE guidelines, the first line of treatment is a prostaglandin analogue (PGA) eyedrop, followed by a beta-blocker, carbonic anhydrase inhibitor, or sympathomimetic eyedrop as a second line of treatment. Surgery or laser treatment can be tried in more advanced cases. Reassessment is important to exclude progression and visual field loss and needs to be done more frequently if IOP is uncontrolled, the patient is high risk, or there
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This question is part of the following fields:
- Neurological System
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Question 51
Incorrect
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What is the characteristic finding on a blood film after a splenectomy?
Your Answer:
Correct Answer: Howell-Jolly bodies
Explanation:In cases of hyposplenism, the blood film may show the presence of Howell-Jolly bodies, Pappenheimer bodies, poikilocytes (specifically target cells), erythrocytes containing siderotic granules, and Heinz bodies.
Splenectomy and its Management
Splenectomy is a surgical procedure that involves the removal of the spleen. After the operation, patients are at a higher risk of infections caused by pneumococcus, Haemophilus, meningococcus, and Capnocytophaga canimorsus. To prevent these infections, patients should receive vaccinations such as Hib, meningitis A & C, annual influenzae, and pneumococcal vaccines. Antibiotic prophylaxis with penicillin V is also recommended for at least two years and until the patient is 16 years old, although some patients may require lifelong prophylaxis.
Splenectomy is indicated for various reasons such as trauma, spontaneous rupture, hypersplenism, malignancy, splenic cysts, hydatid cysts, and splenic abscesses. Elective splenectomy is different from emergency splenectomy, and it is usually performed laparoscopically. Complications of splenectomy include haemorrhage, pancreatic fistula, and thrombocytosis. Post-splenectomy changes include an increase in platelets, Howell-Jolly bodies, target cells, and Pappenheimer bodies. Patients are at an increased risk of post-splenectomy sepsis, which typically occurs with encapsulated organisms. Therefore, prophylactic antibiotics and pneumococcal vaccines are essential to prevent infections.
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This question is part of the following fields:
- General Principles
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Question 52
Incorrect
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Which one of the following statements relating to the greater omentum is false?
Your Answer:
Correct Answer: It has no relationship to the lesser sac.
Explanation:This area is linked to the transverse colon and the lesser sac, and is often accessed during a colonic resection. It is also frequently affected by metastasis in various types of visceral cancers.
The Omentum: A Protective Structure in the Abdomen
The omentum is a structure in the abdomen that invests the stomach and is divided into two parts: the greater and lesser omentum. The greater omentum is attached to the lower lateral border of the stomach and contains the gastro-epiploic arteries. It varies in size and is less developed in children. However, it plays an important role in protecting against visceral perforation, such as in cases of appendicitis.
The lesser omentum is located between the omentum and transverse colon, providing a potential entry point into the lesser sac. Malignant processes can affect the omentum, with ovarian cancer being the most notable. Overall, the omentum is a crucial structure in the abdomen that serves as a protective barrier against potential injuries and diseases.
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This question is part of the following fields:
- Gastrointestinal System
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Question 53
Incorrect
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A 40-year-old woman visits the respiratory clinic complaining of ongoing nighttime cough and difficulty breathing, despite trying various inhalers and oral medications. To alleviate bronchoconstriction, her consultant prescribes a drug that hinders the activity of the enzyme responsible for converting arachidonic acid into hydroperoxyeicosatetraenoic acid (HPETEs).
Which enzyme does this medication inhibit?Your Answer:
Correct Answer: Lipoxygenase
Explanation:The correct answer is lipoxygenase, which is responsible for converting arachidonic acid to HPETEs. This process is important in the formation of leukotrienes, which can cause bronchoconstriction in asthma. Zileuton is a medication that inhibits lipoxygenase and is used in the US for asthma treatment. In the UK, montelukast is used as an oral leukotriene receptor antagonist to block the action of leukotrienes in the lungs.
Cyclo-oxygenase-1 and cyclo-oxygenase-2 are incorrect answers. These enzymes are responsible for converting arachidonic acid to prostaglandins and thromboxanes, not HPETEs and leukotrienes. NSAIDs are a group of medications that block cyclo-oxygenase enzymes and are commonly used for pain relief. However, they can cause gastric irritation and ulceration, which can be reduced by co-prescribing a proton pump inhibitor. NSAIDs also reduce platelet aggregation and increase bleeding, so they should be avoided in patients with a history of gastrointestinal bleeding.
Hydrolase is also an incorrect answer. This enzyme is involved in the conversion of leukotriene A4 to leukotriene B4, which occurs later in the pathway than the conversion of arachidonic acid to HPETEs by lipoxygenase.
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 54
Incorrect
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A mother brought her 5-year-old daughter to a refugee camp clinic due to leg bowing. Over the past few months, the mother has noticed her daughter's legs appear curved, causing a slightly waddling gait. The daughter does not complain of soreness in the legs and has a good range of movement. There are no rashes or bruises noted. The patient has no relevant medical history, although the mother mentions difficulty adjusting to the UK lifestyle and weather since leaving Afghanistan.
Which blood test would be most helpful to request?Your Answer:
Correct Answer: Vitamin D level
Explanation:Rickets is caused by a deficiency in Vitamin D.
The stem correctly identifies Vitamin D as the cause of rickets, which is characterized by bowed legs and a waddling gait. The patient’s reduced calcium absorption is likely due to a change in sunlight exposure, as sunlight is a source of Vitamin D. This deficiency leads to decreased bone mineral density.
Autoantibody screen, coagulation screen, and full blood count are all incorrect as they are not specific to the symptoms described in the question. Vitamin B12 deficiency is also incorrect as it causes peripheral neuropathy, which the patient does not exhibit.
Understanding Vitamin D
Vitamin D is a type of vitamin that is soluble in fat and is essential for the metabolism of calcium and phosphate in the body. It is converted into calcifediol in the liver and then into calcitriol, which is the active form of vitamin D, in the kidneys. Vitamin D can be obtained from two sources: vitamin D2, which is found in plants, and vitamin D3, which is present in dairy products and can also be synthesized by the skin when exposed to sunlight.
The primary function of vitamin D is to increase the levels of calcium and phosphate in the blood. It achieves this by increasing the absorption of calcium in the gut and the reabsorption of calcium in the kidneys. Vitamin D also stimulates osteoclastic activity, which is essential for bone growth and remodeling. Additionally, it increases the reabsorption of phosphate in the kidneys.
A deficiency in vitamin D can lead to two conditions: rickets in children and osteomalacia in adults. Rickets is characterized by soft and weak bones, while osteomalacia is a condition where the bones become weak and brittle. Therefore, it is crucial to ensure that the body receives an adequate amount of vitamin D to maintain healthy bones and overall health.
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This question is part of the following fields:
- General Principles
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Question 55
Incorrect
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A 27-year-old man is involved in a car crash resulting in a fracture of his right tibia. He undergoes fasciotomies and an external fixator is applied. Within 48 hours, his serum creatinine levels increase and his urine is analyzed, revealing the presence of muddy brown casts. What is the probable underlying diagnosis?
Your Answer:
Correct Answer: Acute tubular necrosis
Explanation:It is probable that the patient suffered from compartment syndrome due to a tibial fracture and subsequent fasciotomies, which can result in myoglobinuria. The combination of deteriorating kidney function and the presence of muddy brown casts in the urine strongly indicate acute tubular necrosis. Acute interstitial nephritis is typically caused by drug toxicity and does not typically lead to the presence of muddy brown casts in the urine.
Understanding the Difference between Acute Tubular Necrosis and Prerenal Uraemia
Acute kidney injury can be caused by various factors, including prerenal uraemia and acute tubular necrosis. It is important to differentiate between the two to determine the appropriate treatment. Prerenal uraemia occurs when the kidneys hold on to sodium to preserve volume, leading to decreased blood flow to the kidneys. On the other hand, acute tubular necrosis is caused by damage to the kidney tubules, which can be due to various factors such as toxins, infections, or ischemia.
To differentiate between the two, several factors can be considered. In prerenal uraemia, the urine sodium level is typically less than 20 mmol/L, while in acute tubular necrosis, it is usually greater than 40 mmol/L. The urine osmolality is also higher in prerenal uraemia, typically above 500 mOsm/kg, while in acute tubular necrosis, it is usually below 350 mOsm/kg. The fractional sodium excretion is less than 1% in prerenal uraemia, while it is greater than 1% in acute tubular necrosis. Additionally, the response to fluid challenge is typically good in prerenal uraemia, while it is poor in acute tubular necrosis.
Other factors that can help differentiate between the two include the serum urea:creatinine ratio, fractional urea excretion, urine:plasma osmolality, urine:plasma urea, specific gravity, and urine sediment. By considering these factors, healthcare professionals can accurately diagnose and treat acute kidney injury.
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This question is part of the following fields:
- Renal System
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Question 56
Incorrect
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You are assisting in an open right adrenalectomy for a large adrenal adenoma in a slightly older patient. The consultant is momentarily distracted and you take the initiative to pull the adrenal into the wound to improve visibility. Unfortunately, this maneuver results in brisk bleeding. The most likely culprit vessel responsible for this bleeding is:
- Portal vein
- Phrenic vein
- Right renal vein
- Superior mesenteric vein
- Inferior vena cava
The vessel in question drains directly via a very short vessel and if not carefully sutured, it may become avulsed off the IVC. The best management approach for this injury involves the use of a Satinsky clamp and a 6/0 prolene suture.Your Answer:
Correct Answer: Inferior vena cava
Explanation:The vessel drains directly and is connected by a short pathway. If the sutures are not tied with caution, it could potentially detach from the IVC. In such a scenario, the recommended approach would be to use a Satinsky clamp and a 6/0 prolene suture to manage the injury.
Adrenal Gland Anatomy
The adrenal glands are located superomedially to the upper pole of each kidney. The right adrenal gland is posteriorly related to the diaphragm, inferiorly related to the kidney, medially related to the vena cava, and anteriorly related to the hepato-renal pouch and bare area of the liver. On the other hand, the left adrenal gland is postero-medially related to the crus of the diaphragm, inferiorly related to the pancreas and splenic vessels, and anteriorly related to the lesser sac and stomach.
The arterial supply of the adrenal glands is through the superior adrenal arteries from the inferior phrenic artery, middle adrenal arteries from the aorta, and inferior adrenal arteries from the renal arteries. The right adrenal gland drains via one central vein directly into the inferior vena cava, while the left adrenal gland drains via one central vein into the left renal vein.
In summary, the adrenal glands are small but important endocrine glands located above the kidneys. They have a unique blood supply and drainage system, and their location and relationships with other organs in the body are crucial for their proper functioning.
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This question is part of the following fields:
- Renal System
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Question 57
Incorrect
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In a 70 Kg person, what percentage of the entire body fluid will be provided by plasma?
Your Answer:
Correct Answer: 5%
Explanation:Understanding the Physiology of Body Fluid Compartments
Body fluid compartments are essential components of the human body, consisting of intracellular and extracellular compartments. The extracellular compartment is further divided into interstitial fluid, plasma, and transcellular fluid. In a typical 70 Kg male, the intracellular compartment comprises 60-65% of the total body fluid volume, while the extracellular compartment comprises 35-40%. The plasma volume is approximately 5%, while the interstitial fluid volume is 24%. The transcellular fluid volume is approximately 3%. These figures are only approximate and may vary depending on the individual’s weight and other factors. Understanding the physiology of body fluid compartments is crucial in maintaining proper fluid balance and overall health.
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This question is part of the following fields:
- Renal System
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Question 58
Incorrect
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A senior citizen arrives at the emergency department complaining of abdominal pain, constipation, and confusion. The blood tests reveal hypercalcemia, and the junior doctor suggests that a potential cause of this is an elevated level of parathyroid hormone (PTH) in the bloodstream. Can you provide the most accurate explanation of the functions of PTH?
Your Answer:
Correct Answer: Increases bone resorption, increases renal reabsorption of calcium, increases synthesis of active vitamin D
Explanation:The primary function of PTH is to elevate calcium levels and reduce phosphate levels. It exerts its influence on the bone and kidneys directly, while also indirectly affecting the intestine through vitamin D. PTH promotes bone resorption, enhances calcium reabsorption in the kidneys, and reduces phosphate reabsorption. Additionally, it stimulates the conversion of vitamin D to its active form, which in turn boosts calcium absorption in the intestine.
Maintaining Calcium Balance in the Body
Calcium ions are essential for various physiological processes in the body, and the largest store of calcium is found in the skeleton. The levels of calcium in the body are regulated by three hormones: parathyroid hormone (PTH), vitamin D, and calcitonin.
PTH increases calcium levels and decreases phosphate levels by increasing bone resorption and activating osteoclasts. It also stimulates osteoblasts to produce a protein signaling molecule that activates osteoclasts, leading to bone resorption. PTH increases renal tubular reabsorption of calcium and the synthesis of 1,25(OH)2D (active form of vitamin D) in the kidney, which increases bowel absorption of calcium. Additionally, PTH decreases renal phosphate reabsorption.
Vitamin D, specifically the active form 1,25-dihydroxycholecalciferol, increases plasma calcium and plasma phosphate levels. It increases renal tubular reabsorption and gut absorption of calcium, as well as osteoclastic activity. Vitamin D also increases renal phosphate reabsorption in the proximal tubule.
Calcitonin, secreted by C cells of the thyroid, inhibits osteoclast activity and renal tubular absorption of calcium.
Although growth hormone and thyroxine play a small role in calcium metabolism, the primary regulation of calcium levels in the body is through PTH, vitamin D, and calcitonin. Maintaining proper calcium balance is crucial for overall health and well-being.
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This question is part of the following fields:
- Neurological System
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Question 59
Incorrect
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A 24-year-old man is admitted to the emergency department after a car accident. During the initial evaluation, he complains of difficulty breathing. A portable chest X-ray shows a 3 cm gap between the right lung margin and the chest wall, indicating a significant traumatic pneumothorax. The medical team administers high-flow oxygen and performs a right-sided chest drain insertion to drain the pneumothorax.
What is a potential negative outcome that could arise from the insertion of a chest drain?Your Answer:
Correct Answer: Winging of the scapula
Explanation:Insertion of a chest drain poses a risk of damaging the long thoracic nerve, which runs from the neck to the serratus anterior muscle. This can result in weakness or paralysis of the muscle, causing a winged scapula that is noticeable along the medial border of the scapula. It is important to use aseptic technique during the procedure to prevent hospital-acquired pleural infection. Chylothorax, pneumothorax, and pyothorax are all conditions that may require chest drain insertion, but they are not known complications of the procedure. Therefore, these options are not applicable.
Anatomy of Chest Drain Insertion
Chest drain insertion is necessary for various medical conditions such as trauma, haemothorax, pneumothorax, and pleural effusion. The size of the chest drain used depends on the specific condition being treated. While ultrasound guidance is an option, the anatomical method is typically tested in exams.
It is recommended that chest drains are placed in the safe triangle, which is located in the mid axillary line of the 5th intercostal space. This triangle is bordered by the anterior edge of the latissimus dorsi, the lateral border of pectoralis major, a line superior to the horizontal level of the nipple, and the apex below the axilla. Another triangle, known as the triangle of auscultation, is situated behind the scapula and is bounded by the trapezius, latissimus dorsi, and vertebral border of the scapula. By folding the arms across the chest and bending forward, parts of the sixth and seventh ribs and the interspace between them become subcutaneous and available for auscultation.
References:
– Prof Harold Ellis. The applied anatomy of chest drains insertions. British Journal of hospital medicine 2007; (68): 44-45.
– Laws D, Neville E, Duffy J. BTS guidelines for insertion of chest drains. Thorax, 2003; (58): 53-59. -
This question is part of the following fields:
- Respiratory System
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Question 60
Incorrect
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A 16-year-old girl arrives at the hospital with a 4-day history of headache, photophobia, and fevers, and is diagnosed with meningococcal meningitis. She reveals that she attended a sleepover 6-days ago with several of her friends.
To prevent the spread of the disease, rifampicin is prescribed to the patient's close contacts.
What is the mode of action of this medication?Your Answer:
Correct Answer: Inhibition of DNA-dependent RNA polymerase
Explanation:The mechanism of rifampicin is the inhibition of bacterial DNA-dependent RNA polymerase, which prevents the transcription of DNA into mRNA. Rifampicin is an antibiotic that can be used as a prophylactic treatment for contacts of individuals diagnosed with meningococcal meningitis. Its side effects may include orange urine, and it is important to note that rifampicin is an enzyme-inducer that can reduce the effectiveness of drugs such as the combined oral contraceptive pill.
It is important to distinguish rifampicin from other antibiotics with different mechanisms of action. Fluoroquinolone antibiotics, such as ciprofloxacin and levofloxacin, inhibit DNA gyrase. Isoniazid, an antibiotic used to treat tuberculosis, inhibits mycolic acid synthesis, which is found in the cell walls of mycobacteria. Glycopeptide antibiotics, such as vancomycin and teicoplanin, inhibit peptidoglycan synthesis.
Tuberculosis is a bacterial infection that can be treated with a combination of drugs. Each drug has a specific mechanism of action and can also cause side-effects. Rifampicin works by inhibiting bacterial DNA dependent RNA polymerase, which prevents the transcription of DNA into mRNA. However, it is a potent liver enzyme inducer and can cause hepatitis, orange secretions, and flu-like symptoms.
Isoniazid, on the other hand, inhibits mycolic acid synthesis. It can cause peripheral neuropathy, which can be prevented with pyridoxine (Vitamin B6). It can also cause hepatitis and agranulocytosis, but it is a liver enzyme inhibitor.
Pyrazinamide is converted by pyrazinamidase into pyrazinoic acid, which inhibits fatty acid synthase (FAS) I. However, it can cause hyperuricaemia, leading to gout, as well as arthralgia and myalgia. It can also cause hepatitis.
Finally, Ethambutol inhibits the enzyme arabinosyl transferase, which polymerizes arabinose into arabinan. However, it can cause optic neuritis, so it is important to check visual acuity before and during treatment. The dose also needs adjusting in patients with renal impairment.
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This question is part of the following fields:
- General Principles
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Question 61
Incorrect
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A 65-year-old man has been experiencing acute breathlessness and fatigue alongside his pre-existing myelodysplastic syndrome. Upon initial blood tests, a significantly elevated white cell count with a high percentage of blast cells was observed. A subsequent bone marrow biopsy has confirmed a transformation to acute myeloid leukemia.
In order to gain a better understanding of his prognosis, what biochemical technique can be utilized to identify mutated oncogenes?Your Answer:
Correct Answer: Polymerase chain reaction (PCR)
Explanation:Polymerase chain reactions are commonly utilized to identify mutated oncogenes. This technique involves the use of specific primers that bind to a particular segment of genetic material. If the targeted sequence is present, the DNA is amplified, doubling in quantity during each cycle. Various methods are then employed to determine whether the target DNA sequence has indeed been amplified and is present.
Absorption spectroscopy is a technique that utilizes light absorption to measure the concentrations of absorptive substances in a solution. It does not play a role in detecting oncogenes.
Emulsion tests are used to detect lipids, not DNA.
ELISA testing is an immunological technique that can identify various peptides, proteins, antibodies, and antigens. It is notably used to diagnose HIV through the detection of antibodies.
Similarly, western blotting is a technique used to detect proteins, not DNA.
Reverse Transcriptase PCR
Reverse transcriptase PCR (RT-PCR) is a molecular genetic technique used to amplify RNA. This technique is useful for analyzing gene expression in the form of mRNA. The process involves converting RNA to DNA using reverse transcriptase. The resulting DNA can then be amplified using PCR.
To begin the process, a sample of RNA is added to a test tube along with two DNA primers and a thermostable DNA polymerase (Taq). The mixture is then heated to almost boiling point, causing denaturing or uncoiling of the RNA. The mixture is then allowed to cool, and the complimentary strands of DNA pair up. As there is an excess of the primer sequences, they preferentially pair with the DNA.
The above cycle is then repeated, with the amount of DNA doubling each time. This process allows for the amplification of the RNA, making it easier to analyze gene expression. RT-PCR is a valuable tool in molecular biology and has many applications in research, including the study of diseases and the development of new treatments.
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This question is part of the following fields:
- General Principles
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Question 62
Incorrect
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A 27-year-old male has been admitted to a psychiatric hospital following his arrest for a public order offence. According to reports, he stripped off his clothes in a public park and claimed to be the son of God, offering to cure people of any illness. He has a history of bipolar disorder and has ceased taking his medication. What is the probable nature of his delusions?
Your Answer:
Correct Answer: Grandiose delusions
Explanation:Types of Delusions
Grandiose delusions are a type of delusion where the individual has an inflated sense of self-importance. They believe that they are related to a higher figure, such as a deity, a monarch, or a celebrity. They may also believe that they possess great wealth, power, or social status. These delusions are commonly seen in individuals with bipolar disorder during manic episodes, as well as in other psychotic disorders.
On the other hand, erotomanic delusions are a type of delusion where the individual believes that someone of a higher social status is in love with them. This type of delusion can be dangerous, as the individual may become obsessed with the object of their delusion and may engage in stalking or other inappropriate behaviors.
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This question is part of the following fields:
- Psychiatry
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Question 63
Incorrect
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What viral infection can cause small grey lesions on the inside of the cheek?
Your Answer:
Correct Answer: Measles
Explanation:Common Viral Infections and Their Clinical Manifestations
Measles, caused by the RNA paramyxovirus, is a highly contagious viral infection that spreads through air-borne droplets. Immunisation strategies have been introduced to reduce its incidence in the developed world. The vaccine is given to children between 12 and 18 months of age. Measles has two distinct phases – the infectious phase and the non-infectious phase. The infectious phase is characterised by fever, cough, conjunctivitis, and koplik’s spots. The non-infectious phase is characterised by a maculopapular rash that becomes blotchy. Complications of measles include subacute sclerosing panencephalitis, which is rare but serious.
Herpes varicella virus infection causes chickenpox, a mild childhood illness characterised by fever, headache, and malaise. A rash develops on the face and trunk. The virus remains dormant for many years after which reactivation causes shingles.
Infectious mononucleosis is caused by Epstein-Barr virus and can be asymptomatic. If symptoms occur, the infection presents with a headache, sore throat, fever, and a transient macular rash.
Mumps presents with a headache, fever, malaise, and parotid gland swelling, while symptoms of Rubella include fever, malaise, and lymphadenopathy. the clinical manifestations of these common viral infections is crucial for their timely diagnosis and management.
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This question is part of the following fields:
- Infectious Diseases
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Question 64
Incorrect
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A 54-year-old man with a history of type II diabetes mellitus presents for a routine check-up. He reports no symptoms of increased urination or thirst. Laboratory results reveal an HbA1c level of 67 mmol/mol and a random plasma glucose level of 15.6 mg/l. The patient is currently taking metformin, and his physician decides to add gliclazide to his medication regimen. What is the mechanism of action of gliclazide?
Your Answer:
Correct Answer: Stimulates sulphonylurea-1 receptors
Explanation:The primary mode of action of gliclazide, which belongs to the sulphonylurea class, is to activate the sulphonylurea-1 receptors present on pancreatic cells, thereby promoting insulin secretion. The remaining choices pertain to alternative medications for diabetes.
Common Medications for Type 2 Diabetes
Type 2 diabetes is a chronic condition that affects millions of people worldwide. Fortunately, there are several medications available to help manage the disease. Some of the most commonly prescribed drugs include sulphonylureas, metformin, alpha-glucosidase inhibitors (such as acarbose), glitazones, and insulin.
Sulphonylureas are a type of medication that stimulates the pancreas to produce more insulin. This helps to lower blood sugar levels and improve glucose control. Metformin, on the other hand, works by reducing the amount of glucose produced by the liver and improving insulin sensitivity. Alpha-glucosidase inhibitors, like acarbose, slow down the digestion of carbohydrates in the small intestine, which helps to prevent spikes in blood sugar levels after meals.
Glitazones, also known as thiazolidinediones, improve insulin sensitivity and reduce insulin resistance. They work by activating a specific receptor in the body that helps to regulate glucose metabolism. Finally, insulin is a hormone that is naturally produced by the pancreas and helps to regulate blood sugar levels. In some cases, people with type 2 diabetes may need to take insulin injections to help manage their condition.
Overall, these medications can be very effective in helping people with type 2 diabetes to manage their blood sugar levels and prevent complications. However, it’s important to work closely with a healthcare provider to determine the best treatment plan for each individual.
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This question is part of the following fields:
- Endocrine System
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Question 65
Incorrect
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A 67-year-old male presents with a 3-week history of deteriorating vision in his left eye. During examination of the cranial nerves, it is observed that the left pupil is more constricted than the right. The patient experiences slight ptosis of the left eyelid. The patient reports dryness on the left side of the face with decreased sweating. There are no reports of reduced sweating elsewhere. The patient has no known medical history and lives independently with his family. He drinks 6 units per week and has a smoking history of 35 pack-years. Based on the neurological symptoms and history, where is the lesion most likely located?
Your Answer:
Correct Answer: Sympathetic chain
Explanation:Horner’s syndrome is a condition that can be categorized into three types based on the location of the lesion. The first type is a central lesion that can occur anywhere from the hypothalamus to the synapse at T1. The second type is a preganglionic lesion that occurs between the synapse in the spinal cord to the superior cervical ganglion. The third type is a postganglionic lesion that occurs above the superior cervical ganglion.
The level of anhidrosis, or lack of sweating, can help determine the location of the lesion. Anhidrosis is only seen in the first and second types of lesions. In first-type lesions, it affects the entire sympathetic region, while in second-type lesions, it only affects the face after the ganglion.
In this case, the patient has anhidrosis of the face, suggesting a second-type lesion. The patient’s smoking history increases the likelihood of a Pancoast’s tumor, which compresses the sympathetic chain.
Lesions in the medulla can present more dramatically, with more cranial nerve abnormalities and peripheral neurological signs. Lesions in the nerve fibers after the superior cervical ganglion typically present with ptosis and meiosis but without anhidrosis. Carotid artery dissection is a common cause of these types of lesions. Lesions in the cervical spine or hypothalamus would result in a more extensive disruption of peripheral neurology.
Horner’s syndrome is a condition characterized by several features, including a small pupil (miosis), drooping of the upper eyelid (ptosis), a sunken eye (enophthalmos), and loss of sweating on one side of the face (anhidrosis). The cause of Horner’s syndrome can be determined by examining additional symptoms. For example, congenital Horner’s syndrome may be identified by a difference in iris color (heterochromia), while anhidrosis may be present in central or preganglionic lesions. Pharmacologic tests, such as the use of apraclonidine drops, can also be helpful in confirming the diagnosis and identifying the location of the lesion. Central lesions may be caused by conditions such as stroke or multiple sclerosis, while postganglionic lesions may be due to factors like carotid artery dissection or cluster headaches. It is important to note that the appearance of enophthalmos in Horner’s syndrome is actually due to a narrow palpebral aperture rather than true enophthalmos.
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This question is part of the following fields:
- Neurological System
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Question 66
Incorrect
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At the end of a tiring night shift, you are feeling drained and eager to hit the sack. However, the doctor on call who is supposed to take over from you calls to inform you that he is running late due to traffic. You have a few crucial matters to pass on. How should you proceed?
Your Answer:
Correct Answer: Wait until the oncall doctor arrives, then hand over
Explanation:According to GMC Good medical practice, it is necessary for healthcare providers to ensure the safe transfer of patients between different providers. This involves sharing all relevant information with colleagues involved in the patient’s care, both within and outside the team. It also involves checking that a named clinician or team has taken over responsibility when your role in providing care has ended, especially for vulnerable patients or those with impaired capacity. Therefore, the correct answer is number 5, and it is important to avoid sending confidential information via text message or leaving it on a piece of paper that may get lost.
Maintaining Trust in Medical Practice
Maintaining trust is a crucial aspect of medical practice, and it is one of the four domains in Good Medical Practice. To maintain trust, medical professionals must show respect for their patients, treating them and their colleagues fairly and without discrimination. Honesty and integrity are also essential in building and maintaining trust.
Medical professionals must always show respect for their patients, regardless of their background or circumstances. This includes listening to their concerns, providing clear explanations, and involving them in decision-making processes. Treating patients and colleagues fairly and without discrimination is also crucial in maintaining trust. Medical professionals must ensure that they do not discriminate against patients based on their race, gender, religion, or any other factor.
Finally, honesty and integrity are essential in building and maintaining trust. Medical professionals must act with transparency, providing accurate information and avoiding any conflicts of interest. They must also be honest about their limitations and seek help when necessary.
In summary, maintaining trust is a critical aspect of medical practice. By showing respect for patients, treating them and colleagues fairly, and acting with honesty and integrity, medical professionals can build and maintain trust with their patients and the wider community.
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This question is part of the following fields:
- General Principles
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Question 67
Incorrect
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A 78-year-old male presents to the emergency department with a suspected acute ischaemic stroke. Upon examination, the male displays pendular nystagmus, hypotonia, and an intention tremor primarily in his left hand. During testing, he exhibits hypermetria with his left hand. What is the probable site of the lesion?
Your Answer:
Correct Answer: Left cerebellum
Explanation:Unilateral cerebellar damage results in ipsilateral symptoms, as seen in the patient in this scenario who is experiencing nystagmus, hypotonia, intention tremor, and hypermetria on the left side following a suspected ischemic stroke. This contrasts with cerebral hemisphere damage, which typically causes contralateral symptoms. A stroke in the left motor cortex, for example, would result in weakness on the right side of the body and face. The right cerebellum is an incorrect answer as it would cause symptoms on the same side of the body, while a stroke in the right motor cortex would cause weakness on the left side. Damage to the occipital lobes, responsible for vision, on the right side would lead to left-sided visual symptoms.
Cerebellar syndrome is a condition that affects the cerebellum, a part of the brain responsible for coordinating movement and balance. When there is damage or injury to one side of the cerebellum, it can cause symptoms on the same side of the body. These symptoms can be remembered using the mnemonic DANISH, which stands for Dysdiadochokinesia, Dysmetria, Ataxia, Nystagmus, Intention tremour, Slurred staccato speech, and Hypotonia.
There are several possible causes of cerebellar syndrome, including genetic conditions like Friedreich’s ataxia and ataxic telangiectasia, neoplastic growths like cerebellar haemangioma, strokes, alcohol use, multiple sclerosis, hypothyroidism, and certain medications or toxins like phenytoin or lead poisoning. In some cases, cerebellar syndrome may be a paraneoplastic condition, meaning it is a secondary effect of an underlying cancer like lung cancer. It is important to identify the underlying cause of cerebellar syndrome in order to provide appropriate treatment and management.
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This question is part of the following fields:
- Neurological System
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Question 68
Incorrect
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Activation of which receptor is believed to enhance the activity of brown fat, resulting in the production of heat/energy?
Your Answer:
Correct Answer: Beta-3 receptor
Explanation:The Role of Beta-3 Adrenoceptors and Brown Fat in Energy Metabolism
Fat cells were once believed to be inactive, but recent research has shown that they are actually an endocrine organ that produces hormones involved in regulating energy metabolism. One such hormone is produced by brown fat cells, which contain beta-3 adrenoceptors. These receptors are thought to stimulate lipolysis and thermogenesis, leading to increased energy expenditure. However, despite attempts to activate these receptors with agonists, no significant effect on weight or energy expenditure has been observed. Nonetheless, the discovery of the role of brown fat and beta-3 adrenoceptors in energy metabolism has opened up new avenues for research into potential treatments for obesity and related metabolic disorders.
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This question is part of the following fields:
- Clinical Sciences
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Question 69
Incorrect
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A 30-year-old female arrives at the Emergency Department complaining of eye pain and an unusual posture. During the examination, it is observed that her neck is fixed in a backward and lateral position, and her eyes are deviated upwards. She is unable to control her gaze. The patient has a history of paranoid schizophrenia and is currently taking olanzapine. What is the probable reason behind her symptoms?
Your Answer:
Correct Answer: Acute dystonic reaction
Explanation:Antipsychotics have the potential to cause acute dystonic reactions, with oculogyric crisis being a significant form. Symptoms may include jaw spasm, tongue protrusion, and the eyes rolling upwards.
The recommended treatment for an oculogyric crisis is typically the administration of IV procyclidine and discontinuation of the medication responsible for the reaction.
Akathisia is another side effect of antipsychotics, characterized by restlessness and an inability to remain still.
Tardive dyskinesia is a long-term side effect of antipsychotics that can manifest after several years of use. It often affects the face and involves involuntary, repetitive movements such as lip smacking, tongue protrusion, and grimacing.
Parkinsonism is a term used to describe antipsychotic side effects that mimic Parkinson’s disease, including cogwheel rigidity, bradykinesia, and a shuffling gait.
Antipsychotics are a type of medication used to treat schizophrenia, psychosis, mania, and agitation. They are divided into two categories: typical and atypical antipsychotics. The latter were developed to address the extrapyramidal side-effects associated with the first generation of typical antipsychotics. Typical antipsychotics work by blocking dopaminergic transmission in the mesolimbic pathways through dopamine D2 receptor antagonism. However, they are known to cause extrapyramidal side-effects such as Parkinsonism, acute dystonia, akathisia, and tardive dyskinesia. These side-effects can be managed with procyclidine. Other side-effects of typical antipsychotics include antimuscarinic effects, sedation, weight gain, raised prolactin, impaired glucose tolerance, neuroleptic malignant syndrome, reduced seizure threshold, and prolonged QT interval. The Medicines and Healthcare products Regulatory Agency has issued specific warnings when antipsychotics are used in elderly patients due to an increased risk of stroke and venous thromboembolism.
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This question is part of the following fields:
- Psychiatry
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Question 70
Incorrect
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A 36-year-old woman presents to her general practitioner with sudden-onset painful red-eye and blurred vision in her left eye. She reports that the pain started suddenly while she was out for lunch with her friends. On examination, a hypopyon is present in the left eye, which is also red and has a small and irregularly shaped pupil. Ophthalmoscopy cannot be performed due to photophobia. The patient is diagnosed with anterior uveitis. What medical history might be observed in this patient's past?
Your Answer:
Correct Answer: Ankylosing spondylitis
Explanation:The patient in this scenario is likely suffering from anterior uveitis, which is characterized by inflammation of the ciliary body and iris. Symptoms include a red and painful eye, irregularly shaped pupil, and the presence of a hypopyon. Anterior uveitis is commonly associated with the HLA-B27 haplotype. The correct answer to the question about conditions associated with anterior uveitis is ankylosing spondylitis, which is the only condition mentioned that has a known association with HLA-B27. Coeliac disease, Goodpasture’s syndrome, and haemochromatosis are all incorrect answers as they do not have an association with HLA-B27.
Anterior uveitis, also known as iritis, is a type of inflammation that affects the iris and ciliary body in the front part of the uvea. This condition is often associated with HLA-B27 and may be linked to other conditions such as ankylosing spondylitis, reactive arthritis, ulcerative colitis, Crohn’s disease, Behcet’s disease, and sarcoidosis. Symptoms of anterior uveitis include sudden onset of eye discomfort and pain, small and irregular pupils, intense sensitivity to light, blurred vision, redness in the eye, tearing, and a ring of redness around the cornea. In severe cases, pus and inflammatory cells may accumulate in the front chamber of the eye, leading to a visible fluid level. Treatment for anterior uveitis involves urgent evaluation by an ophthalmologist, cycloplegic agents to relieve pain and photophobia, and steroid eye drops to reduce inflammation.
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This question is part of the following fields:
- Neurological System
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Question 71
Incorrect
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You are designing a research project looking at the sensitivities and specificities of various markers in relation to myocardial necrosis. Specifically you want to assess the molecule which troponin C binds to.
Which molecule will you study in your research project?
You are designing a research project looking at the sensitivities and specificities of various markers in relation to myocardial necrosis. Specifically, you want to assess the molecule which troponin C binds to.
Which molecule will you study in your research project?Your Answer:
Correct Answer: Calcium ions
Explanation:Troponin C plays a crucial role in muscle contraction by binding to calcium ions. However, it is not a specific marker for myocardial necrosis as it can be released due to damage in both skeletal and cardiac muscles.
On the other hand, Troponin T and Troponin I are specific markers for myocardial necrosis. Troponin T binds to tropomyosin to form a complex, while Troponin I holds the troponin-tropomyosin complex in place by binding to actin.
Muscle contraction occurs when actin slides along myosin, which is the thick component of muscle fibers. The sarcoplasmic reticulum plays a crucial role in regulating the concentration of calcium ions in the cytoplasm of striated muscle cells.
Understanding Troponin: The Proteins Involved in Muscle Contraction
Troponin is a group of three proteins that play a crucial role in the contraction of skeletal and cardiac muscles. These proteins work together to regulate the interaction between actin and myosin, which is essential for muscle contraction. The three subunits of troponin are troponin C, troponin T, and troponin I.
Troponin C is responsible for binding to calcium ions, which triggers the contraction of muscle fibers. Troponin T binds to tropomyosin, forming a complex that helps regulate the interaction between actin and myosin. Finally, troponin I binds to actin, holding the troponin-tropomyosin complex in place and preventing muscle contraction when it is not needed.
Understanding the role of troponin is essential for understanding how muscles work and how they can be affected by various diseases and conditions. By regulating the interaction between actin and myosin, troponin plays a critical role in muscle contraction and is a key target for drugs used to treat conditions such as heart failure and skeletal muscle disorders.
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This question is part of the following fields:
- Cardiovascular System
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Question 72
Incorrect
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A 25-year-old man comes to the doctor complaining of difficulty with bowel movements. He reports having a good appetite and drinking enough fluids. He denies experiencing weight loss, night sweats, or fevers. The patient has a history of rhinitis and indigestion. He takes two medications regularly, but he cannot recall their names. Additionally, he has a learning disability.
Which of the following medications could be responsible for his constipation?Your Answer:
Correct Answer: Chlorphenamine
Explanation:Antihistamines for Allergic Rhinitis and Urticaria
Antihistamines, specifically H1 inhibitors, are effective in treating allergic rhinitis and urticaria. Sedating antihistamines like chlorpheniramine have antimuscarinic properties that can cause dry mouth and urinary retention. On the other hand, non-sedating antihistamines like loratadine and cetirizine are less likely to cause drowsiness. However, there is some evidence that cetirizine may still cause some level of drowsiness compared to other non-sedating antihistamines. Overall, antihistamines are a valuable treatment option for those suffering from allergic rhinitis and urticaria.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 73
Incorrect
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A 68-year-old man visits his GP complaining of an 8-week cough and an unintentional weight loss of 7kg. He has a smoking history of 35 pack-years. The GP observes some alterations in his left eye, which are indicative of Horner's syndrome.
The man is referred to the suspected cancer pathway and is subsequently diagnosed with a Pancoast tumour.
What symptom is this individual most likely to exhibit?Your Answer:
Correct Answer: Anhidrosis
Explanation:Horner’s syndrome is characterized by meiosis, ptosis, and enophthalmos, and may also present with anhidrosis. Anhidrosis is a common symptom in preganglionic and central causes of Horner’s syndrome, while postganglionic causes do not typically result in anhidrosis. Exophthalmos is not associated with Horner’s syndrome, but rather with other conditions. Hypopyon and mydriasis are also not symptoms of Horner’s syndrome.
Horner’s syndrome is a condition characterized by several features, including a small pupil (miosis), drooping of the upper eyelid (ptosis), a sunken eye (enophthalmos), and loss of sweating on one side of the face (anhidrosis). The cause of Horner’s syndrome can be determined by examining additional symptoms. For example, congenital Horner’s syndrome may be identified by a difference in iris color (heterochromia), while anhidrosis may be present in central or preganglionic lesions. Pharmacologic tests, such as the use of apraclonidine drops, can also be helpful in confirming the diagnosis and identifying the location of the lesion. Central lesions may be caused by conditions such as stroke or multiple sclerosis, while postganglionic lesions may be due to factors like carotid artery dissection or cluster headaches. It is important to note that the appearance of enophthalmos in Horner’s syndrome is actually due to a narrow palpebral aperture rather than true enophthalmos.
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This question is part of the following fields:
- Neurological System
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Question 74
Incorrect
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A 20-year-old woman is undergoing evaluation by a psychiatrist for her eating patterns. She confesses to engaging in binge eating and then inducing vomiting for the last half-year. During the physical examination, her BMI is measured at 20 kg/m², and enamel erosion is observed.
What acid-base and electrolyte imbalances are commonly linked to her eating disorder?Your Answer:
Correct Answer: Metabolic alkalosis, hypochloraemia, hypokalaemia
Explanation:Metabolic alkalosis, hypokalemia, and hypochloremia are commonly observed in individuals with bulimia nervosa, even if their BMI falls within a normal range. This is due to the excessive self-induced vomiting, which results in the loss of stomach acid (HCl) and potassium.
Understanding Bulimia Nervosa
Bulimia nervosa is an eating disorder that is characterized by recurrent episodes of binge eating followed by purging behaviors such as self-induced vomiting, misuse of laxatives, diuretics, or other medications, fasting, or excessive exercise. According to the DSM 5 diagnostic criteria, individuals with bulimia nervosa experience a sense of lack of control over eating during the episode, and the binge eating and compensatory behaviors occur at least once a week for three months. Recurrent vomiting may lead to erosion of teeth and Russell’s sign – calluses on the knuckles or back of the hand due to repeated self-induced vomiting.
Individuals with bulimia nervosa are unduly influenced by body shape and weight, and their self-evaluation is often based on these factors. It is important to note that the disturbance does not occur exclusively during episodes of anorexia nervosa. Referral for specialist care is appropriate in all cases, and NICE recommends bulimia-nervosa-focused guided self-help for adults. If this approach is not effective, individual eating-disorder-focused cognitive behavioral therapy (CBT-ED) may be considered. Children should be offered bulimia-nervosa-focused family therapy (FT-BN). While pharmacological treatments have a limited role, a trial of high-dose fluoxetine is currently licensed for bulimia, but long-term data is lacking.
In summary, bulimia nervosa is a serious eating disorder that requires specialized care. Early intervention and treatment can help individuals recover and improve their quality of life.
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This question is part of the following fields:
- Psychiatry
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Question 75
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 76
Incorrect
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A 68-year-old man is prescribed clopidogrel to manage his peripheral artery disease-related claudication pain. What is the mechanism of action of this medication?
Your Answer:
Correct Answer: Inhibits ADP binding to platelet receptors
Explanation:Clopidogrel prevents clot formation by blocking the binding of ADP to platelet receptors. Factor Xa inhibitors like rivaroxaban directly inhibit factor Xa and are used to prevent and treat venous thromboembolism and atherothrombotic events. Dabigatran, a direct thrombin inhibitor, is used for prophylaxis and treatment of venous thromboembolism. Heparin/LMWH increase the effect of antithrombin and can be used to treat acute peripheral arterial occlusion, prevent and treat deep vein thrombosis and pulmonary embolism.
Clopidogrel: An Antiplatelet Agent for Cardiovascular Disease
Clopidogrel is a medication used to manage cardiovascular disease by preventing platelets from sticking together and forming clots. It is commonly used in patients with acute coronary syndrome and is now also recommended as a first-line treatment for patients following an ischaemic stroke or with peripheral arterial disease. Clopidogrel belongs to a class of drugs called thienopyridines, which work in a similar way. Other examples of thienopyridines include prasugrel, ticagrelor, and ticlopidine.
Clopidogrel works by blocking the P2Y12 adenosine diphosphate (ADP) receptor, which prevents platelets from becoming activated. However, concurrent use of proton pump inhibitors (PPIs) may make clopidogrel less effective. The Medicines and Healthcare products Regulatory Agency (MHRA) issued a warning in July 2009 about this interaction, and although evidence is inconsistent, omeprazole and esomeprazole are still cause for concern. Other PPIs, such as lansoprazole, are generally considered safe to use with clopidogrel. It is important to consult with a healthcare provider before taking any new medications or supplements.
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This question is part of the following fields:
- Cardiovascular System
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Question 77
Incorrect
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A 25-year-old male presents with a painless swelling of the testis. Histologically the stroma has a lymphocytic infiltrate. What is the most likely diagnosis?
Seminoma is the most common type of testicular tumor and is frequently seen in males aged between 25-40 years. The classical subtype is the most prevalent, and histology shows a lymphocytic stromal infiltrate. Other subtypes include spermatocytic, anaplastic, and syncytiotrophoblast giant cells. A teratoma is more common in males aged 20-30 years.Your Answer:
Correct Answer: Classical seminoma
Explanation:The most prevalent form of testicular tumor is seminoma, which is typically found in males between the ages of 30 and 40. The classical subtype of seminoma is the most common and is characterized by a lymphocytic stromal infiltrate. Other subtypes include spermatocytic, which features tumor cells that resemble spermatocytes and has a favorable prognosis, anaplastic, and syncytiotrophoblast giant cells, which contain β HCG. Teratoma, on the other hand, is more frequently observed in males between the ages of 20 and 30.
Overview of Testicular Disorders
Testicular disorders can range from benign conditions to malignant tumors. Testicular cancer is the most common malignancy in men aged 20-30 years, with germ-cell tumors accounting for 95% of cases. Seminomas are the most common subtype, while non-seminomatous germ cell tumors include teratoma, yolk sac tumor, choriocarcinoma, and mixed germ cell tumors. Risk factors for testicular cancer include cryptorchidism, infertility, family history, Klinefelter’s syndrome, and mumps orchitis. The most common presenting symptom is a painless lump, but pain, hydrocele, and gynecomastia may also be present.
Benign testicular disorders include epididymo-orchitis, which is an acute inflammation of the epididymis often caused by bacterial infection. Testicular torsion, which results in testicular ischemia and necrosis, is most common in males aged between 10 and 30. Hydrocele presents as a mass that transilluminates and may occur as a result of a patent processus vaginalis in children. Treatment for these conditions varies, with orchidectomy being the primary treatment for testicular cancer. Surgical exploration is necessary for testicular torsion, while epididymo-orchitis and hydrocele may require medication or surgical procedures depending on the severity of the condition.
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This question is part of the following fields:
- Renal System
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Question 78
Incorrect
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A 4-year-old girl is brought to the emergency department by her father after the child has been having a fever and has been very irritable since last night. The child has a temperature of 39.5ºC, and the emergency doctor notices that the child has a red tongue and cracked lips. On examination cervical lymph nodes are enlarged. After noticing that the child's palms and soles are erythematous, the emergency doctor calls the pediatrician on call, and they make a decision to begin treatment. What is the severe complication that can occur if this patient is not treated appropriately and on time?
Your Answer:
Correct Answer: Coronary artery aneurysm
Explanation:Kawasaki disease can lead to coronary artery aneurysms, which should be screened for with an echocardiogram. Prompt treatment with intravenous immunoglobulin and aspirin is necessary to prevent this complication. Other potential complications, such as septic shock or febrile seizures, are not as severe as coronary artery aneurysms in this case. Anaphylactic shock is not a possibility based on the information provided.
Understanding Kawasaki Disease
Kawasaki disease is a rare type of vasculitis that primarily affects children. It is important to identify this disease early on as it can lead to serious complications such as coronary artery aneurysms. The disease is characterized by a high-grade fever that lasts for more than five days, which is resistant to antipyretics. Other features include conjunctival injection, bright red, cracked lips, strawberry tongue, cervical lymphadenopathy, and red palms and soles that later peel.
Diagnosis of Kawasaki disease is based on clinical presentation as there is no specific diagnostic test available. Management of the disease involves high-dose aspirin, which is one of the few indications for aspirin use in children. Intravenous immunoglobulin is also used as a treatment option. Echocardiogram is the initial screening test for coronary artery aneurysms instead of angiography.
Complications of Kawasaki disease include coronary artery aneurysm, which can be life-threatening. Early recognition and treatment of Kawasaki disease can prevent serious complications and improve outcomes for affected children.
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This question is part of the following fields:
- Cardiovascular System
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Question 79
Incorrect
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A 20-year-old man is rushed to the emergency department following his ejection from a car during a road accident.
During the examination, the patient responds to simple questions with incomprehensible sounds and opens his eyes in response to pain. There is also an abnormal wrist flexion when a sternal rub is applied, and a positive Battle's sign is observed.
A CT scan of the head is ordered, which reveals a fracture of the petrous temporal bone.
Which nerve is most likely to be affected by the patient's injury?Your Answer:
Correct Answer: Facial nerve
Explanation:The facial nerve passes through the internal acoustic meatus, which is correct. This nerve provides motor innervation to the muscles of facial expression, parasympathetic innervation to salivary and lacrimal glands, and special sensory innervation of taste in the anterior 2/3 of the tongue via the chorda tympani. The patient in question has a Glasgow Coma Score of 7, indicating nonspecific neurotrauma from a recent road traffic accident. It is unlikely that damage to the internal acoustic meatus would affect the glossopharyngeal or hypoglossal nerves, which pass through different structures. Damage to the oculomotor nerve, which passes through the superior orbital fissure, may cause ptosis and a dilated ‘down-and-out’ pupil.
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 80
Incorrect
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As a medical student in a cardiology clinic, you encounter a 54-year-old woman who has been diagnosed with atrial fibrillation by her GP after experiencing chest pain for 12 hours. She informs you that she had a blood clot in her early 30s following lower limb surgery and was previously treated with warfarin. Her CHA2DS2‑VASc score is 3. What is the first-line anticoagulant recommended to prevent future stroke in this patient?
Your Answer:
Correct Answer: Edoxaban
Explanation:According to the 2021 NICE guidelines on preventing stroke in individuals with atrial fibrillation, DOACs should be the first-line anticoagulant therapy offered. The correct answer is ‘edoxaban’. ‘Aspirin’ is not appropriate for managing atrial fibrillation as it is an antiplatelet agent. ‘Low molecular weight heparin’ and ‘unfractionated heparin’ are not recommended for long-term anticoagulation in this case as they require subcutaneous injections.
Atrial fibrillation (AF) is a condition that requires careful management, including the use of anticoagulation therapy. The latest guidelines from NICE recommend assessing the need for anticoagulation in all patients with a history of AF, regardless of whether they are currently experiencing symptoms. The CHA2DS2-VASc scoring system is used to determine the most appropriate anticoagulation strategy, with a score of 2 or more indicating the need for anticoagulation. However, it is important to ensure a transthoracic echocardiogram has been done to exclude valvular heart disease, which is an absolute indication for anticoagulation.
When considering anticoagulation therapy, doctors must also assess the patient’s bleeding risk. NICE recommends using the ORBIT scoring system to formalize this risk assessment, taking into account factors such as haemoglobin levels, age, bleeding history, renal impairment, and treatment with antiplatelet agents. While there are no formal rules on how to act on the ORBIT score, individual patient factors should be considered. The risk of bleeding increases with a higher ORBIT score, with a score of 4-7 indicating a high risk of bleeding.
For many years, warfarin was the anticoagulant of choice for AF. However, the development of direct oral anticoagulants (DOACs) has changed this. DOACs have the advantage of not requiring regular blood tests to check the INR and are now recommended as the first-line anticoagulant for patients with AF. The recommended DOACs for reducing stroke risk in AF are apixaban, dabigatran, edoxaban, and rivaroxaban. Warfarin is now used second-line, in patients where a DOAC is contraindicated or not tolerated. Aspirin is not recommended for reducing stroke risk in patients with AF.
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This question is part of the following fields:
- Cardiovascular System
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Question 81
Incorrect
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A 50-year-old woman comes to you complaining of increased urinary frequency and lower abdominal pain. She has a medical history of hypertension that is managed with a high dose of ramipril.
Upon conducting a urine dipstick test, the results indicate a urinary tract infection. You prescribe a 5-day course of trimethoprim.
What blood test will require monitoring in this patient?Your Answer:
Correct Answer: Urea and electrolytes
Explanation:Patients taking ACE-inhibitors should be cautious when using trimethoprim as it can lead to life-threatening hyperkalaemia, which may result in sudden death. Therefore, it is essential to monitor the potassium levels regularly by conducting urea and electrolyte tests.
When using trimethoprim with methotrexate, it is crucial to monitor the complete blood count regularly due to the increased risk of myelosuppression. However, if the patient is only taking trimethoprim, there is no need to monitor troponins and creatine kinase.
Angiotensin-converting enzyme (ACE) inhibitors are commonly used as the first-line treatment for hypertension and heart failure in younger patients. However, they may not be as effective in treating hypertensive Afro-Caribbean patients. ACE inhibitors are also used to treat diabetic nephropathy and prevent ischaemic heart disease. These drugs work by inhibiting the conversion of angiotensin I to angiotensin II and are metabolized in the liver.
While ACE inhibitors are generally well-tolerated, they can cause side effects such as cough, angioedema, hyperkalaemia, and first-dose hypotension. Patients with certain conditions, such as renovascular disease, aortic stenosis, or hereditary or idiopathic angioedema, should use ACE inhibitors with caution or avoid them altogether. Pregnant and breastfeeding women should also avoid these drugs.
Patients taking high-dose diuretics may be at increased risk of hypotension when using ACE inhibitors. Therefore, it is important to monitor urea and electrolyte levels before and after starting treatment, as well as any changes in creatinine and potassium levels. Acceptable changes include a 30% increase in serum creatinine from baseline and an increase in potassium up to 5.5 mmol/l. Patients with undiagnosed bilateral renal artery stenosis may experience significant renal impairment when using ACE inhibitors.
The current NICE guidelines recommend using a flow chart to manage hypertension, with ACE inhibitors as the first-line treatment for patients under 55 years old. However, individual patient factors and comorbidities should be taken into account when deciding on the best treatment plan.
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This question is part of the following fields:
- Cardiovascular System
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Question 82
Incorrect
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A 35-year-old man arrives at the Emergency Department complaining of pain in his right hand following a fall during a football match earlier in the day. Upon conducting a thorough hand examination, you identify that the pain is concentrated in the anatomical snuffbox. To investigate a possible scaphoid bone fracture, you order an x-ray.
Which structure, passing through the anatomical snuffbox, is most likely to have been affected by this injury?Your Answer:
Correct Answer: The radial artery
Explanation:The radial artery is the only structure that passes through the anatomical snuffbox and is commonly injured by scaphoid bone fractures, as it runs over the bone at the snuffbox. Therefore, it is the most likely structure to be affected by such a fracture.
The median nerve does not pass through the anatomical snuffbox, but rather through the carpal tunnel, so it is less likely to be injured by a scaphoid fracture.
While the radial nerve does pass through the snuffbox, it is the superficial branch, not the deep branch, that does so. Therefore, if a scaphoid bone fracture were to damage the radial nerve, it would likely affect the superficial branch rather than the deep branch.
The basilic vein does not pass through the anatomical snuffbox, but rather travels along the ulnar side of the arm. The cephalic vein is the vein that passes through the snuffbox.
The extensor pollicis longus tendon forms the medial border of the snuffbox, but it is not one of its contents. It runs relatively superficially and is therefore less likely to be affected by a scaphoid bone fracture than a structure that runs closer to the bone, such as the radial artery.
The Anatomical Snuffbox: A Triangle on the Wrist
The anatomical snuffbox is a triangular depression located on the lateral aspect of the wrist. It is bordered by tendons of the extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus muscles, as well as the styloid process of the radius. The floor of the snuffbox is formed by the trapezium and scaphoid bones. The apex of the triangle is located distally, while the posterior border is formed by the tendon of the extensor pollicis longus. The radial artery runs through the snuffbox, making it an important landmark for medical professionals.
In summary, the anatomical snuffbox is a small triangular area on the wrist that is bordered by tendons and bones. It is an important landmark for medical professionals due to the presence of the radial artery.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 83
Incorrect
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A 45-year-old woman has varicose veins originating from the short saphenous vein. During mobilization of the vein near its origin, which structure is at the highest risk of injury?
Your Answer:
Correct Answer: Sural nerve
Explanation:Litigation often arises from damage to the sural nerve, which is closely associated with this structure. While the other structures may also sustain injuries, the likelihood of such occurrences is comparatively lower.
Anatomy of the Popliteal Fossa
The popliteal fossa is a diamond-shaped space located at the back of the knee joint. It is bound by various muscles and ligaments, including the biceps femoris, semimembranosus, semitendinosus, and gastrocnemius. The floor of the popliteal fossa is formed by the popliteal surface of the femur, posterior ligament of the knee joint, and popliteus muscle, while the roof is made up of superficial and deep fascia.
The popliteal fossa contains several important structures, including the popliteal artery and vein, small saphenous vein, common peroneal nerve, tibial nerve, posterior cutaneous nerve of the thigh, genicular branch of the obturator nerve, and lymph nodes. These structures are crucial for the proper functioning of the lower leg and foot.
Understanding the anatomy of the popliteal fossa is important for healthcare professionals, as it can help in the diagnosis and treatment of various conditions affecting the knee joint and surrounding structures.
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This question is part of the following fields:
- Cardiovascular System
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Question 84
Incorrect
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A 7-year-old male patient is exhibiting severe fasting hypoglycemia symptoms and has an enlarged liver upon examination. Elevated levels of blood lactate, uric acid, and triglycerides are also present. Following thorough testing, the patient is diagnosed with Von Gierke disease (glycogen storage disease I). What specific enzyme is deficient in this condition?
Your Answer:
Correct Answer: Glucose-6-phosphatase
Explanation:Glucose-6-phosphatase deficiency is the underlying cause of Von Gierke’s disease, also known as glycogen storage disease type I. This condition results in severe fasting hypoglycemia, elevated levels of lactate, triglycerides, and uric acid, and impaired gluconeogenesis and glycogenolysis. Hepatomegaly is often observed during examination. Treatment involves frequent oral glucose intake and avoidance of fructose and galactose.
Inherited Metabolic Disorders: Types and Deficiencies
Inherited metabolic disorders are a group of genetic disorders that affect the body’s ability to process certain substances. These disorders can be categorized into different types based on the specific substance that is affected. One type is glycogen storage disease, which is caused by deficiencies in enzymes involved in glycogen metabolism. This can lead to the accumulation of glycogen in various organs, resulting in symptoms such as hypoglycemia, lactic acidosis, and hepatomegaly.
Another type is lysosomal storage disease, which is caused by deficiencies in enzymes involved in lysosomal metabolism. This can lead to the accumulation of various substances within lysosomes, resulting in symptoms such as hepatosplenomegaly, developmental delay, and optic atrophy. Examples of lysosomal storage diseases include Gaucher’s disease, Tay-Sachs disease, and Fabry disease.
Finally, mucopolysaccharidoses are a group of disorders caused by deficiencies in enzymes involved in the breakdown of glycosaminoglycans. This can lead to the accumulation of these substances in various organs, resulting in symptoms such as coarse facial features, short stature, and corneal clouding. Examples of mucopolysaccharidoses include Hurler syndrome and Hunter syndrome.
Overall, inherited metabolic disorders can have a wide range of symptoms and can affect various organs and systems in the body. Early diagnosis and treatment are important in managing these disorders and preventing complications.
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This question is part of the following fields:
- General Principles
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Question 85
Incorrect
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You are caring for a woman who has heart failure with reduced ejection fraction due to a previous myocardial infarction.
Starling's Law of the Heart states that:Your Answer:
Correct Answer: As preload progressively increases, stroke volume increases gradually then decreases suddenly
Explanation:Starling’s Law of the Heart states that as preload increases, stroke volume also increases gradually, up to a certain point. However, beyond this point, stroke volume decreases due to overloading of the cardiac muscle fibers. Therefore, the higher the cardiac preload, the greater the stroke volume, but only up to a certain limit.
The heart has four chambers and generates pressures of 0-25 mmHg on the right side and 0-120 mmHg on the left. The cardiac output is the product of heart rate and stroke volume, typically 5-6L per minute. The cardiac impulse is generated in the sino atrial node and conveyed to the ventricles via the atrioventricular node. Parasympathetic and sympathetic fibers project to the heart via the vagus and release acetylcholine and noradrenaline, respectively. The cardiac cycle includes mid diastole, late diastole, early systole, late systole, and early diastole. Preload is the end diastolic volume and afterload is the aortic pressure. Laplace’s law explains the rise in ventricular pressure during the ejection phase and why a dilated diseased heart will have impaired systolic function. Starling’s law states that an increase in end-diastolic volume will produce a larger stroke volume up to a point beyond which stroke volume will fall. Baroreceptor reflexes and atrial stretch receptors are involved in regulating cardiac output.
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This question is part of the following fields:
- Cardiovascular System
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Question 86
Incorrect
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A 72-year-old man comes to the clinic with a 10-month history of joint pain in his hands. After being diagnosed with rheumatoid arthritis, he is prescribed methotrexate and prednisone, but they do not provide sufficient relief. He is then referred to a specialist who starts him on anakinra.
What is the mechanism of action of anakinra?Your Answer:
Correct Answer: Interleukin-1 receptor antagonist
Explanation:The Role of Interleukin 1 in the Immune Response
Interleukin 1 (IL-1) is a crucial mediator of the immune response, secreted primarily by macrophages and monocytes. Its main function is to act as a costimulator of T cell and B cell proliferation. Additionally, IL-1 increases the expression of adhesion molecules on the endothelium, leading to vasodilation and increased vascular permeability. This can cause shock in sepsis, making IL-1 one of the mediators of this condition. Along with IL-6 and TNF, IL-1 also acts on the hypothalamus, causing pyrexia.
Due to its significant role in the immune response, IL-1 inhibitors are increasingly used in medicine. Examples of these inhibitors include anakinra, an IL-1 receptor antagonist used in the management of rheumatoid arthritis, and canakinumab, a monoclonal antibody targeted at IL-1 beta used in systemic juvenile idiopathic arthritis and adult-onset Still’s disease. These inhibitors help to regulate the immune response and manage conditions where IL-1 plays a significant role.
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This question is part of the following fields:
- General Principles
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Question 87
Incorrect
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A young man presents after multiple episodes of optic neuritis, during which he develops unilateral eye pain. Upon examination, he is found to have decreased visual acuity and colour saturation on his affected eye. His doctor suspects multiple sclerosis. What features would be expected on a T2-weighted MRI?
Your Answer:
Correct Answer: Multiple hyperintense lesions
Explanation:MS is characterized by the spread of brain lesions over time and space.
Dementia is often linked to cortical atrophy.
If there is only one hyperintense lesion, it may indicate a haemorrhage rather than other conditions.
A semilunar lesion on one side may indicate a subdural haemorrhage.
Raised intracranial pressure, which can be caused by space-occupying lesions and haemorrhages, can be indicated by midline shift.
Investigating Multiple Sclerosis
Diagnosing multiple sclerosis (MS) requires the identification of lesions that are disseminated in both time and space. There are several methods used to investigate MS, including magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, and visual evoked potentials (VEP).
MRI is a commonly used tool to identify MS lesions. High signal T2 lesions and periventricular plaques are often observed, as well as Dawson fingers, which are hyperintense lesions perpendicular to the corpus callosum. CSF analysis can also aid in diagnosis, as it may reveal oligoclonal bands that are not present in serum and an increased intrathecal synthesis of IgG.
VEP testing can also be used to diagnose MS. This test measures the electrical activity in the visual pathway and can reveal a delayed but well-preserved waveform in MS patients.
Overall, a combination of these methods is often used to diagnose MS and demonstrate the dissemination of lesions in time and space.
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This question is part of the following fields:
- Neurological System
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Question 88
Incorrect
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A 23-year-old male patient visits his GP complaining of breast tissue enlargement that has been progressively worsening for the past 3 months. He also reports the presence of a new lump on his left testicle. Upon thorough examination and taking a detailed medical history, the GP suspects that the patient may be suffering from testicular cancer.
What is the probable diagnosis?Your Answer:
Correct Answer: HCG secreting seminoma
Explanation:Gynaecomastia can be caused by testicular conditions such as seminoma that secrete hCG.
Understanding Gynaecomastia: Causes and Drug Triggers
Gynaecomastia is a condition characterized by the abnormal growth of breast tissue in males, often caused by an increased ratio of oestrogen to androgen. It is important to distinguish the causes of gynaecomastia from those of galactorrhoea, which is caused by the actions of prolactin on breast tissue.
Physiological changes during puberty can lead to gynaecomastia, but it can also be caused by syndromes with androgen deficiency such as Kallmann and Klinefelter’s, testicular failure due to mumps, liver disease, testicular cancer, and hyperthyroidism. Additionally, haemodialysis and ectopic tumour secretion can also trigger gynaecomastia.
Drug-induced gynaecomastia is also a common cause, with spironolactone being the most frequent trigger. Other drugs that can cause gynaecomastia include cimetidine, digoxin, cannabis, finasteride, GnRH agonists like goserelin and buserelin, oestrogens, and anabolic steroids. However, it is important to note that very rare drug causes of gynaecomastia include tricyclics, isoniazid, calcium channel blockers, heroin, busulfan, and methyldopa.
In summary, understanding the causes and drug triggers of gynaecomastia is crucial in diagnosing and treating this condition.
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This question is part of the following fields:
- Endocrine System
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Question 89
Incorrect
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A 32-year-old woman, who is 10 weeks pregnant, has been diagnosed with uncomplicated falciparum malaria after traveling to Tanzania. The infectious disease consultant has prescribed pyrimethamine, but is worried about its impact on folate metabolism and the potential harm to the fetus.
What is the potential interaction between the newly prescribed medication and folate metabolism?Your Answer:
Correct Answer: Inhibits dihydrofolate reductase
Explanation:The inhibition of dihydrofolate reductase by pyrimethamine results in interference with folate metabolism. Pregnant women should not be prescribed drugs that disrupt folate metabolism. The other options are incorrect.
Phenytoin causes disruption in the absorption of folate in the intestines.
Interference with Folate Metabolism by Drugs
Folate metabolism is a crucial process in the body that involves the conversion of folic acid into its active form, which is essential for DNA synthesis and cell division. However, certain drugs can interfere with this process, leading to various health complications.
Trimethoprim, methotrexate, and pyrimethamine are some of the drugs that can interfere with folate metabolism. These drugs inhibit the activity of dihydrofolate reductase, an enzyme that converts dihydrofolate to tetrahydrofolate, which is required for DNA synthesis. As a result, the body’s ability to produce new cells is impaired, leading to anemia, immune system dysfunction, and other health problems.
Phenytoin is another drug that can reduce the absorption of folate in the body. This drug inhibits the absorption of folate in the small intestine, leading to a deficiency of this essential nutrient. Folate deficiency can cause birth defects, anemia, and other health problems, especially in pregnant women.
In conclusion, drugs that interfere with folate metabolism can have serious health consequences. Patients taking these drugs should be closely monitored for signs of folate deficiency and treated accordingly. It is also important to ensure that patients receive adequate folate supplementation to prevent complications.
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This question is part of the following fields:
- General Principles
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Question 90
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:
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 91
Incorrect
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A 27-year-old male admitted to the ICU after a car accident has a pneumothorax. Using a bedside spirometer, his inspiratory and expiratory volumes were measured. What is the typical tidal volume for a male of his age?
Your Answer:
Correct Answer: 500ml
Explanation:The amount of air that is normally breathed in and out without any extra effort is called tidal volume, which is 500ml in males and 350ml in females.
Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 92
Incorrect
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A 58-year-old male complains of intense pain in the center of his abdomen that extends to his back and is accompanied by nausea and vomiting. Upon examination, his abdomen is tender and guarded, and his pulse is 106 bpm while his blood pressure is 120/82 mmHg. What diagnostic test would be beneficial in this case?
Your Answer:
Correct Answer: Amylase
Explanation:Diagnostic Tests and Severity Assessment for Acute Pancreatitis
Acute pancreatitis is a medical condition that requires prompt diagnosis and treatment. One of the most useful diagnostic tests for this condition is the measurement of amylase levels in the blood. In patients with acute pancreatitis, amylase levels are typically elevated, often reaching three times the upper limit of normal. Other blood parameters, such as troponin T, are not specific to pancreatitis and may be used to diagnose other medical conditions.
To assess the severity of acute pancreatitis, healthcare providers may use the Modified Glasgow Criteria, which is a mnemonic tool that helps to evaluate various clinical parameters. These parameters include PaO2, age, neutrophil count, calcium levels, renal function, enzymes such as LDH and AST, albumin levels, and blood sugar levels. Depending on the severity of these parameters, patients may be classified as having mild, moderate, or severe acute pancreatitis.
In summary, the diagnosis of acute pancreatitis relies on the measurement of amylase levels in the blood, while the severity of the condition can be assessed using the Modified Glasgow Criteria. Early diagnosis and prompt treatment are crucial for improving outcomes in patients with acute pancreatitis.
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This question is part of the following fields:
- Cardiovascular System
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Question 93
Incorrect
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What is the enzyme responsible for catalyzing the rate limiting step in glycolysis?
Your Answer:
Correct Answer: Phosphofructokinase
Explanation:The Rate Limiting Step of Glycolysis
The conversion of fructose 6 phosphate to fructose 1,6,bisphosphate is the main rate limiting step of the glycolysis pathway. This conversion is catalysed by the enzyme phosphofructokinase in the presence of ATP. However, excessive cellular concentrations of ATP can inhibit the activity of phosphofructokinase. This inhibition encourages the storage of excess glucose as glycogen instead of making excessive ATP in times of abundance. On the other hand, when there is cellular abundance of ATP but it is undergoing rapid degradation to AMP, the rising levels of AMP reduce the effect of high concentrations of ATP on the inhibition of the enzyme. Although several other steps in the glycolysis pathway are under control or inhibition in times of cellular ATP abundance or due to an accumulation of the products of glycolysis, phosphofructokinase is considered the main rate limiting step of glycolysis.
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This question is part of the following fields:
- Clinical Sciences
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Question 94
Incorrect
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A 79-year-old male is admitted to hospital with dehydration. Blood tests are sent to assess his renal function. The results are below. He is diagnosed with an acute kidney injury.
Na+ 143 mmol/l
K+ 4.8 mmol/l
Urea 32 mmol/l
Creatinine 383 mmol/l
eGFR 15 ml/min
What electrolyte should be monitored closely?Your Answer:
Correct Answer: Potassium
Explanation:The nephron plays a crucial role in maintaining the balance of electrolytes in the bloodstream, particularly potassium and hydrogen ions, which are regulated in the distal convoluted tubule (DCT) and collecting duct (CD).
Dehydration-induced acute kidney injury (AKI) is considered a pre-renal cause that reduces the glomerular filtration rate (GFR). In response, the kidney attempts to reabsorb as much fluid as possible to compensate for the body’s fluid depletion. As a result, minimal filtrate reaches the DCT and CD, leading to reduced potassium excretion. High levels of potassium can be extremely hazardous, especially due to its impact on the myocardium. Therefore, monitoring potassium levels is crucial in such situations, which can be done quickly through a venous blood gas (VBG) test.
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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Question 95
Incorrect
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What is a true statement about the p53 gene?
Your Answer:
Correct Answer: Li-Fraumeni syndrome predisposes to the development of sarcomas
Explanation:Understanding p53 and its Role in Cancer
p53 is a gene that helps suppress tumours and is located on chromosome 17p. It is frequently mutated in breast, colon, and lung cancer. The gene is believed to be essential in regulating the cell cycle, preventing cells from entering the S phase until DNA has been checked and repaired. Additionally, p53 may play a crucial role in apoptosis, the process of programmed cell death.
Li-Fraumeni syndrome is a rare genetic disorder that is inherited in an autosomal dominant pattern. It is characterised by the early onset of various cancers, including sarcoma, breast cancer, and leukaemia. The condition is caused by mutations in the p53 gene, which can lead to a loss of its tumour-suppressing function. Understanding the role of p53 in cancer can help researchers develop new treatments and therapies for those affected by the disease.
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This question is part of the following fields:
- General Principles
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Question 96
Incorrect
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A 67-year-old female smoker with a two-month history of worsening shortness of breath presents for evaluation. On examination, she appears comfortable at rest with a regular pulse of 72 bpm, respiratory rate of 16/min, and blood pressure of 128/82 mmHg. Physical findings include reduced expansion on the left lower zone, dullness to percussion over this area, and absent breath sounds over the left lower zone with bronchial breath sounds just above this region. What is the likely clinical diagnosis?
Your Answer:
Correct Answer: Pleural effusion
Explanation:Pleural Effusion and its Investigation
Pleural effusion is a condition where there is an abnormal accumulation of fluid in the pleural space, which is the space between the lungs and the chest wall. This can be caused by various factors such as post-infection, carcinoma, or emboli. To determine the cause of the pleural effusion, a pleural tap is the most appropriate investigation. The sample obtained from the pleural tap is sent for cytology, protein concentration, and culture.
A normal pleural tap would have clear appearance, pH of 7.60-7.64, protein concentration of less than 2%, white blood cells count of less than 1000/mm³, glucose level similar to that of plasma, LDH level of less than 50% of plasma concentration, amylase level of 30-110 U/L, triglycerides level of less than 2 mmol/l, and cholesterol level of 3.5-6.5 mmol/l.
A transudative tap is associated with conditions such as congestive heart failure, liver cirrhosis, severe hypoalbuminemia, and nephrotic syndrome. On the other hand, an exudative tap is associated with malignancy, infection (such as empyema due to bacterial pneumonia), trauma, pulmonary infarction, and pulmonary embolism.
In summary, pleural effusion can be caused by various factors and a pleural tap is the most appropriate investigation to determine the cause. The results of the pleural tap can help differentiate between transudative and exudative effusions, which can provide important information for diagnosis and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 97
Incorrect
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A 42-year-old woman comes in with a pathological fracture of her left femur. She had a renal transplant in the past due to end stage renal failure. Her blood tests show:
- Serum Ca2+ 2.80
- PTH 88 pg/ml
- Phosphate 0.30
The surgeon decides to perform a parathyroidectomy based on these results. What is the most likely appearance to be identified when the glands are assessed histologically?Your Answer:
Correct Answer: Hyperplasia of the gland
Explanation:It is probable that this is a case of tertiary hyperparathyroidism, characterized by elevated levels of Calcium and PTH, and decreased levels of phosphate. As a result, the glands are likely to be hyperplastic. It is important to note that hypertrophy is an incorrect term to use in this context, as it suggests an increase in size without an increase in the number of cells.
Parathyroid Glands and Disorders of Calcium Metabolism
The parathyroid glands play a crucial role in regulating calcium levels in the body. Hyperparathyroidism is a disorder that occurs when these glands produce too much parathyroid hormone (PTH), leading to abnormal calcium metabolism. Primary hyperparathyroidism is the most common form and is usually caused by a solitary adenoma. Secondary hyperparathyroidism occurs as a result of low calcium levels, often in the setting of chronic renal failure. Tertiary hyperparathyroidism is a rare condition that occurs when hyperplasia of the parathyroid glands persists after correction of underlying renal disorder.
Diagnosis of hyperparathyroidism is based on hormone profiles and clinical features. Treatment options vary depending on the type and severity of the disorder. Surgery is usually indicated for primary hyperparathyroidism if certain criteria are met, such as elevated serum calcium levels, hypercalciuria, and nephrolithiasis. Secondary hyperparathyroidism is typically managed with medical therapy, while surgery may be necessary for persistent symptoms such as bone pain and soft tissue calcifications. Tertiary hyperparathyroidism may resolve on its own within a year after transplant, but surgery may be required if an autonomously functioning parathyroid gland is present. It is important to consider differential diagnoses, such as benign familial hypocalciuric hypercalcaemia, which is a rare but relatively benign condition.
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This question is part of the following fields:
- Endocrine System
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Question 98
Incorrect
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A 9-month-old baby is presented to the emergency department by their mother with recurrent seizures and an increasing head circumference. The infant has been experiencing excessive sleeping, vomiting, and irritability. An MRI scan of the brain reveals an enlarged posterior fossa and an absent cerebellar vermis. Which structure is anticipated to be in a raised position in this infant?
Your Answer:
Correct Answer: Tentorium cerebelli
Explanation:The Dandy-Walker malformation causes an enlargement of the posterior fossa, resulting in an accumulation of cerebrospinal fluid that pushes the tentorium cerebelli upwards. This can lead to symptoms due to the mass effect. The falx cerebri, pituitary gland, sphenoid sinus, and superior cerebellar peduncle are unlikely to be significantly affected by this condition.
The Three Layers of Meninges
The meninges are a group of membranes that cover the brain and spinal cord, providing support to the central nervous system and the blood vessels that supply it. These membranes can be divided into three distinct layers: the dura mater, arachnoid mater, and pia mater.
The outermost layer, the dura mater, is a thick fibrous double layer that is fused with the inner layer of the periosteum of the skull. It has four areas of infolding and is pierced by small areas of the underlying arachnoid to form structures called arachnoid granulations. The arachnoid mater forms a meshwork layer over the surface of the brain and spinal cord, containing both cerebrospinal fluid and vessels supplying the nervous system. The final layer, the pia mater, is a thin layer attached directly to the surface of the brain and spinal cord.
The meninges play a crucial role in protecting the brain and spinal cord from injury and disease. However, they can also be the site of serious medical conditions such as subdural and subarachnoid haemorrhages. Understanding the structure and function of the meninges is essential for diagnosing and treating these conditions.
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This question is part of the following fields:
- Neurological System
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Question 99
Incorrect
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A 26-year-old man with a strong family history of Huntington's disease undergoes genome analysis. The analysis reveals the presence of a single nucleotide polymorphism (SNP) within the Huntington gene. This SNP causes a GUA codon to be transcribed as GUC. However, after careful examination, it is determined that this SNP did not affect the primary structure of the Huntington protein synthesized by the patient.
What is the type of mutation that occurred in this case?Your Answer:
Correct Answer: Silent
Explanation:Types of DNA Mutations
There are different types of DNA mutations that can occur in an organism’s genetic material. One type is called a silent mutation, which does not change the amino acid sequence of a protein. This type of mutation often occurs in the third position of a codon, where the change in the DNA base does not affect the final amino acid produced.
Another type of mutation is called a nonsense mutation, which results in the formation of a stop codon. This means that the protein being produced is truncated and may not function properly.
A missense mutation is a point mutation that changes the amino acid sequence of a protein. This can have significant effects on the protein’s function, as the altered amino acid may not be able to perform its intended role.
Finally, a frameshift mutation occurs when a number of nucleotides are inserted or deleted from the DNA sequence. This can cause a shift in the reading frame of the DNA, resulting in a completely different amino acid sequence downstream. These mutations can have serious consequences for the organism, as the resulting protein may be non-functional or even harmful.
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This question is part of the following fields:
- General Principles
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Question 100
Incorrect
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A 14-year-old unvaccinated girl visits her doctor with her father, reporting a fever, sore throat, and occasional cough. The doctor orders a throat swab for testing.
After a few days, the microbiology lab contacts the doctor to report the identification of an organism on Loeffler's medium.
What is the probable causative agent?Your Answer:
Correct Answer: Corynebacterium diphtheriae
Explanation:Corynebacterium diphtheriae is the correct answer for the cause of the child’s symptoms. The child’s lack of vaccination increases the likelihood of this diagnosis. Corynebacterium diphtheriae is typically grown in Loeffler’s medium, an enrichment medium.
Bordetella pertussis is an incorrect answer. Although it can cause similar symptoms, it is grown in Bordet-Gengou agar.
Haemophilus influenzae is also an incorrect answer. It can cause serious infections, but it is grown in chocolate agar.
Staphylococcus aureus is an unlikely cause of the child’s symptoms and can be grown on general unenriched culture media such as blood agar.
Culture Requirements for Common Organisms
Different microorganisms require specific culture conditions to grow and thrive. The table above lists some of the culture requirements for the more common organisms. For instance, Neisseria gonorrhoeae requires Thayer-Martin agar, which is a variant of chocolate agar, and the addition of Vancomycin, Polymyxin, and Nystatin to inhibit Gram-positive, Gram-negative, and fungal growth, respectively. Haemophilus influenzae, on the other hand, grows on chocolate agar with factors V (NAD+) and X (hematin).
To remember the culture requirements for some of these organisms, some mnemonics can be used. For example, Nice Homes have chocolate can help recall that Neisseria and Haemophilus grow on chocolate agar. If I Tell-U the Corny joke Right, you’ll Laugh can be used to remember that Corynebacterium diphtheriae grows on tellurite agar or Loeffler’s media. Lactating pink monkeys can help recall that lactose fermenting bacteria, such as Escherichia coli, grow on MacConkey agar resulting in pink colonies. Finally, BORDETella pertussis can be used to remember that Bordetella pertussis grows on Bordet-Gengou (potato) agar.
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This question is part of the following fields:
- General Principles
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Question 101
Incorrect
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Which of these openings allows the facial nerve to enter the temporal bone?
Your Answer:
Correct Answer: Internal acoustic meatus
Explanation:The facial nerve passes through the internal acoustic meatus of the temporal bone and emerges from the stylomastoid foramen.
The facial nerve is responsible for supplying the muscles of facial expression, the digastric muscle, and various glandular structures. It also contains a few afferent fibers that originate in the genicular ganglion and are involved in taste. Bilateral facial nerve palsy can be caused by conditions such as sarcoidosis, Guillain-Barre syndrome, Lyme disease, and bilateral acoustic neuromas. Unilateral facial nerve palsy can be caused by these conditions as well as lower motor neuron issues like Bell’s palsy and upper motor neuron issues like stroke.
The upper motor neuron lesion typically spares the upper face, specifically the forehead, while a lower motor neuron lesion affects all facial muscles. The facial nerve’s path includes the subarachnoid path, where it originates in the pons and passes through the petrous temporal bone into the internal auditory meatus with the vestibulocochlear nerve. The facial canal path passes superior to the vestibule of the inner ear and contains the geniculate ganglion at the medial aspect of the middle ear. The stylomastoid foramen is where the nerve passes through the tympanic cavity anteriorly and the mastoid antrum posteriorly, and it also includes the posterior auricular nerve and branch to the posterior belly of the digastric and stylohyoid muscle.
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This question is part of the following fields:
- Neurological System
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Question 102
Incorrect
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Which muscles are responsible for flexing the knee joint?
Your Answer:
Correct Answer: Semitendinosus
Explanation:The Flexors of the Knee Joint and Other Related Muscles
The muscles responsible for flexing the knee joint are the biceps femoris, semimembranosus, semitendinosus, and gastrocnemius. On the other hand, the quadriceps femoris and sartorius muscles are involved in hip flexion, although the latter is weak despite being the longest muscle in the body. Lastly, the soleus muscle is responsible for ankle plantar flexion.
In summary, the flexors of the knee joint are composed of four muscles, while other related muscles are involved in hip flexion and ankle plantar flexion. the functions of these muscles is essential in diagnosing and treating injuries or conditions that affect the lower extremities.
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This question is part of the following fields:
- Clinical Sciences
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Question 103
Incorrect
-
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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Question 104
Incorrect
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A 45-year-old male patient presents with choreiform movements that he is unable to control or cease. During the consultation, you inquire about his family history and discover that his father experienced similar symptoms at a slightly later age. Based on this information, what genetic phenomenon is likely to have taken place between the patient and his father?
Your Answer:
Correct Answer: Anticipation
Explanation:Anticipation may be observed in Huntington’s disease due to its nature as a trinucleotide repeat disorder. The disease is caused by an autosomal dominant gene with CAG repeats in exon 1 of the Huntingtin gene. The number of CAG repeats is indicative of the severity of the disease, with individuals having 36 to 39 repeats potentially developing symptoms, while those with 40 or more repeats almost always develop the disorder. HD can occur in individuals with 36 to 120 CAG repeats.
Anticipation is observed as the number of CAG repeats increases between generations. Offspring of individuals with 27 to 35 CAG repeats are at risk of developing HD, even though the parent does not suffer from the disease. Additionally, higher numbers of CAG repeats tend to cause HD to manifest at earlier ages, resulting in younger generations being affected by the disease.
Huntington’s disease is a genetic disorder that causes progressive and incurable neurodegeneration. It is inherited in an autosomal dominant manner and is caused by a trinucleotide repeat expansion of CAG in the huntingtin gene on chromosome 4. This can result in the phenomenon of anticipation, where the disease presents at an earlier age in successive generations. The disease leads to the degeneration of cholinergic and GABAergic neurons in the striatum of the basal ganglia, which can cause a range of symptoms.
Typically, symptoms of Huntington’s disease develop after the age of 35 and can include chorea, personality changes such as irritability, apathy, and depression, intellectual impairment, dystonia, and saccadic eye movements. Unfortunately, there is currently no cure for Huntington’s disease, and it usually results in death around 20 years after the initial symptoms develop.
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This question is part of the following fields:
- Neurological System
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