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  • Question 1 - An 80-year-old man presents to the emergency department with acute and severe abdominal...

    Correct

    • An 80-year-old man presents to the emergency department with acute and severe abdominal pain, vomiting, and bloody stools. He has a medical history of atrial fibrillation and ischaemic heart disease. Upon examination, his heart rate is 140 beats per minute, blood pressure is 98/58mmHg, respiratory rate is 24 breaths per minute, oxygen saturations are 98% on air, and temperature is 38.8ºC. A CT scan with contrast of the abdomen reveals air in the intestinal wall. During surgery, it is discovered that the distal third of the colon to the superior part of the rectum is necrotic.

      Which artery is responsible for supplying blood to this portion of the bowel?

      Your Answer: Inferior mesenteric artery

      Explanation:

      The correct artery supplying the affected area in this patient is the inferior mesenteric artery. This artery branches off the abdominal aorta and supplies the hindgut, which includes the distal third of the colon and the rectum superior to the pectinate line. It’s important to note that the anal canal is divided into two parts by the pectinate line, with the upper half supplied by the superior rectal artery branch of the inferior mesenteric artery, and the lower half supplied by the inferior rectal artery branch of the internal pudendal artery. Ischaemic heart disease and atrial fibrillation are risk factors for acute mesenteric ischaemia in this patient, which presents with severe, poorly-localised abdominal pain and tenderness. The coeliac trunk, which supplies the foregut, is not involved in this case. The internal pudendal artery supplies the inferior part of the anal canal, perineum, and genitalia, while the right colic artery, a branch of the superior mesenteric artery, supplies the ascending colon, which is not affected in this patient.

      The Inferior Mesenteric Artery: Supplying the Hindgut

      The inferior mesenteric artery (IMA) is responsible for supplying the embryonic hindgut with blood. It originates just above the aortic bifurcation, at the level of L3, and passes across the front of the aorta before settling on its left side. At the point where the left common iliac artery is located, the IMA becomes the superior rectal artery.

      The hindgut, which includes the distal third of the colon and the rectum above the pectinate line, is supplied by the IMA. The left colic artery is one of the branches that emerges from the IMA near its origin. Up to three sigmoid arteries may also exit the IMA to supply the sigmoid colon further down the line.

      Overall, the IMA plays a crucial role in ensuring that the hindgut receives the blood supply it needs to function properly. Its branches help to ensure that the colon and rectum are well-nourished and able to carry out their important digestive functions.

    • This question is part of the following fields:

      • Gastrointestinal System
      33.3
      Seconds
  • Question 2 - A 35-year-old teacher presents to her doctor with a complaint of foot pain...

    Incorrect

    • A 35-year-old teacher presents to her doctor with a complaint of foot pain for the past week. The pain is located on the bottom of her heel and is most severe in the morning and after prolonged periods of sitting at her desk. What is the probable cause of her symptoms?

      Your Answer: Achilles tendonitis

      Correct Answer: Plantar fasciitis

      Explanation:

      Understanding Plantar Fasciitis

      Plantar fasciitis is a prevalent condition that causes heel pain in adults. The pain is typically more severe around the medial calcaneal tuberosity. To manage this condition, it is essential to rest the feet as much as possible. Wearing shoes with good arch support and cushioned heels can also help alleviate the pain. Additionally, insoles and heel pads may be useful in providing extra support and cushioning to the feet. By taking these steps, individuals with plantar fasciitis can manage their symptoms and improve their overall quality of life.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      37.1
      Seconds
  • Question 3 - A young woman comes in with a sudden and severe headache at the...

    Incorrect

    • A young woman comes in with a sudden and severe headache at the back of her head, which quickly leads to seizures. Upon examination, doctors discover an aneurysm. During the assessment, they observe that her right eye is displaced downwards and to the side. What could be the probable reason for this?

      Your Answer: Trochlear nerve palsy

      Correct Answer: Oculomotor nerve palsy

      Explanation:

      When someone has oculomotor nerve palsy, their medial rectus muscle is disabled, which causes the lateral rectus muscle to move the eye uncontrollably to the side. Additionally, the superior rectus, inferior rectus, and inferior oblique muscles are also affected, causing the eye to move downwards due to the unopposed action of the superior oblique muscle. This condition also results in ptosis, or drooping of the eyelid, due to paralysis of the levator palpebrae superioris muscle, and mydriasis, or dilation of the pupil, due to damage to the parasympathetic fibers.

      Disorders of the Oculomotor System: Nerve Path and Palsy Features

      The oculomotor system is responsible for controlling eye movements and pupil size. Disorders of this system can result in various nerve path and palsy features. The oculomotor nerve has a large nucleus at the midbrain and its fibers pass through the red nucleus and the pyramidal tract, as well as through the cavernous sinus into the orbit. When this nerve is affected, patients may experience ptosis, eye down and out, and an inability to move the eye superiorly, inferiorly, or medially. The pupil may also become fixed and dilated.

      The trochlear nerve has the longest intracranial course and is the only nerve to exit the dorsal aspect of the brainstem. Its nucleus is located at the midbrain and it passes between the posterior cerebral and superior cerebellar arteries, as well as through the cavernous sinus into the orbit. When this nerve is affected, patients may experience vertical diplopia (diplopia on descending the stairs) and an inability to look down and in.

      The abducens nerve has its nucleus in the mid pons and is responsible for the convergence of eyes in primary position. When this nerve is affected, patients may experience lateral diplopia towards the side of the lesion and the eye may deviate medially. Understanding the nerve path and palsy features of the oculomotor system can aid in the diagnosis and treatment of disorders affecting this important system.

    • This question is part of the following fields:

      • Neurological System
      18.1
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  • Question 4 - What is the function of factor XIII in the clotting cascade and which...

    Incorrect

    • What is the function of factor XIII in the clotting cascade and which action corresponds to it?

      Your Answer: Interacts with factor VII as part of the extrinsic pathway

      Correct Answer: Stabilises the fibrin clot

      Explanation:

      The Role of Factor XIII in Blood Clotting

      Factor XIII is a crucial component of the clotting cascade, which is involved in both the intrinsic and extrinsic pathways. Its primary function is to stabilize the fibrin clot by cross-linking fibrin polymers that have been formed by the action of thrombin. This process ensures that the clot remains intact and prevents bleeding from the site of injury. Prothrombin is activated to thrombin by factor Xa, which is an essential step in the clotting cascade. Overall, factor XIII plays a critical role in the blood clotting process, and its deficiency can lead to bleeding disorders.

    • This question is part of the following fields:

      • Clinical Sciences
      35.3
      Seconds
  • Question 5 - Which of the following drugs is not associated with thrombocytopenia? ...

    Incorrect

    • Which of the following drugs is not associated with thrombocytopenia?

      Your Answer: Penicillin

      Correct Answer: Warfarin

      Explanation:

      Understanding Drug-Induced Thrombocytopenia

      Drug-induced thrombocytopenia is a condition where a person’s platelet count drops due to the use of certain medications. This condition is believed to be immune-mediated, meaning that the body’s immune system mistakenly attacks and destroys platelets. Some of the drugs that have been associated with drug-induced thrombocytopenia include quinine, abciximab, NSAIDs, diuretics like furosemide, antibiotics such as penicillins, sulphonamides, and rifampicin, and anticonvulsants like carbamazepine and valproate. Heparin, a commonly used blood thinner, is also known to cause drug-induced thrombocytopenia. It is important to be aware of the potential side effects of medications and to consult with a healthcare provider if any concerning symptoms arise. Proper management and monitoring of drug-induced thrombocytopenia can help prevent serious complications.

    • This question is part of the following fields:

      • General Principles
      26.6
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  • Question 6 - Which one of the following is not a typical feature of central chemoreceptors...

    Incorrect

    • Which one of the following is not a typical feature of central chemoreceptors in the regulation of respiration?

      Your Answer: During acute hypercapnia the carotid receptors will be stimulated first

      Correct Answer: They are stimulated primarily by venous hypercapnia

      Explanation:

      Arterial carbon dioxide stimulates them, but it takes longer to reach equilibrium compared to the carotid peripheral chemoreceptors. They are not as responsive to acidity because of the blood-brain barrier.

      The Control of Ventilation in the Human Body

      The control of ventilation in the human body is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration. The respiratory centres, chemoreceptors, lung receptors, and muscles all play a role in this process. The automatic, involuntary control of respiration occurs from the medulla, which is responsible for controlling the respiratory rate and depth of respiration.

      The respiratory centres consist of the medullary respiratory centre, apneustic centre, and pneumotaxic centre. The medullary respiratory centre has two groups of neurons, the ventral group, which controls forced voluntary expiration, and the dorsal group, which controls inspiration. The apneustic centre, located in the lower pons, stimulates inspiration and activates and prolongs inhalation. The pneumotaxic centre, located in the upper pons, inhibits inspiration at a certain point and fine-tunes the respiratory rate.

      Ventilatory variables, such as the levels of pCO2, are the most important factors in ventilation control, while levels of O2 are less important. Peripheral chemoreceptors, located in the bifurcation of carotid arteries and arch of the aorta, respond to changes in reduced pO2, increased H+, and increased pCO2 in arterial blood. Central chemoreceptors, located in the medulla, respond to increased H+ in brain interstitial fluid to increase ventilation. It is important to note that the central receptors are not influenced by O2 levels.

      Lung receptors also play a role in the control of ventilation. Stretch receptors respond to lung stretching, causing a reduced respiratory rate, while irritant receptors respond to smoke, causing bronchospasm. J (juxtacapillary) receptors are also involved in the control of ventilation. Overall, the control of ventilation is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration.

    • This question is part of the following fields:

      • Respiratory System
      23.8
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  • Question 7 - A researcher is tasked with investigating the evidence for a recently developed drug...

    Incorrect

    • A researcher is tasked with investigating the evidence for a recently developed drug used in treating Alzheimer's disease. After conducting a literature search on PubMed, they come across several studies. Which of the following studies they found provides the most reliable evidence?

      Your Answer:

      Correct Answer: A prospective cohort study

      Explanation:

      Levels and Grades of Evidence in Evidence-Based Medicine

      In order to evaluate the quality of evidence in evidence-based medicine, levels or grades are often used to organize the evidence. Traditional hierarchies placed systematic reviews or randomized control trials at the top and case-series/report at the bottom. However, this approach is overly simplistic as certain research questions cannot be answered using RCTs. To address this, the Oxford Centre for Evidence-Based Medicine introduced their 2011 Levels of Evidence system which separates the type of study questions and gives a hierarchy for each. On the other hand, the GRADE system is a grading approach that classifies the quality of evidence as high, moderate, low, or very low. The process begins by formulating a study question and identifying specific outcomes. Outcomes are then graded as critical or important, and the evidence is gathered and criteria are used to grade the evidence. Evidence can be promoted or downgraded based on certain circumstances. The use of levels and grades of evidence helps to evaluate the quality of evidence and make informed decisions in evidence-based medicine.

    • This question is part of the following fields:

      • General Principles
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  • Question 8 - A 32-year-old woman arrives at the emergency department feeling ill with pain in...

    Incorrect

    • A 32-year-old woman arrives at the emergency department feeling ill with pain in her upper abdomen that spreads to her back, but is relieved when she leans forward. Her blood test shows elevated levels of serum amylase and lipase. She had been diagnosed with a viral infection a week ago.

      What type of viral infection is linked to an increased likelihood of her current symptoms?

      Your Answer:

      Correct Answer: Mumps virus

      Explanation:

      Acute pancreatitis can be caused by mumps virus.

      The symptoms described in the scenario are consistent with acute pancreatitis. The mnemonic ‘I GET SMASHED’ is a helpful tool for identifying risk factors for this condition, and mumps virus is included in this list.

      While hepatitis B and C viruses have been associated with cases of pancreatitis, they are not known to directly cause the condition. influenzae virus is also not a known cause of acute pancreatitis.

      However, mumps virus is a known cause of acute pancreatitis. In addition to symptoms of pancreatitis, patients may also experience other symptoms of mumps virus. The severity of the pancreatitis is typically mild in these cases.

      Acute pancreatitis is a condition that is primarily caused by gallstones and alcohol consumption in the UK. However, there are other factors that can contribute to the development of this condition. A popular mnemonic used to remember these factors is GET SMASHED, which stands for gallstones, ethanol, trauma, steroids, mumps, autoimmune diseases, scorpion venom, hypertriglyceridaemia, hyperchylomicronaemia, hypercalcaemia, hypothermia, ERCP, and certain drugs. It is important to note that pancreatitis is seven times more common in patients taking mesalazine than sulfasalazine. CT scans can show diffuse parenchymal enlargement with oedema and indistinct margins in patients with acute pancreatitis.

    • This question is part of the following fields:

      • Gastrointestinal System
      0
      Seconds
  • Question 9 - Where is troponin T located within the body? ...

    Incorrect

    • Where is troponin T located within the body?

      Your Answer:

      Correct Answer: Heart

      Explanation:

      Troponin and Its Significance in Cardiac Health

      Troponin is an enzyme that is specific to the heart and is used to detect injury to the heart muscle. It is commonly measured in patients who present with chest pain that may be related to heart problems. Elevated levels of troponin can indicate a heart attack or other acute coronary syndromes. However, it is important to note that troponin levels may also be slightly elevated in other conditions such as renal failure, cardiomyopathy, myocarditis, and large pulmonary embolism.

      Troponin is a crucial marker in the diagnosis and management of cardiac conditions. It is a reliable indicator of heart muscle damage and can help healthcare professionals determine the best course of treatment for their patients. Additionally, troponin levels can provide prognostic information, allowing doctors to predict the likelihood of future cardiac events. It is important for individuals to understand the significance of troponin in their cardiac health and to seek medical attention if they experience any symptoms of heart problems.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 10 - Whilst an inpatient for a chest infection, a 65-year-old man is seen by...

    Incorrect

    • Whilst an inpatient for a chest infection, a 65-year-old man is seen by the hospital's diabetic specialist nurse. Despite trying various medications, his diabetic control has been generally inadequate. His latest blood test shows his HbA1c to still be above the normal range. The specialist nurse decides to initiate a new medication and advises the GP to review with a repeat blood test in a few months. The patient is cautioned about severe adverse effects, particularly Fournier gangrene.

      What is the mechanism of action of the prescribed medication?

      Your Answer:

      Correct Answer: Inhibits sodium-glucose co-transporter 2

      Explanation:

      SGLT-2 inhibitors work by inhibiting the sodium-glucose co-transporter 2 (SGLT-2) in the renal proximal convoluted tubule. This class of drugs includes empagliflozin and dapagliflozin and can lead to weight loss. However, they may also cause urinary/genital infections and normoglycaemic ketoacidosis. Fournier gangrene is a known serious adverse effect of this drug class.

      Thiazolidinedione drugs, such as pioglitazone, activate peroxisome proliferator-activated receptor-gamma (PPAR gamma). This receptor complex affects various target genes, ultimately decreasing insulin resistance and causing other effects.

      Sulfonylureas, like gliclazide, block ATP-sensitive potassium channels. These drugs may cause weight gain and induce hypoglycaemia.

      GLP-1 mimetics, including exenatide, activate glucagon-like peptide 1 receptors. This relatively new class of drug can lead to weight loss but is not widely used in diabetic guidelines.

      DPP4 inhibitors, such as sitagliptin and linagliptin, work by inhibiting dipeptidyl peptidase-4 (DPP4). This ultimately leads to increased levels of incretin circulation, similar to GLP-1 mimetics.

      Understanding SGLT-2 Inhibitors

      SGLT-2 inhibitors are medications that work by blocking the reabsorption of glucose in the kidneys, leading to increased excretion of glucose in the urine. This mechanism of action helps to lower blood sugar levels in patients with type 2 diabetes mellitus. Examples of SGLT-2 inhibitors include canagliflozin, dapagliflozin, and empagliflozin.

      However, it is important to note that SGLT-2 inhibitors can also have adverse effects. Patients taking these medications may be at increased risk for urinary and genital infections due to the increased glucose in the urine. Fournier’s gangrene, a rare but serious bacterial infection of the genital area, has also been reported. Additionally, there is a risk of normoglycemic ketoacidosis, a condition where the body produces high levels of ketones even when blood sugar levels are normal. Finally, patients taking SGLT-2 inhibitors may be at increased risk for lower-limb amputations, so it is important to closely monitor the feet.

      Despite these potential risks, SGLT-2 inhibitors can also have benefits. Patients taking these medications often experience weight loss, which can be beneficial for those with type 2 diabetes mellitus. Overall, it is important for patients to discuss the potential risks and benefits of SGLT-2 inhibitors with their healthcare provider before starting treatment.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 11 - A 50-year-old woman presents to the Emergency Department with a several-hour history of...

    Incorrect

    • A 50-year-old woman presents to the Emergency Department with a several-hour history of excruciating pain in the left knee. Her medical history is significant for hypertension and a previous episode of gout. She takes amlodipine.

      On examination, she is in severe pain and the left knee is swollen, red, warm and tender. Arthroscopic evaluation of the synovial fluid aspirate showed monosodium crystals that are negatively birefringent under polarized light. A diagnosis of recurrent gout is made and ultimately the patient is commenced on prophylaxis using allopurinol.

      What is the mechanism of action of allopurinol?

      Your Answer:

      Correct Answer: Inhibits xanthine oxidase

      Explanation:

      Allopurinol is a medication that inhibits xanthine oxidase, which is used for gout prophylaxis. By blocking the conversion of hypoxanthine to xanthine and xanthine to uric acid, it reduces the levels of uric acid in the blood. The other options, such as inhibition of dihydrofolate reductase, ribonucleotide reductase, and thymidylate synthase, are not related to gout prophylaxis. Rasburicase, which oxidizes urate to allantoin, is also used for gout prophylaxis, but it works differently than allopurinol.

      Allopurinol can interact with other medications such as azathioprine, cyclophosphamide, and theophylline. It can lead to high levels of 6-mercaptopurine when used with azathioprine, reduced renal clearance when used with cyclophosphamide, and an increase in plasma concentration of theophylline. Patients at a high risk of severe cutaneous adverse reaction should be screened for the HLA-B *5801 allele.

    • This question is part of the following fields:

      • General Principles
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  • Question 12 - A 22-year-old man presents to the physician with recurrent respiratory infections. He reports...

    Incorrect

    • A 22-year-old man presents to the physician with recurrent respiratory infections. He reports that his uncle had similar symptoms and passed away from a 'blood condition' three years ago. On physical examination, he has conjunctival pallor, a pulse of 110/min, and respirations of 19/min. Laboratory studies reveal a hemoglobin level of 100 g/L, platelets of 250 * 109/L, WBC of 7 * 109/L, a reticulocyte count of 6%, and an MCV of 84 fL. A peripheral smear shows numerous sickle-shaped red blood cells and Howell-jolly bodies. What additional investigation would be useful in confirming the diagnosis for this patient?

      Your Answer:

      Correct Answer: Hemoglobin electrophoresis

      Explanation:

      Sickle cell disease can be definitively diagnosed through haemoglobin electrophoresis. In the case of a patient experiencing an acute haemolytic episode due to sickle cell disease, normocytic anaemia with a high reticulocyte count and the presence of Howell jolly bodies indicate hyposplenism. A peripheral smear showing sickle cells is also highly indicative of sickle cell disease, which is an autosomal recessive condition that may be present in other family members.

      The osmotic fragility test is used to diagnose hereditary spherocytosis by exposing red blood cells to varying osmolarity and observing their fragility. Plasma folate deficiency can lead to macrocytic anaemia, but this is not the case in sickle cell disease. Flow cytometry is not useful in diagnosing sickle cell disease, but it can be used to classify leukemias and diagnose paroxysmal nocturnal haemoglobinuria.

      If an autoimmune cause is suspected, a Coombs test can be performed to confirm the pathogenesis, as in the case of haemolytic disease of the newborn. Haemoglobin electrophoresis is one of the definitive tests for diagnosing sickle cell trait and disease, as it shows a decrease in normal haemoglobin A and the presence of haemoglobin S. Genetic analysis can also confirm the diagnosis.

      Understanding Sickle-Cell Anaemia

      Sickle-cell anaemia is a genetic disorder that occurs when an abnormal haemoglobin chain, known as HbS, is synthesized due to an autosomal recessive condition. This condition is more common in people of African descent, as the heterozygous condition offers some protection against malaria. In the UK, around 10% of Afro-Caribbean individuals are carriers of HbS. Symptoms in homozygotes typically do not develop until 4-6 months when the abnormal HbSS molecules take over from fetal haemoglobin.

      The pathophysiology of sickle-cell anaemia involves the substitution of the polar amino acid glutamate with the non-polar valine in each of the two beta chains (codon 6) of haemoglobin. This substitution decreases the water solubility of deoxy-Hb, causing HbS molecules to polymerize and sickle in the deoxygenated state. HbAS patients sickle at p02 2.5 – 4 kPa, while HbSS patients sickle at p02 5 – 6 kPa. Sickle cells are fragile and can cause haemolysis, block small blood vessels, and lead to infarction.

      To diagnose sickle-cell anaemia, haemoglobin electrophoresis is the definitive test. It is essential to understand the pathophysiology and symptoms of sickle-cell anaemia to provide appropriate care and management for affected individuals.

    • This question is part of the following fields:

      • Haematology And Oncology
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  • Question 13 - Following a car crash, a 25-year-old male is brought to the hospital and...

    Incorrect

    • Following a car crash, a 25-year-old male is brought to the hospital and needs a blood transfusion. He has B negative blood type. Which of the following blood types would be the best match?

      Your Answer:

      Correct Answer: O rhesus negative

      Explanation:

      The ideal blood type for the patient would be B rhesus negative, but it is not available. Among the available options, rhesus positive blood is not recommended for a woman of reproductive age as it may lead to haemolytic disease in newborns. A-type blood would also cause hemolysis in this patient. The only suitable option is O rhesus negative, which is the universal donor.

      Blood product transfusion complications can be categorized into immunological, infective, and other complications. Immunological complications include acute haemolytic reactions, non-haemolytic febrile reactions, and allergic/anaphylaxis reactions. Infective complications may arise due to transmission of vCJD, although measures have been taken to minimize this risk. Other complications include transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), hyperkalaemia, iron overload, and clotting.

      Non-haemolytic febrile reactions are thought to be caused by antibodies reacting with white cell fragments in the blood product and cytokines that have leaked from the blood cell during storage. These reactions may occur in 1-2% of red cell transfusions and 10-30% of platelet transfusions. Minor allergic reactions may also occur due to foreign plasma proteins, while anaphylaxis may be caused by patients with IgA deficiency who have anti-IgA antibodies.

      Acute haemolytic transfusion reaction is a serious complication that results from a mismatch of blood group (ABO) which causes massive intravascular haemolysis. Symptoms begin minutes after the transfusion is started and include a fever, abdominal and chest pain, agitation, and hypotension. Treatment should include immediate transfusion termination, generous fluid resuscitation with saline solution, and informing the lab. Complications include disseminated intravascular coagulation and renal failure.

      TRALI is a rare but potentially fatal complication of blood transfusion that is characterized by the development of hypoxaemia/acute respiratory distress syndrome within 6 hours of transfusion. On the other hand, TACO is a relatively common reaction due to fluid overload resulting in pulmonary oedema. As well as features of pulmonary oedema, the patient may also be hypertensive, a key difference from patients with TRALI.

    • This question is part of the following fields:

      • Haematology And Oncology
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  • Question 14 - A 65-year-old man comes to the emergency department after experiencing a sudden, severe...

    Incorrect

    • A 65-year-old man comes to the emergency department after experiencing a sudden, severe headache that started one hour ago. He describes it as feeling like he was hit in the head with a hammer while he was in the shower.

      During the examination, the patient has a dilated left pupil with an eye that is fixed to the lower lateral quadrant. Although he feels nauseous, there is no change in his Glasgow Coma Scale score (GCS).

      Which of the following dural folds is responsible for the compression of the oculomotor nerve, resulting in the eye signs observed in this case?

      Your Answer:

      Correct Answer: Tentorium cerebelli

      Explanation:

      The tentorium cerebelli, which is a fold of the dura mater on both sides, separates the cerebellum from the occipital lobes. When there are expanding mass lesions, the brain can be pushed down past this fold, resulting in the compression of local structures such as the oculomotor nerve. This compression can cause abnormal eye positioning and a dilated pupil in the patient.

      It is important to note that the corpus callosum is not a fold of the meninges. Instead, it is a bundle of neuronal fibers that connect the two hemispheres of the brain.

      The falx cerebri, on the other hand, is a fold of the dura mater that extends inferiorly between the two hemispheres of the brain.

      The arachnoid and pia mater are the middle and innermost layers of the meninges, respectively. They are not involved in the fold of the dura mater that separates the occipital lobe from the cerebellum.

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 15 - A 70-year-old male was admitted to the hospital due to delirium observed in...

    Incorrect

    • A 70-year-old male was admitted to the hospital due to delirium observed in the nursing home. Upon diagnosis, he was found to have a lower respiratory tract infection which progressed to sepsis. During his stay in the ICU, he was discovered to have severe hyponatremia. The medical team has prescribed tolvaptan along with other medications.

      What is the mechanism of action of tolvaptan?

      Your Answer:

      Correct Answer: Vasopressin V2 receptor antagonist

      Explanation:

      Tolvaptan is a drug that blocks the action of vasopressin at the V2 receptor, which reduces water absorption and increases aquaresis without sodium loss. Vasopressin is a hormone that regulates water balance in the body.

      Autosomal dominant polycystic kidney disease (ADPKD) is a commonly inherited kidney disease that affects 1 in 1,000 Caucasians. The disease is caused by mutations in two genes, PKD1 and PKD2, which produce polycystin-1 and polycystin-2 respectively. ADPKD type 1 accounts for 85% of cases, while ADPKD type 2 accounts for 15% of cases. ADPKD type 1 is caused by a mutation in the PKD1 gene on chromosome 16, while ADPKD type 2 is caused by a mutation in the PKD2 gene on chromosome 4. ADPKD type 1 tends to present with renal failure earlier than ADPKD type 2.

      To screen for ADPKD in relatives of affected individuals, an abdominal ultrasound is recommended. The diagnostic criteria for ultrasound include the presence of two cysts, either unilateral or bilateral, if the individual is under 30 years old. If the individual is between 30-59 years old, two cysts in both kidneys are required for diagnosis. If the individual is over 60 years old, four cysts in both kidneys are necessary for diagnosis.

      For some patients with ADPKD, tolvaptan, a vasopressin receptor 2 antagonist, may be an option to slow the progression of cyst development and renal insufficiency. However, NICE recommends tolvaptan only for adults with ADPKD who have chronic kidney disease stage 2 or 3 at the start of treatment, evidence of rapidly progressing disease, and if the company provides it with the agreed discount in the patient access scheme.

    • This question is part of the following fields:

      • Renal System
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  • Question 16 - A 35-year-old obese nulliparous woman has given birth to a live singleton and...

    Incorrect

    • A 35-year-old obese nulliparous woman has given birth to a live singleton and the placenta, but is experiencing excessive bleeding. The registrar estimates that she has lost around 600 ml of blood. Despite receiving both crystalloid and colloid fluids, she remains haemodynamically unstable. As crossmatched blood is not yet available and her blood group is unknown, what blood group should be given to prevent a transfusion mismatch?

      Your Answer:

      Correct Answer: O negative

      Explanation:

      What is the blood group that can be given to anyone regardless of their blood type?

      Blood Products and Cell Saver Devices

      Blood products are essential in various medical procedures, especially in cases where patients require transfusions due to anaemia or bleeding. Packed red cells, platelet-rich plasma, platelet concentrate, fresh frozen plasma, and cryoprecipitate are some of the commonly used whole blood fractions. Fresh frozen plasma is usually administered to patients with clotting deficiencies, while cryoprecipitate is a rich source of Factor VIII and fibrinogen. Cross-matching is necessary for all blood products, and cell saver devices are used to collect and re-infuse a patient’s own blood lost during surgery.

      Cell saver devices come in two types, those that wash the blood cells before re-infusion and those that do not. The former is more expensive and complicated to operate but reduces the risk of re-infusing contaminated blood. The latter avoids the use of donor blood and may be acceptable to Jehovah’s witnesses. However, it is contraindicated in malignant diseases due to the risk of facilitating disease dissemination.

      In some surgical patients, the use of warfarin can pose specific problems and may require the use of specialised blood products. Warfarin reversal can be achieved through the administration of vitamin K, fresh frozen plasma, or human prothrombin complex. Fresh frozen plasma is used less commonly now as a first-line warfarin reversal, and human prothrombin complex is preferred due to its rapid action. However, it should be given with vitamin K as factor 6 has a short half-life.

    • This question is part of the following fields:

      • Haematology And Oncology
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  • Question 17 - A 65-year-old man with a history of claudication for several years is evaluated...

    Incorrect

    • A 65-year-old man with a history of claudication for several years is evaluated in the clinic. A duplex scan reveals an 85% stenosis of the superficial femoral artery. After two weeks, he returns with a sudden onset of severe leg pain that has been present for an hour. Upon examination, absent pulses are noted in the affected limb, and it is significantly cooler than the opposite limb. What is the most likely cause of this presentation?

      Your Answer:

      Correct Answer: Thrombosis

      Explanation:

      When dealing with an already present lesion, the probability of encountering a complication like thrombosis is higher than that of an embolus. To address this, patients should be administered heparin and undergo imaging with duplex scanning. Although an early surgical bypass or intra-arterial thrombolysis may be necessary, performing an embolectomy is generally not recommended as the lesion is not an embolus, rendering the operation ineffective.

      Understanding Claudication

      Claudication is a medical condition that causes pain in the limbs during physical activity. It is usually caused by arterial insufficiency, which occurs when atheroma develops in the arterial wall and blocks the blood flow to the tissues. The most common symptom of claudication is calf pain that worsens during exercise and improves with rest. However, if the disease is located in more proximal areas, other symptoms such as buttock claudication and impotence may occur.

      The condition usually develops progressively, and in severe cases, it can lead to critical limb ischemia, which is characterized by severe pain, diminished sensation, pallor, and absent pulses. Risk factors for claudication include smoking, diabetes, and hyperlipidemia.

      To diagnose claudication, doctors may measure ankle-brachial pressure indices, perform duplex scanning, or conduct formal angiography. Treatment options depend on the severity of the condition. Patients with long claudication distances and no ulceration or gangrene may be managed conservatively, while those with rest pain, ulceration, or gangrene will require intervention. All patients should receive an antiplatelet agent and a statin, unless there are compelling contraindications.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 18 - A 25-year-old healthcare worker from Bangladesh, who migrated to the UK at the...

    Incorrect

    • A 25-year-old healthcare worker from Bangladesh, who migrated to the UK at the age of six, is undergoing an occupational health assessment that includes an interferon-gamma release assay (IGRA). The worker has no knowledge of their vaccination history and has never experienced symptoms of tuberculosis infection. What is the primary physiological function of the cytokine used in this diagnostic test?

      Your Answer:

      Correct Answer: Activation of macrophages

      Explanation:

      Macrophage activation is triggered by interferon-γ.

      Interferon-γ is a cytokine produced by Th1 cells that promotes inflammation and activates macrophages. In medical testing, measuring the release of interferon-gamma by leukocytes in response to Mycobacterium tuberculosis antigens can indicate the presence of active or latent TB infection. This test is preferred over the tuberculin skin test as it does not yield a false positive result in individuals who have received the BCG vaccine.

      Macrophages produce cytokines such as interleukin-8 and tumor necrosis factor-α, which attract neutrophils to the site of infection.

      Eosinophil production is stimulated by interleukin-5, GM-CSF, and IL-3, which promote granulocyte maturation.

      Interferon-γ does not directly cause fever. Pyrogenic cytokines such as interleukin-1 and interleukin-6, produced by macrophages and Th2 cells, induce fever.

      Interferon-γ is a Th1 cytokine that promotes the differentiation of Th0 cells into Th1 cells, creating a positive feedback loop.

      Overview of Cytokines and Their Functions

      Cytokines are signaling molecules that play a crucial role in the immune system. Interleukins are a type of cytokine that are produced by various immune cells and have specific functions. IL-1, produced by macrophages, induces acute inflammation and fever. IL-2, produced by Th1 cells, stimulates the growth and differentiation of T cell responses. IL-3, produced by activated T helper cells, stimulates the differentiation and proliferation of myeloid progenitor cells. IL-4, produced by Th2 cells, stimulates the proliferation and differentiation of B cells. IL-5, also produced by Th2 cells, stimulates the production of eosinophils. IL-6, produced by macrophages and Th2 cells, stimulates the differentiation of B cells and induces fever. IL-8, produced by macrophages, promotes neutrophil chemotaxis. IL-10, produced by Th2 cells, inhibits Th1 cytokine production and is known as an anti-inflammatory cytokine. IL-12, produced by dendritic cells, macrophages, and B cells, activates NK cells and stimulates the differentiation of naive T cells into Th1 cells.

      In addition to interleukins, there are other cytokines with specific functions. Tumor necrosis factor-alpha, produced by macrophages, induces fever and promotes neutrophil chemotaxis. Interferon-gamma, produced by Th1 cells, activates macrophages. Understanding the functions of cytokines is important in developing treatments for various immune-related diseases.

    • This question is part of the following fields:

      • General Principles
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  • Question 19 - A 42-year-old woman is undergoing left kidney donation surgery for her sister. During...

    Incorrect

    • A 42-year-old woman is undergoing left kidney donation surgery for her sister. During the procedure, which structure will be located most anteriorly at the hilum of the left kidney?

      Your Answer:

      Correct Answer: Left renal vein

      Explanation:

      The anterior position is occupied by the renal veins, while the artery and ureter are located posteriorly.

      Anatomy of the Renal Arteries

      The renal arteries are blood vessels that supply the kidneys with oxygenated blood. They are direct branches off the aorta and enter the kidney at the hilum. The right renal artery is longer than the left renal artery. The renal vein, artery, and pelvis also enter the kidney at the hilum.

      The right renal artery is related to the inferior vena cava, right renal vein, head of the pancreas, and descending part of the duodenum. On the other hand, the left renal artery is related to the left renal vein and tail of the pancreas.

      In some cases, there may be accessory arteries, mainly on the left side. These arteries usually pierce the upper or lower part of the kidney instead of entering at the hilum.

      Before reaching the hilum, each renal artery divides into four or five segmental branches that supply each pyramid and cortex. These segmental branches then divide within the sinus into lobar arteries. Each vessel also gives off small inferior suprarenal branches to the suprarenal gland, ureter, and surrounding tissue and muscles.

    • This question is part of the following fields:

      • Renal System
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  • Question 20 - A 72-year-old male presents to the emergency department with severe, central abdominal pain...

    Incorrect

    • A 72-year-old male presents to the emergency department with severe, central abdominal pain that is radiating to his back. He has vomited twice and on examination you find he has hypotension and tachycardia. He is a current smoker with a past medical history of hypertension and hypercholesterolaemia. You suspect a visceral artery aneurysm and urgently request a CT scan to confirm. The CT scan reveals an aneurysm in the superior mesenteric artery.

      From which level of the vertebrae does this artery originate from the aorta?

      Your Answer:

      Correct Answer: L1

      Explanation:

      The common iliac veins come together at

      Anatomical Planes and Levels in the Human Body

      The human body can be divided into different planes and levels to aid in anatomical study and medical procedures. One such plane is the transpyloric plane, which runs horizontally through the body of L1 and intersects with various organs such as the pylorus of the stomach, left kidney hilum, and duodenojejunal flexure. Another way to identify planes is by using common level landmarks, such as the inferior mesenteric artery at L3 or the formation of the IVC at L5.

      In addition to planes and levels, there are also diaphragm apertures located at specific levels in the body. These include the vena cava at T8, the esophagus at T10, and the aortic hiatus at T12. By understanding these planes, levels, and apertures, medical professionals can better navigate the human body during procedures and accurately diagnose and treat various conditions.

    • This question is part of the following fields:

      • Neurological System
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  • Question 21 - A young man comes to the clinic with symptoms suggestive of mania. After...

    Incorrect

    • A young man comes to the clinic with symptoms suggestive of mania. After further inquiry and assessment, he is found to have tachycardia, sweaty palms, and a recent bout of diarrhea. What is the probable diagnosis?

      Your Answer:

      Correct Answer: Grave's disease

      Explanation:

      The correct diagnosis for this patient is Grave’s disease, which is characterized by hyperthyroidism. While mania may be a symptom, it is important to note that tachycardia, sweaty hands, and exophthalmos are specific to Grave’s disease.

      Bipolar disorder may also present with manic episodes, but it does not typically include the other symptoms associated with hyperthyroidism.

      Hashimoto’s thyroiditis is another autoimmune thyroid disorder, but it causes hypothyroidism instead of hyperthyroidism. Symptoms of hypothyroidism may include bradycardia and dry skin.

      Graves’ Disease: Common Features and Unique Signs

      Graves’ disease is the most frequent cause of thyrotoxicosis, which is commonly observed in women aged 30-50 years. The condition presents typical features of thyrotoxicosis, such as weight loss, palpitations, and heat intolerance. However, Graves’ disease also displays specific signs that are not present in other causes of thyrotoxicosis. These include eye signs, such as exophthalmos and ophthalmoplegia, as well as pretibial myxoedema and thyroid acropachy. The latter is a triad of digital clubbing, soft tissue swelling of the hands and feet, and periosteal new bone formation.

      Graves’ disease is characterized by the presence of autoantibodies, including TSH receptor stimulating antibodies in 90% of patients and anti-thyroid peroxidase antibodies in 75% of patients. Thyroid scintigraphy reveals a diffuse, homogenous, and increased uptake of radioactive iodine. These features help distinguish Graves’ disease from other causes of thyrotoxicosis and aid in its diagnosis.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 22 - A case of ischaemic left colon is diagnosed in a patient. Which artery,...

    Incorrect

    • A case of ischaemic left colon is diagnosed in a patient. Which artery, originating from the aorta at approximately the level of L3, is the most probable cause of this condition?

      Your Answer:

      Correct Answer: Inferior mesenteric artery

      Explanation:

      The left side of the colon is most likely to be affected by the IMA, which typically originates at L3.

      The Inferior Mesenteric Artery: Supplying the Hindgut

      The inferior mesenteric artery (IMA) is responsible for supplying the embryonic hindgut with blood. It originates just above the aortic bifurcation, at the level of L3, and passes across the front of the aorta before settling on its left side. At the point where the left common iliac artery is located, the IMA becomes the superior rectal artery.

      The hindgut, which includes the distal third of the colon and the rectum above the pectinate line, is supplied by the IMA. The left colic artery is one of the branches that emerges from the IMA near its origin. Up to three sigmoid arteries may also exit the IMA to supply the sigmoid colon further down the line.

      Overall, the IMA plays a crucial role in ensuring that the hindgut receives the blood supply it needs to function properly. Its branches help to ensure that the colon and rectum are well-nourished and able to carry out their important digestive functions.

    • This question is part of the following fields:

      • Gastrointestinal System
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  • Question 23 - A 50-year-old obese female with twice-yearly flares of ulcerative colitis has presented to...

    Incorrect

    • A 50-year-old obese female with twice-yearly flares of ulcerative colitis has presented to the gastroenterology department with flare. She was previously being managed well with steroids. After doing the thiopurine methyltransferase (TPMT) test she is started on a medication. A complete blood count done after a month of starting treatment shows:

      Hb 112 g/L Male: (135-180)
      Female: (115 - 160)
      Platelets 68 * 109/L (150 - 400)
      WBC 25 * 109/L (4.0 - 11.0)

      What is the active compound that the drug being used in the treatment of this patient's condition is metabolized to?

      Your Answer:

      Correct Answer: Mercaptopurine

      Explanation:

      Azathioprine is utilized for treating Crohn’s disease in this patient, and it is likely that the drug is metabolized into mercaptopurine, an active compound that acts as a purine analogue and inhibits purine synthesis.

      In the purine catabolism pathway, inosine is produced when AMP is deaminated by adenylate (AMP) deaminase to form IMP. Inosine is then formed by hydrolysis of IMP with nucleotidase.

      Hypoxanthine is also produced in the purine catabolism pathway through the phosphorylation of inosine. Xanthine is formed when hypoxanthine is oxidized by xanthine oxidase.

      The answer purine is incorrect because azathioprine does not convert into purines, but rather it inhibits their synthesis.

      Azathioprine is a medication that is converted into mercaptopurine, which is an active compound that inhibits the production of purine. To determine if someone is at risk for azathioprine toxicity, a test for thiopurine methyltransferase (TPMT) may be necessary. Adverse effects of this medication include bone marrow depression, nausea and vomiting, pancreatitis, and an increased risk of non-melanoma skin cancer. If infection or bleeding occurs, a full blood count should be considered. It is important to note that there may be a significant interaction between azathioprine and allopurinol, so lower doses of azathioprine should be used. However, azathioprine is generally considered safe to use during pregnancy.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
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  • Question 24 - A 35-year-old male has received his test results for a recent STD test....

    Incorrect

    • A 35-year-old male has received his test results for a recent STD test. He has tested positive. According to a study on the test, 894 patients with a positive test result for the STD are true positives and 496 are false positives. Additionally, out of 1240 patients with a negative test result, 1120 are true negatives and 120 are false negatives. What is the positive predictive value of this test?

      Your Answer:

      Correct Answer: 64%

      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.

    • This question is part of the following fields:

      • General Principles
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  • Question 25 - A 26-year-old female is undergoing examination for an atypical cyst on her left...

    Incorrect

    • A 26-year-old female is undergoing examination for an atypical cyst on her left ovary. Her AFP levels are elevated. Upon biopsy, the following report is obtained:

      Biopsy report: Schiller-Duval bodies are present

      What type of ovarian tumor has developed in this patient?

      Your Answer:

      Correct Answer: Yolk sac tumour

      Explanation:

      Schiller-Duval bodies seen on histology are a characteristic feature of yolk sac tumor, making it a pathognomonic finding.

      1. Incorrect. Yolk sac tumor would not present with diffuse sheets, nests, and cords of large uniform tumor cells like testicular seminoma.

      2. Incorrect. Call-Exner bodies are not present in yolk sac tumor.

      3. Incorrect. Yolk sac tumor is not a metastasis from a diffuse-type gastric adenocarcinoma, which would have a signet cell histology appearance.

      4. Incorrect. Yolk sac tumor contains tissues from all three germ layers, including ectodermal, mesodermal, and endodermal tissues.

      5. Correct. Schiller-Duval bodies are a unique feature of yolk sac tumor, and it also secretes AFP.

      Types of Ovarian Tumours

      There are four main types of ovarian tumours, including surface derived tumours, germ cell tumours, sex cord-stromal tumours, and metastasis. Surface derived tumours are the most common, accounting for around 65% of ovarian tumours, and include the greatest number of malignant tumours. These tumours can be either benign or malignant and include serous cystadenoma, serous cystadenocarcinoma, mucinous cystadenoma, mucinous cystadenocarcinoma, and Brenner tumour. Germ cell tumours are more common in adolescent girls and account for 15-20% of tumours. These tumours are similar to cancer types seen in the testicle and can be either benign or malignant. Examples include teratoma, dysgerminoma, yolk sac tumour, and choriocarcinoma. Sex cord-stromal tumours represent around 3-5% of ovarian tumours and often produce hormones. Examples include granulosa cell tumour, Sertoli-Leydig cell tumour, and fibroma. Metastatic tumours account for around 5% of tumours and include Krukenberg tumour, which is a mucin-secreting signet-ring cell adenocarcinoma resulting from metastases from a gastrointestinal tumour.

    • This question is part of the following fields:

      • Reproductive System
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  • Question 26 - During a radical neck dissection, at what age would division of which of...

    Incorrect

    • During a radical neck dissection, at what age would division of which of the following fascial layers expose the ansa cervicalis?

      Your Answer:

      Correct Answer: Pretracheal fascia

      Explanation:

      To access the ansa cervicalis, one must cut through the pretracheal fascia on the posterolateral side of the thyroid gland. This nerve is located in front of the carotid sheath. However, it should be noted that the pre vertebral fascia is situated further back and cannot be reached by dividing the investing layer of fascia.

      The ansa cervicalis is a nerve that provides innervation to the sternohyoid, sternothyroid, and omohyoid muscles. It is composed of two roots: the superior root, which branches off from C1 and is located anterolateral to the carotid sheath, and the inferior root, which is derived from the C2 and C3 roots and passes posterolateral to the internal jugular vein. The inferior root enters the inferior aspect of the strap muscles, which are located in the neck, and should be divided in their upper half when exposing a large goitre. The ansa cervicalis is situated in front of the carotid sheath and is an important nerve for the proper functioning of the neck muscles.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 27 - Which section of the digestive system is primarily involved in the enterohepatic circulation?...

    Incorrect

    • Which section of the digestive system is primarily involved in the enterohepatic circulation?

      Your Answer:

      Correct Answer: Terminal ileum

      Explanation:

      The Enterohepatic Circulation and Bile Recycling

      The enterohepatic circulation is a process that allows for the recycling of certain waste materials that are excreted in the bile. This process occurs at the terminal ileum, where bile salts and some bilirubin derivatives are reabsorbed and returned to the liver through the portal circulation. The regulation of this process involves transporter proteins in both the liver canaliculi and the ileum.

      Bacterial flora in the colon also play a role in the enterohepatic circulation of bilirubin derivatives. Some bacteria contain an enzyme called beta-glucuronidase, which converts conjugated bilirubin to unconjugated bilirubin. This unconjugated form is more lipid-soluble and can be more easily reabsorbed.

      Overall, the enterohepatic circulation is an important mechanism for bile recycling and waste management in the body.

    • This question is part of the following fields:

      • Clinical Sciences
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  • Question 28 - A 7-year-old girl with Down Syndrome presents to her General Practitioner (GP) with...

    Incorrect

    • A 7-year-old girl with Down Syndrome presents to her General Practitioner (GP) with complaints of getting tired easily while playing with her friends and experiencing shortness of breath. The mother informs the GP that the patient was born with an uncorrected cardiac defect. On examination, the GP observes clubbing and plethora.

      What is the probable reason for the patient's current symptoms?

      Your Answer:

      Correct Answer: Eisenmenger syndrome

      Explanation:

      The presence of clubbing, cyanosis, and easy fatigue in this patient suggests Eisenmenger syndrome, which can occur as a result of an uncorrected VSD commonly seen in individuals with Down syndrome. The increased pulmonary blood flow caused by the VSD can lead to pulmonary hypertension and vascular remodeling, resulting in RV hypertrophy and a reversal of the shunt. In contrast, coarctation of the aorta typically presents with hypertension and pulse discrepancies, but not clubbing or plethora. Ebstein abnormality, caused by prenatal exposure to lithium, can cause fatigue and early tiring, but does not typically result in clubbing. Transposition of the great vessels would likely have been fatal without correction, making it an unlikely diagnosis in this case.

      Understanding Eisenmenger’s Syndrome

      Eisenmenger’s syndrome is a medical condition that occurs when a congenital heart defect leads to pulmonary hypertension, causing a reversal of a left-to-right shunt. This happens when the left-to-right shunt is not corrected, leading to the remodeling of the pulmonary microvasculature, which eventually obstructs pulmonary blood and causes pulmonary hypertension. The condition is commonly associated with ventricular septal defect, atrial septal defect, and patent ductus arteriosus.

      The original murmur may disappear, and patients may experience cyanosis, clubbing, right ventricular failure, haemoptysis, and embolism. Management of Eisenmenger’s syndrome requires heart-lung transplantation. It is essential to diagnose and treat the condition early to prevent complications and improve the patient’s quality of life. Understanding the causes, symptoms, and management of Eisenmenger’s syndrome is crucial for healthcare professionals to provide appropriate care and support to patients with this condition.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 29 - A 62-year-old man comes to the emergency department with recent involuntary movements. During...

    Incorrect

    • A 62-year-old man comes to the emergency department with recent involuntary movements. During the examination, it is observed that he has unmanageable thrashing movements of his left arm and leg, which cannot be diverted. A CT scan reveals a fresh acute infarct.

      What part of the brain has been impacted by this infarct, causing these symptoms?

      Your Answer:

      Correct Answer: Subthalamic nucleus

      Explanation:

      Lesions of the subthalamic nucleus (STN) within the basal ganglia can result in a hemiballismus, characterized by uncontrollable thrashing movements. The STN plays a role in unconscious motor control by providing excitatory input to the globus pallidus internus (GPi), which then acts in an inhibitory way on motor outflow from the cortex. When the STN is damaged, there is less activity within the GPi and relative hyperactivity of the motor cortex, leading to excessive movements.

      In contrast, lesions of the caudate nucleus within the basal ganglia can cause behavioral changes and agitation. The caudate processes motor information from the cortex and provides an excitatory input to the globus pallidus externus (GPe), which then has an excitatory input to the STN. Lesions of the caudate result in motor hyperactivity, but this manifests as a restless state rather than uncontrolled movements. The caudate also plays a role in the neural circuits underlying goal-directed behaviors, and lesions can result in personality and behavioral changes.

      Lesions of the medial pons can cause hemiplegia and hemisensory loss or locked-in syndrome, depending on the level of disruption to the motor and sensory pathways. Lesions above the level of the trigeminal and facial motor nuclei can result in a full locked-in syndrome, while lesions below these nuclei result in hemiplegia and hemisensory loss but with preservation of facial sensation and movement.

      Lesions of the substantia nigra result in Parkinsonism, as the dopaminergic neurons of the substantia nigra have an inhibitory effect on the outflow of the striatum. This prevents motor information from leaving the cortex, resulting in the bradykinesia characteristic of Parkinsonism.

      Thalamic lesions most commonly cause hemisensory loss, as the thalamus acts as a sensory gateway that allows processing of sensory information before relaying it to the relevant primary cortex. Lesions disrupt this pathway and prevent information from reaching the cortex.

      Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.

      In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.

    • This question is part of the following fields:

      • Neurological System
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  • Question 30 - A woman presents with symptoms of agalactorrhoea, amenorrhoea, intolerance to cold, constipation, and...

    Incorrect

    • A woman presents with symptoms of agalactorrhoea, amenorrhoea, intolerance to cold, constipation, and weight loss six months after giving birth. She experienced postpartum bleeding during delivery and has now been diagnosed with hypopituitarism. What could be the possible reason for this condition?

      Your Answer:

      Correct Answer: Sheehan's syndrome

      Explanation:

      Sheehan’s syndrome is a condition that arises from pituitary ischaemia, which is caused by blood loss during or after childbirth. The syndrome is characterized by symptoms that indicate global hypopituitarism, including agalactorrhoea (lack of prolactin), amenorrhoea (lack of FSH and LH), cold intolerance and constipation (lack of thyroid hormones), and weight loss (lack of steroid hormones).

      Malignancy is an uncommon cause of hypopituitarism.

      While pituitary adenoma is a frequent cause of hypopituitarism, it is unlikely to be the cause of this patient’s symptoms, given that they occurred after childbirth. Pituitary adenoma may also present with symptoms related to mass effect, such as headache and bilateral hemianopia.

      Understanding Hypopituitarism: Causes, Symptoms, and Management

      Hypopituitarism is a medical condition that occurs when the pituitary gland fails to produce enough hormones. This can be caused by various factors such as compression of the gland by non-secretory pituitary macroadenoma, pituitary apoplexy, Sheehan’s syndrome, hypothalamic tumors, trauma, iatrogenic irradiation, and infiltrative diseases like hemochromatosis and sarcoidosis. The symptoms of hypopituitarism depend on which hormones are deficient. For instance, low ACTH can cause tiredness and postural hypotension, while low FSH/LH can lead to amenorrhea, infertility, and loss of libido. Low TSH can cause constipation and feeling cold, while low GH can result in short stature if it occurs during childhood. Low prolactin can cause problems with lactation.

      To diagnose hypopituitarism, hormone profile testing and imaging are usually conducted. Treatment involves addressing the underlying cause, such as surgical removal of pituitary macroadenoma, and replacement of deficient hormones. It is important to manage hypopituitarism promptly to prevent complications and improve the patient’s quality of life.

    • This question is part of the following fields:

      • Renal System
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