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  • Question 1 - A 25-year-old man comes to the clinic complaining of chest pain in the...

    Incorrect

    • A 25-year-old man comes to the clinic complaining of chest pain in the center of his chest. Based on his symptoms, pericarditis is suspected as the cause. The patient is typically healthy, but recently had a viral throat infection according to his primary care physician.

      What is the most probable observation in this patient?

      Your Answer: A pansystolic cardiac murmur heard on auscultation

      Correct Answer: Chest pain which is relieved on leaning forwards

      Explanation:

      Pericarditis is inflammation of the pericardium, a sac surrounding the heart. It can be caused by various factors, including viral infections. The typical symptom of pericarditis is central chest pain that is relieved by sitting up or leaning forward. ST-segment depression on a 12-lead ECG is not a sign of pericarditis, but rather a sign of subendocardial tissue ischemia. A pansystolic cardiac murmur heard on auscultation is also not associated with pericarditis, as it is caused by valve defects. Additionally, pericarditis is not typically associated with bradycardia, but rather tachycardia.

      Acute Pericarditis: Causes, Features, Investigations, and Management

      Acute pericarditis is a possible diagnosis for patients presenting with chest pain. The condition is characterized by chest pain, which may be pleuritic and relieved by sitting forwards. Other symptoms include non-productive cough, dyspnoea, and flu-like symptoms. Tachypnoea and tachycardia may also be present, along with a pericardial rub.

      The causes of acute pericarditis include viral infections, tuberculosis, uraemia, trauma, post-myocardial infarction, Dressler’s syndrome, connective tissue disease, hypothyroidism, and malignancy.

      Investigations for acute pericarditis include ECG changes, which are often global/widespread, as opposed to the ‘territories’ seen in ischaemic events. The ECG may show ‘saddle-shaped’ ST elevation and PR depression, which is the most specific ECG marker for pericarditis. All patients with suspected acute pericarditis should have transthoracic echocardiography.

      Management of acute pericarditis involves treating the underlying cause. A combination of NSAIDs and colchicine is now generally used as first-line treatment for patients with acute idiopathic or viral pericarditis.

      In summary, acute pericarditis is a possible diagnosis for patients presenting with chest pain. The condition is characterized by chest pain, which may be pleuritic and relieved by sitting forwards, along with other symptoms. The causes of acute pericarditis are varied, and investigations include ECG changes and transthoracic echocardiography. Management involves treating the underlying cause and using a combination of NSAIDs and colchicine as first-line treatment.

    • This question is part of the following fields:

      • Cardiovascular System
      15.5
      Seconds
  • Question 2 - A 45-year-old male patient presents to his doctor with complaints of coughing up...

    Incorrect

    • A 45-year-old male patient presents to his doctor with complaints of coughing up green phlegm and experiencing shortness of breath during physical activity. Upon examination, the doctor detects crackles in the lower region of the patient's left lung and bronchial breathing. The patient also has reduced chest expansion on the left side. The doctor diagnoses the patient with pneumonia and prescribes amoxicillin. What is the most prevalent immunoglobulin found in the patient's serum?

      Your Answer: IgM

      Correct Answer: IgG

      Explanation:

      In blood, IgG is the antibody that is present in the highest amount.

      Immunoglobulins, also known as antibodies, are proteins produced by the immune system to help fight off infections and diseases. There are five types of immunoglobulins found in the body, each with their own unique characteristics.

      IgG is the most abundant type of immunoglobulin in blood serum and plays a crucial role in enhancing phagocytosis of bacteria and viruses. It also fixes complement and can be passed to the fetal circulation.

      IgA is the most commonly produced immunoglobulin in the body and is found in the secretions of digestive, respiratory, and urogenital tracts and systems. It provides localized protection on mucous membranes and is transported across the interior of the cell via transcytosis.

      IgM is the first immunoglobulin to be secreted in response to an infection and fixes complement, but does not pass to the fetal circulation. It is also responsible for producing anti-A, B blood antibodies.

      IgD’s role in the immune system is largely unknown, but it is involved in the activation of B cells.

      IgE is the least abundant type of immunoglobulin in blood serum and is responsible for mediating type 1 hypersensitivity reactions. It provides immunity to parasites such as helminths and binds to Fc receptors found on the surface of mast cells and basophils.

    • This question is part of the following fields:

      • General Principles
      13.6
      Seconds
  • Question 3 - A 58-year-old man presents to his GP with difficulty ascending stairs and transitioning...

    Correct

    • A 58-year-old man presents to his GP with difficulty ascending stairs and transitioning from sitting to standing. He reports experiencing relief from buttock pain with ibuprofen. He has no prior medical or surgical history, but has a 20-pack year smoking habit and works in finance for a large multinational corporation, requiring him to sit for extended periods during meetings. Upon examination, there is limited hip extension and lateral rotation. During gait analysis, he exhibits a backward trunk lurch. The GP refers him for further physiotherapy evaluation, suspecting nerve entrapment from prolonged sitting.

      Which nerve is likely to be entrapped in this patient's presentation?

      Your Answer: Inferior gluteal nerve

      Explanation:

      The patient in the vignette is experiencing impaired hip extension and lateral rotation, making it difficult for them to rise from a seat and climb stairs. These symptoms are consistent with inferior gluteal nerve palsy, which can be caused by nerve entrapment or compression. The inferior gluteal nerve runs anterior to the piriformis and can be damaged during hip replacement surgery or by sitting for prolonged periods with a wallet in a rear pocket.

      Other nerves that can be affected in the lower limb include the femoral nerve, which supplies the lower limb extensively and can be injured by direct trauma or compression. Lateral femoral cutaneous nerve compression can cause meralgia paresthetica, which leads to burning, tingling, and numbness in the front and lateral aspect of the thigh. The obturator nerve is rarely injured but can cause medial thigh sensory changes, weak hip adduction, and a wide-based gait if damaged. The superior gluteal nerve innervates the gluteus medius and minimus and can be assessed with tests that assess hip abductor and stabilizer function.

      Overall, understanding the anatomy and function of these nerves can help diagnose and manage lower limb nerve injuries.

      Lower limb anatomy is an important topic that often appears in examinations. One aspect of this topic is the nerves that control motor and sensory functions in the lower limb. The femoral nerve controls knee extension and thigh flexion, and provides sensation to the anterior and medial aspect of the thigh and lower leg. It is commonly injured in cases of hip and pelvic fractures, as well as stab or gunshot wounds. The obturator nerve controls thigh adduction and provides sensation to the medial thigh. It can be injured in cases of anterior hip dislocation. The lateral cutaneous nerve of the thigh provides sensory function to the lateral and posterior surfaces of the thigh, and can be compressed near the ASIS, resulting in a condition called meralgia paraesthetica. The tibial nerve controls foot plantarflexion and inversion, and provides sensation to the sole of the foot. It is not commonly injured as it is deep and well protected, but can be affected by popliteral lacerations or posterior knee dislocation. The common peroneal nerve controls foot dorsiflexion and eversion, and can be injured at the neck of the fibula, resulting in foot drop. The superior gluteal nerve controls hip abduction and can be injured in cases of misplaced intramuscular injection, hip surgery, pelvic fracture, or posterior hip dislocation. Injury to this nerve can result in a positive Trendelenburg sign. The inferior gluteal nerve controls hip extension and lateral rotation, and is generally injured in association with the sciatic nerve. Injury to this nerve can result in difficulty rising from a seated position, as well as difficulty jumping or climbing stairs.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      25
      Seconds
  • Question 4 - A teenager presents with the belief that they can fly. This is likely...

    Incorrect

    • A teenager presents with the belief that they can fly. This is likely to be a primary delusion.

      Which of the following is most commonly associated with this symptom?

      Your Answer: Severe depression

      Correct Answer: Schizophrenia

      Explanation:

      Primary delusions are unique in that they cannot be attributed to any previous psychopathological state, such as a mood disorder. Delusions are characterized by an unshakeable, false belief that is not accepted by others in the patient’s culture. The patient perceives no difference between a delusional belief and a true belief.

      The correct answer is Schizophrenia, as primary delusions are often observed in this disorder and other psychotic disorders. In contrast, mania and severe depression are more likely to cause secondary delusions that are related to the patient’s underlying mood.

      Anorexia nervosa typically does not involve true delusions, but it may involve over-valued ideas that the person becomes preoccupied with.

      Understanding Psychosis: Symptoms and Associated Features

      Psychosis is a term used to describe a person’s experience of perceiving things differently from those around them. This can manifest in a variety of ways, including hallucinations, delusions, thought disorganization, alogia, tangentiality, clanging, and word salad. These symptoms can be associated with agitation, aggression, neurocognitive impairment, depression, and thoughts of self-harm.

      Psychotic symptoms can occur in a number of conditions, including schizophrenia, depression, bipolar disorder, puerperal psychosis, brief psychotic disorder, neurological conditions like Parkinson’s disease and Huntington’s disease, and as a result of prescribed drugs or certain illicit drugs like cannabis and phencyclidine.

      The peak age of first-episode psychosis is around 15-30 years. It is important to understand the symptoms and associated features of psychosis in order to recognize and seek appropriate treatment for those experiencing these symptoms.

    • This question is part of the following fields:

      • Psychiatry
      7.1
      Seconds
  • Question 5 - A 6-year-old girl is brought to the clinic by her mother who is...

    Incorrect

    • A 6-year-old girl is brought to the clinic by her mother who is worried about her daughter's hearing loss. The girl has a history of frequent bone fractures. During the examination, the doctor observes that the external ear canal and tympanic membrane appear normal and there is no discharge or swelling. However, the girl's sclera has a bluish tint. What type of collagen is most likely affected in this case?

      Your Answer: Type 3

      Correct Answer: Type 1

      Explanation:

      Osteogenesis imperfecta is caused by a defect in type 1 collagen, which is found in the skin, tendons, vasculature, and bones. This abnormality results in fragile bones, leading to multiple fractures, as seen in a child with deafness, blue sclera, and fractures. Type 2 collagen is present in cartilage and is not typically affected in osteogenesis imperfecta. Type 3 collagen is the primary component of reticular fibers, which are also not typically affected in this condition. Type 4 collagen makes up basement membranes, which are also not typically affected in osteogenesis imperfecta.

      Understanding Osteogenesis Imperfecta

      Osteogenesis imperfecta, also known as brittle bone disease, is a group of disorders that affect collagen metabolism, leading to bone fragility and fractures. The most common type of osteogenesis imperfecta is type 1, which is inherited in an autosomal dominant manner and is caused by decreased synthesis of pro-alpha 1 or pro-alpha 2 collagen polypeptides.

      This condition typically presents in childhood, with individuals experiencing fractures following minor trauma. Other common features include blue sclera, deafness secondary to otosclerosis, and dental imperfections. Despite these symptoms, adjusted calcium, phosphate, parathyroid hormone, and ALP results are usually normal in individuals with osteogenesis imperfecta.

      Overall, understanding the symptoms and underlying causes of osteogenesis imperfecta is crucial for proper diagnosis and management of this condition.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      9.5
      Seconds
  • Question 6 - An aged woman with malabsorption and weight loss was diagnosed with small bowel...

    Incorrect

    • An aged woman with malabsorption and weight loss was diagnosed with small bowel amyloidosis. She was initially found to have osteomalacia and hypocalcemia. Despite receiving total parenteral nutrition with sufficient calcium replacement for the past seven days, she remained hypocalcemic. Which electrolyte deficiency is most likely responsible for this condition?

      Your Answer: None of the above

      Correct Answer: Magnesium

      Explanation:

      Magnesium deficiency may occur in patients with malabsorption, even if they receive magnesium through TPN feeds, as it may not be enough to compensate for their losses. Serum calcium levels are not affected by sodium, phosphate, and potassium.

      The Importance of Magnesium and Calcium in the Body

      Magnesium and calcium are essential minerals in the body. Magnesium plays a crucial role in the secretion and action of parathyroid hormone (PTH) on target tissues. However, a deficiency in magnesium can cause hypocalcaemia and make patients unresponsive to calcium and vitamin D supplementation.

      The body contains 1000 mmol of magnesium, with half stored in bones and the rest in muscle, soft tissues, and extracellular fluid. Unlike calcium, there is no specific hormonal control of magnesium. Hormones such as PTH and aldosterone affect the renal handling of magnesium.

      Magnesium and calcium also interact at a cellular level. A decrease in magnesium levels can affect the permeability of cellular membranes to calcium, leading to hyperexcitability. Therefore, it is essential to maintain adequate levels of both magnesium and calcium in the body for optimal health.

    • This question is part of the following fields:

      • Endocrine System
      18.1
      Seconds
  • Question 7 - A middle-aged man visits the doctor and presents with multiple skin nodules and...

    Correct

    • A middle-aged man visits the doctor and presents with multiple skin nodules and cafe au lait spots on his body. The doctor suspects neurofibromatosis and advises genetic counselling. The patient is informed that if he has children, they may inherit the condition with variable manifestations that could be more or less severe than his own. What genetic concept is the doctor trying to convey?

      Your Answer: Variable expressivity

      Explanation:

      Expressivity refers to the degree to which a particular genotype is manifested in an individual’s phenotype in genetics.

      Understanding Penetrance and Expressivity in Genetic Disorders

      Penetrance and expressivity are two important concepts in genetics that help explain why individuals with the same gene mutation may exhibit different degrees of observable characteristics. Penetrance refers to the proportion of individuals in a population who carry a disease-causing allele and express the related disease phenotype. In contrast, expressivity describes the extent to which a genotype shows its phenotypic expression in an individual.

      There are several factors that can influence penetrance and expressivity, including modifier genes, environmental factors, and allelic variation. For example, some genetic disorders, such as retinoblastoma and Huntington’s disease, exhibit incomplete penetrance, meaning that not all individuals with the disease-causing allele will develop the condition. On the other hand, achondroplasia shows complete penetrance, meaning that all individuals with the disease-causing allele will develop the condition.

      Expressivity, on the other hand, describes the severity of the phenotype. Some genetic disorders, such as neurofibromatosis, exhibit a high level of expressivity, meaning that the phenotype is more severe in affected individuals. Understanding penetrance and expressivity is important in genetic counseling and can help predict the likelihood and severity of a genetic disorder in individuals and their families.

    • This question is part of the following fields:

      • General Principles
      12.4
      Seconds
  • Question 8 - A 9-month-old baby boy is presented to the GP clinic by his mother...

    Incorrect

    • A 9-month-old baby boy is presented to the GP clinic by his mother who recently moved to the UK. The mother is worried about her son's physical appearance, which she believes is different from other children in his daycare center.

      During the examination, the baby appears healthy, but the doctor observes a shortened neck and a protruding tongue. Additionally, there are several white spots visible in the iris.

      What is the most frequent cytogenetic cause of this patient's condition?

      Your Answer: Autosomal recessive

      Correct Answer: Nondisjunction

      Explanation:

      Down’s Syndrome: Epidemiology and Genetics

      Down’s syndrome is a genetic disorder that is caused by the presence of an extra copy of chromosome 21. The risk of having a child with Down’s syndrome increases with maternal age, with a 1 in 1,500 chance at age 20 and a 1 in 50 or greater chance at age 45. This can be remembered by dividing the denominator by 3 for every extra 5 years of age starting at 1/1,000 at age 30.

      There are three main types of Down’s syndrome: nondisjunction, Robertsonian translocation, and mosaicism. Nondisjunction accounts for 94% of cases and occurs when the chromosomes fail to separate properly during cell division. Robertsonian translocation, which usually involves chromosome 14, accounts for 5% of cases and occurs when a piece of chromosome 21 attaches to another chromosome. Mosaicism, which accounts for 1% of cases, occurs when there are two genetically different populations of cells in the body.

      The risk of recurrence for Down’s syndrome varies depending on the type of genetic abnormality. If the trisomy 21 is a result of nondisjunction, the chance of having another child with Down’s syndrome is approximately 1 in 100 if the mother is less than 35 years old. If the trisomy 21 is a result of Robertsonian translocation, the risk is much higher, with a 10-15% chance if the mother is a carrier and a 2.5% chance if the father is a carrier.

    • This question is part of the following fields:

      • General Principles
      39
      Seconds
  • Question 9 - Which of the following poses the most significant threat to the external validity...

    Correct

    • Which of the following poses the most significant threat to the external validity of a research?

      Your Answer: Representativeness of the sample

      Explanation:

      Validity refers to how accurately something measures what it claims to measure. There are two main types of validity: internal and external. Internal validity refers to the confidence we have in the cause and effect relationship in a study. This means we are confident that the independent variable caused the observed change in the dependent variable, rather than other factors. There are several threats to internal validity, such as poor control of extraneous variables and loss of participants over time. External validity refers to the degree to which the conclusions of a study can be applied to other people, places, and times. Threats to external validity include the representativeness of the sample and the artificiality of the research setting. There are also other types of validity, such as face validity and content validity, which refer to the general impression and full content of a test, respectively. Criterion validity compares tests, while construct validity measures the extent to which a test measures the construct it aims to.

    • This question is part of the following fields:

      • General Principles
      11.3
      Seconds
  • Question 10 - After a carotid endarterectomy, a woman experiences weakness in her tongue. Which nerve...

    Correct

    • After a carotid endarterectomy, a woman experiences weakness in her tongue. Which nerve is most likely to have been damaged in this process?

      Your Answer: Hypoglossal

      Explanation:

      Carotid surgery poses a higher risk to the hypoglossal nerve, which is responsible for innervating the tongue.

      The internal carotid artery originates from the common carotid artery near the upper border of the thyroid cartilage and travels upwards to enter the skull through the carotid canal. It then passes through the cavernous sinus and divides into the anterior and middle cerebral arteries. In the neck, it is surrounded by various structures such as the longus capitis, pre-vertebral fascia, sympathetic chain, and superior laryngeal nerve. It is also closely related to the external carotid artery, the wall of the pharynx, the ascending pharyngeal artery, the internal jugular vein, the vagus nerve, the sternocleidomastoid muscle, the lingual and facial veins, and the hypoglossal nerve. Inside the cranial cavity, the internal carotid artery bends forwards in the cavernous sinus and is closely related to several nerves such as the oculomotor, trochlear, ophthalmic, and maxillary nerves. It terminates below the anterior perforated substance by dividing into the anterior and middle cerebral arteries and gives off several branches such as the ophthalmic artery, posterior communicating artery, anterior choroid artery, meningeal arteries, and hypophyseal arteries.

    • This question is part of the following fields:

      • Neurological System
      6.1
      Seconds
  • Question 11 - A 45-year-old female patient attends a neurology follow-up consultation. Her medical records indicate...

    Incorrect

    • A 45-year-old female patient attends a neurology follow-up consultation. Her medical records indicate impairment to a cranial nerve that arises from the anterior olive of the medulla oblongata.

      What is the most probable area of impact in this patient as a result of the nerve damage?

      Your Answer: Abduction of the lateral rectus muscle

      Correct Answer: Deviation of the tongue

      Explanation:

      The hypoglossal nerve arises anterior to the olive of the medulla oblongata and is responsible for innervating the muscles of the tongue. CN IX, X, and XI, on the other hand, emerge posterior to the olive. Hypoglossal nerve palsy can cause ipsilateral tongue deviation towards the side of the lesion.

      It is important to note that the lateral rectus muscle is supplied by CN VI, which emerges from the junction of the pons and medulla. The glossopharyngeal nerve (CN IX) is responsible for the sensory/afferent pathway of the gag reflex, while the vagus nerve (CN X) regulates the autonomic function of the cardiac muscle. Both CN IX and CN X arise posterior to the olive.

      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.

    • This question is part of the following fields:

      • Neurological System
      12.8
      Seconds
  • Question 12 - How many valves are present between the right atrium and the superior vena...

    Incorrect

    • How many valves are present between the right atrium and the superior vena cava (SVC)?

      Your Answer: Three

      Correct Answer: None

      Explanation:

      Inserting a CVP line from the internal jugular vein into the right atrium is relatively easy due to the absence of valves.

      The Superior Vena Cava: Anatomy, Relations, and Developmental Variations

      The superior vena cava (SVC) is a large vein that drains blood from the head and neck, upper limbs, thorax, and part of the abdominal walls. It is formed by the union of the subclavian and internal jugular veins, which then join to form the right and left brachiocephalic veins. The SVC is located in the anterior margins of the right lung and pleura, and is related to the trachea and right vagus nerve posteromedially, and the posterior aspects of the right lung and pleura posterolaterally. The pulmonary hilum is located posteriorly, while the right phrenic nerve and pleura are located laterally on the right side, and the brachiocephalic artery and ascending aorta are located laterally on the left side.

      Developmental variations of the SVC are recognized, including anomalies of its connection and interruption of the inferior vena cava (IVC) in its abdominal course. In some individuals, a persistent left-sided SVC may drain into the right atrium via an enlarged orifice of the coronary sinus, while in rare cases, the left-sided vena cava may connect directly with the superior aspect of the left atrium, usually associated with an unroofing of the coronary sinus. Interruption of the IVC may occur in patients with left-sided atrial isomerism, with drainage achieved via the azygos venous system.

      Overall, understanding the anatomy, relations, and developmental variations of the SVC is important for medical professionals in diagnosing and treating related conditions.

    • This question is part of the following fields:

      • Cardiovascular System
      8.3
      Seconds
  • Question 13 - A 55-year-old man, who has a history of type 2 diabetes, is prescribed...

    Incorrect

    • A 55-year-old man, who has a history of type 2 diabetes, is prescribed losartan for his hypertension due to the development of a dry cough from ramipril. Losartan works by inhibiting the activity of a substance that acts on the AT1 receptor.

      What accurately characterizes the function of this substance?

      Your Answer: Decreases filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus to preserve GFR

      Correct Answer: Increases filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus to preserve GFR

      Explanation:

      Angiotensin II is responsible for increasing the filtration fraction by constricting the efferent arteriole of the glomerulus, which helps to maintain the glomerular filtration rate (GFR). This mechanism has been found to slow down the progression of diabetic nephropathy. AT1 receptor blockers such as azilsartan, candesartan, and olmesartan can also block the action of Ang II. Desmopressin activates aquaporin, which is mainly located in the collecting duct of the kidneys. Norepinephrine and epinephrine, not Ang II, can cause vasoconstriction of the afferent arteriole of the glomerulus.

      The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.

    • This question is part of the following fields:

      • Renal System
      35.7
      Seconds
  • Question 14 - A gravida 3, para 0 (G3P0) woman at 8 weeks gestation presents to...

    Incorrect

    • A gravida 3, para 0 (G3P0) woman at 8 weeks gestation presents to the clinic with a 2-week history of vomiting. She reports that she has been unable to keep anything down for the last 4 days and now feels extremely tired. She also reports 8 kg of weight loss since the start of her pregnancy, stating that she now weighs 57kg.

      During the examination, the patient's eyes are sunken, and her mucous membranes appear dry.

      A urine dip shows marked ketosis, but is otherwise unremarkable.

      What is a risk factor for the most likely diagnosis?

      Your Answer: Smoking tobacco

      Correct Answer: Trophoblastic disease

      Explanation:

      Hyperemesis gravidarum is a severe form of nausea and vomiting that affects around 1% of pregnancies. It is usually experienced between 8 and 12 weeks of pregnancy but can persist up to 20 weeks. The condition is thought to be related to raised beta hCG levels and is more common in women who are obese, nulliparous, or have multiple pregnancies, trophoblastic disease, or hyperthyroidism. Smoking is associated with a decreased incidence of hyperemesis.

      The Royal College of Obstetricians and Gynaecologists recommend that a woman must have a 5% pre-pregnancy weight loss, dehydration, and electrolyte imbalance before a diagnosis of hyperemesis gravidarum can be made. Validated scoring systems such as the Pregnancy-Unique Quantification of Emesis (PUQE) score can be used to classify the severity of NVP.

      Management of hyperemesis gravidarum involves using antihistamines as a first-line treatment, with oral cyclizine or oral promethazine being recommended by Clinical Knowledge Summaries. Oral prochlorperazine is an alternative, while ondansetron and metoclopramide may be used as second-line treatments. Ginger and P6 (wrist) acupressure can be tried, but there is little evidence of benefit. Admission may be needed for IV hydration.

      Complications of hyperemesis gravidarum can include Wernicke’s encephalopathy, Mallory-Weiss tear, central pontine myelinolysis, acute tubular necrosis, and fetal growth restriction, pre-term birth, and cleft lip/palate (if ondansetron is used during the first trimester). The NICE Clinical Knowledge Summaries recommend considering admission if a woman is unable to keep down liquids or oral antiemetics, has ketonuria and/or weight loss (greater than 5% of body weight), or has a confirmed or suspected comorbidity that may be adversely affected by nausea and vomiting.

    • This question is part of the following fields:

      • Reproductive System
      31
      Seconds
  • Question 15 - As a junior doctor, you are taking the medical history of a patient...

    Incorrect

    • As a junior doctor, you are taking the medical history of a patient who is scheduled for an elective knee replacement. During the physical examination, you hear a diastolic murmur and observe a collapsing pulse while checking the heart rate. Upon examining the hands, you notice pulsations of red coloration on the nail beds. Other than these findings, the examination appears normal.

      What could be the probable reason behind these examination results if the patient is slightly older?

      Your Answer: Mitral stenosis

      Correct Answer: Aortic regurgitation

      Explanation:

      The patient’s examination findings suggest aortic regurgitation, which is characterized by an early diastolic, high-pitched, blowing murmur that is louder when the patient sits forward and at the left sternal edge. Aortic regurgitation can also cause a collapsing pulse, dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, and visible pulsing red colouration of the nails (quincke’s sign).

      It is important to note that aortic stenosis does not cause a diastolic murmur or collapsing pulse. Instead, it typically produces an ejection systolic murmur that is louder on expiration and may cause a slow rising pulse.

      Similarly, mitral regurgitation does not cause a diastolic murmur or collapsing pulse. It typically produces a pansystolic murmur.

      Mitral stenosis causes a mid-late diastolic murmur but does not commonly cause a collapsing pulse.

      Pulmonary stenosis causes an ejection systolic murmur but does not commonly cause a collapsing pulse or diastolic murmur.

      Aortic regurgitation is a condition where the aortic valve of the heart leaks, causing blood to flow in the opposite direction during ventricular diastole. This can be caused by disease of the aortic valve or by distortion or dilation of the aortic root and ascending aorta. The most common causes of AR due to valve disease include rheumatic fever, calcific valve disease, and infective endocarditis. On the other hand, AR due to aortic root disease can be caused by conditions such as aortic dissection, hypertension, and connective tissue diseases like Marfan’s and Ehler-Danlos syndrome.

      The features of AR include an early diastolic murmur, a collapsing pulse, wide pulse pressure, Quincke’s sign, and De Musset’s sign. In severe cases, a mid-diastolic Austin-Flint murmur may also be present. Suspected AR should be investigated with echocardiography.

      Management of AR involves medical management of any associated heart failure and surgery in symptomatic patients with severe AR or asymptomatic patients with severe AR who have LV systolic dysfunction.

    • This question is part of the following fields:

      • Cardiovascular System
      24
      Seconds
  • Question 16 - What are the typical clinical manifestations of a deficiency in vitamin B6 (pyridoxine)?...

    Incorrect

    • What are the typical clinical manifestations of a deficiency in vitamin B6 (pyridoxine)?

      Your Answer: Sleep disturbance

      Correct Answer: Sensory neuropathy

      Explanation:

      The Importance of Pyridoxine in the Body

      Pyridoxine is a group of B-vitamins that are crucial in various bodily functions. They act as essential cofactors in many reactions, particularly in the metabolism of amino acids and neurotransmitters. Pyridoxine also plays a role in regulating gene transcription and controlling steroid hormones.

      The body can produce pyridoxine through bacterial flora in the gut, and it is also present in many dietary sources. However, overheating certain foods can destroy pyridoxine, and some medications can alter its metabolism. Pyridoxine is also used therapeutically to prevent neuropathy in the treatment of tuberculosis.

      Deficiency in pyridoxine can lead to sensory neuropathy, skin changes, and damage to mucous membranes. On the other hand, deficiency in vitamin C can cause gingivitis and increased bleeding, while vitamin K deficiency can also lead to bleeding. Sleep disturbance is rarely attributed to vitamin B3 (niacin) deficiency.

      In summary, pyridoxine is a vital nutrient that plays a crucial role in various bodily functions. Its deficiency can lead to various health problems, highlighting the importance of maintaining adequate levels of this vitamin in the body.

    • This question is part of the following fields:

      • Basic Sciences
      10.6
      Seconds
  • Question 17 - A 68-year-old woman arrives at the emergency department with a complaint of a...

    Correct

    • A 68-year-old woman arrives at the emergency department with a complaint of a painful, red toe. The pain began a few hours ago and has been getting worse. Upon examination, her 1st metatarsophalangeal joint is inflamed, erythematous, and tender to the touch.

      What are the joint aspiration findings that would confirm a gout flare diagnosis?

      Your Answer: Negatively birefringent needle-shaped monosodium urate crystals

      Explanation:

      Joint aspiration is a valuable diagnostic tool for differentiating between various causes of joint swelling, including septic arthritis and pseudogout. In the case of gout, joint aspiration will reveal needle-shaped monosodium urate crystals that are negatively birefringent under polarised light. These crystals form when uric acid levels remain persistently high and deposit in tissues, leading to the characteristic inflammatory response seen in gout.

      It is important to note that a green-colored aspirate with a positive gram stain for Staphylococcus aureus is not indicative of gout, but rather suggests septic arthritis. In this case, the aspirate may have a raised white cell count and appear yellow or green.

      Similarly, the presence of negatively birefringent needle-shaped calcium oxalate crystals is not associated with gout, but rather with kidney stones. These crystals form when there are high concentrations of calcium oxalate in the urine and are typically octahedral or envelope-shaped.

      Finally, positively birefringent rhomboid-shaped calcium pyrophosphate crystals are not seen in gout, but rather in pseudogout. Pseudogout presents with similar symptoms to gout and more commonly affects the knee joint.

      Understanding Gout: Symptoms and Diagnosis

      Gout is a type of arthritis that causes inflammation and pain in the joints. Patients experience episodes of intense pain that can last for several days, followed by periods of no symptoms. The acute episodes usually reach their peak within 12 hours and can affect various joints, with the first metatarsophalangeal joint being the most commonly affected. Swelling and redness are also common symptoms of gout.

      If left untreated, repeated acute episodes of gout can lead to joint damage and chronic joint problems. To diagnose gout, doctors may perform synovial fluid analysis to look for needle-shaped, negatively birefringent monosodium urate crystals under polarised light. Uric acid levels may also be checked once the acute episode has subsided, as they can be high, normal, or low during the attack.

      Radiological features of gout include joint effusion, well-defined punched-out erosions with sclerotic margins, and eccentric erosions. Unlike rheumatoid arthritis, gout does not cause periarticular osteopenia. Soft tissue tophi may also be visible.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
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  • Question 18 - A 65-year-old man, who has a history of non-Hodgkin's lymphoma, is scheduled to...

    Correct

    • A 65-year-old man, who has a history of non-Hodgkin's lymphoma, is scheduled to start chemotherapy treatment. During his consultation with the oncologist, he expressed concern about the potential side effects of his chemotherapy drugs. Specifically, he is worried about the side effects associated with vincristine.

      What side effect is commonly linked to the use of vincristine in chemotherapy treatment?

      Your Answer: Peripheral neuropathy

      Explanation:

      Vincristine is a medication that belongs to the vinca alkaloid class and works by inhibiting microtubule formation, which prevents the cell cycle from progressing beyond the metaphase stage. However, it is commonly associated with peripheral neuropathy as a side effect.

      Anthracyclines, such as doxorubicin, are known to cause cardiomyopathy. These medications stabilize topoisomerase II, which prevents DNA replication by inhibiting the coiling of DNA.

      5-fluorouracil is a thymidylate synthase inhibitor that is associated with dermatitis. It works by preventing the formation of the thymidine nucleotide, which is essential for DNA replication. Palmar-plantar erythrodysesthesia is a severe form of dermatitis that can occur as a blistering rash on the hands and feet of patients taking this medication.

      Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.

    • This question is part of the following fields:

      • Haematology And Oncology
      13.9
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  • Question 19 - You are the nephrology consultant conducting a post-take ward round. The next patient...

    Correct

    • You are the nephrology consultant conducting a post-take ward round. The next patient is a 38-year-old man who was admitted after an overdose of aspirin. His wife reported he took 50 tablets.

      Upon admission, he received 55g of activated charcoal and IV sodium bicarbonate. You are contemplating initiating haemodialysis for this patient.

      What is the rationale behind your decision to proceed with haemodialysis?

      Your Answer: Acute renal failure

      Explanation:

      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.

    • This question is part of the following fields:

      • General Principles
      13.7
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  • Question 20 - A 50-year-old woman presents with an unknown cause of jaundice. She noticed the...

    Incorrect

    • A 50-year-old woman presents with an unknown cause of jaundice. She noticed the yellowing of her skin and eyes in the mirror that morning. Upon examination, a palpable mass is found in the right upper quadrant of her abdomen. Her lab results show a total bilirubin level of 124 umol/L and high levels of conjugated bilirubin in her urine. What is the most probable diagnosis?

      Your Answer: Ascending cholangitis

      Correct Answer: Cholangiocarcinoma

      Explanation:

      To correctly diagnose this patient, knowledge of Courvoisier’s sign is necessary. This sign indicates that a palpable gallbladder in the presence of painless jaundice is unlikely to be caused by gallstones. Therefore, biliary colic is an incorrect answer as it is a painful condition. Haemolytic anaemia is also an incorrect answer as the blood test results would differ from this patient’s results. The correct answer is cholangiocarcinoma, which is a cancer of the biliary tree that can cause painless obstructive jaundice. Gilbert’s syndrome is not the most appropriate answer as it only presents with a raised bilirubin and does not cause an increase in ALP.

      Understanding Cholangiocarcinoma

      Cholangiocarcinoma, also known as bile duct cancer, is a serious medical condition that can be caused by primary sclerosing cholangitis. This disease is characterized by persistent biliary colic symptoms, which can be accompanied by anorexia, jaundice, and weight loss. In some cases, a palpable mass in the right upper quadrant may be present, which is known as the Courvoisier sign. Additionally, periumbilical lymphadenopathy (Sister Mary Joseph nodes) and left supraclavicular adenopathy (Virchow node) may be seen.

      One of the main risk factors for cholangiocarcinoma is primary sclerosing cholangitis. This condition can cause inflammation and scarring of the bile ducts, which can lead to the development of cancer over time. To detect cholangiocarcinoma in patients with primary sclerosing cholangitis, doctors often use a blood test to measure CA 19-9 levels.

    • This question is part of the following fields:

      • Gastrointestinal System
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  • Question 21 - An individual in their mid-20s is identified to have a superior vena cava...

    Incorrect

    • An individual in their mid-20s is identified to have a superior vena cava on the left side. What is the most probable route for blood from this system to reach the heart?

      Your Answer: Via the azygos venous system and into the superior vena cava

      Correct Answer: Via the coronary sinus

      Explanation:

      The Superior Vena Cava: Anatomy, Relations, and Developmental Variations

      The superior vena cava (SVC) is a large vein that drains blood from the head and neck, upper limbs, thorax, and part of the abdominal walls. It is formed by the union of the subclavian and internal jugular veins, which then join to form the right and left brachiocephalic veins. The SVC is located in the anterior margins of the right lung and pleura, and is related to the trachea and right vagus nerve posteromedially, and the posterior aspects of the right lung and pleura posterolaterally. The pulmonary hilum is located posteriorly, while the right phrenic nerve and pleura are located laterally on the right side, and the brachiocephalic artery and ascending aorta are located laterally on the left side.

      Developmental variations of the SVC are recognized, including anomalies of its connection and interruption of the inferior vena cava (IVC) in its abdominal course. In some individuals, a persistent left-sided SVC may drain into the right atrium via an enlarged orifice of the coronary sinus, while in rare cases, the left-sided vena cava may connect directly with the superior aspect of the left atrium, usually associated with an un-roofing of the coronary sinus. Interruption of the IVC may occur in patients with left-sided atrial isomerism, with drainage achieved via the azygos venous system.

      Overall, understanding the anatomy, relations, and developmental variations of the SVC is important for medical professionals in diagnosing and treating related conditions.

    • This question is part of the following fields:

      • Cardiovascular System
      22.8
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  • Question 22 - A 7-year-old girl is being evaluated by paediatric endocrinology services due to concerns...

    Incorrect

    • A 7-year-old girl is being evaluated by paediatric endocrinology services due to concerns about her height. Her BMI measures 18 kg/m2.

      How should this child's weight be classified?

      Your Answer: Very underweight

      Correct Answer: Normal weight

      Explanation:

      Assessing Stature and Obesity in Childhood

      The assessment of stature and obesity in childhood can be challenging due to various factors that affect growth, such as hormones, puberty, and nutrition. To address this, the World Health Organization recommends using age- and gender-specific BMI charts, with a cut-off of >85% percentile for overweight and >95th percentile for obesity. These values are similar to the BMI levels used for adults aged >18 years old.

      In general, healthy children aged 1-10 years old have BMIs ranging from 14-17 kg/m2. By age 12, the median BMI is around 18 kg/m2, and it increases to around 22 kg/m2 by age 18 years. However, there may be slight variations in the cut-offs used between countries, which can be found in appropriate charts. Overall, using these charts can aid in accurately assessing stature and diagnosing obesity in children.

    • This question is part of the following fields:

      • Paediatrics
      9.3
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  • Question 23 - A 25-year-old female patient visits her general practitioner due to ongoing investigations for...

    Incorrect

    • A 25-year-old female patient visits her general practitioner due to ongoing investigations for infertility. She has a BMI of 32 kg/m² and noticeable facial hair on her upper lip. A recent transvaginal ultrasound scan revealed the presence of numerous cystic lesions on her ovaries.

      What is the probable reason behind her infertility?

      Your Answer: Hypergonadotropic hypoestrogenic anovulation

      Correct Answer: Normogonadotropic normoestrogenic anovulation

      Explanation:

      The most common type of ovulatory disorder is normogonadotropic normoestrogenic anovulation, which is often associated with polycystic ovarian syndrome (PCOS). This condition is characterized by normal levels of gonadotropin and estrogen, but low levels of FSH during the follicular phase can lead to anovulation. It is important to perform a thorough evaluation of both male and female factors when investigating infertility. Hypogonadotropic hypogonadal anovulation, which is characterized by low levels of GnRH or pituitary unresponsiveness to GnRH, resulting in low gonadotropins and low estrogen, is seen in conditions such as amenorrhea due to low weight, stress, or Sheehan syndrome. Uterine abnormalities, such as fibroids, may also contribute to infertility, but this is not consistent with the clinical findings in this case. Hypergonadotropic hypoestrogenic anovulation, which is characterized by high levels of gonadotropins but unresponsive ovaries and low estrogen levels, is more commonly seen in conditions such as Turner’s syndrome, primary ovarian failure, or ovary damage.

      Understanding Ovulation Induction and Its Categories

      Ovulation induction is a common treatment for couples who have difficulty conceiving naturally due to ovulation disorders. The process of ovulation requires a balance of hormones and feedback loops between the hypothalamus, pituitary gland, and ovaries. Anovulation can occur due to alterations in this balance, which can be classified into three categories: hypogonadotropic hypogonadal anovulation, normogonadotropic normoestrogenic anovulation, and hypergonadotropic hypoestrogenic anovulation. The goal of ovulation induction is to induce mono-follicular development and subsequent ovulation, leading to a singleton pregnancy.

      There are various forms of ovulation induction, starting with the least invasive and simplest management option first. Exercise and weight loss are typically the first-line treatment for patients with polycystic ovarian syndrome, as ovulation can spontaneously return with even a modest 5% weight loss. Letrozole is now considered the first-line medical therapy for patients with PCOS due to its reduced risk of adverse effects on endometrial and cervical mucous compared to clomiphene citrate. Clomiphene citrate is a selective estrogen receptor modulator that acts primarily at the hypothalamus, blocking the negative feedback effect of estrogens. Gonadotropin therapy tends to be the treatment used mostly for women with hypogonadotropic hypogonadism.

      One potential side effect of ovulation induction is ovarian hyperstimulation syndrome (OHSS), which can be life-threatening if not identified and managed promptly. OHSS occurs when ovarian enlargement with multiple cystic spaces form, and an increase in the permeability of capillaries leads to a fluid shift from the intravascular to the extra-vascular space. The severity of OHSS varies, with the risk of severe OHSS occurring in less than 1% of all women undergoing ovarian induction. Management includes fluid and electrolyte replacement, anticoagulation therapy, abdominal ascitic paracentesis, and pregnancy termination to prevent further hormonal imbalances.

    • This question is part of the following fields:

      • Reproductive System
      22.8
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  • Question 24 - A 35-year-old woman has been experiencing ongoing muscle weakness in her arms and...

    Incorrect

    • A 35-year-old woman has been experiencing ongoing muscle weakness in her arms and legs for the past 4 months. She has been referred to the hospital and has agreed to undergo a muscle biopsy of her right quadriceps. The collected samples have been sent to histopathology for examination. When observing under a microscope, which type(s) of muscle would typically display sarcomeres?

      Your Answer: Smooth muscle

      Correct Answer: Skeletal and cardiac muscle

      Explanation:

      The typical striated appearance of skeletal and cardiac muscle is due to sarcomeres, which are the fundamental unit of muscles.

      The Process of Muscle Contraction

      Muscle contraction is a complex process that involves several steps. It begins with an action potential reaching the neuromuscular junction, which causes a calcium ion influx through voltage-gated calcium channels. This influx leads to the release of acetylcholine into the extracellular space, which activates nicotinic acetylcholine receptors, triggering an action potential. The action potential then spreads through the T-tubules, activating L-type voltage-dependent calcium channels in the T-tubule membrane, which are close to calcium-release channels in the adjacent sarcoplasmic reticulum. This causes the sarcoplasmic reticulum to release calcium, which binds to troponin C, causing a conformational change that allows tropomyosin to move, unblocking the binding sites. Myosin then binds to the newly released binding site, releasing ADP and pulling the Z bands towards each other. ATP binds to myosin, releasing actin.

      The components involved in muscle contraction include the sarcomere, which is the basic unit of muscles that gives skeletal and cardiac muscles their striated appearance. The I-band is the zone of thin filaments that is not superimposed by thick filaments, while the A-band contains the entire length of a single thick filament. The H-zone is the zone of the thick filaments that is not superimposed by the thin filaments, and the M-line is in the middle of the sarcomere, cross-linking myosin. The sarcoplasmic reticulum releases calcium ion in response to depolarization, while actin is the thin filaments that transmit the forces generated by myosin to the ends of the muscle. Myosin is the thick filaments that bind to the thin filament, while titin connects the Z-line to the thick filament, altering the structure of tropomyosin. Tropomyosin covers the myosin-binding sites on actin, while troponin-C binds with calcium ions. The T-tubule is an invagination of the sarcoplasmic reticulum that helps co-ordinate muscular contraction.

      There are two types of skeletal muscle fibres: type I and type II. Type I fibres have a slow contraction time, are red in colour due to the presence of myoglobin, and are used for sustained force. They have a high mitochondrial density and use triglycerides as

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
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  • Question 25 - Oliver is a 32-year-old male who has been diagnosed with syphilis. He receives...

    Incorrect

    • Oliver is a 32-year-old male who has been diagnosed with syphilis. He receives treatment with intramuscular benzathine penicillin, but experiences a sudden onset of fever, chills, headache, and an intensification of his rash. What is the reason for this reaction, known as the Jarisch-Herxheimer reaction?

      Your Answer: Binding of IgE to mast cells resulting in histamine release

      Correct Answer: Release of endotoxins into bloodstream following bacterial cell lysis

      Explanation:

      The Jarisch-Herxheimer reaction is a response that can occur after antibiotic treatment for syphilis, as well as other spirochetal infections like Lyme disease and leptospirosis. It is caused by the release of endotoxins into the bloodstream when bacterial cells are destroyed by antibiotics. This leads to a systemic inflammatory response, resulting in symptoms such as fever, rash, chills, and headache. The reaction is self-limiting and can be treated symptomatically with oral paracetamol. Anaphylaxis can be caused by the binding of IgE to mast cells, resulting in histamine release, or by non-immunologic mechanisms such as direct degranulation of mast cells and basophils. Febrile non-haemolytic transfusion reactions are caused by antibodies against HLA antigens, which can result in a febrile reaction after blood transfusion. It is important to note that the Jarisch-Herxheimer reaction is not caused by re-activation of syphilis.

      Managing Syphilis

      Syphilis can be managed through the administration of intramuscular benzathine penicillin, which is the first-line treatment. In cases where this is not possible, doxycycline may be used as an alternative. After treatment, it is important to monitor nontreponemal titres (such as rapid plasma reagin or Venereal Disease Research Laboratory) to assess the response. A fourfold decline in titres is often considered an adequate response to treatment.

      It is important to note that the Jarisch-Herxheimer reaction may occur following treatment. This is characterized by symptoms such as fever, rash, and tachycardia after the first dose of antibiotic. Unlike anaphylaxis, there is no wheezing or hypotension. This reaction is thought to be due to the release of endotoxins following bacterial death and typically occurs within a few hours of treatment. No treatment is needed for this reaction other than antipyretics if required.

    • This question is part of the following fields:

      • General Principles
      11.1
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  • Question 26 - Which one of the following statements relating to abnormal coagulation is not true?...

    Incorrect

    • Which one of the following statements relating to abnormal coagulation is not true?

      Your Answer: Massive transfusion is associated with reduced levels of factor 5 and 8

      Correct Answer: The prothrombin time is prolonged in Haemophilia A

      Explanation:

      Haemophilia A is characterized by prolonged APTT and reduced levels of factor 8:C, while bleeding time and PT remain normal. Cholestatic jaundice hinders the absorption of vitamin K, which is fat-soluble. Patients who undergo massive transfusions, equivalent to more than 10 units of blood or their entire blood volume, are at risk of thrombocytopenia, as well as deficiencies in factor 5 and 8.

      Abnormal coagulation can be caused by various factors such as heparin, warfarin, disseminated intravascular coagulation (DIC), and liver disease. Heparin prevents the activation of factors 2, 9, 10, and 11, while warfarin affects the synthesis of factors 2, 7, 9, and 10. DIC affects factors 1, 2, 5, 8, and 11, and liver disease affects factors 1, 2, 5, 7, 9, 10, and 11.

      When interpreting blood clotting test results, different disorders can be identified based on the levels of activated partial thromboplastin time (APTT), prothrombin time (PT), and bleeding time. Haemophilia is characterized by increased APTT levels, normal PT levels, and normal bleeding time. On the other hand, von Willebrand’s disease is characterized by increased APTT levels, normal PT levels, and increased bleeding time. Lastly, vitamin K deficiency is characterized by increased APTT and PT levels, and normal bleeding time. Proper interpretation of these results is crucial in diagnosing and treating coagulation disorders.

    • This question is part of the following fields:

      • Haematology And Oncology
      14.5
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  • Question 27 - A 42-year-old female arrives at the emergency department with sudden onset of drooping...

    Incorrect

    • A 42-year-old female arrives at the emergency department with sudden onset of drooping on the right side of her mouth. She is unable to smile on the right-hand side but can frown and lift her eyebrows. The patient has a medical history of asthma and has experienced four miscarriages in the past. She does not smoke and drinks alcohol moderately on weekends. Based on this information, what is the probable diagnosis?

      Your Answer: Acoustic neuroma

      Correct Answer: Stroke

      Explanation:

      If a facial palsy only affects the lower face and spares the forehead, it is likely caused by an upper motor neuron (UMN) lesion. In this case, stroke is the most probable cause of the UMN lesion. However, the patient’s young age and social history make stroke less likely. The patient’s history of multiple miscarriages suggests antiphospholipid syndrome, which is a significant risk factor for stroke. Bell’s palsy, HIV, diabetes mellitus, and acoustic neuroma would all cause lower motor neuron (LMN) lesions, resulting in LMN signs that involve the forehead.

      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 disease like Bell’s palsy and upper motor neuron disease 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 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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 28 - A 79-year-old man is brought to the emergency department after fainting. Prior to...

    Correct

    • A 79-year-old man is brought to the emergency department after fainting. Prior to losing consciousness, he experienced dizziness and heart palpitations. He was unconscious for less than a minute and denies any chest discomfort. Upon cardiac examination, no abnormalities are detected. An ECG is conducted and reveals indications of hyperkalaemia. What is an ECG manifestation of hyperkalaemia?

      Your Answer: Tall tented T waves

      Explanation:

      Hyperkalaemia can be identified on an ECG by tall tented T waves, small or absent P waves, and broad bizarre QRS complexes. In severe cases, the QRS complexes may form a sinusoidal wave pattern, and asystole may occur. On the other hand, hypokalaemia can be detected by ST segment depression, prominent U waves, small or inverted T waves, a prolonged PR interval (which can also be present in hyperkalaemia), and a long QT interval.

      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.

    • This question is part of the following fields:

      • Renal System
      9.4
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  • Question 29 - Which virus is associated with the development of cervical cancer? ...

    Correct

    • Which virus is associated with the development of cervical cancer?

      Your Answer: Human papillomavirus 16

      Explanation:

      Understanding Oncoviruses and Their Associated Cancers

      Oncoviruses are viruses that have the potential to cause cancer. These viruses can be detected through blood tests and prevented through vaccination. There are several types of oncoviruses, each associated with a specific type of cancer.

      The Epstein-Barr virus, for example, is linked to Burkitt’s lymphoma, Hodgkin’s lymphoma, post-transplant lymphoma, and nasopharyngeal carcinoma. Human papillomavirus 16/18 is associated with cervical cancer, anal cancer, penile cancer, vulval cancer, and oropharyngeal cancer. Human herpes virus 8 is linked to Kaposi’s sarcoma, while hepatitis B and C viruses are associated with hepatocellular carcinoma. Finally, human T-lymphotropic virus 1 is linked to tropical spastic paraparesis and adult T cell leukemia.

      It is important to understand the link between oncoviruses and cancer so that appropriate measures can be taken to prevent and treat these diseases. Vaccination against certain oncoviruses, such as HPV, can significantly reduce the risk of developing associated cancers. Regular screening and early detection can also improve outcomes for those who do develop cancer as a result of an oncovirus.

    • This question is part of the following fields:

      • General Principles
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  • Question 30 - A 22-year-old man arrives at the emergency department with a stab wound on...

    Correct

    • A 22-year-old man arrives at the emergency department with a stab wound on the left side of his neck above the clavicle. Upon examination, there is no indication of damage to the pleura or any major blood vessels. However, a winged scapula is observed on the left side of his back, with the scapula protruding from the chest wall and the inferior angle pointing towards the midline. What nerve is responsible for this condition?

      Your Answer: Long thoracic nerve

      Explanation:

      The nerve responsible for a winged scapula is the long thoracic nerve, which originates from C5-7 and travels along the thorax to reach the serratus anterior muscle. Damage to this nerve can cause the scapula to lift off the thoracic wall and limit shoulder movement. Other nerves that can cause a winged scapula include the accessory nerve and dorsal scapular nerve. The transverse cervical nerve supplies the neck, the phrenic nerve supplies the diaphragm, the greater auricular nerve supplies the mandible and ear, and the suprascapular nerve supplies the shoulder muscles and joints.

      The Long Thoracic Nerve and its Role in Scapular Winging

      The long thoracic nerve is derived from the ventral rami of C5, C6, and C7, which are located close to their emergence from intervertebral foramina. It runs downward and passes either anterior or posterior to the middle scalene muscle before reaching the upper tip of the serratus anterior muscle. From there, it descends on the outer surface of this muscle, giving branches into it.

      One of the most common symptoms of long thoracic nerve injury is scapular winging, which occurs when the serratus anterior muscle is weakened or paralyzed. This can happen due to a variety of reasons, including trauma, surgery, or nerve damage. In addition to long thoracic nerve injury, scapular winging can also be caused by spinal accessory nerve injury (which denervates the trapezius) or a dorsal scapular nerve injury.

      Overall, the long thoracic nerve plays an important role in the function of the serratus anterior muscle and the stability of the scapula. Understanding its anatomy and function can help healthcare professionals diagnose and treat conditions that affect the nerve and its associated muscles.

    • This question is part of the following fields:

      • Neurological System
      7.1
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  • Question 31 - A 50-year-old man arrives at the emergency department after colliding with a lamppost...

    Incorrect

    • A 50-year-old man arrives at the emergency department after colliding with a lamppost while riding his bicycle. He reports experiencing left arm pain and limited mobility.

      Upon examination, there is noticeable swelling and bruising in the left upper arm, along with a visible deformity. The left shoulder has reduced abduction.

      After an X-ray, it is confirmed that the patient has a fractured neck of the left humerus.

      What is the most probable additional sign that will be present?

      Your Answer: Reduced internal rotation of the shoulder

      Correct Answer: Loss of sensation over C5 dermatome

      Explanation:

      The likely cause of the patient’s symptoms is an axillary nerve injury, which can result from a fractured neck of the humerus. This nerve originates from the C5 nerve root, which also provides innervation to the regimental badge area, leading to a loss of sensation in that region.

      However, the patient is unlikely to experience a loss of sensation in the lateral 3 and 1/2 fingers, reduced internal rotation of the shoulder, a reduced pincer grip, or a winged scapula as these symptoms are not associated with an axillary nerve injury.

      Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      31.3
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  • Question 32 - A 45-year-old man presents to the surgical team with abdominal pain, bloating, and...

    Correct

    • A 45-year-old man presents to the surgical team with abdominal pain, bloating, and vomiting. Based on an abdominal x-ray, there is suspicion of a malignancy causing intestinal obstruction. Which of the following antiemetics should be avoided for managing the patient's vomiting?

      Your Answer: Metoclopramide

      Explanation:

      It is not recommended to use metoclopramide as an antiemetic in cases of bowel obstruction. This is because metoclopramide works by blocking dopamine receptors and stimulating peripheral 5HT3 receptors, which promote gastric emptying. However, in cases of intestinal obstruction, gastric emptying is not possible and this effect can be harmful. The choice of antiemetic should be based on the patient’s individual needs and the underlying cause of their nausea.

      Understanding the Mechanism and Uses of Metoclopramide

      Metoclopramide is a medication primarily used to manage nausea, but it also has other uses such as treating gastro-oesophageal reflux disease and gastroparesis secondary to diabetic neuropathy. It is often combined with analgesics for the treatment of migraines. However, it is important to note that metoclopramide has adverse effects such as extrapyramidal effects, acute dystonia, diarrhoea, hyperprolactinaemia, tardive dyskinesia, and parkinsonism. It should also be avoided in bowel obstruction but may be helpful in paralytic ileus.

      The mechanism of action of metoclopramide is quite complicated. It is primarily a D2 receptor antagonist, but it also has mixed 5-HT3 receptor antagonist/5-HT4 receptor agonist activity. Its antiemetic action is due to its antagonist activity at D2 receptors in the chemoreceptor trigger zone, and at higher doses, the 5-HT3 receptor antagonist also has an effect. The gastroprokinetic activity is mediated by D2 receptor antagonist activity and 5-HT4 receptor agonist activity.

      In summary, metoclopramide is a medication with multiple uses, but it also has adverse effects that should be considered. Its mechanism of action is complex, involving both D2 receptor antagonist and 5-HT3 receptor antagonist/5-HT4 receptor agonist activity. Understanding the uses and mechanism of action of metoclopramide is important for its safe and effective use.

    • This question is part of the following fields:

      • Gastrointestinal System
      9.5
      Seconds
  • Question 33 - As a medical student on a general surgical team, I am currently treating...

    Incorrect

    • As a medical student on a general surgical team, I am currently treating an 82-year-old female who is scheduled for a mastectomy due to breast cancer. Can you inform me of the most prevalent form of breast cancer?

      Your Answer: Invasive lobular carcinoma

      Correct Answer: Invasive ductal carcinoma

      Explanation:

      Breast Cancer Pathology: Understanding the Histological Features

      Breast cancer pathology involves examining the histological features of the cancer cells to determine the underlying diagnosis. The invasive component of breast cancer is typically made up of ductal cells, although invasive lobular cancer may also occur. In situ lesions, such as DCIS, may also be present.

      When examining breast cancer pathology, several typical changes are seen in conjunction with invasive breast cancer. These include nuclear pleomorphism, coarse chromatin, angiogenesis, invasion of the basement membrane, dystrophic calcification (which may be seen on mammography), abnormal mitoses, vascular invasion, and lymph node metastasis.

      To grade the primary tumor, a scale of 1-3 is used, with 1 being the most benign lesion and 3 being the most poorly differentiated. Immunohistochemistry for estrogen receptor and herceptin status is routinely performed to further understand the cancer’s characteristics.

      The grade, lymph node stage, and size are combined to provide the Nottingham prognostic index, which helps predict the patient’s prognosis and guide treatment decisions. Understanding the histological features of breast cancer is crucial in determining the best course of treatment for patients.

    • This question is part of the following fields:

      • Haematology And Oncology
      9.6
      Seconds
  • Question 34 - Which one of the following is not a branch of the posterior cord...

    Correct

    • Which one of the following is not a branch of the posterior cord of the brachial plexus?

      Your Answer: Musculocutaneous nerve

      Explanation:

      The posterior cord gives rise to mnemonic branches, including the subscapular (upper and lower), thoracodorsal, axillary, and radial nerves. On the other hand, the musculocutaneous nerve is a branch originating from the lateral cord.

      Understanding the Brachial Plexus and Cutaneous Sensation of the Upper Limb

      The brachial plexus is a network of nerves that originates from the anterior rami of C5 to T1. It is divided into five sections: roots, trunks, divisions, cords, and branches. To remember these sections, a common mnemonic used is Real Teenagers Drink Cold Beer.

      The roots of the brachial plexus are located in the posterior triangle and pass between the scalenus anterior and medius muscles. The trunks are located posterior to the middle third of the clavicle, with the upper and middle trunks related superiorly to the subclavian artery. The lower trunk passes over the first rib posterior to the subclavian artery. The divisions of the brachial plexus are located at the apex of the axilla, while the cords are related to the axillary artery.

      The branches of the brachial plexus provide cutaneous sensation to the upper limb. This includes the radial nerve, which provides sensation to the posterior arm, forearm, and hand; the median nerve, which provides sensation to the palmar aspect of the thumb, index, middle, and half of the ring finger; and the ulnar nerve, which provides sensation to the palmar and dorsal aspects of the fifth finger and half of the ring finger.

      Understanding the brachial plexus and its branches is important in diagnosing and treating conditions that affect the upper limb, such as nerve injuries and neuropathies. It also helps in understanding the cutaneous sensation of the upper limb and how it relates to the different nerves of the brachial plexus.

    • This question is part of the following fields:

      • Neurological System
      14.5
      Seconds
  • Question 35 - A 28-week-old premature baby is born and develops tachypnoea, tachycardia, and chest wall...

    Correct

    • A 28-week-old premature baby is born and develops tachypnoea, tachycardia, and chest wall retractions shortly after birth. The neonate also shows blue discolouration of the skin. The doctor starts administering intravenous fluids and CPAP and informs the parents that the baby's lungs are lacking surfactant, a substance that aids breathing.

      What type of cells produce surfactant?

      Your Answer: Type 2 pneumocytes

      Explanation:

      Infant respiratory distress syndrome, also known as surfactant deficiency disorder, is caused by a lack of surfactant development and is commonly found in premature infants. To identify the correct answer, we must focus on lung cells, excluding paneth cells and microfold cells found in the intestinal epithelium, as well as alveolar macrophages, which are responsible for clearing infections and debris. The correct answer is type 2 pneumocytes, which produce pulmonary surfactant, while type 1 pneumocytes facilitate gas exchange between the alveoli and the blood.

      Surfactant Deficient Lung Disease in Premature Infants

      Surfactant deficient lung disease (SDLD), previously known as hyaline membrane disease, is a condition that affects premature infants. It occurs due to the underproduction of surfactant and the immaturity of the lungs’ structure. The risk of SDLD decreases with gestation, with 50% of infants born at 26-28 weeks and 25% of infants born at 30-31 weeks being affected. Other risk factors include male sex, diabetic mothers, Caesarean section, and being the second born of premature twins.

      The clinical features of SDLD are similar to those of respiratory distress in newborns, including tachypnea, intercostal recession, expiratory grunting, and cyanosis. Chest x-rays typically show a ground-glass appearance with an indistinct heart border.

      Prevention during pregnancy involves administering maternal corticosteroids to induce fetal lung maturation. Management of SDLD includes oxygen therapy, assisted ventilation, and exogenous surfactant given via an endotracheal tube.

    • This question is part of the following fields:

      • General Principles
      16.3
      Seconds
  • Question 36 - A 28-year-old man visits a doctor after noticing the recent appearance of some...

    Correct

    • A 28-year-old man visits a doctor after noticing the recent appearance of some skin lesions on his shin. He works in social healthcare and has no significant medical history except for an appendectomy seven years ago. He denies smoking, using illicit drugs, and drinks alcohol occasionally. He had a couple of needle-stick injuries while caring for known HIV-positive individuals but never received any HIV prophylaxis or underwent testing for HIV. Upon agreeing to an HIV test, he was found to be HIV-positive. What is the most strongly associated condition with being HIV-positive?

      Your Answer: Kaposi sarcoma

      Explanation:

      The patient has a skin lesion associated with HIV, most likely Kaposi sarcoma caused by HHV8. Other vascular neoplasms include angiosarcoma, pyogenic granuloma, glomus tumor, and strawberry hemangioma.

      Kaposi’s sarcoma is a type of cancer that is caused by the human herpes virus 8 (HHV-8). It is characterized by the appearance of purple papules or plaques on the skin or mucosa, such as in the gastrointestinal and respiratory tract. These skin lesions may eventually ulcerate, while respiratory involvement can lead to massive haemoptysis and pleural effusion. Treatment options for Kaposi’s sarcoma include radiotherapy and resection. It is commonly seen in patients with HIV.

    • This question is part of the following fields:

      • General Principles
      15.3
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  • Question 37 - A clinical trial was conducted to evaluate the impact of aspirin on mortality...

    Correct

    • A clinical trial was conducted to evaluate the impact of aspirin on mortality in patients who underwent coronary bypass surgery. The study was double-blinded and randomized. The results showed that administering aspirin within 48 hours of the surgery led to a 70% decrease in overall mortality. The p-value of the study was found to be very low (0.01).

      What conclusions can be drawn from the information provided about the study?

      Your Answer: Chances of type I error are low

      Explanation:

      In hypothesis testing, a type I error occurs when the null hypothesis is rejected even though it is true. This error is denoted by alpha (α) and is typically set at 0.05. By setting a low alpha level, researchers can minimize the chance of accepting a false alternative hypothesis.

      On the other hand, a type II error occurs when the null hypothesis is accepted even though it is false. This error is denoted by beta (β) and is determined by both sample size and alpha. In the given scenario, the null hypothesis was not accepted, so a type II error did not occur.

      The power of a study is the probability of correctly rejecting the null hypothesis when it is false. It is inversely proportional to the probability of type II error (Power = 1 – β) and is dependent on sample size. However, the information provided in the vignette is insufficient to accurately determine the power of the study.

      Significance tests are used to determine the likelihood of a null hypothesis being true. The null hypothesis states that two treatments are equally effective, while the alternative hypothesis suggests that there is a difference between the two treatments. The p value is the probability of obtaining a result by chance that is at least as extreme as the observed result, assuming the null hypothesis is true. Two types of errors can occur during significance testing: type I, where the null hypothesis is rejected when it is true, and type II, where the null hypothesis is accepted when it is false. The power of a study is the probability of correctly rejecting the null hypothesis when it is false, and it can be increased by increasing the sample size.

    • This question is part of the following fields:

      • General Principles
      23
      Seconds
  • Question 38 - A 50-year-old male has undergone renal transplantation due to end-stage renal disease. There...

    Incorrect

    • A 50-year-old male has undergone renal transplantation due to end-stage renal disease. There are concerns about solid organ rejection and the use of cyclosporine and tacrolimus is being considered for prevention. Is there a difference in the mechanism of action between these two drugs, and is one superior to the other in preventing rejection?

      Your Answer: Inhibit the activation of the mammalian target of rapamycin

      Correct Answer: Inhibit calcineurin

      Explanation:

      Cyclosporine and tacrolimus are immunosuppressants that work by inhibiting calcineurin, a phosphatase that activates various transcription factors. This inhibition leads to a decrease in the production of IL-2, which in turn reduces the clonal proliferation of T cells.

      Azathioprine works by antagonizing purine metabolism, while methotrexate inhibits dihydrofolate reductase. Sirolimus inhibits the activation of the mammalian target of rapamycin, and mycophenolate mofetil reversibly inhibits inosine monophosphate dehydrogenase.

      Understanding Ciclosporin: An Immunosuppressant Drug

      Ciclosporin is a medication that is used as an immunosuppressant. It works by reducing the clonal proliferation of T cells by decreasing the release of IL-2. The drug binds to cyclophilin, forming a complex that inhibits calcineurin, a phosphatase that activates various transcription factors in T cells.

      Despite its effectiveness, Ciclosporin has several adverse effects. It can cause nephrotoxicity, hepatotoxicity, fluid retention, hypertension, hyperkalaemia, hypertrichosis, gingival hyperplasia, tremors, impaired glucose tolerance, hyperlipidaemia, and increased susceptibility to severe infection. However, it is interesting to note that Cyclosporin is virtually non-myelotoxic, which means it does not affect the bone marrow.

      Ciclosporin is used to treat various conditions such as following organ transplantation, rheumatoid arthritis, psoriasis, ulcerative colitis, and pure red cell aplasia. It has a direct effect on keratinocytes and modulates T cell function, making it an effective treatment for psoriasis.

      In conclusion, Ciclosporin is a potent immunosuppressant drug that can effectively treat various conditions. However, it is essential to monitor patients for adverse effects and adjust the dosage accordingly.

    • This question is part of the following fields:

      • General Principles
      14.4
      Seconds
  • Question 39 - In which part of the cell are the electron transport chain carriers situated?...

    Correct

    • In which part of the cell are the electron transport chain carriers situated?

      Your Answer: Mitochondrial cristae

      Explanation:

      The Electron Transport Chain in Mitochondria

      The electron transport chain (ETC) is a crucial process in cellular aerobic respiration that occurs in the mitochondrial cristae. These are folded membranes inside the organelle. During respiration, NADH and FADH produced from other parts of the process, such as glycolysis, transfer electrons from electron donors to electron acceptors through redox reactions. This electron transfer is coupled with proton transfer across the mitochondrial membrane, creating an electrochemical proton gradient. This gradient induces the production of ATP, which is used as an energy currency by the cell.

      ATP is produced through a mechanism called chemiosmotic phosphorylation. The structure of the mitochondrion is essential for this process to occur. The cristae provide a large surface area for the ETC to take place, and the mitochondrial membrane is impermeable to protons, allowing for the creation of the proton gradient. The inner membrane also contains ATP synthase, the enzyme responsible for producing ATP through chemiosmotic phosphorylation.

      In summary, the electron transport chain in mitochondria is a complex process that involves the transfer of electrons and protons across the mitochondrial membrane to create a proton gradient. This gradient is then used to produce ATP through chemiosmotic phosphorylation. The structure of the mitochondrion is crucial for this process to occur efficiently.

    • This question is part of the following fields:

      • Basic Sciences
      10.1
      Seconds
  • Question 40 - The medical team at a pediatric unit faces difficulty in determining the sex...

    Incorrect

    • The medical team at a pediatric unit faces difficulty in determining the sex of a newborn baby as the external genitalia appear ambiguous. The suspected condition is linked to an excess of androgen and a deficiency of mineralocorticoid. Can you explain the underlying pathophysiology?

      Your Answer: Defect in FOXP3 gene

      Correct Answer: Deficiency of 21-alphahydroxylase

      Explanation:

      The clinical scenario described in the question is indicative of congenital adrenal hyperplasia, which is caused by a deficiency of the enzyme 21-alphahydroxylase. This leads to an increase in androgen production, resulting in virilization of genitalia in XX females, making them appear as males at birth.

      On the other hand, a deficiency of 5-alpha reductase causes the opposite situation, where genetically XY males have external female genitalia.

      Type 1 diabetes mellitus may be associated with the presence of autoantibodies against glutamic acid decarboxylase.

      A defect in the AIRE gene can lead to APECED, which is characterized by hypoparathyroidism, adrenal failure, and candidiasis.

      Similarly, a defect in the FOXP3 gene can cause IPEX, which presents with immune dysregulation, polyendocrinopathy, and enteropathy.

      Congenital adrenal hyperplasia is a genetic condition that affects the adrenal glands and can result in various symptoms depending on the specific enzyme deficiency. One common form is 21-hydroxylase deficiency, which can cause virilization of female genitalia, precocious puberty in males, and a salt-losing crisis in 60-70% of patients during the first few weeks of life. Another form is 11-beta hydroxylase deficiency, which can also cause virilization and precocious puberty, as well as hypertension and hypokalemia. A third form is 17-hydroxylase deficiency, which typically does not cause virilization in females but can result in intersex characteristics in boys and hypertension.

      Overall, congenital adrenal hyperplasia can have significant impacts on a person’s physical development and health, and early diagnosis and treatment are important for managing symptoms and preventing complications.

    • This question is part of the following fields:

      • Endocrine System
      11.4
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular System (0/4) 0%
General Principles (7/11) 64%
Musculoskeletal System And Skin (2/5) 40%
Psychiatry (0/1) 0%
Endocrine System (0/2) 0%
Neurological System (3/5) 60%
Renal System (1/2) 50%
Reproductive System (0/2) 0%
Basic Sciences (1/2) 50%
Haematology And Oncology (1/3) 33%
Gastrointestinal System (1/2) 50%
Paediatrics (0/1) 0%
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