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  • Question 1 - A 28-year-old has recently been diagnosed with a sarcoma. Due to their young...

    Correct

    • A 28-year-old has recently been diagnosed with a sarcoma. Due to their young age, further genetic investigations were ordered which showed a p53 mutation. Their family history was assessed and they have been diagnosed with Li-Fraumeni syndrome.

      What other condition is this person most susceptible to developing?

      Your Answer: Leukaemia

      Explanation:

      Li-Fraumeni syndrome, which is caused by a mutation in the p53 gene, is a rare autosomal dominant disorder that increases the risk of early-onset breast cancer, sarcoma, and leukaemia. While basal cell carcinomas are not linked to p53 mutations and are instead associated with UV exposure, bladder cancer is more strongly associated with smoking than with p53 mutations. Additionally, while the risk of lymphoma increases with age, individuals with a p53 mutation are more likely to develop leukaemia.

      Understanding p53 and its Role in Cancer

      p53 is a gene that helps suppress tumours and is located on chromosome 17p. It is frequently mutated in breast, colon, and lung cancer. The gene is believed to be essential in regulating the cell cycle, preventing cells from entering the S phase until DNA has been checked and repaired. Additionally, p53 may play a crucial role in apoptosis, the process of programmed cell death.

      Li-Fraumeni syndrome is a rare genetic disorder that is inherited in an autosomal dominant pattern. It is characterised by the early onset of various cancers, including sarcoma, breast cancer, and leukaemia. The condition is caused by mutations in the p53 gene, which can lead to a loss of its tumour-suppressing function. Understanding the role of p53 in cancer can help researchers develop new treatments and therapies for those affected by the disease.

    • This question is part of the following fields:

      • General Principles
      31.5
      Seconds
  • Question 2 - A 54-year-old factory worker gets his arm caught in a metal grinder and...

    Correct

    • A 54-year-old factory worker gets his arm caught in a metal grinder and is rushed to the ER. Upon examination, he displays an inability to extend his metacarpophalangeal joints and abduct his shoulder. Additionally, he experiences weakness in his elbow and wrist. What specific injury has occurred?

      Your Answer: Posterior cord of brachial plexus

      Explanation:

      Lesion of the posterior cord results in the impairment of the axillary and radial nerve, which are responsible for innervating various muscles such as the deltoid, triceps, brachioradialis, wrist extensors, finger extensors, subscapularis, teres minor, and latissimus dorsi.

      Brachial Plexus Cords and their Origins

      The brachial plexus cords are categorized based on their position in relation to the axillary artery. These cords pass over the first rib near the lung’s dome and under the clavicle, just behind the subclavian artery. The lateral cord is formed by the anterior divisions of the upper and middle trunks and gives rise to the lateral pectoral nerve, which originates from C5, C6, and C7. The medial cord is formed by the anterior division of the lower trunk and gives rise to the medial pectoral nerve, the medial brachial cutaneous nerve, and the medial antebrachial cutaneous nerve, which originate from C8, T1, and C8, T1, respectively. The posterior cord is formed by the posterior divisions of the three trunks (C5-T1) and gives rise to the upper and lower subscapular nerves, the thoracodorsal nerve to the latissimus dorsi (also known as the middle subscapular nerve), and the axillary and radial nerves.

    • This question is part of the following fields:

      • Neurological System
      95.6
      Seconds
  • Question 3 - A 65-year-old African American woman has been diagnosed with iodine deficiency.

    What are...

    Incorrect

    • A 65-year-old African American woman has been diagnosed with iodine deficiency.

      What are the primary clinical manifestations of iodine deficiency?

      Your Answer: Muscle aches

      Correct Answer: Impaired memory and concentration

      Explanation:

      The Importance of Iodine in the Diet

      Iodine is a crucial mineral that is necessary for the proper functioning of the body. Unfortunately, it is also one of the most common nutrient deficiencies worldwide. This deficiency can lead to a variety of iodine-related disorders, which are considered one of the most common preventable causes of mental incapacity.

      One of the primary functions of iodine is the production of thyroid hormones, which are essential for all body cells. These hormones are particularly important for the development of the fetal brain, and a lack of thyroid hormones at this stage can lead to devastating and irreversible effects. Iodine deficiency commonly causes goitre, and the clinical effects are comparable to profound hypothyroidism.

      The effects of iodine deficiency can be severe and long-lasting. In utero, it can lead to impaired cognitive function, deafness, and motor defects, a condition known as cretinism. In children and adolescents, it can cause cognitive impairment and poor growth. In adults, it can lead to confusion, poor concentration, and goitre.

      Iodine is abundant in the sea, but inland areas are more at risk of iodine deficiency. If the soil is iodine deficient, all plants that grow on it, and livestock that feed upon them, will also be iodine deficient. It is essential to ensure that the diet contains sufficient iodine to prevent these devastating effects.

    • This question is part of the following fields:

      • Clinical Sciences
      26.1
      Seconds
  • Question 4 - A new medication for treating high blood pressure is currently in phase III...

    Correct

    • A new medication for treating high blood pressure is currently in phase III of development. The study has established a margin, represented by -delta to +delta, for the mean reduction in blood pressure. If the confidence interval of the difference between the new medication and the current standard treatment, ramipril, falls within this margin, the trial will be considered successful. What type of study design is this?

      Your Answer: Equivalence trial

      Explanation:

      When a new drug is introduced, there are various study design options available. One of these options is a placebo-controlled trial, which can provide strong evidence but may be considered unethical if established treatments are available. Additionally, it does not offer a comparison with standard treatments. Therefore, if a drug is to be compared to an existing treatment, a statistician must determine whether the trial is intended to show superiority, equivalence, or non-inferiority.

      Superiority trials may seem like the natural aim of a trial, but they require a large sample size to demonstrate a significant benefit over an existing treatment. On the other hand, equivalence trials define an equivalence margin (-delta to +delta) on a specified outcome. If the confidence interval of the difference between the two drugs falls within the equivalence margin, the drugs may be assumed to have a similar effect. Non-inferiority trials are similar to equivalence trials, but only the lower confidence interval needs to fall within the equivalence margin (i.e. -delta). These trials require smaller sample sizes. Once a drug has been shown to be non-inferior, large studies may be conducted to demonstrate superiority.

      It is important to note that drug companies may not necessarily aim to show superiority over an existing product. If they can demonstrate that their product is equivalent or even non-inferior, they may compete on price or convenience.

    • This question is part of the following fields:

      • General Principles
      43.9
      Seconds
  • Question 5 - A 42-year-old man is admitted to the gastroenterology ward with a flare-up of...

    Incorrect

    • A 42-year-old man is admitted to the gastroenterology ward with a flare-up of his Crohn's disease. He has been experiencing up to 6 bowel movements per day for the past 2 weeks and has lost around 5kg in weight.

      What are the expected biochemical abnormalities in this clinical scenario?

      Your Answer: Metabolic alkalosis, hyperkalaemia

      Correct Answer: Metabolic acidosis, normal anion gap, hypokalaemia

      Explanation:

      Prolonged diarrhoea can lead to a normal anion gap metabolic acidosis and hypokalaemia. This is due to the loss of potassium and other electrolytes through the gastrointestinal tract. The anion gap remains within normal limits despite the metabolic acidosis caused by diarrhoea. It is important to monitor electrolyte levels in patients with prolonged diarrhoea to prevent complications.

      Understanding Metabolic Acidosis

      Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.

      Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.

      Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.

    • This question is part of the following fields:

      • Renal System
      65.3
      Seconds
  • Question 6 - A 55-year-old woman presents with cellulitis surrounding her leg ulcer. A skin swab...

    Incorrect

    • A 55-year-old woman presents with cellulitis surrounding her leg ulcer. A skin swab is taken and she is started on oral flucloxacillin. The swab results reveal Group A streptococcus. What modifications should be made to her antibiotic treatment?

      Your Answer: No change

      Correct Answer: Add penicillin

      Explanation:

      When it comes to group A streptococcal infections, penicillin is the preferred antibiotic. If a patient with cellulitis is confirmed to have a streptococcal infection, the BNF recommends discontinuing flucloxacillin because of its high sensitivity. However, it’s important to consider the inconsistent absorption of phenoxymethylpenicillin.

      Streptococci are spherical bacteria that are gram-positive. They can be classified into two types based on their hemolytic properties: alpha and beta. Alpha haemolytic streptococci, such as Streptococcus pneumoniae and Streptococcus viridans, cause partial hemolysis. Pneumococcus is a common cause of pneumonia, meningitis, and otitis media. Beta haemolytic streptococci, on the other hand, cause complete hemolysis and can be further divided into groups A-H. Only groups A, B, and D are significant in humans. Group A streptococci, particularly Streptococcus pyogenes, are responsible for various infections such as erysipelas, impetigo, cellulitis, and pharyngitis/tonsillitis. They can also cause rheumatic fever or post-streptococcal glomerulonephritis due to immunological reactions. Scarlet fever can also be caused by erythrogenic toxins produced by group A streptococci. Group B streptococci, specifically Streptococcus agalactiae, can lead to neonatal meningitis and septicaemia. Enterococcus belongs to group D streptococci.

    • This question is part of the following fields:

      • General Principles
      19.3
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  • Question 7 - A 30-year-old male presents to his GP with concerns about lumps on his...

    Incorrect

    • A 30-year-old male presents to his GP with concerns about lumps on his hands. He recalls his father having similar spots and is worried about their appearance after comments from his colleagues. On examination, soft yellow papules are found on the base of the 1st and 3rd digit. A blood test reveals elevated cholesterol and triglycerides, with low HDL and high LDL. What is the underlying genetic mutation causing this patient's lipid transport defect?

      Your Answer: Low-density lipoprotein (LDL) receptor

      Correct Answer: Apolipoprotein E (Apo-E)

      Explanation:

      Hyperlipidaemia Classification

      Hyperlipidaemia is a condition characterized by high levels of lipids (fats) in the blood. The Fredrickson classification system was previously used to categorize hyperlipidaemia based on the type of lipid and genetic factors. However, it is now being replaced by a classification system based solely on genetics.

      The Fredrickson classification system included five types of hyperlipidaemia, each with a specific genetic cause. Type I was caused by lipoprotein lipase deficiency or apolipoprotein C-II deficiency, while type IIa was caused by familial hypercholesterolaemia. Type IIb was caused by familial combined hyperlipidaemia, and type III was caused by remnant hyperlipidaemia or apo-E2 homozygosity. Type IV was caused by familial hypertriglyceridaemia or familial combined hyperlipidaemia, and type V was caused by familial hypertriglyceridaemia.

      Hyperlipidaemia can primarily be caused by raised cholesterol or raised triglycerides. Familial hypercholesterolaemia and polygenic hypercholesterolaemia are primarily caused by raised cholesterol, while familial hypertriglyceridaemia and lipoprotein lipase deficiency or apolipoprotein C-II deficiency are primarily caused by raised triglycerides. Mixed hyperlipidaemia disorders, such as familial combined hyperlipidaemia and remnant hyperlipidaemia, involve a combination of raised cholesterol and raised triglycerides.

    • This question is part of the following fields:

      • Renal System
      34.9
      Seconds
  • Question 8 - A 70-year-old woman complains of throbbing hip pain that has been gradually developing...

    Incorrect

    • A 70-year-old woman complains of throbbing hip pain that has been gradually developing for 2 months. She had a fall during gardening a year ago that resulted in a fracture of the neck of her right femur.

      During examination, she displays a decent range of motion at the hip, but she is experiencing a considerable amount of pain.

      Based on the probable reason for her persistent pain, which blood vessel is most likely affected?

      Your Answer: Superficial femoral artery

      Correct Answer: Medial femoral circumflex artery

      Explanation:

      The primary supplier of blood to the femoral head is the medial femoral circumflex artery. If this artery is compromised, it can lead to avascular necrosis, a condition where the bone’s blood supply is disrupted, causing ischemic and necrotic changes. This can slow down recovery and increase the risk of arthritis and bone collapse. In children, the artery of ligamentum teres is the main blood supply to the femoral head and is commonly compromised due to dislocations. The internal iliac artery supplies much of the pelvis but is unlikely to be damaged in a neck of femur fracture, while the lateral femoral circumflex artery supplies the muscles of the anterior thigh.

      Anatomy of the Femur: Structure and Blood Supply

      The femur is the longest and strongest bone in the human body, extending from the hip joint to the knee joint. It consists of a rounded head that articulates with the acetabulum and two large condyles at its inferior aspect that articulate with the tibia. The superior aspect of the femur comprises a head and neck that pass inferolaterally to the body and the two trochanters. The neck meets the body of the femur at an angle of 125o and is demarcated from it by a wide rough intertrochanteric crest. The greater trochanter has discernible surfaces that form the site of attachment of the gluteal muscles, while the linea aspera forms part of the origin of the attachments of the thigh adductors.

      The femur has a rich blood supply, with numerous vascular foramina existing throughout its length. The blood supply to the femoral head is clinically important and is provided by the medial circumflex femoral and lateral circumflex femoral arteries, which are branches of the profunda femoris. The inferior gluteal artery also contributes to the blood supply. These arteries form an anastomosis and travel up the femoral neck to supply the head. It is important to note that the neck is covered by synovial membrane up to the intertrochanteric line, and the posterior aspect of the neck is demarcated from the shaft by the intertrochanteric crest. Understanding the anatomy of the femur, including its structure and blood supply, is crucial for medical professionals in diagnosing and treating injuries and conditions related to this bone.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      59.2
      Seconds
  • Question 9 - A 39-year-old, with an elevated BMI and confirmed type II diabetes is attending...

    Correct

    • A 39-year-old, with an elevated BMI and confirmed type II diabetes is attending a clinic for a check-up on his glucose control.

      Despite being on treatment for a few months, his latest Hb1Ac and home blood glucose readings are still high. The healthcare provider decides to start the patient on gliclazide. The patient is informed that this medication may cause hypoglycaemia as a side effect by increasing insulin production and release.

      Which pancreatic cell membrane channels does gliclazide bind to?

      Your Answer: ATP-dependent potassium

      Explanation:

      Gliclazide is a medication used to treat diabetes by increasing insulin release from pancreatic beta cells. It works by binding to ATP-dependent potassium channels on these cells, causing depolarization and an increase in intracellular calcium. This leads to the secretion of insulin.

      Dipeptidyl peptidase-4 (DDP) inhibitors are another type of medication used to manage diabetes. They work by increasing levels of incretin hormones such as GLP-1 and GIP, which stimulate insulin secretion and decrease blood glucose levels.

      Chloride channels are not affected by sulfonylureas, and they play a role in regulating fluid transport in various organs.

      Insulin binds to tyrosine kinase receptors on the cell membrane, which triggers a signal transduction pathway that activates enzymes and transcription factors within the cell. Sulfonylureas do not affect these receptors.

      Sulfonylureas are a type of medication used to treat type 2 diabetes mellitus. They work by increasing the amount of insulin produced by the pancreas, but only if the beta cells in the pancreas are functioning properly. Sulfonylureas bind to a specific channel on the cell membrane of pancreatic beta cells, known as the ATP-dependent K+ channel (KATP).

      While sulfonylureas can be effective in managing diabetes, they can also cause some adverse effects. The most common side effect is hypoglycemia, which is more likely to occur with long-acting preparations like chlorpropamide. Another common side effect is weight gain. However, there are also rarer side effects that can occur, such as hyponatremia (low sodium levels) due to inappropriate ADH secretion, bone marrow suppression, hepatotoxicity (liver damage), and peripheral neuropathy.

      It is important to note that sulfonylureas should not be used during pregnancy or while breastfeeding.

    • This question is part of the following fields:

      • Endocrine System
      50.7
      Seconds
  • Question 10 - A 19-year-old man was recently admitted to hospital with invasive meningococcal disease. He...

    Correct

    • A 19-year-old man was recently admitted to hospital with invasive meningococcal disease. He has no other medical history but is now complaining of extreme fatigue, light-headedness and rapid weight loss. He has also noticed his skin appears much more tanned than usual. His BP is 98/60 mmHg. Capillary glucose is found to be 2.2 mmol/L.

      Hb 135 g/L Male: (130 - 180)
      Platelets 280 * 109/L (150 - 400)
      WBC 5.5 * 109/L (4.0 - 11.0)
      Na+ 128 mmol/L (135 - 145)
      K+ 5.8 mmol/L (3.5 - 5.0)
      Bicarbonate 19 mmol/L (22 - 29)
      Urea 8.0 mmol/L (2.0 - 7.0)
      Creatinine 125 µmol/L (55 - 120)

      What is the most likely cause of his symptoms?

      Your Answer: Waterhouse-Friedrichsen syndrome

      Explanation:

      Understanding Waterhouse-Friderichsen Syndrome

      Waterhouse-Friderichsen syndrome is a condition that occurs when the adrenal glands fail due to a previous adrenal haemorrhage caused by a severe bacterial infection. The most common cause of this condition is Neisseria meningitidis, but it can also be caused by other bacteria such as Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, and Streptococcus pneumoniae.

      The symptoms of Waterhouse-Friderichsen syndrome are similar to those of hypoadrenalism, including lethargy, weakness, anorexia, nausea and vomiting, and weight loss. Other symptoms may include hyperpigmentation, especially in the palmar creases, vitiligo, and loss of pubic hair in women. In severe cases, a crisis may occur, which can lead to collapse, shock, and pyrexia.

    • This question is part of the following fields:

      • Endocrine System
      106.9
      Seconds
  • Question 11 - As a physician on the surgical ward, you are evaluating a patient who...

    Correct

    • As a physician on the surgical ward, you are evaluating a patient who has been experiencing dysphagia of both solids and liquids for the past 6 years. A barium swallow revealed a 'bird's beak' appearance, and the patient was diagnosed with achalasia. Despite previous medical treatments using oesophago-gastroduodenoscopy (OGD), the patient's condition has not improved, and it has been determined that surgical intervention is necessary.

      What is the preferred surgical treatment for this condition?

      Your Answer: Heller's cardiomyotomy

      Explanation:

      Surgical intervention should be considered for patients with achalasia who experience recurrent or persistent symptoms. The recommended procedure is Heller’s cardiomyotomy, which is particularly suitable for young patients who would require lifelong dilations or botulinum toxin injections, those who have not responded to multiple nonsurgical treatments, those who choose surgery as their initial treatment, and those who are at high risk of perforation with pneumatic dilation due to previous surgery in the oesophagogastric junction. It is important to note that Billroth’s operation is a different surgical procedure that involves removing the pylorus and anastomosing the proximal stomach directly to the duodenum, while Whipple’s procedure is typically performed for pancreatic cancer.

      Understanding Achalasia: Symptoms, Diagnosis, and Treatment

      Achalasia is a medical condition characterized by the failure of oesophageal peristalsis and relaxation of the lower oesophageal sphincter (LOS) due to the degenerative loss of ganglia from Auerbach’s plexus. This results in a contracted LOS and a dilated oesophagus above it. It is a condition that typically presents in middle-aged individuals and is equally common in both men and women.

      The clinical features of achalasia include dysphagia of both liquids and solids, heartburn, regurgitation of food, and variation in the severity of symptoms. If left untreated, it may lead to cough, aspiration pneumonia, and even malignant changes in a small number of patients. To diagnose achalasia, oesophageal manometry is considered the most important diagnostic test. It shows excessive LOS tone that doesn’t relax on swallowing. A barium swallow may also be used to show a grossly expanded oesophagus, fluid level, and a ‘bird’s beak’ appearance. A chest x-ray may show a wide mediastinum and fluid level.

      The preferred first-line treatment for achalasia is pneumatic (balloon) dilation, which is less invasive and has a quicker recovery time than surgery. However, patients should be a low surgical risk as surgery may be required if complications occur. Surgical intervention with a Heller cardiomyotomy should be considered if recurrent or persistent symptoms occur. In some cases, intra-sphincteric injection of botulinum toxin is used in patients who are a high surgical risk. Drug therapy, such as nitrates and calcium channel blockers, may also have a role in treatment but is limited by side-effects. Understanding the symptoms, diagnosis, and treatment options for achalasia is crucial in managing this condition effectively.

    • This question is part of the following fields:

      • Gastrointestinal System
      69.2
      Seconds
  • Question 12 - A 32-year-old man has a sarcoma removed from his right buttock, resulting in...

    Correct

    • A 32-year-old man has a sarcoma removed from his right buttock, resulting in sacrifice of the sciatic nerve. What is one outcome that will not occur as a result of this procedure?

      Your Answer: Loss of extension at the knee joint

      Explanation:

      The obturator and femoral nerves are responsible for causing extension of the knee joint.

      Understanding the Sciatic Nerve

      The sciatic nerve is the largest nerve in the body, formed from the sacral plexus and arising from spinal nerves L4 to S3. It passes through the greater sciatic foramen and emerges beneath the piriformis muscle, running under the cover of the gluteus maximus muscle. The nerve provides cutaneous sensation to the skin of the foot and leg, as well as innervating the posterior thigh muscles and lower leg and foot muscles. Approximately halfway down the posterior thigh, the nerve splits into the tibial and common peroneal nerves. The tibial nerve supplies the flexor muscles, while the common peroneal nerve supplies the extensor and abductor muscles.

      The sciatic nerve also has articular branches for the hip joint and muscular branches in the upper leg, including the semitendinosus, semimembranosus, biceps femoris, and part of the adductor magnus. Cutaneous sensation is provided to the posterior aspect of the thigh via cutaneous nerves, as well as the gluteal region and entire lower leg (except the medial aspect). The nerve terminates at the upper part of the popliteal fossa by dividing into the tibial and peroneal nerves. The nerve to the short head of the biceps femoris comes from the common peroneal part of the sciatic, while the other muscular branches arise from the tibial portion. The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis, which is innervated by the common peroneal nerve.

    • This question is part of the following fields:

      • Neurological System
      53.4
      Seconds
  • Question 13 - What is the daily recommended amount of carbohydrates to consume? ...

    Incorrect

    • What is the daily recommended amount of carbohydrates to consume?

      Your Answer: 100 g

      Correct Answer: 50 g

      Explanation:

      The Importance of Carbohydrates in the Diet

      Carbohydrates are essential for the body as they provide fuel for the brain, red blood cells, and the renal medulla. Although the average daily intake of carbohydrates is around 180 g/day, the body can function on a much lower intake of 30-50 g/day. During pregnancy or lactation, the recommended minimum daily requirement of carbohydrates increases to around 100 g/day.

      When carbohydrate intake is restricted, the body can produce glucose through gluconeogenesis, which is the process of making glucose from other fuel sources such as protein and fat. However, when carbohydrate intake is inadequate, the body produces ketones during the oxidation of fats. While ketones can be used by the brain as an alternative fuel source to glucose, prolonged or excessive reliance on ketones can lead to undesirable side effects. Ketones are acidic and can cause systemic acidosis.

      It is important to note that most people consume 200-400 g/day of carbohydrates, which is much higher than the recommended minimum daily requirement. Therefore, it is essential to maintain a balanced diet that includes carbohydrates in the appropriate amount to ensure optimal health.

    • This question is part of the following fields:

      • Clinical Sciences
      70.4
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  • Question 14 - A 50-year-old woman visits her general practitioner with a complaint of severe facial...

    Incorrect

    • A 50-year-old woman visits her general practitioner with a complaint of severe facial pain. The pain occurs several times a day and is described as the worst she has ever experienced. It is sudden in onset and termination and is felt in the right ophthalmic and maxillary regions of her face.

      During the examination, the cranial nerves appear normal except for the absence of a blink reflex in the patient's right eye when cotton wool is rubbed against it. However, the patient blinks when cotton wool is rubbed against her left eye.

      Which efferent pathway of this reflex is responsible for this nerve?

      Your Answer: CN III

      Correct Answer: CN VII

      Explanation:

      Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.

      In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.

    • This question is part of the following fields:

      • Neurological System
      24.1
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  • Question 15 - During a 5-year-old male child's routine check-up, a doctor observes macroglossia, hepatomegaly and...

    Correct

    • During a 5-year-old male child's routine check-up, a doctor observes macroglossia, hepatomegaly and renomegaly along with a characteristic ear crease. The child was born at 38 weeks gestation and had a prolonged spontaneous vaginal delivery. His birth weight was 4 kg (8Ib 13oz). He had neonatal hypoglycaemia during the first 12 hours which was treated with IV dextrose. The doctor suspects Beckwith-Wiedemann syndrome. What childhood cancers are associated with this syndrome?

      Your Answer: Wilms tumour (nephroblastoma)

      Explanation:

      Beckwith-Wiedemann syndrome (BWS) is a rare condition that causes excessive growth in children and increases their risk of developing tumors. It affects approximately 1 in 10,300 to 13,700 people. Symptoms of BWS include large body size, enlarged tongue, protruding belly button or hernia, ear creases or pits, enlarged organs in the abdomen, and low blood sugar in newborns. The most common cancer associated with BWS is Wilms tumor, although other childhood cancers can also occur.

      Wilms’ Tumour: A Common Childhood Malignancy

      Wilms’ tumour, also known as nephroblastoma, is a prevalent type of cancer in children, with a median age of diagnosis at 3 years old. It is often associated with Beckwith-Wiedemann syndrome, hemihypertrophy, and a loss-of-function mutation in the WT1 gene on chromosome 11. The most common presenting feature is an abdominal mass, which is usually painless, but other symptoms such as haematuria, flank pain, anorexia, and fever may also occur. In 95% of cases, the tumour is unilateral, and metastases are found in 20% of patients, most commonly in the lungs.

      If a child presents with an unexplained enlarged abdominal mass, it is crucial to arrange a paediatric review within 48 hours to rule out Wilms’ tumour. The management of this cancer typically involves nephrectomy, chemotherapy, and radiotherapy if the disease is advanced. Fortunately, the prognosis for Wilms’ tumour is good, with an 80% cure rate.

      Histologically, Wilms’ tumour is characterized by epithelial tubules, areas of necrosis, immature glomerular structures, stroma with spindle cells, and small cell blastomatous tissues resembling the metanephric blastema. Overall, early detection and prompt treatment are essential for a successful outcome in children with Wilms’ tumour.

    • This question is part of the following fields:

      • Renal System
      57.6
      Seconds
  • Question 16 - A 43-year-old man is seeking information about the COVID-19 vaccine. He has heard...

    Incorrect

    • A 43-year-old man is seeking information about the COVID-19 vaccine. He has heard that the vaccine may not provide complete protection and wants to know how effective it is. As his healthcare provider, you provide him with the following data for this specific vaccine:

      Vaccinated Not vaccinated Total
      COVID-19 occurred 10 90 100
      COVID-19 did not occur 90 10 100
      Column totals 100 100 200

      What is the most appropriate response to this patient's inquiry?

      Your Answer: 90/100 - 10/100 = 80%

      Correct Answer: (10/100 - 90/100) / 90/100 = -90%

      Explanation:

      Understanding Relative Risk in Clinical Trials

      Relative risk (RR) is a measure used in clinical trials to compare the risk of an event occurring in the experimental group to the risk in the control group. It is calculated by dividing the experimental event rate (EER) by the control event rate (CER). If the resulting ratio is greater than 1, it means that the event is more likely to occur in the experimental group than in the control group. Conversely, if the ratio is less than 1, the event is less likely to occur in the experimental group.

      To calculate the relative risk reduction (RRR) or relative risk increase (RRI), the absolute risk change is divided by the control event rate. This provides a percentage that indicates the magnitude of the difference between the two groups. Understanding relative risk is important in evaluating the effectiveness of interventions and treatments in clinical trials. By comparing the risk of an event in the experimental group to the control group, researchers can determine whether the intervention is beneficial or not.

    • This question is part of the following fields:

      • General Principles
      35.2
      Seconds
  • Question 17 - A study is conducted to compare two chemotherapy treatments for patients with pancreatic...

    Incorrect

    • A study is conducted to compare two chemotherapy treatments for patients with pancreatic cancer. The study aims to determine the survival time as the endpoint. Which statistical measure is most suitable for comparing survival time?

      Your Answer: Odds ratio

      Correct Answer: Hazard ratio

      Explanation:

      Understanding Hazard Ratio

      The hazard ratio (HR) is a statistical measure used to determine the likelihood of an event occurring over time. It is similar to the relative risk, but it takes into account the fact that the risk of an event may change over time. The HR is commonly used in survival analysis, where researchers are interested in understanding how long it takes for an event to occur, such as death or disease progression.

      Unlike the relative risk, which assumes a constant risk over time, the hazard ratio takes into account the changing risk of an event occurring. For example, the risk of death may be higher in the first year after a cancer diagnosis, but then decrease over time as the patient receives treatment. The HR allows researchers to compare the risk of an event occurring between two groups, such as a treatment group and a control group, while accounting for the changing risk over time.

      Overall, the hazard ratio is a useful tool for understanding the likelihood of an event occurring over time, particularly in survival analysis. By taking into account the changing risk of an event, researchers can make more accurate comparisons between groups and draw more meaningful conclusions from their data.

    • This question is part of the following fields:

      • General Principles
      19.6
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  • Question 18 - A 75-year-old man is having a left pneumonectomy for bronchial carcinoma. When the...

    Incorrect

    • A 75-year-old man is having a left pneumonectomy for bronchial carcinoma. When the surgeons reach the root of the lung, which structure will be the most anterior in the anatomical plane?

      Your Answer: Pulmonary artery

      Correct Answer: Phrenic nerve

      Explanation:

      The lung root contains two nerves, with the phrenic nerve positioned in the most anterior location and the vagus nerve situated in the most posterior location.

      Anatomy of the Lungs

      The lungs are a pair of organs located in the chest cavity that play a vital role in respiration. The right lung is composed of three lobes, while the left lung has two lobes. The apex of both lungs is approximately 4 cm superior to the sternocostal joint of the first rib. The base of the lungs is in contact with the diaphragm, while the costal surface corresponds to the cavity of the chest. The mediastinal surface contacts the mediastinal pleura and has the cardiac impression. The hilum is a triangular depression above and behind the concavity, where the structures that form the root of the lung enter and leave the viscus. The right main bronchus is shorter, wider, and more vertical than the left main bronchus. The inferior borders of both lungs are at the 6th rib in the mid clavicular line, 8th rib in the mid axillary line, and 10th rib posteriorly. The pleura runs two ribs lower than the corresponding lung level. The bronchopulmonary segments of the lungs are divided into ten segments, each with a specific function.

    • This question is part of the following fields:

      • Respiratory System
      43.1
      Seconds
  • Question 19 - A 82-year-old female experiences a fall and is brought to the emergency department....

    Correct

    • A 82-year-old female experiences a fall and is brought to the emergency department. X-rays reveal a displaced fracture above the greater and lesser trochanter of the proximal femur on the right side. What would be the best surgical approach for this patient?

      Your Answer: Hemiarthroplasty

      Explanation:

      When a hip fracture occurs within the joint capsule, there is a higher chance of the femoral head experiencing avascular necrosis. This type of fracture is considered displaced and requires treatment with hemiarthroplasty or total hip replacement, especially for older patients. However, younger patients may opt for hip fixation instead of replacement as prosthetic joints have a limited lifespan.

      Hip fractures are a common occurrence, particularly in elderly women with osteoporosis. The femoral head’s blood supply runs up the neck, making avascular necrosis a risk in displaced fractures. Symptoms include pain and a shortened and externally rotated leg. Patients with non-displaced or incomplete neck of femur fractures may still be able to bear weight. Hip fractures are classified based on their location, either intracapsular or extracapsular. The Garden system is a commonly used classification system that categorizes fractures into four types based on stability and displacement. Blood supply disruption is most common in Types III and IV.

      Undisplaced intracapsular fractures can be treated with internal fixation or hemiarthroplasty if the patient is unfit. Displaced fractures require replacement arthroplasty, with total hip replacement being preferred over hemiarthroplasty if the patient was able to walk independently outdoors with no more than a stick, is not cognitively impaired, and is medically fit for anesthesia and the procedure. Extracapsular fractures are managed with a dynamic hip screw for stable intertrochanteric fractures and an intramedullary device for reverse oblique, transverse, or subtrochanteric fractures.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      62.6
      Seconds
  • Question 20 - Which drugs exhibit zero-order kinetics? ...

    Incorrect

    • Which drugs exhibit zero-order kinetics?

      Your Answer: Bendrofluazide

      Correct Answer: Phenytoin

      Explanation:

      Phenytoin exhibits zero-order kinetics.

      Understanding Drug Metabolism: Phase I and Phase II Reactions

      Drug metabolism involves two types of biochemical reactions, namely phase I and phase II reactions. Phase I reactions include oxidation, reduction, and hydrolysis, which are mainly performed by P450 enzymes. However, some drugs are metabolized by specific enzymes such as alcohol dehydrogenase and xanthine oxidase. The products of phase I reactions are typically more active and potentially toxic. On the other hand, phase II reactions involve conjugation, where glucuronyl, acetyl, methyl, sulphate, and other groups are typically involved. The products of phase II reactions are typically inactive and excreted in urine or bile. The majority of phase I and phase II reactions take place in the liver.

      First-Pass Metabolism and Drugs Affected by Zero-Order Kinetics and Acetylator Status

      First-pass metabolism is a phenomenon where the concentration of a drug is greatly reduced before it reaches the systemic circulation due to hepatic metabolism. This effect is seen in many drugs, including aspirin, isosorbide dinitrate, glyceryl trinitrate, lignocaine, propranolol, verapamil, isoprenaline, testosterone, and hydrocortisone.

      Zero-order kinetics describe metabolism that is independent of the concentration of the reactant. This is due to metabolic pathways becoming saturated, resulting in a constant amount of drug being eliminated per unit time. Drugs exhibiting zero-order kinetics include phenytoin, salicylates (e.g. high-dose aspirin), heparin, and ethanol.

      Acetylator status is also an important consideration in drug metabolism. Approximately 50% of the UK population are deficient in hepatic N-acetyltransferase. Drugs affected by acetylator status include isoniazid, procainamide, hydralazine, dapsone, and sulfasalazine. Understanding these concepts is important in predicting drug efficacy and toxicity, as well as in optimizing drug dosing.

    • This question is part of the following fields:

      • General Principles
      44.8
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  • Question 21 - A middle-aged woman with severe refractory psoriasis, a chronic inflammatory skin condition, has...

    Correct

    • A middle-aged woman with severe refractory psoriasis, a chronic inflammatory skin condition, has been prescribed cyclosporin by her dermatologist.

      What is the mechanism of action of this drug as an immunosuppressant?

      Your Answer: It inhibits calcineurin activity, preventing a rise in IL-2 levels and proliferation of T lymphocytes

      Explanation:

      Cyclosporine and tacrolimus work by inhibiting calcineurin, which reduces the levels of IL-2 and suppresses the cell-mediated immune response. This is different from targeting the humoral immune response associated with B lymphocytes. It is important to note that cyclosporin is not a TNF-alpha inhibitor, which is a different group of biologic agents used to treat severe psoriasis. Methotrexate works by inhibiting dihydrofolate reductase, not by the same mechanism as ciclosporin. Ciclosporin does not affect the proliferation of keratinocytes, which are targeted by vitamin D analogues commonly used in psoriasis treatment, such as calcitriol.

      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
      32.7
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  • Question 22 - A 55-year-old man undergoes a regular health examination, including observation, ECG, and routine...

    Incorrect

    • A 55-year-old man undergoes a regular health examination, including observation, ECG, and routine blood tests. The ECG reveals an extended corrected QT interval. Which abnormality detected in his blood test could explain the ECG results?

      Your Answer: Hyperkalaemia

      Correct Answer: Hypokalaemia

      Explanation:

      Long QT syndrome can be caused by hypokalaemia, among other electrolyte imbalances.

      Electrolyte imbalances such as hypocalcaemia and hypomagnesaemia can also result in long QT syndrome.

      However, hyperkalaemia, hypercalcaemia, and hypermagnesaemia are not linked to long QT syndrome.

      Long QT syndrome (LQTS) is a genetic condition that causes a delay in the ventricles’ repolarization. This delay can lead to ventricular tachycardia/torsade de pointes, which can cause sudden death or collapse. The most common types of LQTS are LQT1 and LQT2, which are caused by defects in the alpha subunit of the slow delayed rectifier potassium channel. A normal corrected QT interval is less than 430 ms in males and 450 ms in females.

      There are various causes of a prolonged QT interval, including congenital factors, drugs, and other conditions. Congenital factors include Jervell-Lange-Nielsen syndrome and Romano-Ward syndrome. Drugs that can cause a prolonged QT interval include amiodarone, sotalol, tricyclic antidepressants, and selective serotonin reuptake inhibitors. Other factors that can cause a prolonged QT interval include electrolyte imbalances, acute myocardial infarction, myocarditis, hypothermia, and subarachnoid hemorrhage.

      LQTS may be detected on a routine ECG or through family screening. Long QT1 is usually associated with exertional syncope, while Long QT2 is often associated with syncope following emotional stress, exercise, or auditory stimuli. Long QT3 events often occur at night or at rest and can lead to sudden cardiac death.

      Management of LQTS involves avoiding drugs that prolong the QT interval and other precipitants if appropriate. Beta-blockers are often used, and implantable cardioverter defibrillators may be necessary in high-risk cases. It is important to note that sotalol may exacerbate LQTS.

    • This question is part of the following fields:

      • Cardiovascular System
      8.8
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  • Question 23 - Jill, a 54-year-old female, visits her doctor complaining of chest pain. She reports...

    Correct

    • Jill, a 54-year-old female, visits her doctor complaining of chest pain. She reports that the pain worsens when she walks and subsides when she rests.

      Jill's medical history includes diabetes, hypercholesterolemia, and hypertension. She also has a family history of myocardial infarction.

      Based on her symptoms, the doctor diagnoses Jill with angina and prescribes a nitrate spray.

      At what stage of the cardiac cycle do the coronary arteries primarily fill?

      Your Answer: Ventricular diastole

      Explanation:

      The filling of the coronary arteries takes place during ventricular diastole and not during ventricular systole, which is when isovolumetric contraction occurs.

      Understanding Coronary Circulation

      Coronary circulation refers to the blood flow that supplies the heart with oxygen and nutrients. The arterial supply of the heart is divided into two main branches: the left coronary artery (LCA) and the right coronary artery (RCA). The LCA originates from the left aortic sinus, while the RCA originates from the right aortic sinus. The LCA further divides into two branches, the left anterior descending (LAD) and the circumflex artery, while the RCA supplies the posterior descending artery.

      The LCA supplies the left ventricle, left atrium, and interventricular septum, while the RCA supplies the right ventricle and the inferior wall of the left ventricle. The SA node, which is responsible for initiating the heartbeat, is supplied by the RCA in 60% of individuals, while the AV node, which is responsible for regulating the heartbeat, is supplied by the RCA in 90% of individuals.

      On the other hand, the venous drainage of the heart is through the coronary sinus, which drains into the right atrium. During diastole, the coronary arteries fill with blood, allowing for the delivery of oxygen and nutrients to the heart muscles. Understanding the coronary circulation is crucial in the diagnosis and management of various heart diseases.

    • This question is part of the following fields:

      • Cardiovascular System
      12.7
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  • Question 24 - A 30-year-old man has been referred to a dermatology clinic due to the...

    Incorrect

    • A 30-year-old man has been referred to a dermatology clinic due to the presence of widespread flaccid superficial blisters and oral mucosal ulceration. He has no known history of coeliac disease. Upon biopsy, it was discovered that he has antibodies against the desmosomes that connect epithelial cells.

      What is the underlying skin condition?

      Your Answer: Dermatitis herpetiformis

      Correct Answer: Pemphigus

      Explanation:

      Pemphigus is a skin disorder caused by autoimmune reactions where IgG antibodies attack the desmosomes that connect the skin cells. This results in acantholysis, where the keratinocytes detach from each other. In contrast, pemphigoid is another autoimmune blistering skin disorder, but it is caused by IgG autoantibodies targeting the basement membrane instead of the desmosomes.

      Pemphigus vulgaris is an autoimmune condition that occurs when the body’s immune system attacks desmoglein 3, a type of cell adhesion molecule found in epithelial cells. This disease is more prevalent in the Ashkenazi Jewish population. The most common symptom is mucosal ulceration, which can be the first sign of the disease. Oral involvement is seen in 50-70% of patients. Skin blistering is also a common symptom, with easily ruptured vesicles and bullae. These lesions are typically painful but not itchy and may appear months after the initial mucosal symptoms. Nikolsky’s sign is a characteristic feature of pemphigus vulgaris, where bullae spread following the application of horizontal, tangential pressure to the skin. Biopsy results often show acantholysis.

      The first-line treatment for pemphigus vulgaris is steroids, which help to reduce inflammation and suppress the immune system. Immunosuppressants may also be used to manage the disease.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      16
      Seconds
  • Question 25 - A 40-year-old male patient complains of shortness of breath, weight loss, and night...

    Incorrect

    • A 40-year-old male patient complains of shortness of breath, weight loss, and night sweats for the past six weeks. Despite being generally healthy, he is experiencing these symptoms. During the examination, the patient's fingers show clubbing, and his temperature is 37.8°C. His pulse is 88 beats per minute, and his blood pressure is 128/80 mmHg. Upon listening to his heart, a pansystolic murmur is audible. What signs are likely to be found in this patient?

      Your Answer: Cyanosis

      Correct Answer: Splinter haemorrhages

      Explanation:

      Symptoms and Diagnosis of Infective Endocarditis

      This individual has a lengthy medical history of experiencing night sweats and has developed clubbing of the fingers, along with a murmur. These symptoms are indicative of infective endocarditis. In addition to splinter hemorrhages in the nails, other symptoms that may be present include Roth spots in the eyes, Osler’s nodes and Janeway lesions in the palms and fingers of the hands, and splenomegaly instead of cervical lymphadenopathy. Cyanosis is not typically associated with clubbing and may suggest idiopathic pulmonary fibrosis or cystic fibrosis in younger individuals. However, this individual has no prior history of cystic fibrosis and has only been experiencing symptoms for six weeks.

    • This question is part of the following fields:

      • Cardiovascular System
      58.8
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  • Question 26 - A 60-year-old male presents with increasing fatigue.

    Three months ago, he was diagnosed...

    Correct

    • A 60-year-old male presents with increasing fatigue.

      Three months ago, he was diagnosed with bronchial carcinoma and has undergone chemotherapy. Upon admission, his electrolyte levels were measured as follows:

      - Sodium: 118 mmol/L (137-144)
      - Potassium: 3.5 mmol/L (3.5-4.9)
      - Urea: 3.2 mmol/L (2.5-7.5)
      - Creatinine: 65 µmol/L (60-110)

      What would be the most appropriate initial investigation for this patient?

      Your Answer: Urine osmolality and sodium concentration

      Explanation:

      Hyponatraemia in Bronchial Carcinoma Patients

      Hyponatraemia is a common condition in patients with bronchial carcinoma. It is characterized by a marked decrease in sodium levels, which appears to be dilutional based on other test results that fall within the lower end of the normal range. The most likely cause of this condition is the syndrome of inappropriate ADH secretion (SIADH), which occurs when the tumour produces ADH in an ectopic manner. However, the diagnosis of SIADH is one of exclusion, and other possibilities such as hypoadrenalism due to metastatic disease to the adrenals should also be considered.

      To determine the cause of hyponatraemia, initial tests such as urine sodium and osmolality are recommended. These tests can help rule out other possible causes and confirm the diagnosis of SIADH. Treatment for this condition typically involves fluid restriction. It is important to note that measuring ADH concentrations is not a reliable diagnostic tool as it is not widely available and does not provide any useful information.

      In summary, hyponatraemia is a common condition in bronchial carcinoma patients, and SIADH is the most likely cause. Initial tests such as urine sodium and osmolality can help confirm the diagnosis, and treatment involves fluid restriction.

    • This question is part of the following fields:

      • Endocrine System
      45.1
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  • Question 27 - The foramen indicating the end of the adductor canal is situated in which...

    Correct

    • The foramen indicating the end of the adductor canal is situated in which of the subsequent options?

      Your Answer: Adductor magnus

      Explanation:

      The adductor canal’s distal boundary is demarcated by a foramen located within the adductor magnus. The vessel traverses this area to reach the popliteal fossa.

      The Adductor Canal: Anatomy and Contents

      The adductor canal, also known as Hunter’s or the subsartorial canal, is a structure located in the middle third of the thigh, immediately distal to the apex of the femoral triangle. It is bordered laterally by the vastus medialis muscle and posteriorly by the adductor longus and adductor magnus muscles. The roof of the canal is formed by the sartorius muscle. The canal terminates at the adductor hiatus.

      The adductor canal contains three important structures: the saphenous nerve, the superficial femoral artery, and the superficial femoral vein. The saphenous nerve is a sensory nerve that supplies the skin of the medial leg and foot. The superficial femoral artery is a major artery that supplies blood to the lower limb. The superficial femoral vein is a large vein that drains blood from the lower limb.

      In order to expose the contents of the adductor canal, the sartorius muscle must be removed. Understanding the anatomy and contents of the adductor canal is important for medical professionals who perform procedures in this area, such as nerve blocks or vascular surgeries.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      11.9
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  • Question 28 - You are developing a research project investigating the pathophysiology of abetalipoproteinemia. You determine...

    Incorrect

    • You are developing a research project investigating the pathophysiology of abetalipoproteinemia. You determine that a viable focus would be the rate-limiting enzyme involved in lipogenesis.

      Which enzyme will be the target of your investigation?

      Your Answer: Carbamoyl phosphate synthetase I

      Correct Answer: Acetyl CoA carboxylase

      Explanation:

      The enzyme that limits the rate of lipogenesis is acetyl CoA carboxylase.

      During lipogenesis, fatty acids are produced from acetyl-CoA. Acetyl CoA carboxylase is the enzyme that controls the rate of this process.

      Carbamoyl phosphate synthetase I is the enzyme that limits the rate of the urea cycle.

      Glycogen phosphorylase is the enzyme that controls the rate of glycogenolysis.

      Isocitrate dehydrogenase is the enzyme that limits the rate of the citric acid cycle.

      Rate-Determining Enzymes in Metabolic Processes

      Metabolic processes involve a series of chemical reactions that occur in living organisms to maintain life. Enzymes play a crucial role in these processes by catalyzing the reactions. However, not all enzymes have the same impact on the rate of the reaction. Some enzymes are rate-determining, meaning that they control the overall rate of the process. The table above lists the rate-determining enzymes involved in common metabolic processes.

      For example, in the TCA cycle, isocitrate dehydrogenase is the rate-determining enzyme. In glycolysis, phosphofructokinase-1 controls the rate of the process. In gluconeogenesis, fructose-1,6-bisphosphatase is the rate-determining enzyme. Similarly, glycogen synthase controls the rate of glycogenesis, while glycogen phosphorylase controls the rate of glycogenolysis.

      Other metabolic processes, such as lipogenesis, lipolysis, cholesterol synthesis, and ketogenesis, also have rate-determining enzymes. Acetyl-CoA carboxylase controls the rate of lipogenesis, while carnitine-palmitoyl transferase I controls the rate of lipolysis. HMG-CoA reductase is the rate-determining enzyme in cholesterol synthesis, while HMG-CoA synthase controls the rate of ketogenesis.

      The urea cycle, de novo pyrimidine synthesis, and de novo purine synthesis also have rate-determining enzymes. Carbamoyl phosphate synthetase I controls the rate of the urea cycle, while carbamoyl phosphate synthetase II controls the rate of de novo pyrimidine synthesis. Glutamine-PRPP amidotransferase is the rate-determining enzyme in de novo purine synthesis.

      Understanding the rate-determining enzymes in metabolic processes is crucial for developing treatments for metabolic disorders and diseases. By targeting these enzymes, researchers can potentially regulate the rate of the process and improve the health outcomes of individuals with these conditions.

    • This question is part of the following fields:

      • General Principles
      41.3
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  • Question 29 - A 75-year-old woman experiences a fracture at the surgical neck of her humerus...

    Correct

    • A 75-year-old woman experiences a fracture at the surgical neck of her humerus and requires surgery. During the operation, there are challenges in realigning the fracture, and a blood vessel located behind the surgical neck is damaged. What is the most probable vessel that was injured?

      Your Answer: Posterior circumflex humeral artery

      Explanation:

      The surgical neck is where the circumflex humeral arteries are located, with the posterior circumflex humeral artery being the most susceptible to injury in this situation. The thoracoacromial and transverse scapular arteries are situated in a more superomedial position. It is worth noting that the axillary artery gives rise to the posterior circumflex humeral artery.

      The shoulder joint is a shallow synovial ball and socket joint that is inherently unstable but capable of a wide range of movement. Stability is provided by the muscles of the rotator cuff. The glenoid labrum is a fibrocartilaginous rim attached to the free edge of the glenoid cavity. The fibrous capsule attaches to the scapula, humerus, and tendons of various muscles. Movements of the shoulder joint are controlled by different muscles. The joint is closely related to important anatomical structures such as the brachial plexus, axillary artery and vein, and various nerves and vessels.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      16
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  • Question 30 - An 80-year-old man presents to the emergency department with hip pain following an...

    Incorrect

    • An 80-year-old man presents to the emergency department with hip pain following an unwitnessed fall. He is diagnosed with a hip fracture and undergoes hip arthroplasty. The patient has a medical history of peptic ulcer disease and is currently taking PPI and aluminium hydroxide. His DEXA score is -3, and the doctors recommend starting denosumab for bone protection. Before starting this medication, which complication should the patient be informed about?

      Your Answer: Constipation

      Correct Answer: Increased risk of osteonecrosis jaw

      Explanation:

      When using denosumab, there is a higher chance of developing osteonecrosis of the jaw. This is because denosumab inhibits the formation, function, and survival of osteoclasts, which are responsible for bone resorption and calcium release. However, denosumab does not cause constipation, but it can lead to dyspnea and diarrhea as common side effects. Patients should be informed of the risk of osteonecrosis of the jaw before starting denosumab treatment.

      Denosumab for Osteoporosis: Uses, Side Effects, and Safety Concerns

      Denosumab is a human monoclonal antibody that inhibits the development of osteoclasts, the cells that break down bone tissue. It is given as a subcutaneous injection every six months to treat osteoporosis. For patients with bone metastases from solid tumors, a larger dose of 120mg may be given every four weeks to prevent skeletal-related events. While oral bisphosphonates are still the first-line treatment for osteoporosis, denosumab may be used as a next-line drug if certain criteria are met.

      The most common side effects of denosumab are dyspnea and diarrhea, occurring in about 1 in 10 patients. Other less common side effects include hypocalcemia and upper respiratory tract infections. However, doctors should be aware of the potential for atypical femoral fractures in patients taking denosumab and should monitor for unusual thigh, hip, or groin pain.

      Overall, denosumab is generally well-tolerated and may have an increasing role in the management of osteoporosis, particularly in light of recent safety concerns regarding other next-line drugs. However, as with any medication, doctors should carefully consider the risks and benefits for each individual patient.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      58.5
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SESSION STATS - PERFORMANCE PER SPECIALTY

General Principles (3/8) 38%
Neurological System (2/3) 67%
Clinical Sciences (0/2) 0%
Renal System (1/3) 33%
Musculoskeletal System And Skin (3/6) 50%
Endocrine System (3/3) 100%
Gastrointestinal System (1/1) 100%
Respiratory System (0/1) 0%
Cardiovascular System (1/3) 33%
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