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  • Question 1 - A 28-year-old man with schizophrenia who began taking clozapine 2 weeks ago visits...

    Incorrect

    • A 28-year-old man with schizophrenia who began taking clozapine 2 weeks ago visits for his routine blood test. What is a known severe side effect of clozapine?

      Your Answer: Thrombocytopenia

      Correct Answer: Agranulocytosis

      Explanation:

      Clozapine, an antipsychotic medication used to treat refractory schizophrenia, requires continuous monitoring for patients taking it. This involves weekly blood tests for the first 18 weeks, followed by bi-weekly tests until the first year, and then monthly tests thereafter.

      Atypical antipsychotics are now recommended as the first-line treatment for patients with schizophrenia, as per the 2005 NICE guidelines. These agents have a significant advantage over traditional antipsychotics in that they cause fewer extrapyramidal side-effects. However, atypical antipsychotics can still cause adverse effects such as weight gain, hyperprolactinaemia, and clozapine-associated agranulocytosis. Elderly patients who take antipsychotics are at an increased risk of stroke and venous thromboembolism, according to the Medicines and Healthcare products Regulatory Agency.

      Clozapine is one of the first atypical antipsychotics to be developed, but it carries a significant risk of agranulocytosis. Therefore, full blood count monitoring is essential during treatment. Clozapine should only be used in patients who are resistant to other antipsychotic medication. The BNF recommends introducing clozapine if schizophrenia is not controlled despite the sequential use of two or more antipsychotic drugs, one of which should be a second-generation antipsychotic drug, each for at least 6-8 weeks. Clozapine can cause adverse effects such as reduced seizure threshold, constipation, myocarditis, and hypersalivation. Dose adjustment of clozapine may be necessary if smoking is started or stopped during treatment.

    • This question is part of the following fields:

      • Psychiatry
      116.5
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  • Question 2 - A 50-year-old man with dyspepsia is scheduled for an upper GI endoscopy. During...

    Correct

    • A 50-year-old man with dyspepsia is scheduled for an upper GI endoscopy. During the procedure, an irregular erythematous area is observed protruding proximally from the gastro-oesophageal junction. To confirm a diagnosis of Barrett's esophagus, which of the following cell types must be present in addition to specialised intestinal metaplasia?

      Your Answer: Goblet cell

      Explanation:

      The presence of goblet cells is a requirement for the diagnosis of Barrett’s esophagus.

      Barrett’s oesophagus is a condition where the lower oesophageal mucosa is replaced by columnar epithelium, which increases the risk of oesophageal adenocarcinoma by 50-100 fold. It is usually identified during an endoscopy for upper gastrointestinal symptoms such as dyspepsia, as there are no screening programs for it. The length of the affected segment determines the chances of identifying metaplasia, with short (<3 cm) and long (>3 cm) subtypes. The prevalence of Barrett’s oesophagus is estimated to be around 1 in 20, and it is identified in up to 12% of those undergoing endoscopy for reflux.

      The columnar epithelium in Barrett’s oesophagus may resemble that of the cardiac region of the stomach or that of the small intestine, with goblet cells and brush border. The single strongest risk factor for Barrett’s oesophagus is gastro-oesophageal reflux disease (GORD), followed by male gender, smoking, and central obesity. Alcohol is not an independent risk factor for Barrett’s, but it is associated with both GORD and oesophageal cancer. Patients with Barrett’s oesophagus often have coexistent GORD symptoms.

      The management of Barrett’s oesophagus involves high-dose proton pump inhibitor, although the evidence base for its effectiveness in reducing the progression to dysplasia or inducing regression of the lesion is limited. Endoscopic surveillance with biopsies is recommended every 3-5 years for patients with metaplasia but not dysplasia. If dysplasia of any grade is identified, endoscopic intervention is offered, such as radiofrequency ablation, which is the preferred first-line treatment, particularly for low-grade dysplasia, or endoscopic mucosal resection.

    • This question is part of the following fields:

      • Gastrointestinal System
      56.9
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  • Question 3 - A 54-year-old man visits the clinic after his spouse was diagnosed with hypertension...

    Incorrect

    • A 54-year-old man visits the clinic after his spouse was diagnosed with hypertension and advised him to get his blood pressure checked. He has no symptoms. Upon measurement, his blood pressure is 155/92 mmHg. To further evaluate, a 24-hour blood pressure monitoring is scheduled. During the consultation, you discuss the physiology of blood pressure and mention the significance of the renin-angiotensin-aldosterone system in maintaining blood pressure homeostasis. Can you identify the primary site of aldosterone action in the kidney?

      Your Answer:

      Correct Answer: Distal convoluted tubule and collecting duct of the nephron

      Explanation:

      Aldosterone functions in the distal convoluted tubule and collecting ducts of the nephron. Spironolactone is a diuretic that preserves potassium levels by blocking aldosterone receptors. The loop of Henle and Bowman’s capsule are located closer to the beginning of the nephron. Prostaglandins regulate the afferent arteriole of the glomerulus, causing vasodilation. NSAIDs can lead to renal failure by inhibiting prostaglandin production. The vasa recta are straight capillaries that run parallel to the loop of Henle in the kidney. To confirm a diagnosis of hypertension, NICE recommends a 24-hour ambulatory blood pressure reading to account for the potential increase in blood pressure in clinical settings.

      Aldosterone is a hormone that is primarily produced by the adrenal cortex in the zona glomerulosa. Its main function is to stimulate the reabsorption of sodium from the distal tubules, which results in the excretion of potassium. It is regulated by various factors such as angiotensin II, potassium, and ACTH, which increase its secretion. However, when there is an overproduction of aldosterone, it can lead to primary hyperaldosteronism, which is a common cause of secondary hypertension. This condition can be caused by an adrenal adenoma, which is also known as Conn’s syndrome. It is important to note that spironolactone, an aldosterone antagonist, can cause hyperkalemia.

    • This question is part of the following fields:

      • Renal System
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  • Question 4 - A 56-year-old man is sent home following an uneventful left total hip replacement....

    Incorrect

    • A 56-year-old man is sent home following an uneventful left total hip replacement. He has been prescribed a direct factor Xa inhibitor for thromboprophylaxis.

      What is the probable medication that the patient has been prescribed?

      Your Answer:

      Correct Answer: Apixaban

      Explanation:

      Apixaban directly inhibits factor Xa, while bivalirudin and dabigatran directly inhibit thrombin. On the other hand, enoxaparin is a type of low molecular weight heparin that indirectly inhibits factor Xa by forming a complex with antithrombin III, leading to irreversible inactivation of factor Xa.

      Direct oral anticoagulants (DOACs) are medications used to prevent stroke in non-valvular atrial fibrillation (AF), as well as for the prevention and treatment of venous thromboembolism (VTE). To be prescribed DOACs for stroke prevention, patients must have certain risk factors, such as a prior stroke or transient ischaemic attack, age 75 or older, hypertension, diabetes mellitus, or heart failure. There are four DOACs available, each with a different mechanism of action and method of excretion. Dabigatran is a direct thrombin inhibitor, while rivaroxaban, apixaban, and edoxaban are direct factor Xa inhibitors. The majority of DOACs are excreted either through the kidneys or the liver, with the exception of apixaban and edoxaban, which are excreted through the feces. Reversal agents are available for dabigatran and rivaroxaban, but not for apixaban or edoxaban.

    • This question is part of the following fields:

      • Haematology And Oncology
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  • Question 5 - What is the primary function of riboflavin (vitamin B2) in the human body?...

    Incorrect

    • What is the primary function of riboflavin (vitamin B2) in the human body?

      Your Answer:

      Correct Answer: Energy production

      Explanation:

      The Importance of Riboflavin in the Body

      Riboflavin, also known as vitamin B2, is a vital nutrient in the body. Its structure consists of a sugar molecule attached to a flavin ring structure, which gives it a yellow color. One of the main roles of riboflavin is to aid in energy production and cellular metabolism of fuels. This is achieved by the creation of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are essential for generating ATP from carbohydrates and other fuel sources. Additionally, riboflavin has antioxidant properties that help protect cells from damage caused by free radicals.

      Riboflavin can be found in a variety of foods, including yeast and yeast extract, liver and kidney, wheat germ, milk and cheese, eggs, and some breakfast cereals and drinks that are fortified with riboflavin. It is important to ensure that you are getting enough riboflavin in your diet to support your body’s energy production and antioxidant functions.

    • This question is part of the following fields:

      • Clinical Sciences
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  • Question 6 - A woman visits her physician and undergoes lying and standing blood pressure tests....

    Incorrect

    • A woman visits her physician and undergoes lying and standing blood pressure tests. Upon standing, her baroreceptors sense reduced stretch, triggering the baroreceptor reflex. This results in a decrease in baroreceptor activity, leading to an elevation in sympathetic discharge.

      What is the function of the neurotransmitter that is released?

      Your Answer:

      Correct Answer: Noradrenaline binds to β 1 receptors in the SA node increasing depolarisation

      Explanation:

      The binding of noradrenaline to β 1 receptors in the SA node is responsible for an increase in heart rate due to an increase in depolarisation in the pacemaker action potential, allowing for more frequent firing of action potentials. As the SA node is the pacemaker in a healthy individual, the predominant β receptor found in the heart, β 1, is the one that noradrenaline acts on more than β 2 and α 2 receptors. Therefore, the correct answer is that noradrenaline binds to β 1 receptors in the SA node.

      The heart has four chambers and generates pressures of 0-25 mmHg on the right side and 0-120 mmHg on the left. The cardiac output is the product of heart rate and stroke volume, typically 5-6L per minute. The cardiac impulse is generated in the sino atrial node and conveyed to the ventricles via the atrioventricular node. Parasympathetic and sympathetic fibers project to the heart via the vagus and release acetylcholine and noradrenaline, respectively. The cardiac cycle includes mid diastole, late diastole, early systole, late systole, and early diastole. Preload is the end diastolic volume and afterload is the aortic pressure. Laplace’s law explains the rise in ventricular pressure during the ejection phase and why a dilated diseased heart will have impaired systolic function. Starling’s law states that an increase in end-diastolic volume will produce a larger stroke volume up to a point beyond which stroke volume will fall. Baroreceptor reflexes and atrial stretch receptors are involved in regulating cardiac output.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 7 - A 68-year-old woman presents to the respiratory clinic for a follow-up of her...

    Incorrect

    • A 68-year-old woman presents to the respiratory clinic for a follow-up of her COPD. She informs the healthcare provider that she has quit smoking, resulting in fewer COPD exacerbations, none of which required hospitalization. However, she has observed a slight increase in her weight and swelling in her ankles.

      During the physical examination, the patient's weight is noted to be 76kg, up from her previous weight of 72kg. The healthcare provider listens to her heart and lungs and detects normal breath and heart sounds. The patient has bilateral edema that extends up to her mid-calves.

      What other examination findings may be evident, given the probable diagnosis?

      Your Answer:

      Correct Answer: Smooth hepatomegaly

      Explanation:

      The patient’s symptoms suggest that they have developed cor pulmonale due to COPD, resulting in right-sided heart failure. On examination, signs of fluid congestion such as peripheral edema, raised jugular venous pressure (JVP), ascites, and hepatomegaly may be present. Therefore, the most likely finding would be an enlarged liver with a firm, smooth, tender, and pulsatile edge.

      Caput medusae, which refers to the swelling of superficial veins in the epigastric area, is unlikely to occur in a new presentation of cor pulmonale.

      Narrow pulse pressure is a characteristic of aortic stenosis, which causes left ventricular dysfunction. However, this patient only shows signs of right-sided heart failure.

      A palpable thrill, which indicates turbulent flow across a heart valve, may be felt in severe valvular disease that causes left ventricular dysfunction. Murmurs are often present in valvular disease, but not in this patient’s case.

      Reverse splitting of the second heart sound may occur in aortic stenosis or left bundle branch block, which can cause left ventricular dysfunction.

      Understanding Hepatomegaly and Its Common Causes

      Hepatomegaly refers to an enlarged liver, which can be caused by various factors. One of the most common causes is cirrhosis, which can lead to a decrease in liver size in later stages. In this case, the liver is non-tender and firm. Malignancy, such as metastatic spread or primary hepatoma, can also cause hepatomegaly. In this case, the liver edge is hard and irregular. Right heart failure can also lead to an enlarged liver, which is firm, smooth, and tender. It may even be pulsatile.

      Aside from these common causes, hepatomegaly can also be caused by viral hepatitis, glandular fever, malaria, abscess (pyogenic or amoebic), hydatid disease, haematological malignancies, haemochromatosis, primary biliary cirrhosis, sarcoidosis, and amyloidosis.

      Understanding the causes of hepatomegaly is important in diagnosing and treating the underlying condition. Proper diagnosis and treatment can help prevent further complications and improve overall health.

    • This question is part of the following fields:

      • Gastrointestinal System
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  • Question 8 - A 32-year-old woman is being evaluated for an abdominal mass. She delivered her...

    Incorrect

    • A 32-year-old woman is being evaluated for an abdominal mass. She delivered her first child vaginally and without any issues. Biopsy results indicate the presence of differentiated fibroblasts in sheets, which is indicative of a desmoid tumor. What is a potential risk factor for this type of tumor?

      Your Answer:

      Correct Answer: APC mutations

      Explanation:

      Desmoid tumours are more likely to occur in individuals with APC mutations.

      Pancreatic and hepatic cancer have been linked to CA-199.

      Breast cancer is strongly linked to BRCA1 and BRCA2 mutations.

      Burkitt’s lymphoma, a high-grade B-cell neoplasm, is associated with translocation of the C-myc gene.

      Desmoid tumours are growths that arise from musculoaponeurotic structures and are made up of clonal proliferations of myofibroblasts. They are typically firm and have a tendency to infiltrate surrounding tissue. These tumours are often seen in patients with familial adenomatous polyposis coli, and are most commonly found in women after childbirth in the rectus abdominis muscle. Bi allelic APC mutations are usually present in desmoid tumours.

      The preferred treatment for desmoid tumours is radical surgical resection, although radiotherapy and chemotherapy may be considered in some cases. Non-surgical therapy is generally less effective than surgical resection. In certain cases of abdominal desmoids, observation may be preferred as some tumours may spontaneously regress. However, desmoids have a high likelihood of local recurrence. These tumours consist of sheets of differentiated fibroblasts.

    • This question is part of the following fields:

      • Gastrointestinal System
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  • Question 9 - A 67-year-old male arrives at the emergency department complaining of crushing chest pain,...

    Incorrect

    • A 67-year-old male arrives at the emergency department complaining of crushing chest pain, sweating, and palpitations. Upon examination, an ECG reveals ST elevation in leads V1-V4, indicating a myocardial infarction. Which coronary artery is most likely blocked?

      Your Answer:

      Correct Answer: Anterior descending artery

      Explanation:

      Anteroseptal myocardial infarction is typically caused by blockage of the left anterior descending artery. This is supported by the patient’s symptoms and ST segment elevation in leads V1-V4, which correspond to the territory supplied by this artery. Other potential occlusions, such as the left circumflex artery, left marginal artery, posterior descending artery, or right coronary artery, would cause different changes in specific leads.

      The following table displays the relationship between ECG changes and the affected coronary artery territories. Anteroseptal changes in V1-V4 indicate involvement of the left anterior descending artery, while inferior changes in II, III, and aVF suggest the right coronary artery is affected. Anterolateral changes in V4-6, I, and aVL may indicate involvement of either the left anterior descending or left circumflex artery, while lateral changes in I, aVL, and possibly V5-6 suggest the left circumflex artery is affected. Posterior changes in V1-3 may indicate a posterior infarction, which is typically caused by the left circumflex artery but can also be caused by the right coronary artery. Reciprocal changes of STEMI are often seen as horizontal ST depression, tall R waves, upright T waves, and a dominant R wave in V2. Posterior infarction is confirmed by ST elevation and Q waves in posterior leads (V7-9), usually caused by the left circumflex artery but also possibly the right coronary artery. It is important to note that a new LBBB may indicate acute coronary syndrome.

      Diagram showing the correlation between ECG changes and coronary territories in acute coronary syndrome.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 10 - A 38-year-old man visits his doctor with complaints of numbness and tingling in...

    Incorrect

    • A 38-year-old man visits his doctor with complaints of numbness and tingling in his right thenar eminence for the past 6 months, which is most severe in the mornings. Upon examination, the doctor observes reduced sensation and muscle wasting in the thenar eminence of the right hand. The doctor suspects carpal tunnel syndrome as the likely diagnosis and informs the patient that excessive protein breakdown in the muscles of the thenar eminence has caused the muscle wasting. Which molecule plays a crucial role in this biological process?

      Your Answer:

      Correct Answer: Ubiquitin

      Explanation:

      Functions of Cell Organelles

      The functions of major cell organelles can be summarized in a table. The rough endoplasmic reticulum (RER) is responsible for the translation and folding of new proteins, as well as the manufacture of lysosomal enzymes. It is also the site of N-linked glycosylation. Cells such as pancreatic cells, goblet cells, and plasma cells have extensive RER. On the other hand, the smooth endoplasmic reticulum (SER) is involved in steroid and lipid synthesis. Cells of the adrenal cortex, hepatocytes, and reproductive organs have extensive SER.

      The Golgi apparatus modifies, sorts, and packages molecules that are destined for cell secretion. The addition of mannose-6-phosphate to proteins designates transport to lysosome. The mitochondrion is responsible for aerobic respiration and contains mitochondrial genome as circular DNA. The nucleus is involved in DNA maintenance, RNA transcription, and RNA splicing, which removes the non-coding sequences of genes (introns) from pre-mRNA and joins the protein-coding sequences (exons).

      The lysosome is responsible for the breakdown of large molecules such as proteins and polysaccharides. The nucleolus produces ribosomes, while the ribosome translates RNA into proteins. The peroxisome is involved in the catabolism of very long chain fatty acids and amino acids, resulting in the formation of hydrogen peroxide. Lastly, the proteasome, along with the lysosome pathway, is involved in the degradation of protein molecules that have been tagged with ubiquitin.

    • This question is part of the following fields:

      • General Principles
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  • Question 11 - Which drugs exhibit zero-order kinetics? ...

    Incorrect

    • Which drugs exhibit zero-order kinetics?

      Your Answer:

      Correct Answer: Phenytoin

      Explanation:

      Phenytoin exhibits zero-order kinetics.

      Understanding Drug Metabolism: Phase I and Phase II Reactions

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

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

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

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

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

    • This question is part of the following fields:

      • General Principles
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  • Question 12 - A 32-year-old man who is HIV-positive comes in for a medication review. During...

    Incorrect

    • A 32-year-old man who is HIV-positive comes in for a medication review. During the discussion of his prescribed drugs, you observe that he is taking an integrase inhibitor, which functions by obstructing the enzyme integrase. This enzyme is responsible for inserting viral genetic material into human genomes.

      Which specific medication is he likely taking?

      Your Answer:

      Correct Answer: Raltegravir

      Explanation:

      Integrase inhibitors, also known as ‘gravirs’, block the enzyme responsible for inserting the viral genome into the DNA of the host cell. Raltegravir is an example of a drug with this mechanism of action, and other drugs with the suffix ‘-gravir’ also function as integrase inhibitors. By preventing HIV viral information from integrating into host DNA, these drugs effectively halt further replication of HIV virions. It is important to note that Maraviroc, Nevirapine, and Rifampicin are not integrase inhibitors and do not function in the same way as ‘gravirs’.

      Antiretroviral therapy (ART) is a treatment for HIV that involves a combination of at least three drugs. This combination typically includes two nucleoside reverse transcriptase inhibitors (NRTI) and either a protease inhibitor (PI) or a non-nucleoside reverse transcriptase inhibitor (NNRTI). ART reduces viral replication and the risk of viral resistance emerging. The 2015 BHIVA guidelines recommend that patients start ART as soon as they are diagnosed with HIV, rather than waiting until a particular CD4 count.

      Entry inhibitors, such as maraviroc and enfuvirtide, prevent HIV-1 from entering and infecting immune cells. Nucleoside analogue reverse transcriptase inhibitors (NRTI), such as zidovudine, abacavir, and tenofovir, can cause peripheral neuropathy and other side effects. Non-nucleoside reverse transcriptase inhibitors (NNRTI), such as nevirapine and efavirenz, can cause P450 enzyme interaction and rashes. Protease inhibitors (PI), such as indinavir and ritonavir, can cause diabetes, hyperlipidaemia, and other side effects. Integrase inhibitors, such as raltegravir and dolutegravir, block the action of integrase, a viral enzyme that inserts the viral genome into the DNA of the host cell.

    • This question is part of the following fields:

      • General Principles
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  • Question 13 - A 79-year-old male patient who was admitted with a middle cerebral artery infarct...

    Incorrect

    • A 79-year-old male patient who was admitted with a middle cerebral artery infarct that was complicated by a haemorrhagic transformation had a cardiac arrest on the medical ward. The team arrived and began chest compressions. According to the Resuscitation Council UK adult advanced life support (ALS) algorithm, the patient was given 1 mg of intravenous medication and chest compressions were continued. What is the receptor type that this drug acts on?

      Your Answer:

      Correct Answer: G protein-coupled receptors

      Explanation:

      Adrenaline functions by binding to G protein-coupled receptors, which are located in the cell membrane and transmit signals intracellularly. These receptors undergo a conformational change when a ligand, such as adrenaline, binds to them, activating an associated G protein. The two main intracellular signaling pathways involved in G protein-coupled receptors are the cyclic AMP pathway and the phosphatidylinositol pathway. Other types of receptors include internal receptors, enzyme-linked receptors, and ion channel-linked receptors, which respond to different types of ligands and activate different intracellular pathways.

      Membrane receptors are proteins located on the surface of cells that receive signals from outside the cell and transmit them inside. There are four main types of membrane receptors: ligand-gated ion channel receptors, tyrosine kinase receptors, guanylate cyclase receptors, and G protein-coupled receptors. Ligand-gated ion channel receptors mediate fast responses and include nicotinic acetylcholine, GABA-A & GABA-C, and glutamate receptors. Tyrosine kinase receptors include receptor tyrosine kinase such as insulin, insulin-like growth factor (IGF), and epidermal growth factor (EGF), and non-receptor tyrosine kinase such as PIGG(L)ET, which stands for Prolactin, Immunomodulators (cytokines IL-2, Il-6, IFN), GH, G-CSF, Erythropoietin, and Thrombopoietin.

      Guanylate cyclase receptors contain intrinsic enzyme activity and include atrial natriuretic factor and brain natriuretic peptide. G protein-coupled receptors generally mediate slow transmission and affect metabolic processes. They are activated by a wide variety of extracellular signals such as peptide hormones, biogenic amines (e.g. adrenaline), lipophilic hormones, and light. These receptors have 7-helix membrane-spanning domains and consist of 3 main subunits: alpha, beta, and gamma. The alpha subunit is linked to GDP. Ligand binding causes conformational changes to the receptor, GDP is phosphorylated to GTP, and the alpha subunit is activated. G proteins are named according to the alpha subunit (Gs, Gi, Gq).

      The mechanism of G protein-coupled receptors varies depending on the type of G protein involved. Gs stimulates adenylate cyclase, which increases cAMP and activates protein kinase A. Gi inhibits adenylate cyclase, which decreases cAMP and inhibits protein kinase A. Gq activates phospholipase C, which splits PIP2 to IP3 and DAG and activates protein kinase C. Examples of G protein-coupled receptors include beta-1 receptors (epinephrine, norepinephrine, dobutamine), beta-2 receptors (epinephrine, salbuterol), H2 receptors (histamine), D1 receptors (dopamine), V2 receptors (vas

    • This question is part of the following fields:

      • General Principles
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  • Question 14 - A 35-year-old male presents with gynaecomastia. He is later diagnosed with a testicular...

    Incorrect

    • A 35-year-old male presents with gynaecomastia. He is later diagnosed with a testicular germ cell tumour.

      What is the underlying mechanism that causes this type of cancer to present with gynaecomastia?

      Your Answer:

      Correct Answer: Testicular tumours secrete beta-HCG, which increases oestrogen levels, promoting the proliferation of breast tissue

      Explanation:

      Gynaecomastia can be caused by testicular cancer, specifically seminoma that secretes beta-HCG. This hormone acts as a tumour marker for testicular germ cell cancer and increases oestrogen levels, leading to an imbalance of oestrogen to androgen ratio. This imbalance promotes the growth of breast tissue, resulting in gynaecomastia.

      Alpha-fetoprotein is another tumour marker for testicular cancer, but it does not affect oestrogen levels or breast glandular tissue. It is important to note that gynaecomastia is a separate condition from metastatic testicular cancer in the breast.

      Testicular involution, or shrinkage of the testes, is not a common symptom of testicular cancer. Instead, patients typically present with a painless swelling or nodule in the testis.

      Elevated testosterone levels are not associated with testicular cancer, as they would prevent the growth of breast tissue and gynaecomastia.

      Understanding Gynaecomastia: Causes and Drug Triggers

      Gynaecomastia is a condition characterized by the abnormal growth of breast tissue in males, often caused by an increased ratio of oestrogen to androgen. It is important to distinguish the causes of gynaecomastia from those of galactorrhoea, which is caused by the actions of prolactin on breast tissue.

      Physiological changes during puberty can lead to gynaecomastia, but it can also be caused by syndromes with androgen deficiency such as Kallmann and Klinefelter’s, testicular failure due to mumps, liver disease, testicular cancer, and hyperthyroidism. Additionally, haemodialysis and ectopic tumour secretion can also trigger gynaecomastia.

      Drug-induced gynaecomastia is also a common cause, with spironolactone being the most frequent trigger. Other drugs that can cause gynaecomastia include cimetidine, digoxin, cannabis, finasteride, GnRH agonists like goserelin and buserelin, oestrogens, and anabolic steroids. However, it is important to note that very rare drug causes of gynaecomastia include tricyclics, isoniazid, calcium channel blockers, heroin, busulfan, and methyldopa.

      In summary, understanding the causes and drug triggers of gynaecomastia is crucial in diagnosing and treating this condition.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 15 - A 15-year-old female presents to her primary care physician with concerns about her...

    Incorrect

    • A 15-year-old female presents to her primary care physician with concerns about her height and delayed puberty. Upon further questioning, she reports never having had a menstrual period. The patient's height is notably below her midparental height.

      During the physical examination, the patient is found to be in Tanner Stage I for breast development and early Tanner Stage II for pubic hair development. Additionally, she has a webbed neck.

      Laboratory tests reveal elevated levels of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) with decreased estrogen levels. The diagnosis is confirmed through karyotyping.

      Which cardiac abnormality is most frequently associated with this condition?

      Your Answer:

      Correct Answer: Coarctation of the aorta

      Explanation:

      Aortic coarctation is a common cardiac complication associated with Turner Syndrome.

      Understanding Turner’s Syndrome

      Turner’s syndrome is a genetic condition that affects approximately 1 in 2,500 females. It is caused by the absence of one sex chromosome (X) or a deletion of the short arm of one of the X chromosomes. This condition is identified as 45,XO or 45,X.

      The features of Turner’s syndrome include short stature, a shield chest with widely spaced nipples, a webbed neck, a bicuspid aortic valve (present in 15% of cases), coarctation of the aorta (present in 5-10% of cases), primary amenorrhea, cystic hygroma (often diagnosed prenatally), a high-arched palate, a short fourth metacarpal, multiple pigmented naevi, lymphoedema in neonates (especially in the feet), and elevated gonadotrophin levels. Hypothyroidism is also more common in individuals with Turner’s syndrome, as well as an increased incidence of autoimmune diseases such as autoimmune thyroiditis and Crohn’s disease.

      In summary, Turner’s syndrome is a chromosomal disorder that affects females and is characterized by various physical features and health conditions. Early diagnosis and management can help individuals with Turner’s syndrome lead healthy and fulfilling lives.

    • This question is part of the following fields:

      • General Principles
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  • Question 16 - A middle-aged woman who is obese comes in with complaints of polyuria. She...

    Incorrect

    • A middle-aged woman who is obese comes in with complaints of polyuria. She has a history of squamous cell lung carcinoma. What could be the possible reason for her polyuria?

      Your Answer:

      Correct Answer: Hyperparathyroidism

      Explanation:

      Polyuria is caused by all the options listed above, except for syndrome of inappropriate ADH secretion. However, the patient’s age does not match the typical onset of type 1 diabetes, which usually occurs in young individuals. Furthermore, squamous cell lung carcinoma is commonly associated with a paraneoplastic syndrome that results in the release of excess parathyroid hormone by the tumor, leading to hypercalcemia and subsequent polyuria, along with other symptoms such as renal and biliary stones, bone pain, abdominal discomfort, nausea, vomiting, depression, and anxiety.

      Lung cancer can present with paraneoplastic features, which are symptoms caused by the cancer but not directly related to the tumor itself. Small cell lung cancer can cause the secretion of ADH and, less commonly, ACTH, which can lead to hypertension, hyperglycemia, hypokalemia, alkalosis, and muscle weakness. Lambert-Eaton syndrome is also associated with small cell lung cancer. Squamous cell lung cancer can cause the secretion of parathyroid hormone-related protein, leading to hypercalcemia, as well as clubbing and hypertrophic pulmonary osteoarthropathy. Adenocarcinoma can cause gynecomastia and hypertrophic pulmonary osteoarthropathy. Hypertrophic pulmonary osteoarthropathy is a painful condition involving the proliferation of periosteum in the long bones. Although traditionally associated with squamous cell carcinoma, some studies suggest that adenocarcinoma is the most common cause.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 17 - A 47-year-old male with alcoholic cirrhosis and decompensated liver failure is wondering which...

    Incorrect

    • A 47-year-old male with alcoholic cirrhosis and decompensated liver failure is wondering which clotting factor is least likely to be affected.

      Your Answer:

      Correct Answer: Factor VIII

      Explanation:

      Factor VIII is produced in the endothelial cells located in the liver, which makes it less susceptible to the impact of liver dysfunction.

      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
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  • Question 18 - A 25-year-old male arrives at the emergency department with a deep cut on...

    Incorrect

    • A 25-year-old male arrives at the emergency department with a deep cut on his left forearm following a knife assault. Upon examination, a deep laceration is observed on his anterior forearm, exposing muscle and subcutaneous tissue. He is unable to flex his left metacarpophalangeal and proximal interphalangeal joints, but his distal interphalangeal joint flexion remains intact. Which structure is the most likely to have been affected?

      Your Answer:

      Correct Answer: Flexor digitorum superficialis

      Explanation:

      The forearm flexor muscles include the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis, and flexor digitorum profundus. These muscles originate from the common flexor origin and surrounding fascia, and are innervated by the median and ulnar nerves. Their actions include flexion and abduction of the carpus, wrist flexion, adduction of the carpus, and flexion of the metacarpophalangeal and interphalangeal joints.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
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  • Question 19 - Which one of the following nerves is the primary source of innervation to...

    Incorrect

    • Which one of the following nerves is the primary source of innervation to the anterior skin of the scrotum?

      Your Answer:

      Correct Answer: Ilioinguinal nerve

      Explanation:

      The pudendal nerve innervates the posterior skin of the scrotum, while the ilioinguinal nerve primarily innervates the anterior scrotum. The genital branch of the genitofemoral nerve also provides some innervation.

      Scrotal Sensation and Nerve Innervation

      The scrotum is a sensitive area of the male body that is innervated by two main nerves: the ilioinguinal nerve and the pudendal nerve. The ilioinguinal nerve originates from the first lumbar vertebrae and passes through the internal oblique muscle before reaching the superficial inguinal ring. From there, it provides sensation to the anterior skin of the scrotum.

      The pudendal nerve, on the other hand, is the primary nerve of the perineum. It arises from three nerve roots in the pelvis and passes through the greater and lesser sciatic foramina to enter the perineal region. Its perineal branches then divide into posterior scrotal branches, which supply the skin and fascia of the perineum. The pudendal nerve also communicates with the inferior rectal nerve.

      Overall, the innervation of the scrotum is complex and involves multiple nerves. However, understanding the anatomy and function of these nerves is important for maintaining proper scrotal sensation and overall male health.

    • This question is part of the following fields:

      • Neurological System
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  • Question 20 - A 28-year-old woman presents with symptoms of carpal tunnel syndrome and requires surgical...

    Incorrect

    • A 28-year-old woman presents with symptoms of carpal tunnel syndrome and requires surgical exploration of the carpal tunnel. What structure will be closest to the hamate bone within the carpal tunnel during the procedure?

      Your Answer:

      Correct Answer: The tendons of flexor digitorum profundus

      Explanation:

      The nine flexor tendons found in the carpal tunnel include the flexor digitorum profundus, flexor digitorum superficialis, and flexor pollicis longus. Among these tendons, the flexor digitorum profundus is situated deepest in the tunnel and is therefore closest to the hamate bone.

      Carpal Bones: The Wrist’s Building Blocks

      The wrist is composed of eight carpal bones, which are arranged in two rows of four. These bones are convex from side to side posteriorly and concave anteriorly. The trapezium is located at the base of the first metacarpal bone, which is the base of the thumb. The scaphoid, lunate, and triquetrum bones do not have any tendons attached to them, but they are stabilized by ligaments.

      In summary, the carpal bones are the building blocks of the wrist, and they play a crucial role in the wrist’s movement and stability. The trapezium bone is located at the base of the thumb, while the scaphoid, lunate, and triquetrum bones are stabilized by ligaments. Understanding the anatomy of the wrist is essential for diagnosing and treating wrist injuries and conditions.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
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  • Question 21 - A 55-year-old woman visits her doctor complaining of insomnia, sweating, tachycardia, and unintentional...

    Incorrect

    • A 55-year-old woman visits her doctor complaining of insomnia, sweating, tachycardia, and unintentional weight loss. During the examination, the doctor notices some exophthalmos. Her blood test results reveal a TSH level of 0.05 mU/L (0.5-5.5) and a free T4 level of 36 pmol/L (9.0 - 18). After further evaluation, she is diagnosed with Graves' disease, an autoimmune disorder that causes hyperthyroidism by targeting self-antigens with autoantibodies.

      What part of the antibody monomers is involved in this condition?

      Your Answer:

      Correct Answer: Fab region

      Explanation:

      The antigen binding sites of immunoglobulins are located within the Fab region, which is composed of a constant and variable domain from both heavy and light chains. The variable domain within the Fab region is responsible for determining antigen specificity and binding. The Fc region, which is consistent across each class of immunoglobulins, interacts with cell surface receptors and determines the class effect. The epitope, or the region of the antigen that binds the antibody, is specifically located within the Fab region. While both heavy and light chains contribute to antigen binding through their variable regions, neither is solely responsible.

      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
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  • Question 22 - A woman with suspected heart failure has a transthoracic echocardiogram (TTE) to investigate...

    Incorrect

    • A woman with suspected heart failure has a transthoracic echocardiogram (TTE) to investigate the function of her heart. The goal is to measure her ejection fraction, however, to do this first her stroke volume must be measured.

      What is the formula for stroke volume?

      Your Answer:

      Correct Answer: End diastolic volume - end systolic volume

      Explanation:

      Cardiovascular physiology involves the study of the functions and processes of the heart and blood vessels. One important measure of heart function is the left ventricular ejection fraction, which is calculated by dividing the stroke volume (the amount of blood pumped out of the left ventricle with each heartbeat) by the end diastolic LV volume (the amount of blood in the left ventricle at the end of diastole) and multiplying by 100%. Another key measure is cardiac output, which is the amount of blood pumped by the heart per minute and is calculated by multiplying stroke volume by heart rate.

      Pulse pressure is another important measure of cardiovascular function, which is the difference between systolic pressure (the highest pressure in the arteries during a heartbeat) and diastolic pressure (the lowest pressure in the arteries between heartbeats). Factors that can increase pulse pressure include a less compliant aorta (which can occur with age) and increased stroke volume.

      Finally, systemic vascular resistance is a measure of the resistance to blood flow in the systemic circulation and is calculated by dividing mean arterial pressure (the average pressure in the arteries during a heartbeat) by cardiac output. Understanding these measures of cardiovascular function is important for diagnosing and treating cardiovascular diseases.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 23 - A 23-year-old woman comes to your clinic with a complaint of ear pain...

    Incorrect

    • A 23-year-old woman comes to your clinic with a complaint of ear pain and difficulty hearing on one side. During the examination, you observe that she has a fever and a bulging tympanic membrane. What nerve transmits pain from the middle ear?

      Your Answer:

      Correct Answer: Glossopharyngeal nerve

      Explanation:

      The correct answer is the glossopharyngeal nerve, which is responsible for carrying sensation from the middle ear.

      The ninth cranial nerve, or glossopharyngeal nerve, carries taste and sensation from the posterior one-third of the tongue, as well as sensation from various areas such as the pharyngeal wall, tonsils, pharyngotympanic tube, middle ear, tympanic membrane, external auditory canal, and auricle. It also provides motor fibers to the stylopharyngeus and parasympathetic fibers to the parotid gland. Additionally, it carries information from the baroreceptors and chemoreceptors of the carotid sinus.

      On the other hand, the seventh cranial nerve, or facial nerve, innervates the muscles of facial expression, stylohyoid, stapedius, and the posterior belly of digastric. It carries sensation from part of the external acoustic meatus, auricle, and behind the auricle, and taste from the anterior two-thirds of the tongue. It also provides parasympathetic fibers to the submandibular, sublingual, nasal, and lacrimal glands.

      The eighth cranial nerve, or vestibulocochlear nerve, has a vestibular component that carries balance information from the labyrinths of the inner ear and a cochlear component that carries hearing information from the cochlea of the inner ear.

      The twelfth cranial nerve, or hypoglossal nerve, supplies motor innervation to all of the intrinsic muscles of the tongue and all of the extrinsic muscles of the tongue except for palatoglossus.

      Lastly, the maxillary nerve is the second division of the trigeminal nerve, the fifth cranial nerve, which carries sensation from the upper teeth and gingivae, the nasal cavity, and skin across the lower eyelids and cheeks.

      Based on the patient’s symptoms of ear pain, the most likely diagnosis is otitis media, as indicated by her fever and the presence of a bulging tympanic membrane on otoscopy.

      Anatomy of the Ear

      The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 24 - A 26-year-old woman has recently begun her career as a graphic designer. Her...

    Incorrect

    • A 26-year-old woman has recently begun her career as a graphic designer. Her partner has observed that she spends extensive amounts of time working on what she believes will be the most innovative design project ever created that will transform the industry. Despite acknowledging that she may not succeed, she remains highly motivated. How would you describe her thought process?

      Your Answer:

      Correct Answer: Overvalued idea

      Explanation:

      Overvalued Ideas

      An overvalued idea is a comprehensible and acceptable belief that dominates a person’s life and preoccupies their mind. It is not a delusion, and the person acknowledges the possibility that their belief may or may not be true. However, they pursue their aim with an overwhelming desire. Despite the intensity of their belief, the person remains functioning, and there is no evidence of psychotic symptoms.

      According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), an overvalued idea is an unreasonable and sustained belief that is maintained with less than delusional intensity. This means that the person is aware that their belief may not be accepted by others in their culture or subculture.

      In summary, an overvalued idea is a strong belief that is not firmly fixed as true, but still dominates a person’s life. It is not a delusion, and the person remains functioning. overvalued ideas is important in distinguishing them from delusions and other mental health conditions.

    • This question is part of the following fields:

      • Psychiatry
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  • Question 25 - Sarah, a 70-year-old female, visits her doctor with a lump in her groin....

    Incorrect

    • Sarah, a 70-year-old female, visits her doctor with a lump in her groin. Upon examination, the doctor observes that the lump becomes more prominent when the patient coughs. Considering Sarah's age and the location of the lump, the doctor diagnoses her with a direct inguinal hernia. What structure did Sarah's bowel pass through to be classified as a direct inguinal hernia?

      Your Answer:

      Correct Answer: Hesselbach's triangle

      Explanation:

      Hesselbach’s triangle is a weak area in the anterior abdominal wall through which direct inguinal hernias can travel. Indirect inguinal hernias occur when the bowel passes through the inguinal canal via the deep inguinal ring. Femoral hernias occur when a portion of the bowel enters the femoral canal through the femoral ring. The failure of the processus vaginalis to close during embryonic development increases the risk of developing an indirect inguinal hernia.

      Hesselbach’s Triangle and Direct Hernias

      Hesselbach’s triangle is an anatomical region located in the lower abdomen. It is bordered by the epigastric vessels on the superolateral side, the lateral edge of the rectus muscle medially, and the inguinal ligament inferiorly. This triangle is important in the diagnosis and treatment of direct hernias, which pass through this region.

      To better understand the location of direct hernias, it is essential to know the boundaries of Hesselbach’s triangle. The epigastric vessels are located on the upper and outer side of the triangle, while the lateral edge of the rectus muscle is on the inner side. The inguinal ligament forms the lower boundary of the triangle.

      In medical exams, it is common to test the knowledge of Hesselbach’s triangle and its boundaries. Understanding this region is crucial for identifying and treating direct hernias, which can cause discomfort and other complications. By knowing the location of Hesselbach’s triangle, medical professionals can better diagnose and treat patients with direct hernias.

    • This question is part of the following fields:

      • Gastrointestinal System
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  • Question 26 - A 16-year-old male patient is experiencing an acute asthma attack and is struggling...

    Incorrect

    • A 16-year-old male patient is experiencing an acute asthma attack and is struggling to breathe. Which of the following options is not a correct description of anatomical dead space?

      Your Answer:

      Correct Answer: Poorly perfused alveoli

      Explanation:

      Anatomical and Physiological Dead Space

      Anatomical dead space refers to the parts of the respiratory system that do not participate in gaseous exchange. These include the pharynx, larynx, trachea, bronchi, and bronchioles. Although these structures fill with air during inhalation, the air is exhaled without ever being available for circulation. On the other hand, physiological dead space includes not only the anatomical dead space but also regions of alveoli that do not participate in gaseous exchange due to a ventilation/perfusion mismatch.

      In simpler terms, anatomical dead space is the portion of the respiratory system that does not contribute to gas exchange, while physiological dead space includes both the anatomical dead space and areas of the lungs that are not functioning properly. these concepts is important in diagnosing and treating respiratory disorders, as well as in monitoring the effectiveness of respiratory therapies. By identifying and addressing dead space, healthcare professionals can help improve a patient’s breathing and overall respiratory function.

    • This question is part of the following fields:

      • Clinical Sciences
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  • Question 27 - A young physician encounters two patients with ulnar nerve palsy in rapid succession....

    Incorrect

    • A young physician encounters two patients with ulnar nerve palsy in rapid succession. The initial patient has a wrist injury and displays a severe hand deformity resembling a claw. The subsequent patient has an elbow injury and exhibits a similar, albeit less severe, deformity. What is the reason for the counterintuitive observation that the presentation is milder at the site of injury closer to the body?

      Your Answer:

      Correct Answer: Denervation of flexor digitorum profundus muscle

      Explanation:

      Injuries to the proximal ulnar nerve result in the loss of function of the flexor digitorum profundus muscle, leading to a decrease in finger flexion and a reduction in the claw-like appearance seen in more distal injuries. This process does not involve the flexor digitorum superficialis muscle or any protective action from surrounding muscles.

      The ulnar nerve originates from the medial cord of the brachial plexus, specifically from the C8 and T1 nerve roots. It provides motor innervation to various muscles in the hand, including the medial two lumbricals, adductor pollicis, interossei, hypothenar muscles (abductor digiti minimi, flexor digiti minimi), and flexor carpi ulnaris. Sensory innervation is also provided to the medial 1 1/2 fingers on both the palmar and dorsal aspects. The nerve travels through the posteromedial aspect of the upper arm and enters the palm of the hand via Guyon’s canal, which is located superficial to the flexor retinaculum and lateral to the pisiform bone.

      The ulnar nerve has several branches that supply different muscles and areas of the hand. The muscular branch provides innervation to the flexor carpi ulnaris and the medial half of the flexor digitorum profundus. The palmar cutaneous branch arises near the middle of the forearm and supplies the skin on the medial part of the palm, while the dorsal cutaneous branch supplies the dorsal surface of the medial part of the hand. The superficial branch provides cutaneous fibers to the anterior surfaces of the medial one and one-half digits, and the deep branch supplies the hypothenar muscles, all the interosseous muscles, the third and fourth lumbricals, the adductor pollicis, and the medial head of the flexor pollicis brevis.

      Damage to the ulnar nerve at the wrist can result in a claw hand deformity, where there is hyperextension of the metacarpophalangeal joints and flexion at the distal and proximal interphalangeal joints of the 4th and 5th digits. There may also be wasting and paralysis of intrinsic hand muscles (except for the lateral two lumbricals), hypothenar muscles, and sensory loss to the medial 1 1/2 fingers on both the palmar and dorsal aspects. Damage to the nerve at the elbow can result in similar symptoms, but with the addition of radial deviation of the wrist. It is important to diagnose and treat ulnar nerve damage promptly to prevent long-term complications.

    • This question is part of the following fields:

      • Neurological System
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  • Question 28 - In the proximal third of the upper arm, where is the musculocutaneous nerve...

    Incorrect

    • In the proximal third of the upper arm, where is the musculocutaneous nerve situated?

      Your Answer:

      Correct Answer: Between the biceps brachii and brachialis muscles

      Explanation:

      The biceps and brachialis muscles are located on either side of the musculocutaneous nerve.

      The Musculocutaneous Nerve: Function and Pathway

      The musculocutaneous nerve is a nerve branch that originates from the lateral cord of the brachial plexus. Its pathway involves penetrating the coracobrachialis muscle and passing obliquely between the biceps brachii and the brachialis to the lateral side of the arm. Above the elbow, it pierces the deep fascia lateral to the tendon of the biceps brachii and continues into the forearm as the lateral cutaneous nerve of the forearm.

      The musculocutaneous nerve innervates the coracobrachialis, biceps brachii, and brachialis muscles. Injury to this nerve can cause weakness in flexion at the shoulder and elbow. Understanding the function and pathway of the musculocutaneous nerve is important in diagnosing and treating injuries or conditions that affect this nerve.

    • This question is part of the following fields:

      • Neurological System
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  • Question 29 - A 48-year-old woman visits the neurology clinic for a follow-up on her long-standing...

    Incorrect

    • A 48-year-old woman visits the neurology clinic for a follow-up on her long-standing generalized epilepsy. She has been experiencing seizures since childhood and has tried various medications to manage the condition. Among these medications, she believes that carbamazepine has been the most effective.

      What is the mechanism of action of carbamazepine?

      Your Answer:

      Correct Answer: Inhibits sodium channels

      Explanation:

      Sodium valproate and carbamazepine are both inhibitors of sodium channels, which leads to the suppression of excitation by preventing repetitive and sustained firing of an action potential. Additionally, sodium valproate increases levels of GABA in the brain.

      Tiagabine, on the other hand, blocks the cellular uptake of GABA by inhibiting the GABA transporter, making it a GABA reuptake inhibitor.

      Ethosuximide blocks T-type calcium channels and is primarily used to treat absence seizures, while benzodiazepines elongate the opening time of GABAA receptors. Barbiturates, on the other hand, act as agonists of GABAA receptors and potentiate the effect of GABA.

      Treatment Options for Epilepsy

      Epilepsy is a neurological disorder that affects millions of people worldwide. Treatment for epilepsy typically involves the use of antiepileptic drugs (AEDs) to control seizures. The decision to start AEDs is usually made after a second seizure, but there are certain circumstances where treatment may be initiated after the first seizure. These include the presence of a neurological deficit, structural abnormalities on brain imaging, unequivocal epileptic activity on EEG, or if the patient or their family considers the risk of having another seizure to be unacceptable.

      It is important to note that there are specific drug treatments for different types of seizures. For generalized tonic-clonic seizures, males are typically prescribed sodium valproate, while females may be given lamotrigine or levetiracetam. For focal seizures, first-line treatment options include lamotrigine or levetiracetam, with carbamazepine, oxcarbazepine, or zonisamide used as second-line options. Ethosuximide is the first-line treatment for absence seizures, with sodium valproate or lamotrigine/levetiracetam used as second-line options. For myoclonic seizures, males are usually given sodium valproate, while females may be prescribed levetiracetam. Finally, for tonic or atonic seizures, males are typically given sodium valproate, while females may be prescribed lamotrigine.

      It is important to work closely with a healthcare provider to determine the best treatment plan for each individual with epilepsy. Additionally, it is important to be aware of potential risks associated with certain AEDs, such as the use of sodium valproate during pregnancy, which has been linked to neurodevelopmental delays in children.

    • This question is part of the following fields:

      • Neurological System
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  • Question 30 - A teenage girl and her mother come to the doctor's office with concerns...

    Incorrect

    • A teenage girl and her mother come to the doctor's office with concerns about ambiguous genitalia. After gathering information and conducting various tests, the doctor determines that the cause is congenital adrenal hyperplasia, which is linked to a deficiency in which specific enzyme?

      Your Answer:

      Correct Answer: 21-hydroxylase

      Explanation:

      Insufficient production of cortisol and compensatory adrenal hyperplasia are the consequences of 21-hydroxylase deficiency. This leads to elevated androgen production and ambiguous genitalia. However, enzymes such as 5-a reductase, aromatase, 17B-HSD, and aldosterone synthase are not involved in this disorder. Other enzymes, including 11-beta hydroxylase and 17-hydroxylase, may also be involved.

      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
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