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  • Question 1 - A new chemotherapy drug is being tested. The intervention reduces the risk of...

    Correct

    • A new chemotherapy drug is being tested. The intervention reduces the risk of death from 10 in 1000 to 5 in 1000. What is the number needed to treat to prevent one death:

      Your Answer: 200

      Explanation:

      Absolute risk reduction (ARR) of treatment
      = risk of death in control group – risk of death in treatment group
      ARR = (10/1000) – (5/1000)
      = 5/1000 = 0.005
      Number needed to treat (NNT)
      = 1/ARR
      = 1/0.005
      = 200
      Therefore 200 people would need to be treated to prevent one extra death.

    • This question is part of the following fields:

      • Evidence Based Medicine
      • Statistics
      18.1
      Seconds
  • Question 2 - The causative organism for an infection in a patient you are reviewing...

    Incorrect

    • The causative organism for an infection in a patient you are reviewing is a facultative anaerobe.

      Which of these is a facultative anaerobic organism?

      Your Answer: Pseudomonas aeruginosa

      Correct Answer: Staphylococcus aureus

      Explanation:

      Facultative anaerobic bacteria make energy in the form of ATP by aerobic respiration in an oxygen rich environment and can switch to fermentation in an oxygen poor environment.

      Examples of facultative anaerobes are:
      Staphylococcus spp.
      Listeria spp.
      Streptococcus spp.
      Escherichia coli

      Mycobacterium tuberculosis, and Pseudomonas aeruginosa are obligate aerobe. They require oxygen to grow

      Campylobacter jejuni and Clostridium spp are obligate anaerobes.
      They live and grow in the absence of oxygen.

    • This question is part of the following fields:

      • Microbiology
      • Principles Of Microbiology
      95.2
      Seconds
  • Question 3 - You've been asked to visit a 20-year-old patient  who has been complaining of stomach pain,...

    Correct

    • You've been asked to visit a 20-year-old patient  who has been complaining of stomach pain, diarrhoea, and bloating. The  GP recently saw the patient and is now looking into numerous possible reasons for stomach hypermotility.

      Which of the following factors contributes to increased stomach motility?

      Your Answer: Gastrin

      Explanation:

      Gastrin is a peptide hormone that aids in gastric motility by stimulating the generation of gastric acid by the parietal cells of the stomach. G-cells in the stomach’s pyloric antrum, the duodenum, and the pancreas release it.

      The following stimuli cause the release of gastrin:

      Stimulation of the vagus nerve
      Hypercalcaemia
      stomach bloating
      Proteins that have been partially digested, particularly amino acids.
      The presence of acid and somatostatin inhibits the release of gastrin.
      Gastrin’s main actions are as follows:
      Gastric parietal cells are stimulated to release hydrochloric acid.
      ECL cells are stimulated to produce histamine.
      Gastric parietal cell maturation and fundal growth stimulation
      Causes the secretion of pepsinogen by the gastric chief cells.
      Improves antral muscle mobility
      stimulates gastric contractions
      Increases gastric emptying rate and stimulates pancreatic secretion
      Gallbladder emptying is induced.

    • This question is part of the following fields:

      • Gastrointestinal Physiology
      • Physiology
      23.7
      Seconds
  • Question 4 - In the United Kingdom, which of the following is the most often used...

    Incorrect

    • In the United Kingdom, which of the following is the most often used intravenous aesthetic:

      Your Answer: Ketamine

      Correct Answer: Propofol

      Explanation:

      In the United Kingdom, propofol is the most widely used intravenous anaesthetic. In adults and children, it can be used to induce or maintain anaesthesia, although it is not commonly used in newborns. It can also be used to sedate individuals in intensive care and for sedation during operations.

    • This question is part of the following fields:

      • Anaesthesia
      • Pharmacology
      10.5
      Seconds
  • Question 5 - Which of the following is caused by an alpha-1 antitrypsin deficiency? ...

    Incorrect

    • Which of the following is caused by an alpha-1 antitrypsin deficiency?

      Your Answer: Cystic fibrosis

      Correct Answer: Early onset emphysema

      Explanation:

      Mucus contains chemicals such as alpha-1-antitrypsin, lysozyme, and IgA that protect the airway from pathogens and damaging proteases released from dead bacteria and immune cells. Early-onset emphysema results from a genetic deficit of alpha-1-antitrypsin, which is caused by unregulated protease activity in the lungs, which results in the degradation of elastin in the alveoli.

    • This question is part of the following fields:

      • Physiology
      • Respiratory
      9.5
      Seconds
  • Question 6 - The only statement that is correct regarding diffusion is which of the following?...

    Correct

    • The only statement that is correct regarding diffusion is which of the following?

      Your Answer: The permeability of a membrane is related to the membrane thickness and composition.

      Explanation:

      Passive diffusion is a process that describes the movement down a concentration gradient. This process accounts for movement across small distances like within the cytosol or across membranes. Factors that affect the diffusion of a substance across a membrane are the permeability (p) of the membrane, a difference in concentration across the membrane and the membrane area over which diffusion occurs. The membrane thickness and composition, and the diffusion coefficient of the substance also affects the permeability. Fick’s law describes the rate of diffusion of a substance within a solution, which can be modified to describe the rate of diffusion across a membrane.

    • This question is part of the following fields:

      • Basic Cellular
      • Physiology
      25.5
      Seconds
  • Question 7 - Which of the following factors does NOT decrease glucagon secretion: ...

    Correct

    • Which of the following factors does NOT decrease glucagon secretion:

      Your Answer: Catecholamines

      Explanation:

      Factors that increase glucagon secretion:
      ↓ Blood glucose
      ↑ Amino acids
      Cholecystokinin
      Catecholamines
      Acetylcholine

      Factors that decrease glucagon secretion:
      ↑ Blood glucose
      Insulin
      Somatostatin
      Fatty acids, ketoacids

    • This question is part of the following fields:

      • Endocrine
      • Physiology
      24.7
      Seconds
  • Question 8 - Fenestrated capillaries are typically found where in the body: ...

    Correct

    • Fenestrated capillaries are typically found where in the body:

      Your Answer: Renal glomeruli

      Explanation:

      Fenestrated capillaries, found in renal glomeruli, endocrine glands and intestinal villi, are more permeable than continuous capillaries with less tight junctions, and the endothelial cells are also punctured by pores which allow large amounts of fluids or metabolites to pass.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      9.9
      Seconds
  • Question 9 - Excessive gastric acid output is detected in a patient with a history of...

    Incorrect

    • Excessive gastric acid output is detected in a patient with a history of recurrent stomach ulcers. It's possible that the patient has Zollinger-Ellison syndrome.

      Which of the following statements about stomach acid is correct?

      Your Answer: The stomach produces approximately 300 mL per day

      Correct Answer: The proton pump located in the canalicular membrane is vital to its secretion

      Explanation:

      The stomach produces gastric acid, which is a digesting fluid. The stomach secretes about 2-3 litres every day. It is involved in tissue breakdown, the conversion of pepsinogen to active pepsin, and the creation of soluble salts with calcium and iron, and has a pH range of 1.5-3.5. It also serves as an immune system by destroying microbes.

      The following substances are found in gastric acid:
      Water
      Acid hydrochloride
      Pepsinogen
      mucous
      Intrinsic factor

      The parietal cells in the proximal 2/3 (body) of the stomach release gastric acid. The concentration of hydrogen ions in parietal cell secretions is 1-2 million times that of blood. Chloride is released against both a concentration and an electric gradient, and active transport is required for the parietal cell to produce acid.

      The following is how stomach acid is secreted:

      1. Gastric acid secretion is dependent on the H+/K+ ATPase (proton pump) situated in the canalicular membrane. The breakdown of water produces hydrogen ions within the parietal cell. The hydroxyl ions produced in this reaction mix quickly with carbon dioxide to generate bicarbonate ions. Carbonic anhydrase is the enzyme that catalyses this process.

      2. In return for chloride, bicarbonate is carried out of the basolateral membrane. The ‘alkaline tide’ occurs when bicarbonate is released into the bloodstream, resulting in a modest rise in blood pH. The parietal cell’s intracellular pH is maintained by this procedure. Conductance channels carry chloride and potassium ions into the lumen of canaliculi.

      3. Through the action of the proton pump, hydrogen ions are pushed out of the cell and into the lumen in exchange for potassium; potassium is thus efficiently recycled.

      4. The canaliculi accumulate osmotically active hydrogen ions, which creates an osmotic gradient across the membrane, allowing water to diffuse outward.

    • This question is part of the following fields:

      • Gastrointestinal Physiology
      • Physiology
      28.2
      Seconds
  • Question 10 - Regarding skeletal muscle contraction, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding skeletal muscle contraction, which of the following statements is CORRECT:

      Your Answer: The force of contraction of a muscle is controlled by increasing the number of contracting muscle fibres.

      Correct Answer: The force of contraction of a muscle can be controlled by increasing recruitment of motor units.

      Explanation:

      Each motor unit contracts in an all or nothing fashion, i.e. if a motor unit is excited, it will stimulate all of its muscle fibres to contract. The force of contraction of a muscle is controlled by varying the motor unit recruitment (spatial summation), and by varying the firing rate of the motor units (temporal summation). During a gradual increase in contraction of a muscle, the first units start to discharge and increase their firing rate, and, as the force needs to increase, new units are recruited and, in turn, also increase their firing rate. For most motor units, the firing rate for a steady contraction is between 5 and 8 Hz. Because the unitary firing rates for each motor unit are different and not synchronised, the overall effect is a smooth force profile from the muscle. Increasing the firing rate of motor units is temporal summation where the tension developed by the first action potential has not completely decayed when the second action potential and twitch is grafted onto the first and so on. If the muscle fibres are stimulated repeatedly at a faster frequency, a sustained contraction results where it is not possible to detect individual twitches. This is called tetanus.

    • This question is part of the following fields:

      • Basic Cellular
      • Physiology
      49.6
      Seconds
  • Question 11 - A patient is found to be anaemic. Which one of the following blood...

    Correct

    • A patient is found to be anaemic. Which one of the following blood results would favour a diagnosis of anaemia of chronic disease rather than iron deficiency:

      Your Answer: Low total iron binding capacity (TIBC)

      Explanation:

      Anaemia of chronic disease is one of the most common causes of normocytic anaemia. The anaemia is usually mild (Hb > 90 g/L) and non-progressive. Anaemia of chronic disease is usually associated with low serum iron, low transferrin saturation, and a low total iron binding capacity (TIBC) with normal or raised ferritin which differentiates it from iron deficiency anaemia.

    • This question is part of the following fields:

      • Haematology
      • Pathology
      42.3
      Seconds
  • Question 12 - A 25 year old man presents to the emergency room with abdominal pain,...

    Correct

    • A 25 year old man presents to the emergency room with abdominal pain, vomiting and constipation. A CT scan is done which is suggestive of Meckel's diverticulum. Where does the blood supply of the Meckel's diverticulum originate?

      Your Answer: Superior mesenteric artery

      Explanation:

      Meckel’s diverticulum has certain classic characteristics.
      1. It lies on the antimesenteric border of the middle-to-distal ileum
      2. It is approximately 2 feet proximal to the ileocaecal junction
      3. It appears as a blind-ended tubular outpouching of bowel
      4. It is about 2 inches long,
      5. It occurs in about 2% of the population,
      6. It may contain two types of ectopic tissue (gastric and pancreatic).
      7. The diverticulum is supplied by the superior mesenteric artery.
      8. Proximal to the major duodenal papilla the duodenum is supplied by the gastroduodenal artery (branch of the coeliac trunk)
      9. Distal to the major duodenal papilla it is supplied by the inferior pancreaticoduodenal artery (branch of superior mesenteric artery).
      10. The arterial supply to the jejunoileum is from the superior mesenteric artery.

    • This question is part of the following fields:

      • Abdomen
      • Anatomy
      15.8
      Seconds
  • Question 13 - A young male has presented to you with respiratory depression and small pupils...

    Incorrect

    • A young male has presented to you with respiratory depression and small pupils on examination. You diagnose opioid overdose and immediately start therapy with Naloxone.

      Which of the following statements is TRUE regarding naloxone?

      Your Answer: It can only be given by the intravenous route

      Correct Answer: It can be given by a continuous infusion if repeated doses are required

      Explanation:

      Naloxone is a short-acting, specific antagonist of mu(μ)-opioid receptors. It is used to reverse the effects of opioid toxicity.

      It can be given by a continuous infusion if repeated doses are required and the infusion rate is adjusted according to the vital signs. Initially, the infusion rate can be set at 60% of the initial resuscitative IV dose per hour.

      Naloxone has a shorter duration of action (6-24 hours) than most opioids and so close monitoring according to the respiratory rate and depth of coma and repeated injections are necessary. When repeated doses are needed in opioid addicts, naloxone administration may precipitate a withdrawal syndrome with abdominal cramps, nausea and diarrhoea, but these usually settle within 2 hours.

      An initial dose of 0.4 to 2 mg can be given intravenously and can be repeated at 2 to 3-minute intervals to a maximum of 10mg.

      If the intravenous route is inaccessible, naloxone can be administered via an IO line, subcutaneously (SQ), IM, or via the intranasal (IN) route.

    • This question is part of the following fields:

      • CNS Pharmacology
      • Pharmacology
      35.7
      Seconds
  • Question 14 - Swelling of the lips, tongue, and face is observed in a 59-year-old African-American...

    Correct

    • Swelling of the lips, tongue, and face is observed in a 59-year-old African-American woman. In the emergency room, she is given intramuscular adrenaline, but her symptoms do not improve. Her GP recently started her on a new medication.

      Which of the following drugs is most likely to have caused her symptoms?

      Your Answer: Ramipril

      Explanation:

      Angiotensin-converting enzyme (ACE) inhibitors are the most common cause of drug-induced angioedema in the United Kingdom and the United States, owing to their widespread use.

      Angioedema is caused by ACE inhibitors in 0.1 to 0.7 percent of patients, with data indicating a persistent and relatively constant risk year after year. People of African descent have a five-fold higher chance of contracting the disease.

      Swelling of the lips, tongue, or face is the most common symptom, but another symptom is episodic abdominal pain due to intestinal angioedema. Itching and urticaria are noticeably absent.

      The mechanism appears to be activated complement or other pro-inflammatory cytokines like prostaglandins and histamine, which cause rapid vasodilation and oedema.

      Other medications that are less frequently linked to angioedema include:
      Angiotensin-receptor blockers (ARBs)
      Nonsteroidal anti-inflammatory drugs (NSAIDs)
      Bupropion (e.g. Zyban and Wellbutrin)
      Beta-lactam antibiotics
      Statins
      Proton pump inhibitors

      The majority of these reactions are minor and can be treated by stopping the drug and prescribing antihistamines.

    • This question is part of the following fields:

      • Cardiovascular Pharmacology
      • Pharmacology
      923.8
      Seconds
  • Question 15 - Atrial natriuretic peptide (ANP) acts to cause all of the following effects EXCEPT...

    Incorrect

    • Atrial natriuretic peptide (ANP) acts to cause all of the following effects EXCEPT for:

      Your Answer: Inhibits aldosterone secretion

      Correct Answer: Vasoconstricts the afferent arteriole

      Explanation:

      ANP acts to:
      Inhibit Na+ reabsorption in the distal nephron (through inhibition of ENaC in principal cells)
      Suppress the production of renin
      Suppress the production of aldosterone
      Suppress the production of ADH
      Cause renal vasodilation, increasing the glomerular filtration rate

    • This question is part of the following fields:

      • Physiology
      • Renal
      30.3
      Seconds
  • Question 16 - Antispasmodic drugs are primarily indicated in which of the following conditions: ...

    Correct

    • Antispasmodic drugs are primarily indicated in which of the following conditions:

      Your Answer: Irritable bowel syndrome

      Explanation:

      Antispasmodics, such as antimuscarinics, may be used in the management of irritable bowel syndrome. Other antispasmodics used include direct-acting smooth muscle relaxants such as mebeverine, alverine, and peppermint oil. Antispasmodics are contraindicated in bowel obstruction and severe inflammatory bowel disease. Antispasmodics are occasionally of value in treating abdominal cramp associated with diarrhoea but they should not be used for primary treatment. Antispasmodics should be avoided in young children with gastroenteritis because they are rarely effective and have troublesome side effects. Antimuscarinics are contraindicated in urinary retention.

    • This question is part of the following fields:

      • Gastrointestinal
      • Pharmacology
      25.6
      Seconds
  • Question 17 - Severe vomiting and diarrhoea were reported by a 25-year-old man. He's dehydrated and...

    Incorrect

    • Severe vomiting and diarrhoea were reported by a 25-year-old man. He's dehydrated and needs intravenous fluids to rehydrate. You give him cyclizine as part of his treatment.

      What is cyclizine's main mechanism of action?

      Your Answer: Dopamine receptor antagonism

      Correct Answer: Antihistamine action

      Explanation:

      Cyclizine is a piperazine derivative that functions as an antihistamine (H1-receptor antagonist). To prevent nausea and vomiting, it is thought to act on the chemoreceptor trigger zone (CTZ) and the labyrinthine apparatus. It has a lower antimuscarinic effect as well.

    • This question is part of the following fields:

      • CNS Pharmacology
      • Pharmacology
      28.7
      Seconds
  • Question 18 - Regarding a case-control study, which of the following statements is INCORRECT: ...

    Incorrect

    • Regarding a case-control study, which of the following statements is INCORRECT:

      Your Answer: It is retrospective.

      Correct Answer: The usual outcome measure is the relative risk.

      Explanation:

      A case-control study is a longitudinal, retrospective, observational study which investigates the relationship between a risk factor and one or more outcomes. This is done by selecting patients who already have a specific disease (cases), matching them to patients who do not (controls) and then collecting data from the patients to compare past exposure to a possible risk factor. The usual outcome measure is the odds ratio.

    • This question is part of the following fields:

      • Evidence Based Medicine
      • Study Methodology
      65.1
      Seconds
  • Question 19 - Regarding folate requirements, which of the following statements is CORRECT: ...

    Correct

    • Regarding folate requirements, which of the following statements is CORRECT:

      Your Answer: Dietary folate is found particularly in leafy green vegetables and liver.

      Explanation:

      Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress from the growth stage to the mitosis stage. This leads to continuing cell growth without division, which presents as macrocytosis, with an increase in mean corpuscular volume (MCV). The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically vitamin B12 deficiency or folate deficiency.
      Folate is an essential vitamin found in most foods, especially liver, green vegetables and yeast. The normal daily diet contains 200 – 250 μg, of which about 50% is absorbed. Daily adult requirements are about 100 μg. Absorption of folate is principally from the duodenum and jejunum. Stores of folate are normally only adequate for 4 months and so features of deficiency may be apparent after this time.

    • This question is part of the following fields:

      • Haematology
      • Pathology
      23.8
      Seconds
  • Question 20 - A 65-year-old female presents to the Emergency Department with complaints of chest pain...

    Correct

    • A 65-year-old female presents to the Emergency Department with complaints of chest pain pointing to angina. A dose of glyceryl trinitrate (GTN) was administered, rapidly resolving her symptoms. Unfortunately, she develops a side-effect of the drug.

      Which one of the following is the side effect she is most likely to have developed?

      Your Answer: Flushing

      Explanation:

      Angina pectoris is the most common symptom of ischemic heart disease and presents with chest pain relieved by rest and nitro-glycerine.

      Nitrates are the first-line treatment to relieve chest pain caused by angina. The commonly used nitrates are:
      1. Glyceryl trinitrate
      2. Isosorbide dinitrate

      Side effects to nitrate therapy are common especially
      The most common side effects are:
      1. Headaches
      2. Feeling dizzy, weak, or tired
      3. Nausea
      4. Flushing

      The serious but less likely to occur side effects are:
      1. Methemoglobinemia (rare)
      2. Syncope
      3. Prolonged bleeding time
      4. Exfoliative dermatitis
      5. Unstable angina
      6. Rebound hypertension
      7. Thrombocytopenia

      Dry eyes, bradycardia, and metabolic acidosis have not been reported.

    • This question is part of the following fields:

      • Cardiovascular Pharmacology
      • Pharmacology
      22.3
      Seconds
  • Question 21 - A 28-year-old known intravenous drug user has a history of persistent high-fever. On...

    Correct

    • A 28-year-old known intravenous drug user has a history of persistent high-fever. On examination you hear a harsh systolic murmur and the patient says a murmur has never been heard before in previous hospital visits. A diagnosis of endocarditis is suspect.

      Which of these antibacterial agents would be most appropriate to prescribe in this case?

      Your Answer: Flucloxacillin and gentamicin

      Explanation:

      Endocarditis is infective or non infective inflammation (marantic endocarditis) of the inner layer of the heart and it often involves the heart valves.

      Risk factors include:
      Prosthetic heart valves
      Congenital heart defects
      Prior history of endocarditis
      Rheumatic fever
      Illicit intravenous drug use

      In the presentation of endocarditis, the following triad is often quoted:
      Persistent fever
      Embolic phenomena
      New or changing murmur

      Flucloxacillin and gentamicin are current recommended by NICE and the BNF for the initial ‘blind’ therapy in endocarditis.

    • This question is part of the following fields:

      • Microbiology
      • Specific Pathogen Groups
      21.3
      Seconds
  • Question 22 - A 25 year old man has sustained a fracture to the surgical neck...

    Incorrect

    • A 25 year old man has sustained a fracture to the surgical neck of the humerus after falling from his bike. Examination suggests an axillary nerve injury. The clinical features expected to be seen in this patient are:

      Your Answer: Weakness of shoulder flexion

      Correct Answer: Weakness of shoulder abduction

      Explanation:

      Axillary nerve injury results in:
      1. weakness of arm abduction (paralysis of deltoid),
      2. weakness of lateral rotation of the arm (paralysis of teres minor)
      3. loss of sensation over the regimental badge area.

    • This question is part of the following fields:

      • Anatomy
      • Upper Limb
      40.8
      Seconds
  • Question 23 - Regarding endothelin-1, which of the following statements is INCORRECT: ...

    Correct

    • Regarding endothelin-1, which of the following statements is INCORRECT:

      Your Answer: Endothelin-1 release is inhibited by noradrenaline.

      Explanation:

      Endothelin-1 (ET-1) is an extremely potent vasoconstrictor peptide which is released from the endothelium in the presence of many other vasoconstrictors, including angiotensin II, antidiuretic hormone (ADH) and noradrenaline, and may be increased in disease and hypoxia.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      23.6
      Seconds
  • Question 24 - Which of the following is required for vitamin B12 absorption: ...

    Correct

    • Which of the following is required for vitamin B12 absorption:

      Your Answer: Intrinsic factor

      Explanation:

      Intrinsic factor is essential for the absorption of the small amounts of vitamin B12 normally present in the diet from the terminal ileum. The parietal cells of the stomach produce intrinsic factor, and following a gastrectomy, the absorption of vitamin B12 will be markedly reduced, and a deficiency state will exist.

    • This question is part of the following fields:

      • Gastrointestinal
      • Physiology
      11.7
      Seconds
  • Question 25 - The transport of oxygen from maternal to fetal circulation is made possible by...

    Correct

    • The transport of oxygen from maternal to fetal circulation is made possible by fetal haemoglobin. Which of the statements about fetal haemoglobin (HbF) is also correct?

      Your Answer: The oxygen dissociation curve for foetal haemoglobin is shifted to the left of that of adult haemoglobin

      Explanation:

      Fetal haemoglobin is the most common type of haemoglobin found in the foetus during pregnancy. It transports oxygen from the maternal circulation to the fetal circulation. It can easily bind to oxygen from the maternal circulation because it has a high affinity for oxygen. From 10 to 12 weeks of pregnancy to the first six months after birth, the erythroid precursor cells produce fetal haemoglobin. In comparison to adult haemoglobin, fetal haemoglobin has two alpha and two gamma subunits, whereas adult haemoglobin has two alpha and two beta subunits in its major form.

      And, unlike adult haemoglobin, the oxygen dissociation curve of fetal haemoglobin is left-shifted. Myoglobin is an oxygen storage molecule with a very high affinity for oxygen. Only when the partial pressure of oxygen is exceeded does it release oxygen.

    • This question is part of the following fields:

      • Physiology
      • Respiratory Physiology
      21.8
      Seconds
  • Question 26 - You've been asked to give a discussion to a group of medical students...

    Correct

    • You've been asked to give a discussion to a group of medical students about skeletal muscle physiology and its use in clinical medicine. They pose a series of difficult questions to you.

      Which of the following definitions for the A-band of the sarcomere is correct?

      Your Answer: A band that contains the entire length of a single thick filament (myosin)

      Explanation:

      Myofibrils, which are around 1 m in diameter, make up each myofiber. The cytoplasm separates them and arranges them in a parallel pattern along the cell’s long axis. These myofibrils are made up of actin and myosin filaments that are repeated in sarcomeres, which are the myofiber’s basic functional units.

      Myofilaments are the filaments that make up myofibrils, and they’re made mostly of proteins. Myofilaments are divided into three categories:

      Myosin filaments are thick filaments made up mostly of the protein myosin.
      Actin filaments are thin filaments made up mostly of the protein actin.
      Elastic filaments are mostly made up of the protein titin.
      The sarcomere is a Z-line segment that connects two adjacent Z-lines.
      The I-bands are thin filament zones that run from either side of the Z-lines to the thick filament’s beginning.
      Between the I-bands is the A-band, which spans the length of a single thick filament.
      The H-zone is a zone of thick filaments that is not overlaid by thin filaments in the sarcomere’s centre. The H-zone keeps the myosin filaments in place by surrounding them with six actin filaments each.
      The M-band (or M-line) is a disc of cross-connecting cytoskeleton elements in the centre of the H-zone.
      The thick filament is primarily made up of myosin. The thin filament is primarily made up of actin. Actin, tropomyosin, and troponin are found in a 7:1:1 ratio in thin filaments.

    • This question is part of the following fields:

      • Basic Cellular Physiology
      • Physiology
      108
      Seconds
  • Question 27 - Which of the following is NOT an advantage of a case-control study used...

    Incorrect

    • Which of the following is NOT an advantage of a case-control study used to identify past exposure to a risk factor in patients with a disease:

      Your Answer: Particularly suitable for studying association between an exposure and an outcome when the outcome is delayed after exposure

      Correct Answer: Can directly measure absolute and relative risk of a disease

      Explanation:

      Advantages:relatively quickrelatively cheap and easy to performparticularly suitable for studying associations between an exposure and an outcome when the outcome is uncommon or if the outcome occurs decades after exposurea wide range of risk factors can be investigated in each studyDisadvantages:subject to recall biasunlike in a whole population study, absolute risk cannot be quantifiedtemporal relationship between exposure and outcome can be difficult to establishunsuitable for rare risk factorsprone to confounding

    • This question is part of the following fields:

      • Evidence Based Medicine
      • Study Methodology
      51
      Seconds
  • Question 28 - Through which of the following anatomical structures does an indirect inguinal hernia pass?...

    Correct

    • Through which of the following anatomical structures does an indirect inguinal hernia pass?

      Your Answer: External oblique

      Explanation:

      Inguinal hernias are subdivided into direct and indirect.

      An indirect hernia occurs when abdominal contents protrude through the internal inguinal ring and into the inguinal canal. This occurs lateral to the inferior epigastric vessels. The hernia contents may extend into the scrotum.

      A direct inguinal hernia is protrusion of abdominal contents through the transversalis fascia within Hesselbach’s triangle. The borders of Hesselbach’s triangle are the inferior epigastric vessels superolaterally, the rectus sheath medially, and inguinal ligament inferiorly.

      The deep (internal) inguinal ring is located above and halfway between the pubic tubercle and the anterior superior iliac spine. This serves as the entrance to the inguinal canal. The superficial (external) inguinal ring lies immediately above and medial to the pubic tubercle. This triangular opening is a defect in the external oblique aponeurosis, and forms the exit of the inguinal canal.

    • This question is part of the following fields:

      • Abdomen And Pelvis
      • Anatomy
      16.3
      Seconds
  • Question 29 - The Philadelphia chromosome is a genetic abnormality associated primarily with which of the...

    Correct

    • The Philadelphia chromosome is a genetic abnormality associated primarily with which of the following malignancies:

      Your Answer: Chronic myeloid leukaemia

      Explanation:

      Chronic myeloid leukaemia (CML) is a clonal disorder of a pluripotent stem cell. The disease accounts for around 15% of leukaemias and may occur at any age. The diagnosis of CML is rarely difficult and is assisted by the characteristic presence of the Philadelphia (ph) chromosome. This disease occurs in either sex, most frequently between the ages of 40 and 60 years. In up to 50% of cases the diagnosis is made incidentally from a routine blood count. Leucocytosis is the main feature, with a complete spectrum of myeloid cells seen in the peripheral blood. The levels of neutrophils and myelocytes exceed those of blast cells and promyelocytes.Increased circulating basophils are a characteristic feature. Normochromic normocytic anaemia is usual. Platelet count may be increased (most frequently), normal or decreased. The clinical outlook is very good and 90% of patients can expect long-term control of disease.

    • This question is part of the following fields:

      • Haematology
      • Pathology
      14.9
      Seconds
  • Question 30 - In the Paediatric Emergency Department, you saw a 6-year-old girl with severe bilateral conjunctivitis....

    Incorrect

    • In the Paediatric Emergency Department, you saw a 6-year-old girl with severe bilateral conjunctivitis. You give her mother some general eye hygiene advice and prescribe chloramphenicol eye drops.

      What is the chloramphenicol's mechanism of action?

      Your Answer: Inhibition of nucleic acid synthesis

      Correct Answer: Inhibition of protein synthesis

      Explanation:

      Chloramphenicol is a broad-spectrum antibiotic that inhibits bacterial protein synthesis by blocking the 50S subunit of the bacterial ribosome’s peptidyl transferase activity. When administered systemically, it has limited usage due to the potential of significant side effects such as aplastic anaemia, peripheral neuropathy, and optic neuritis. It’s only used to treat typhoid fever and Haemophilus influenzae meningitis, but it’s usually better to use a broad-spectrum cephalosporin.

    • This question is part of the following fields:

      • Infections
      • Pharmacology
      27.6
      Seconds

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