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Question 1
Correct
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Regarding Clostridium tetani, which of the following statements is CORRECT:
Your Answer: Infection is predominantly derived from animal faeces and soil.
Explanation:Clostridium tetaniis a Gram positive, rod shaped, obligate anaerobic bacterium.The incubation period is quoted as anywhere between 4-21 days and can occur after several months but symptoms usually occur within the first 7 days after exposure.Approximately 80% of patients develop generalised tetanus. The commonest presenting feature of generalised tetanus is trismus (lockjaw), occurring in approximately 75% of affected individuals. Other clinical features include:Facial spasms (risus sardonicus)Opisthotonus (characteristic body shape during spasms)Neck stiffnessDysphagiaCalf and pectoral muscle rigidityFeverHypertensionTachycardiaSpasms can occur frequently and last for several minutes, they can continue to occur for up to 4 weeks. Current mortality rates are between 10 and 15%.Tetanic spasms are caused by the exotoxin tetanospasmin. The effects of tetanolysin are not fully understood but it is not believed to have clinical significance.Localised tetanus is a rare form of the disease, occurring in around 1% of affected individuals. Patients have persistent contraction of muscles in the same anatomic area as the injury. It may precede generalised tetanus.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 2
Correct
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Regarding water and electrolyte absorption in the small intestine, which of the following statements is INCORRECT:
Your Answer: Na+ enters the cell across the apical membrane against its concentration gradient by both membrane channels and transporter protein mechanisms.
Explanation:As the contents of the intestine are isotonic with body fluids and mostly have the same concentration of the major electrolytes, their absorption is active. Water cannot be moved directly, but follows osmotic gradients set up by the transport of ions, primarily mediated by the sodium pump.Na+/K+ ATPase located on the basolateral membrane of the epithelial cells pumps three Na+ ions from the cell in exchange for two K+ ions, against their respective concentration gradients. This leads to a low intracellular concentration of Na+ and a high intracellular concentration of K+. The low intracellular concentration of Na+ ensures a movement of Na+ from the intestinal contents into the cell down its concentration gradient by both membrane channels and transporter protein mechanisms. Na+ is then rapidly pumped again by the basolateral sodium pump. K+ leaves the cell across the basolateral membrane down its concentration gradient linked to an outward movement of Cl- against its concentration gradient (Cl- having entered the cell across the luminal membrane down its concentration gradient).
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 3
Incorrect
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Regarding V/Q mismatch, which of the following statements is CORRECT:
Your Answer: A normal A-a gradient is seen in V/Q mismatch.
Correct Answer: In a true shunt, increasing inspired oxygen has no effect on improving hypoxaemia.
Explanation:Both ventilation and perfusion increase towards the lung base, because of the effects of gravity, but the gravitational effects are greater on perfusion than ventilation and therefore there is a regional variation in V/Q ratio from lung apex (high V/Q) to lung base (low V/Q). In a pure shunt, there is normal perfusion but absent ventilation and the V/Q ratio = 0. In a true shunt increasing oxygen fraction has no effect because the oxygen-enriched air fails to reach the shunted blood. An increased A-a gradient is seen in V/Q mismatch.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 4
Incorrect
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Which of the following clinical features is NOT a typical feature of haemolytic anaemias:
Your Answer: Leg ulcers
Correct Answer: Angular cheilitis
Explanation:Features include: AnaemiaJaundice (caused by unconjugated bilirubin in plasma, bilirubin is absent from urine)Pigment gallstonesSplenomegalyAnkle ulcersExpansion of marrow with, in children, bone expansion e.g. frontal bossing in beta-thalassaemia majorAplastic crisis caused by parvovirus
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This question is part of the following fields:
- Haematology
- Pathology
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Question 5
Correct
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A suspicious growth on the posterior tongue of a 40-year-old man was discovered by his dentist and was immediately referred for possible oral cancer. The lymph from the posterior tongue will drain to which of the following nodes?
Your Answer: Deep cervical nodes
Explanation:Lymph from the medial anterior two thirds of the tongue travels to the deep cervical lymph nodes.Lymph from the lateral anterior tongue goes to the submandibular nodes.
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This question is part of the following fields:
- Anatomy
- Head And Neck
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Question 6
Correct
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As a result of a cardiovascular drug she was prescribed, a 67-year-old woman develops corneal microdeposits.Which of the following drugs is the MOST LIKELY cause?
Your Answer: Amiodarone
Explanation:Corneal microdeposits are almost universally present (over 90%) in people who have been taking amiodarone for more than six months, especially at doses above 400 mg/day. Although these deposits usually cause no symptoms, about 10% of patients report seeing a ‘bluish halo.’ This goes away once the treatment is stopped, and it rarely causes vision problems.Other effects of amiodarone on the eye are much rarer, occurring in only 1-2 percent of patients:Optic neuropathy is a condition that affects the eyes.Non-arteritic anterior ischaemic optic neuropathy (N-AION)Swelling of the optic disc
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 7
Correct
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A 43 year old lady who has a previous medical history of hyperthyroidism presents to the emergency room with sweating, palpitations and agitation. On examination, she is tachycardic, hypertensive and hyperpyrexic. She recently had a stomach bug and has not been able to take her medication regularly. The best medication to immediately treat her symptoms is which of the following?
Your Answer: Propranolol
Explanation:There is a high suspicion of a thyroid crisis in this patient and emergent treatment should be initiated even before the results of TFT’s have returned. Antiadrenergic drugs like IV propranolol should be administered immediately to minimise sympathomimetic symptoms. Antithyroid medications like propylthiouracil or carbimazole should be administered to block further synthesis of thyroid hormones. After thionamide therapy has been started to prevent stimulation of new hormone synthesis, there should then be delayed administration of oral iodine solution. Hydrocortisone administration is also recommended as it treats possible relative adrenal insufficiency while also decreases peripheral conversion of T4 to T3.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 8
Incorrect
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A 70-year-old patient presents with a chronic digoxin overdose. She has vomited several times, is extremely tired, and her vision 'appears yellow,' according to her.Which of the following is a reason for this patient's use of Digifab?
Your Answer: Potassium level of 2.6 mmol/l
Correct Answer: Coexistent renal failure
Explanation:An antidote for digoxin overdose is digoxin-specific antibody (Digifab). It’s a lyophilized preparation of digoxin-immune ovine Fab immunoglobulin fragments that’s sterile, purified, and lyophilized. These fragments were extracted from the blood of healthy sheep that had been immunised with a digoxin derivative called digoxin-dicarboxymethoxylamine (DDMA), a digoxin analogue that contains the functionally important cyclopentaperhydrophenanthrene:lactone ring moiety coupled to keyhole limpet hemocyanin (KLH).Digifab has a higher affinity for digoxin than digoxin does for its sodium pump receptor, which is thought to be the site of its therapeutic and toxic effects. When given to a patient who is intoxicated, Digifab binds to digoxin molecules, lowering free digoxin levels and shifting the equilibrium away from binding to receptors, reducing cardio-toxic effects. The kidney and reticuloendothelial system then clear the Fab-digoxin complexes.The following summarises the indications for Digifab in acute and chronic digoxin toxicity:Acute digoxin toxicityChronic digoxin toxicityCardiac arrestLife-threatening arrhythmiaPotassium level > 5 mmol/l>10 mg digoxin ingested (adult)>4 mg digoxin ingested (child)Digoxin level > 12 ng/mlCardiac arrestLife-threatening arrhythmiaSignificant gastrointestinal symptomsSymptoms of digoxin toxicity
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 9
Correct
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Question 10
Correct
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A 32-year-old woman with a history of bipolar disorder exhibits lithium toxicity symptoms.Which of the following is the MOST LIKELY feature to be present?
Your Answer: Clonus
Explanation:Lithium toxicity manifests itself in the following ways:AtaxiaClonusComaConfusionConvulsionsDiarrhoeaIncreased muscle toneNausea and vomitingNephrogenic diabetes insipidusRenal failureTremor
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 11
Correct
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A patient with a history of worsening chronic breathlessness on exertion undergoes lung function testing. The results demonstrate an FEV 1 that is 58% predicted and an FEV 1 /FVC ratio less than 0.7.Which of the following is the most likely diagnosis? Select ONE answer only.
Your Answer: COPD
Explanation:Obstructive lung disorders are characterised by airway obstruction. Many obstructive diseases of the lung result from narrowing of the smaller bronchi and larger bronchioles, often because of excessive contraction of the smooth muscle itself.In obstructive lung disease, FEV1is reduced to <80% of normal and FVC is usually reduced but to a lesser extent than FEV1. The FEV1/FVC ratio is reduced to <0.7.Types of obstructive lung disorders include:Chronic obstructive pulmonary disease (COPD)AsthmaBronchiectasis
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 12
Correct
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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 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.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 13
Correct
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Regarding drug interactions with erythromycin, which of the following statements is INCORRECT:
Your Answer: Erythromycin decreases plasma levels of warfarin.
Explanation:Erythromycin and clarithromycin inhibit cytochrome P450-mediated metabolism of warfarin, phenytoin and carbamazepine and may lead to accumulation of these drugs. There is an increased risk of myopathy (due to cytochrome P450 enzyme CYP3A4 inhibition) if erythromycin or clarithromycin is taken with atorvastatin or simvastatin. Erythromycin increases plasma concentrations of theophylline, and theophylline may also reduce absorption of oral erythromycin. All macrolides can prolong the QT-interval and concomitant use of drugs that prolong the QT interval is not recommended.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 14
Incorrect
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For which of the following is micelle formation necessary to facilitate intestinal absorption?
Your Answer: Small peptides
Correct Answer: Vitamin D
Explanation:The arrangement of micelles is such that hydrophobic lipid molecules lie in the centre, surrounded by hydrophilic bile acids that are arranged in the outer region. This arrangement allows the entry of micelles into the aqueous layers surrounding the microvilli. As a result, the products of fat digestion (fatty acids and monoglycerides), cholesterol and fat-soluble vitamins (such as vitamin D) can then diffuse passively into the enterocytes. The bile salts are left within the lumen of the gut where they are reabsorbed from the ileum or excreted in faeces.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 15
Correct
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You are teaching a group of medical students about cardiovascular examination. You are discussing heart sounds and the cardiac cycle. Which of the following stages of the cardiac cycle occurs immediately after the aortic valve closes:
Your Answer: Isovolumetric relaxation
Explanation:Immediately after the closure of the semilunar valves, the ventricles rapidly relax and ventricular pressure decreases rapidly but the AV valves remain closed as initially the ventricular pressure is still greater than atrial pressure. This is isovolumetric relaxation. Atrial pressure continues to rise because of venous return, with the v wave of the JVP waveform peaking during this phase. Rapid flow of blood from the atria into the ventricles during the ventricular filling phase causes thethird heart sound, which is normal in children but, in adults, is associated with disease such as ventricular dilation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 16
Correct
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Regarding antihistamines, which of the following statements is CORRECT:
Your Answer: Elderly patients and children are more susceptible to side effects.
Explanation:Elderly patients and children are more susceptible to side effects. Antihistamines are competitive inhibitors at the H1-receptor. The newer antihistamines e.g. cetirizine cause less sedation and psychomotor impairment than the older antihistamines because they are much less lipid soluble and penetrate the blood brain barrier only to a slight extent. Antihistamines are used as a second line adjunct to adrenaline in anaphylaxis.
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This question is part of the following fields:
- Pharmacology
- Respiratory
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Question 17
Correct
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Regarding anaemia, which of the following statements is INCORRECT:
Your Answer: Anaemia is usually associated with a decrease in red cell 2,3 - DPG.
Explanation:Anaemia is defined as a reduction in haemoglobin concentration below the normal range for the age and sex of the individual. Children tend to have lower haemoglobin than adults, and women tend to have lower haemoglobin than men. Anaemia may occur from an actual reduction in total circulating haemoglobin mass, or with an increase in plasma volume e.g. in pregnancy, causing a dilutional anaemia. After acute major blood loss, anaemia is not immediately apparent because total blood volume is reduced and it takes up to a day for plasma volume to be replaced and hence the degree of anaemia to become apparent. The initial clinical features in acute haemorrhage are therefore a result of reduction in blood volume rather than that of anaemia. When anaemia develops slowly, the associated symptoms are often very mild as the body has time to adapt to the fall in haemoglobin. This involves mechanisms such as an increase in red cell 2,3 -diphosphoglycerate (2,3 – DPG), which shifts the oxygen dissociation curve to the right, allowing enhanced delivery of O2 to the tissues, and an increase in stroke volume and heart rate.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 18
Correct
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What is the mechanism of action of penicillin antibiotics:
Your Answer: Inhibition of bacterial cell wall synthesis
Explanation:Penicillins and the other ß-lactam antibiotics are bactericidal. They produce their antimicrobial action by preventing cross-linkage between the linear peptidoglycan polymer chains that make up the bacterial cell wall. They, therefore, inhibit cell wall synthesis.The integrity of the ß-lactam ring is essential for antimicrobial activity. Many bacteria (including most Staphylococci) are resistant to benzylpenicillin and phenoxymethylpenicillin because they produce enzymes (penicillinases, ß-lactamases) that open the ß-lactam ring.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 19
Correct
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Which of the following statements accurately describes the flexor digitorum superficialis muscle?
Your Answer: It flexes the middle phalanges of the medial four fingers at the proximal interphalangeal joints
Explanation:Flexor digitorum superficialis is the largest muscle of the anterior compartment of the forearm. It belongs to the superficial flexors of the forearm, together with pronator teres, flexor carpi radialis, flexor carpi ulnaris and palmaris longus. Some sources alternatively classify this muscle as an independent middle/intermediate layer of the anterior forearm, found between the superficial and deep groups.Flexor digitorum superficialis is innervated by muscular branches of the median nerve, derived from roots C8 and T1 that arises from the medial and lateral cords of the brachial plexus. The skin that overlies the muscle is supplied by roots C6-8 and T1.The primary arterial blood supply to the flexor digitorum superficialis is derived from the ulnar artery and its anterior recurrent branch. In addition to branches of the ulnar artery, the anterior and lateral surfaces of the muscle are supplied by branches of the radial artery; and its posterior surface also receives branches from the median artery.The main function of flexor digitorum superficialis is flexion of the digits 2-5 at the proximal interphalangeal and metacarpophalangeal joints. Unlike the flexor digitorum profundus, flexor digitorum superficialis has independent muscle slips for all four digits. This allows it to flex the digits individually at their proximal interphalangeal joints. In addition, flexor digitorum superficialis aids the aids flexion of the wrist.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 20
Correct
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C3 deficiency leads to particular susceptibility of infection with which of the following:
Your Answer: Encapsulated bacteria
Explanation:Macrophages and neutrophils have C3b receptors and they phagocytose C3b-coated cells. C3 deficiency thus leads to increased susceptibility of infection with encapsulated organisms (e.g. S. pneumoniae, H. influenzae).The early stages of the complement cascade leading to coating of the cells with C3b can occur by two different pathways:The classical pathway usually activated by IgG or IgM coating of cellsThe alternative pathway which is more rapid and activated by IgA, endotoxin and other factors
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 21
Incorrect
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The patient is a 61-year-old man with severe central chest pain. An acute myocardial infarction is revealed by his ECG. Clopidogrel is one of the medications he takes as part of his treatment.Clopidogrel's direct mechanism of action is which of the following?
Your Answer: Antagonsim of glycoprotein IIb/IIIa receptors
Correct Answer: Inhibition of platelet ADP receptors
Explanation:Clopidogrel, a thienopyridine derivative, prevents platelet aggregation and cross-linking by the protein fibrin by inhibiting the ADP receptor on platelet cell membranes (inhibits binding of ADP to its platelet receptor (P2Y12 ADP-receptor).
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 22
Incorrect
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Gastric emptying is increased by all of the following EXCEPT for:
Your Answer: A fall in gastric pH
Correct Answer: Secretin
Explanation:Gastric emptying is increased by:Distension of the pyloric antrumA fall in the pH of chyme in the stomachParasympathetic stimulation (via vagus)GastrinThe hormones secretin, cholecystokinin and gastric inhibitory polypeptide (GIP) inhibit gastric emptying.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 23
Correct
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A 20-year-old male who is a known patient of sickle cell disease presents to the Emergency Room with a sustained erection that is extremely painful. Out of the following clinical syndromes, which one does this patient most likely have?
Your Answer: Priapism
Explanation:Sickling of red blood cells can lead to several different clinical syndromes. If the sickling occurs in the corpora cavernosa, it can lead to a sustained, painful erection of the penis, referred to as priapism. One of the complications is long-term impotence. It is important to seek a urological opinion immediately in this case, but in the interim, treat with perineal ice packs and walk up and down the stairs.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 24
Correct
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A 28-year-old medical student ate a reheated Chinese takeaway and developed severe vomiting a few hours after.What is the SINGLE MOST likely causative organism?
Your Answer: Bacillus cereus
Explanation:Bacillus cereusis is the correct answer. It is a Gram-positive, rod-shaped, beta-haemolytic bacterium that causes ‘fried rice syndrome’.Hardy spores in rice can survive boiling. When left at room temperature for long periods prior to frying these spores germinate. The emetic enterotoxin-producing strains cause nausea and vomiting between 1 and 6 hours after consumption while the diarrheagenic enterotoxin-producing strains (commonly associated with ingestion of meat, vegetables and dairy products) causes abdominal pain and vomiting, which starts 8-12 hours after ingestion.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 25
Correct
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A 70-year-old man has severe diarrhoea one week after taking co-amoxiclav for a chest infection. The diarrhoea is yellow in colour and smell is offensive.What is the SINGLE MOST likely causative organism?
Your Answer: Clostridium difficile
Explanation:Clostridium difficile, a Gram-positive, anaerobic, spore forming bacteria is present in the gut of approximately 3% of healthy adults (2012 UK HPA estimates). Following use of broad spectrum antibiotics, which alter normal gut flora, Clostridium difficile associated diarrhoea (CDAD) occurs.About 80% of Clostridium difficile infections are seen in people over the age of 65 and its main clinical features are:Abdominal cramps, severe bloody and/or watery diarrhoea, offensive smelling diarrhoea, and fever.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 26
Incorrect
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Which of the following statement is correct with regards to the female urethra?
Your Answer: The urethra begins at the apex of the bladder.
Correct Answer: The urethra opens in the vestibule that lies between the labia minora.
Explanation:The urethra in women is short (about 4 cm long), and begins at the base of the bladder. Its course runs inferiorly through the urogenital diaphragm, then into the perineum. It then opens in the vestibule which lies between the labia minora. The inferior aspect of the urethra is bound to the anterior surface of the vagina. The urethral opening is anterior to the vaginal opening in the vestibule. As the urethra passes through the pelvic floor, it is surrounded by the external urethral sphincter.
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This question is part of the following fields:
- Abdomen
- Anatomy
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Question 27
Incorrect
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The most important Complement protein for antigen opsonization is:
Your Answer: C9
Correct Answer: C3b
Explanation:Phagocytosis is largely responsible for depletion of cells coated with antibodies. Cells opsonized by IgG antibodies are recognized by phagocyte Fc receptors, which are specific for the Fc portions of some IgG subclasses. In addition, when IgM or IgG antibodies are deposited on the surfaces of cells, they may activate the complement system by the classical pathway. Complement activation generates by-products, mainly C3b and C4b, which are deposited on the surfaces of the cells and recognized by phagocytes that express receptors for these proteins. The net result is phagocytosis of the opsonized cells and their destruction.
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 28
Correct
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A 30-year-old male with a known allergy to natural latex rubber presents with an allergic reaction to a food he has just eaten. Which ONE of these foods is most likely to cause an associated hypersensitivity in him?
Your Answer: Banana
Explanation:About one third of patients with allergy to natural latex rubber (NRL) have an associated allergy to some plant-derived foods. It is known as the latex-fruit syndrome and occurs commonly with consumption of fresh fruits. Banana and avocado are the most implicated fruits but it can also be seen with tomato, kiwi and chestnut.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 29
Correct
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Which of the following statements about vitamin B12 absorption is TRUE:
Your Answer: On ingestion, vitamin B12 is bound to R protein which protects it from digestion in the stomach.
Explanation:The substance intrinsic factor,essential for absorption of vitamin B12 in the ileum, issecreted by the parietal cells along with the secretion ofhydrochloric acid. When the acid-producing parietalcells of the stomach are destroyed, which frequentlyoccurs in chronic gastritis, the person develops not onlyachlorhydria (lack of stomach acid secretion) but oftenalso pernicious anaemia because of failure of maturationof the red blood cells in the absence of vitamin B12 stimulation of the bone marrow.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 30
Incorrect
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A 35-year-old man suffers an open fracture of his forearm. The nerve that innervates the pronator quadratus muscle is damaged as a consequence of this injury.Which of the following nerves has been damaged in this case? Select ONE answer only.
Your Answer: The musculocutaneous nerve
Correct Answer: The anterior interosseous nerve
Explanation:Pronator quadratus is a small, square-shaped muscle that lies in the anterior compartment of the forearm. It arises from the distal fourth of the anterior surface of the ulna and inserts into the distal fourth of the anterior surface of the radius.Pronator quadratus is innervated by the anterior interosseous nerve. It receives its blood supply from the anterior interosseous artery, which is a branch of the common interosseous artery, which in turn is a branch of the ulnar artery.The main action of pronator quadratus is to assist pronator teres with pronation of the forearm. The deep fibres bind the radius and ulna together.The pronator quadratus muscle highlighted in blue (adapted from Gray’s Anatomy)
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This question is part of the following fields:
- Anatomy
- Upper Limb
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SESSION STATS - PERFORMANCE PER SPECIALTY
