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Question 1
Incorrect
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What is the partial pressure of oxygen if it makes up 20.9 percent of the ambient air composition and the atmospheric pressure of ambient air is 760 mmHg?
Your Answer: 300 mmHg
Correct Answer: 159 mmHg
Explanation:Ambient air is atmospheric air in its natural state. Ambient air is typically 78.6% nitrogen and 20.9% oxygen. The extra 1% is made up of carbon, helium, methane, argon and hydrogen. The partial pressure of any gas can be calculated using this formula: P = atmospheric pressure (760 mmHg) x percent content in the mixture. Atmospheric pressure is the sum of all of the partial pressures of the atmospheric gases added together: The formula for atmospheric pressure is: Patm = PN2 + PO2 + PH2O + PCO2. The atmospheric pressure is known to be 760 mmHg. The partial pressures of the various gases can be estimated to have partial pressures of approximately 597.4 mmHg for nitrogen, 158.8 mm Hg for oxygen, and 7.6 mmHg for argon.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 2
Incorrect
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A 26-year-old man is involved in a motorcycle accident that results in an open fracture of his tibia and fibula. The nerve that innervates peroneus tertius is damaged as a consequence of his injuries.Peroneus tertius receives its innervation from which of the following nerves? Select ONE answer only.
Your Answer: Tibial nerve
Correct Answer: Deep peroneal nerve
Explanation:Peroneus brevis is innervated by the superficial peroneal nerve.Peroneus longus is innervated by the superficial peroneal nerve.Peroneus tertius is innervated by the deep peroneal nerve.
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This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 3
Incorrect
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You examine a 43-year-old woman who was referred to you by a friend. She suffers from a variety of medical conditions and takes a variety of medications, including amitriptyline.Which of the following is NOT a contraindication to amitriptyline treatment?
Your Answer: Manic phase of bipolar affective disorder
Correct Answer: Breastfeeding
Explanation:Amitriptyline is a tricyclic antidepressant (TCA) that is most commonly used to treat depression, but it can also be used to treat anxiety disorders, chronic pain, and attention deficit hyperactivity disorder (ADHD). It inhibits reuptake, raising serotonin and noradrenaline levels while also inhibiting acetylcholine action.TCAs have a number of drawbacks, including:Acute PorphyriaArrhythmiasDuring bipolar disorder’s manic phaseHeart blockAfter a myocardial infarction, there is an immediate recovery period.TCA levels in breast milk are too low to be harmful, and use can be continued while breastfeeding.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 4
Correct
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You examine a 48-year-old woman's blood results and notice that her glucose level is elevated. When you tell her about it, she tells you that her doctor recently ran some tests and discovered that she has impaired glucose tolerance.Which of the following medications has not been linked to a reduction in glucose tolerance?
Your Answer: Amlodipine
Explanation:The following drugs have been linked to impaired glucose tolerance:Thiazide diuretics, e.g. BendroflumethiazideLoop diuretics, e.g. furosemideSteroids, e.g. prednisoloneBeta-blockers, e.g. atenolol
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 5
Incorrect
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All of the following typically occurs as part of normal inspiration except:
Your Answer: Contraction of the diaphragm
Correct Answer: Contraction of the internal intercostal muscles
Explanation:Passive inspiration is a result of contraction of the diaphragm (depressing the diaphragm) and the external intercostal muscles (elevating the ribs). In inspiration, several movements occur. These are:1. elevation of the sternal ends of the ribs (‘pump handle’ movement), 2. elevation of the lateral shafts of the ribs (‘bucket handle’ movement) 3. depression of the diaphragm. These result in expansion of the thorax in an anteroposterior, transverse and vertical direction respectively. There is an increased intrathoracic volume and decreased intrathoracic pressure and air is drawn into the lungs.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 6
Incorrect
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The following all cause a right shift in the oxygen dissociation curve EXCEPT for:
Your Answer: Increase in PCO 2
Correct Answer: Foetal haemoglobin
Explanation:A decreased affinity of haemoglobin for oxygen (and hence increased ease of dissociation), shown by a right shift in the oxygen dissociation curve, is caused by a fall in pH, a rise in PCO2(the Bohr effect) and an increase in temperature. These changes occur in metabolically active tissues such as in exercise, and encourage oxygen release. The metabolic by-product 2,3-diphosphoglycerate (2,3 -DPG) also causes a right shift; 2, 3 -DPG may also be raised in chronic anaemia, chronic lung disease, or at high altitude. Foetal haemoglobin (HbF) binds 2, 3 -DPG less strongly than does adult haemoglobin (HbA), and so the HbF dissociation curve lies to the left of that for HbA, reflecting its higher oxygen affinity. This helps transfer oxygen from mother to foetus.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 7
Correct
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A patient presents with severe vomiting. They take a maintenance dose of 12.5 mg of prednisolone daily for their COPD. They are unable to swallow or keep down tablets at present, and you plan on converting them to IV hydrocortisone.What dose of hydrocortisone is equivalent to this dose of prednisolone? Select ONE answer only.
Your Answer: 50 mg
Explanation:Prednisolone is four times more potent than hydrocortisone, and therefore, a dose of 12.5 mg would be equivalent to 50 mg of hydrocortisone.The following table summarises the relative potency of the main corticosteroids compared with hydrocortisone:CorticosteroidPotency relative to hydrocortisonePrednisolone4 times more potentTriamcinolone5 times more potentMethylprednisolone5 times more potentDexamethasone25 times more potent
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This question is part of the following fields:
- Endocrine Pharmacology
- Pharmacology
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Question 8
Correct
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Which of the following cell types in the stomach secretes histamine?
Your Answer: Enterochromaffin-like cells
Explanation:The parietal cells operate in close association with another type of cell called enterochromaffin-like cells (ECL cells), the primary function of which is to secrete histamine. The ECL cells lie in the deep recesses of the oxyntic glands and therefore release histamine indirect contact with the parietal cells of the glands.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 9
Correct
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A 60 -year-old man is tested to have low calcium levels . After additional questioning, it becomes clear that he has a calcium-deficient diet.What is the daily calcium intake recommendation for a healthy adult?Â
Your Answer: 1300 mg
Explanation:A daily calcium intake of 1,000 to 1,300 mg is advised for adults. Women have a slightly higher calcium need than men and are at a higher risk of developing osteoporosis as they age.Calcium-rich foods include the following:Milk, cheese, and butter as dairy products.Broccoli, spinach, and green beans as green veggies.Bread, rice, and cereals as whole grain foods.Sardines, salmon, and other bony fishEggsNutsThe following foods have the least calcium:CarrotFruits such as kiwis, raspberries, oranges, and papayaChicken and pork in meats.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 10
Incorrect
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Which of the following occurs at the transverse thoracic plane:
Your Answer: Thoracic duct crosses from left to right hand side
Correct Answer: Bifurcation of the trachea
Explanation:A way to help remember the structures transected by the transverse thoracic plane is CLAPTRAP:C: cardiac plexusL: ligamentum arteriosumA: aortic arch (inner concavity)P: pulmonary trunkT: tracheal bifurcation (carina)R: right-to-left movement of the thoracic duct (posterior to the oesophagus)A: azygos vein drains into superior vena cavaP: pre-vertebral fascia and pre-tracheal fascia end
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 11
Correct
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Which of the following is a primary action of aldosterone:
Your Answer: Renal sodium reabsorption
Explanation:Aldosterone acts mainly at the renal distal convoluted tubule (DCT) to cause sodium retention and potassium loss. It increases the synthesis of transport mechanisms in the distal nephron including the Na+pump, Na+/H+symporter, and Na+and K+channels in principal cells, and H+ATPase in intercalated cells. Na+(and thus water) reabsorption and K+and H+secretion are thereby enhanced.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 12
Incorrect
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Achlorhydria is diagnosed in a 37-year-old individual who has had recurring episodes of gastroenteritis. This is an autoimmune illness of the gastric parietal cells that causes insufficient stomach acid production.Damage to stomach parietal cells will alter the secretion of which other substance?Â
Your Answer: Gastrin
Correct Answer: Intrinsic factor
Explanation:Achlorhydria is an autoimmune illness of the gastric parietal cells that causes insufficient stomach acid production. The parietal cells that have been injured are unable to create the necessary amount of stomach acid. As a result, the pH of the stomach rises, food digestion suffers, and the risk of gastroenteritis rises.The secretion of hydrochloric acid and intrinsic factor is controlled by the gastric parietal cells, which are epithelial cells in the stomach. These cells can be found in the gastric glands, the fundus lining, and the stomach body.In response to the following three stimuli, the stomach parietal cells release hydrochloric acid:H2 Histamine receptors are stimulated by histamine (most significant contribution)Acetylcholine stimulates M3 Receptors via parasympathetic action.CCK2 receptors are stimulated by Gastrin.Intrinsic factor, which is essential for vitamin B12 absorption, is also produced by stomach parietal cells.Omeprazole is a proton pump inhibitor that is both selective and irreversible. It inhibits the H+/K+-ATPase system present on the secretory membrane of gastric parietal cells, which lowers stomach acid secretion.Ranitidine inhibits histamine H2-receptors in a competitive manner. The reversible inhibition of H2-receptors in gastric parietal cells reduces both the volume and concentration of gastric acid.
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This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
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Question 13
Incorrect
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Regarding forest plots, which of the following is the purpose of this graph?
Your Answer: To assess the accuracy of a diagnostic test
Correct Answer: To graphically display the relative strength of multiple studies attempting to answer the same question
Explanation:The results of meta-analysis are often displayed graphically in a forest plot. A properly constructed forest plot is the most effective way to graphically display the relative strength of multiple studies attempting to answer the same question. A typical meta-analysis consists of three main objectives that include estimation of effect sizes from individual studies and a pooled summary estimate with their confidence intervals (CIs), heterogeneity among the studies, and any publication bias. The forest plot illustrates the first two of these objectives. Forest plots visualize the effect measure and CI of individual studies, which provide the raw data for the meta-analysis, as well the pooled-effect measure and CI. The individual studies also can be grouped in the forest plot by some of their characteristics for ease of interpretation such as by study size or year of publication. When comparing the outcomes between an intervention and a control group, dichotomous outcome variables are expressed as ratios (i.e. odds ratios, ORs or risk ratios, RRs), while for continuous outcomes, a weighted mean difference is reported.
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This question is part of the following fields:
- Evidence Based Medicine
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Question 14
Incorrect
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Which of the following is NOT an indication for a H1 receptor antihistamine:
Your Answer: Insomnia
Correct Answer: Gastroesophageal reflux disease
Explanation:Antihistamines are competitive inhibitors at the H1-receptor (in contrast to H2 receptor antagonists used to decrease gastric acid secretion in gastroesophageal reflux disease).Indications: Allergic rhinitis and conjunctivitisUrticarial rashes, pruritus, insect bites and stingsAngioedemaAnaphylaxis (second line adjunct to adrenaline)Nausea/vomiting and prevention of motion sicknessInsomnia
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This question is part of the following fields:
- Pharmacology
- Respiratory
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Question 15
Incorrect
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Which of these is NOT a naturally occurring anticoagulant:
Your Answer: Tissue factor pathway inhibitor
Correct Answer: Factor V Leiden
Explanation:It’s crucial that thrombin’s impact is restricted to the injured site. Tissue factor pathway inhibitor (TFPI), which is produced by endothelial cells and found in plasma and platelets, is the first inhibitor to function. It accumulates near the site of harm induced by local platelet activation. Xa and VIIa, as well as tissue factor, are inhibited by TFPI. Other circulating inhibitors, the most potent of which is antithrombin, can also inactivate thrombin and other protease factors directly. Coagulation cofactors V and VIII are inhibited by protein C and protein S. Tissue plasminogen activator (TPA) from endothelial cells facilitates fibrinolysis by promoting the conversion of plasminogen to plasmin.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 16
Correct
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An very unwell patient is receiving treatment in your hospital's HDU and is found to have an Escherichia coli O157 infection.Which one of these statements about Escherichia coli O157 is true?
Your Answer: Haemolytic uraemic syndrome develops in approximately 6% of patients
Explanation:Escherichia coli O157 is a serotype of Escherichia coli.The Escherichia coliO157 strain is ‘enterohaemorrhagic’ and causes severe forms of acute haemorrhagic diarrhoea. It can also cause non-haemorrhagic diarrhoea. Incubation period of Escherichia coli O157 is usually 3-4 days and bloody diarrhoea usually begins on the 3rd or 4th day of the infection.Infections with Escherichia coliO157 are more common during the warmer months than in winter.Haemolytic uraemic syndrome develops in approximately 6% of patients. It is commonly seen in children and in the elderly. Escherichia coli O157 can also cause:Haemorrhagic colitisHaemolytic uraemic syndromeThrombotic thrombocytopenic purpura but not immune thrombocytopenic purpura.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 17
Incorrect
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Which of the following statements is not true regarding ion channels?
Your Answer: Ion channels are selective for a particular ion.
Correct Answer: Ion channels provide a charged, hydrophobic pore through which ions can diffuse across the lipid bilayer.
Explanation:Ion channels are pore-forming protein complexes that facilitate the flow of ions across the hydrophobic core of cell membranes. They are present in the plasma membrane and membranes of intracellular organelles of all cells, and perform essential physiological functions. They provide a charged, hydrophilic pore through which ions can move across the lipid bilayer. They are selective for particular ions and their pores may be opened or closed. Because of this ability to open and close, ion channels allow the cell to have the ability to closely control the movement of ions across the membrane. Gating refers to the transition between an open and closed ion channel state, and is brought about by a conformationational change in the protein subunits that open or close the ion-permeable pore. Ion channels can be:1. voltage-gated these are regulated according to the potential difference across the cell membrane or2. ligand-gated – these are regulated by the presence of a specific signal molecule.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 18
Correct
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A 56-year-old male with a 10-year history of Diabetes Mellitus and Hypertension was rushed to the Emergency Department due to sudden onset crushing chest pain. ECG showed an ST-elevation myocardial infarct in the left anterior descending artery territory. The patient's condition was stabilised and managed with angioplasty, but he sustained significant myocardial damage. Which one of the following statements best agrees with the myocardial healing process?
Your Answer: The left ventricle will likely hypertrophy first to maintain cardiac output
Explanation:Following a myocardial infarction scar tissue formation will take place at the site of the damaged muscle. This places increased load on the rest of the myocardium causing it to hypertrophy. The left ventricle will hypertrophy first as it is pumping blood against a greater afterload as compared to the right ventricle. There are three types of cells in the body with regards to the cell cycle: 1. permanent2. labile3. stable cellsPermanent cells do not re-enter the cell cycle and remain in G0. If there is a pool of stem cells the stem cells will enter the cell cycle to form more cells. Myocardial cells are a type of permanent cell and there is no pool of stem cells in the heart muscle. The anterior wall will not hypertrophy as it is formed by the right atrium and ventricle and both of these hypertrophy after the left ventricle.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 19
Correct
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A 54-year-old man returns from a recently holiday on a cruise ship with a dry cough and a fever. Today he has also had several episodes of diarrhoea and has developed bilateral pleuritic chest pain. He states that he is short of breath, most notably on exertion. He had been prescribed amoxicillin by the cruise ship doctor a few days earlier but has not seen any improvement.Which of the following is the most likely causative organism? Select ONE answer only.
Your Answer: Legionella pneumophila
Explanation:Legionella pneumophilais a Gram negative bacterium that is found in natural water supplies and in the soil, transmitted predominantly via inhalation of aerosols generated from contaminated water (direct person-to-person spread of infected patients does not occur). It is the cause of Legionnaires’ disease. Outbreaks of Legionnaires’ disease have been linked to poorly maintained air conditioning systems, whirlpool spas and hot tubs.The clinical features of the pneumonic form of Legionnaires’ disease include:Mild flu-like prodrome for 1-3 daysCough (usually non-productive and occurs in approximately 90%)Pleuritic chest painHaemoptysisHeadacheNausea, vomiting and diarrhoeaAnorexiaLegionella pneumophilainfections can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used.The syndrome of inappropriate antidiuretic hormone secretion (SIADH) can occur with Legionnaires’ disease and will result in hyponatraemia as is seen in this case.Legionella pneumophilainfections are resistant to amoxicillin but can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used. The majority of cases of Legionnaires’ disease are caused by Legionella pneumophila, however many other species of Legionella have been identified.Legionella longbeachae is another less commonly encountered species that has also been implicated in outbreaks. It is predominantly found in soil and potting compost, and has caused outbreaks of Pontiac fever, the non-respiratory and less severe variant of Legionnaires’ disease.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 20
Incorrect
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Which of the following is NOT a typical side effect of thiopental sodium:
Your Answer: Involuntary muscle movements on induction
Correct Answer: Seizures
Explanation:Extravasation of thiopental during injection can lead to tissue damage. Accidental intra-arterial injection causes vasospasm and may lead to thrombosis and tissue necrosis. Other side effects include involuntary muscle movements on induction, cough and laryngospasm, arrhythmias, hypotension, headache and hypersensitivity reactions. Thiopental sodium has anticonvulsant properties and does not cause seizures.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 21
Incorrect
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A 30-year-old male presents with easy bruising and bleeding gums, feeling very tired lately, and recurrent chest infections over the past few months. He had glandular fever approximately 6 months ago and feels that his symptoms started after that. His full blood count today is as follows: Hb 6.3 g/dl (11.5-14 g/dl) MCV 90 fl (80-100 fl) WCC 2.0 x 10 9 /l (4-11 x 10 9 /l) Platelets 15 x 10 9 /l (150-450 x 10 9 /l)The SINGLE most likely diagnosis is?
Your Answer: Vitamin B12 deficiency
Correct Answer: Aplastic anaemia
Explanation:Aplastic anaemia is a life-threatening failure of haemopoiesis characterised by pancytopenia and hypocellular bone marrow. It is rare and patients present with features of recurrent infections secondary to (leukocytopenia), increased bleeding tendency (secondary to thrombocytopenia) and anaemia. In aplastic anaemia, there is damage to the bone marrow and the haematopoietic stems cells leading to pancytopenia.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 22
Incorrect
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Regarding red blood cell group antigens and antibodies, which of the following statements is CORRECT:
Your Answer: Only IgM antibodies are capable of transplacental passage.
Correct Answer: Anti-D antibodies are usually IgG.
Explanation:Approximately 400 red blood cell group antigens have been described. The ABO group antigens are unusual in that naturally occurring antibodies occur in the plasma of subjects who lack the corresponding antigen, even if they have not been exposed to that antigen previously. The most important of these natural antibodies are anti-A and anti-B, which are usually IgM. Anti-D antibodies don’t occur naturally, and are therefore immune antibodies that result from previous transfusions or pregnancy. Only IgG antibodies are capable of transplacental passage and the most important immune antibody is the Rh antibody, anti-D.
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 23
Incorrect
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A 22-year-old woman is brought in by ambulance from her GP surgery with suspected meningitis. She has been given a dose of benzylpenicillin already.What is the mechanism of action of benzylpenicillin? Select ONE answer only.
Your Answer: Inhibition of protein synthesis
Correct Answer: Inhibition of 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.An overview of the different mechanisms of action of the various types of antimicrobial agents is shown below:Mechanism of actionExamplesInhibition of cell wall synthesisPenicillinsCephalosporinsVancomycinDisruption of cell membrane functionPolymyxinsNystatinAmphotericin BInhibition of protein synthesisMacrolidesAminoglycosidesTetracyclinesChloramphenicolInhibition of nucleic acid synthesisQuinolonesTrimethoprim5-nitroimidazolesRifampicinAnti-metabolic activitySulfonamidesIsoniazid
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 24
Correct
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What proportion of peripheral blood leukocytes are monocytes?
Your Answer: 5 - 10%
Explanation:Monocytes account for around 5 to 10% of peripheral white cells. Monocytes in peripheral blood are generally bigger than other leukocytes and feature a large central oval or indented nucleus with clumped chromatin. The abundant cytoplasm staining blue and containing numerous fine vacuoles gives the appearance of ground glass. Cytoplasmic granules are another type of granule. Monocytes evolve from the granulocyte-macrophage progenitor to become monoblasts, promonocytes, monocytes, and tissue macrophages (in increasing order of maturity). Monocytes only stay in the bone marrow for a short time before exiting to circulate in the bloodstream for 20-40 hours before becoming macrophages.
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This question is part of the following fields:
- Immune Responses
- Pathology
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Question 25
Correct
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A 55-year-old male diabetic patient presents to the Emergency Room complaining of severe chest pain. His medical record shows that he had coronary angioplasty one week ago, during which he was administered abciximab. Which of the following haematological diseases has a similar mechanism of action to this drug?
Your Answer: Glanzmann’s thrombasthenia
Explanation:Abciximab is glycoprotein IIb/IIIa receptor antagonist that decreases aggregation of platelets by prevent their cross-linking. In Glanzmann’s thrombasthenia there are low levels of these same receptors leading to decreased bridging of platelets as fibrinogen cannot attach. There is increased bleeding time both in this disease and when there is use of abciximab.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 26
Incorrect
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Regarding haemoglobin, which of the following statements is CORRECT:
Your Answer: Normal adult haemoglobin contains 4 identical globin polypeptide chains.
Correct Answer: In degradation of haemoglobin, the haem group is split from the haemoglobin and converted to biliverdin and ultimately to bilirubin.
Explanation:Haemoglobin is composed of four polypeptide globin chains each with its own iron containing haem molecule. Haem synthesis occurs largely in the mitochondria by a series of biochemical reactions commencing with the condensation of glycine and succinyl coenzyme A under the action of the key rate-limiting enzyme delta-aminolevulinic acid (ALA) synthase. The globin chains are synthesised by ribosomes in the cytosol. Haemoglobin synthesis only occurs in immature red blood cells.There are three types of haemoglobin in normal adult blood: haemoglobin A, A2 and F:- Normal adult haemoglobin (HbA) makes up about 96 – 98 % of total adult haemoglobin, and consists of two alpha (α) and two beta (β) globin chains. – Haemoglobin A2 (HbA2), a normal variant of adult haemoglobin, makes up about 1.5 – 3.5 % of total adult haemoglobin and consists of two α and two delta (δ) globin chains.- Foetal haemoglobin is the main Hb in the later two-thirds of foetal life and in the newborn until approximately 12 weeks of age. Foetal haemoglobin has a higher affinity for oxygen than adult haemoglobin. Red cells are destroyed by macrophages in the liver and spleen after , 120 days. The haem group is split from the haemoglobin and converted to biliverdin and then bilirubin. The iron is conserved and recycled to plasma via transferrin or stored in macrophages as ferritin and haemosiderin. An increased rate of haemoglobin breakdown results in excess bilirubin and jaundice.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 27
Incorrect
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Which of the following microbes adheres to the genital mucosa using fimbriae:
Your Answer: Treponema pallidum
Correct Answer: Neisseria gonorrhoeae
Explanation:Infection of the genital mucosa by Neisseria gonorrhoeae involves attachment to and invasion of epithelial cells. Initial adherence of gonococci to columnar epithelial cells is mediated by type IV pili assembled from pilin subunit PilE proteins and pilus tip-associated PilC proteins, it then invades the epithelial layer, triggering a local acute inflammatory response.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 28
Incorrect
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Pancreatic acinar digestive enzyme secretion is mainly stimulated by which of the following hormones:
Your Answer: Secretin
Correct Answer: Cholecystokinin
Explanation:Exocrine pancreatic secretion is controlled by:Parasympathetic stimulation which enhances secretion of both the enzyme and aqueous componentsSympathetic stimulation which inhibits pancreatic secretionSecretin which stimulates secretion of the alkaline-rich fluid from ductal cellsCholecystokinin which stimulates secretion of the enzyme-rich fluid from acinar cellsSomatostatin which inhibits secretion from both acinar and ductal cellsGastrin which stimulates pancreatic acinar cells to secrete digestive enzymes
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 29
Incorrect
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Where in the nephron is most K+reabsorbed:
Your Answer: Descending loop of Henle
Correct Answer: Proximal tubule
Explanation:Approximately 65 – 70% of filtered K+is reabsorbed in the proximal tubule. Potassium reabsorption is tightly linked to that of sodium and water. The reabsorption of sodium drives that of water, which may carry some potassium with it. The potassium gradient resulting from the reabsorption of water from the tubular lumen drives the paracellular reabsorption of potassium and may be enhanced by the removal of potassium from the paracellular space via the Na+/K+ATPase pump. In the later proximal tubule, the positive potential in the lumen also drives the potassium reabsorption through the paracellular route.
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This question is part of the following fields:
- Physiology
- Renal
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Question 30
Incorrect
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Which of the following is most true of the sinoatrial node:
Your Answer: It is located between the right atrium and ventricle near the atrial septum.
Correct Answer: Frequency of depolarisation is increased by sympathetic stimulation.
Explanation:Cardiac myocyte contraction is not dependent on an external nerve supply but instead the heart generates its own rhythm, demonstrating inherent rhythmicity. The heartbeat is initiated by spontaneous depolarisation of the sinoatrial node (SAN), a region of specialised myocytes in the right atrium close to the coronary sinus, at a rate of 100-110 beats/min. This intrinsic rhythm is primarily influenced by autonomic nerves, with vagal influences being dominant over sympathetic influences at rest. This vagal tone reduces the resting heart rate down to 60-80 beats/min. To increase heart rate, the autonomic nervous system increases sympathetic outflow to the SAN, with concurrent inhibition of vagal tone. These changes mean the pacemaker potential more rapidly reaches the threshold for action potential generation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
