1- Physiology MCQs Only Flashcards
1 of 192
A 54 year old lady has her serum calcium measured. Assuming her renal function is normal, what proportion of calcium filtered at the glomerulus will be reabsorbed by the renal tubules?
95%
Most filtered calcium is reabsorbed (95%) a rare disorder of familial hypocalcemic calciurea may affect this proportion.
2 of 192
Which of the following statements is true of glucagon?
Glucagon is produced in response to hyperglycaemia
Released by beta cells
Inhibits gluconeogenesis
Produced in response to an increase of amino acids(Right)
Composed of 2 alpha polypeptide chains linked by hydrogen bonds
……………………………..
Glucagon is a protein comprised of a single polypeptide chain.
Produced by alpha cells of pancreatic islets of Langerhans in response to hypoglycaemia and amino acids.
It increases plasma glucose and ketones.
3 of 192
Which of the following is not caused by cortisol in the stress response?
Anti-inflammatory effects
Hypoglycaemia(Right)
Skeletal muscle protein breakdown
Stimulation of lipolysis
Mineralocorticoid effects
…………………………………………….
An ‘anti insulin’ effect occurs leading to hyperglycaemia.
4 of 192
Which of the following statements relating to abnormal coagulation is false?
Warfarin affects the synthesis of factor 2,7,9,10
The prothrombin time is prolonged in Haemophilia A(Right)
Cholestatic jaundice can cause vitamin K deficiency
Disseminated intravascular coagulation is associated with thrombocytopenia
Massive transfusion is associated with reduced levels of factor 5 and 8
………………………………………….
In haemophilia A the APTT is prolonged and there is reduced levels of factor 8:C.
The bleeding time and PT are normal. Cholestatic jaundice prevents the absorption of the fat soluble vitamin K. Massive transfusion (>10u blood or equivalent to the blood volume of a person) puts the patient at risk of thrombocytopaenia, factor 5 and 8 deficiency.
5 of 192
Which of the following is not classically seen in coning resulting from raised intra cranial pressure?
Coma
Hypotension(Right)
Unreactive mid sized pupils
Cheyne Stokes style respiratory efforts
Bradycardia
……………………………………
Cushings triad
Widening of the pulse pressure
Respiratory changes
Bradycardia
Due to raised ICP systemic hypertension is usually seen. Compression of the respiratory centre will typically result in Cheyne Stokes style respiration.
6 of 192
Control of ventilation. Which statement is false?
Peripheral chemoreceptors are located in the bifurcation of the carotid arteries and arch of the aorta
Central chemoreceptors respond to changes in O2(Right)
The respiratory centres control the rate and depth of respiration
Involuntary control of respiration is from the medulla and pons
Irritant receptors cause bronchospasm
……………………………………………
- Central chemoreceptors: Respond to increased H+ in BRAIN INTERSTITIAL FLUID to increase ventilation.
7 of 192
A 52-year-old woman with a history of gastrectomy reports lethargy and a sore tongue. Blood tests are reported as follows:
Hb 10.7 g/dl
MCV 121 fl
Plt 177 * 10^9/l
WBC 5.4 * 10^9/l
What is the most likely cause?
Vitamin B12 deficiency
A history of gastrectomy and a macrocytic anaemia should indicate a diagnosis of B12 deficiency.
8 of 192
Which of the following surgical procedures will have the greatest long term impact on a patients calcium metabolism?
Extensive small bowel resection
Calcium is mainly absorbed from the small bowel and this will have a direct long term impact on calcium metabolism and increase the risk of osteoporosis. Gastric banding and distal gastrectomy may affect a patients dietary choices but any potential deleterious nutritional intake may be counteracted by administration of calcium supplements orally. Only 10% of calcium is absorbed from the colon so that a sub total colectomy will only have a negligible effect.
9 of 192
What is measured to obtain renal plasma flow?
Para-amino hippuric acid (PAH)
10 of 192
Which of the following statements relating to alveolar ventilation is untrue?
Anatomical dead space is measured by helium dilution.(Right)
Physiological dead space is increased in PE.
Alveolar ventilation is defined as the volume of fresh air entering the alveoli per minute.
Anatomical dead space is increased by adrenaline.(Right)*
Type 2 pneumocytes in the alveoli secrete surfactant.
…………………………………………………..
Anatomical dead space is measured by Fowlers method.
A patient inhales 100% oxygen to empty the conducting zone gases of nitrogen and then exhales through a mouthpiece which analyses the nitrogen concentration at the mouth. Initially the exhaled gases contain no nitrogen as this is dead space gas; the nitrogen concentration will increase as the alveolar gases are exhaled. Nitrogen which is measured following the breath of 100% oxygen must then have come only from gas exchanging areas of the lung and not dead space.
11 of 192
Which of the following is associated with reduced lung compliance?
Adjusting a ventilator to maintain high lung volumes
……………………………………………………….
Increased lung compliance = Older age, COPD
Lung compliance is a measure of the ease of expansion of the lungs and thorax, determined by pulmonary volume and elasticity. A high degree of compliance indicates a loss of elastic recoil of the lungs, as in old age or emphysema. This increased lung compliance is due to loss of supportive tissue around the airways.
While a normal lung has a high passive elastic recoil, the sick lung has a decreased elasticity (i.e. decreased transpulmonary pressure) which leads to increased lung compliance.
Decreased compliance means that a greater change in pressure is needed for a given change in volume, as in atelectasis, pulmonary fibrosis, pneumonia, or lack of surfactant.
12 of 192
A 43 year old lady presents with urinary incontinence. At which of the following locations is Onufs nucleus likely to be found?
Anterior horn of S2 nerve roots
Onufs nucleus is located in the anterior horn of S2 and is the origin of neurones to the external urethral sphincter.
13 of 192
A 67 year old male is admitted to the surgical unit with acute abdominal pain. He is found to have a right sided pneumonia. The nursing staff put him onto 15L O via a non rebreathe mask. After 30 minutes the patient is found moribund, sweaty and agitated by the nursing staff. An arterial blood gas reveals:
pH 7.15
pCO 10.2
pO 8
Bicarbonate 32
Base excess - 5.2
What is the most likely cause for this patients deterioration?
Over administration of oxygen in a COPD patient
This patient has an acute respiratory acidosis, however this is on a background of chronic respiratory acidosis (due to COPD) with a compensatory metabolic alkalosis (the elevated bicarbonate is the main clue to the chronic nature of the respiratory acidosis). This blood gas picture is typical in a COPD patient who has received too much oxygen; these patients lose their hypoxic drive for respiration, therefore retain CO and subsequently hypoventilate leading to respiratory arrest. If the bicarbonate was normal, then the answer would be acute respiratory acidosis secondary to pneumonia.
14 of 192
Which of the following statements relating to low molecular weight heparins is false?
They act via inhibition of Factor Xa
Large doses may be used prior to commencing cardiopulmonary bypass(Right)
They have a highly predictable pharmacokinetic profile
They are derivatives of unfractionated heparin
They have a molecular mass in the range of 3000-10000Da
……………………………………………………….
As they are not easily reversed they are unsuitable for this purpose.
15 of 192
A 43 year old lady undergoes a day case laparoscopic cholecystectomy. The operation is more difficult than anticipated and a drain is placed to the operative site. Whilst in recovery, the patient loses 1800ml of frank blood into the drain. Which of the following will not occur?
Release of aldosterone via the Bainbridge reflex(Right)
Reduced urinary sodium excretion
Increase in sympathetic discharge to ventricular muscle
Fall in parasympathetic discharge to the sino atrial node
Decreased stimulation from atrial pressure receptors
…………………………………..
The Bainbridge reflex is the increase in heart rate mediated via atrial stretch receptors that occurs following a rapid infusion of blood. Note the question asks which will not occur and that is why it is A and not the other options.
16 of 192
Which one of the following is least associated with thrombocytopenia?
Heparin therapy
Rheumatoid arthritis(Right)
Infectious mononucleosis
Liver disease
Pregnancy
……………………………………..
Rheumatoid arthritis, unlike systemic lupus erythematous, is generally associated with a thrombocytosis. In some cases of Felty’s syndrome thrombocytopaenia may be seen secondary to hypersplenism. This however represents a small percentage of patients with rheumatoid arthritis.
17 of 192
Which of the following statements relating to the pharmacology of warfarin is untrue?
Interferes with clotting factors 2,7,9 and 10
It may not be clinically effective for up to 72 hours
The half life of warfarin is 40 hours
Warfarin has a large volume of distribution(Right)
It is metabolized in the liver
………………………………………………………
Factors 2,7,9,10 affected
Warfarin interferes with fibrin formation by affecting carboxylation of glutamic acid residues in factors 2,7,9 and 10. Factor 2 has the longest half life of approximately 60 hours, therefore it can take up to 3 days for warfarin to be fully effective.
Warfarin has a small volume of distribution as it is protein bound.
18 of 192
Which of the following drugs is least likely to cause syndrome of inappropriate anti diuretic hormone release?
Haloperidol
Carbamazepine
Amitriptylline
Cyclophosphamide
Methotrexate(Right)
………………………………………..
Drugs causing SIADH: ABCD
A nalgesics: opioids, NSAIDs
B arbiturates
C yclophosphamide/ Chlorpromazine/ Carbamazepine
D iuretic (thiazides)
19 of 192
Which of the following substances related to thyroid function has its effects mediated by a nuclear receptor?
Triiodothyronine
T3 binds to a receptor on chromatin to induce protein synthesis.
20 of 192
The blood - brain barrier is not highly permeable to which of the following?
Hydrogen ions
The blood brain barrier is relatively impermeable to highly dissociated compounds.
22 of 192
Which of the following arterial blood gas results would fit with chronic respiratory acidosis with a compensatory metabolic alkalosis?
pH 7.36, PaCO 7.3, PO 8.9 (FiO 40%), Bicarbonate 30.2, Base excess +5.3
21 of 192
A 73 year old man has an arterial line in situ. On studying the trace the incisura can be seen. What is the physiological event which accounts for this process?
Elastic recoil of the aorta
It is the temporary rise in aortic pressure occurring as a result of elastic recoil. its the same thing as the dicrotic notch.
23 of 192
A 44 year old man receives a large volume transfusion of whole blood. The whole blood is two weeks old. Which of the following best describes its handling of oxygen?
will have an increased affinity for oxygen
Stored blood has less 2,3 DPG and therefore has a higher affinity for oxygen, this reduces its ability to release it at metabolising tissues.
24 of 192
A 43 year old presents to the urology clinic complaining of impotence. Which of the following will occur in response to increased penile parasympathetic stimulation?
Erection
Memory aid for erection
p=parasympathetic=points
s=sympathetic=shoots
Parasympathetic stimulation causes erection. Sympathetic stimulation will produce ejaculation, detumescence and vasospasm of the pudendal artery. It will also cause contraction of the smooth muscle in the epididymis and vas to convey the ejaculate.
25 of 192
A 28 year old man undergoes a completion right hemicolectomy for treatment of a 5cm appendiceal carcinoid. As part of his follow up he is due to undergo 24 hour urine collection for 5-HIAA. Which of the following causes an elevated 5-HIAA in a 24-hour urine collection?
Naproxen
It is important to be aware of what can falsely elevate 5-HIAA to avoid diagnosing carcinoid syndrome incorrectly. These include:
Food: spinach, cheese, wine, caffeine, tomatoes
Drugs: Naproxen, Monoamine oxidase inhibitors
Recent surgery
26 of 192
Which is the least likely to cause hyperuricaemia?
Severe psoriasis
Lesch-Nyhan syndrome
Amiodarone(Right)
Diabetic ketoacidosis
Alcohol
…………………………………………
Mnemonic of the drugs causing hyperuricaemia as a result of reduced excretion of urate
‘Can’t leap’
C iclosporin
A lcohol
N icotinic acid
T hiazides
L oop diuretics
E thambutol
A spirin
P yrazinamide
Decreased tubular secretion of urate occurs in patients with acidosis (eg, diabetic ketoacidosis, ethanol or salicylate intoxication, starvation ketosis). The organic acids that accumulate in these conditions compete with urate for tubular secretion.
27 of 192
Approximately what proportion of basal salivary secretions are provided by the submandibular glands?
70%
Although they are small, the submandibular glands provide the bulk of salivary secretions and contribute 70%, the sublingual glands provide 5% and the remainder from the parotid. During food consumption the contribution of the parotid secretions is greater.
28 of 192
Which of the following changes are not typically seen in established dehydration?
Rising haematocrit
Urinary sodium <20mmol/ litre
Metabolic acidosis
Decreased serum urea to creatinine ratio (Right)
Hypernatraemia
…………………………………….
Diagnosing dehydration can be complicated, laboratory features include:
Hypernatraemia
Rising haematocrit
Metabolic acidosis
Rising lactate
Increased serum urea to creatinine ratio
Urinary sodium <20 mmol/litre
Urine osmolality approaching 1200mosmol/kg
29 of 192
Which of the following best accounts for the action of PTH in increasing serum calcium levels?
Activation of vitamin D to increase absorption of calcium from the small intestine.
……………………………………………………
PTH increases the activity of 1-α-hydroxylase enzyme, which converts 25- hydroxycholecalciferol to 1,25-dihydroxycholecalciferol, the active form of vitamin D.
Osteoclasts do not have a PTH receptor and effects are mediated via osteoblasts.
33 of 192
Which main group of receptors does dobutamine bind to?
ß-1
Dobutamine is a sympathomimetic with both alpha- and beta-agonist properties; it displays a considerable selectivity for beta1-cardiac receptors.
30 of 192
Which of the following cell types is least likely to be found in a wound 1 week following injury?
Macrophages
Fibroblasts
Myofibroblasts(Right)
Endothelial cells
Neutrophils
……………………………………………
Myofibroblasts are differentiated fibroblasts, in which the cytoskeleton contains actin filaments. These cell types facilitate wound contracture and are the hallmark of a mature wound. They are almost never found in wounds less than 1 month old.
Remember the question asks about the cell type asks about which cells are least likely to be found.
32 of 192
Which of the following is responsible for the release and synthesis of calcitonin?
Thyroid gland
Calcitonin has the opposite effect of PTH and is released from the thyroid gland.
31 of 192
What is the half life of insulin in the circulation of a normal healthy adult?
Less than 30 minutes
Insulin is degraded by enzymes in the circulation. It typically has a half life of less than 30 minutes. Abnormalities of the clearance of insulin may occur in type 2 diabetes.
34 of 192
A 43 year old man has recurrent episodes of dyspepsia and treatment is commenced with oral antacids. Which of the substances listed below is released in response to increased serum gastrin levels and decreases intra gastric pH?
Histamine
Remember that a low pH value indicates an acidic solution. Solutions of less than 7 (i.e. 1) have more free hydrogen ions than solutions of pH 10.
Histamine is released from enterochromaffin cells in the stomach mucosa which stimulates acid secretion. It is usually released in response to increased serum gastrin levels. Histamine blockers (e.g. cimetidine) were extremely popular treatments until the advent of proton pump inhibitors.
35 of 192
A 22 year old man suffers a blunt head injury. He is drowsy and has a GCS of 7 on admission. Which of the following is the major determinant of cerebral blood flow in this situation?
Intra cranial pressure
Hypoxaemia and acidosis may both affect cerebral blood flow. However, in the traumatic situation increases in intracranial pressure are far more likely to occur especially when GCS is low. This will adversely affect cerebral blood flow.
36 of 192
A surgeon is considering using lignocaine as local anasthesia for a minor procedure. Which of the following best accounts for its actions?
Blockade of neuronal sodium channels
Lignocaine blocks sodium channels. They will typically be activated first, hence the pain some patients experience on administration.
38 of 192
A 23 year old man is undergoing an inguinal hernia repair under local anaesthesia. The surgeon encounters a bleeding site which he manages with diathermy. About a minute or so later the patient complains that he is able to feel the burning pain of the heat at the operative site. Which of the following nerve fibres is responsible for the transmission of this signal?
C fibres
Slow transmission of mechanothermal stimuli is transmitted via C fibres. A γ fibres transmit information relating to motor proprioception, A β fibres transmit touch and pressure and B fibres are autonomic fibres.
37 of 192
A 25 year old man undergoes an appendicetomy for appendicitis. The appendix is submitted for histopathological evaluation. Which of the following is most likely to be identified microscopically?
Neutrophils
Neutrophil polymorphs are the cell type most commonly encountered in acute inflammation.
39 of 192
In a 70 Kg male, what proportion of total body fluid will be contributed by plasma?
5%
70 Kg male = 42 L water (60% of total body weight)
42 of 192
A 25 year old man is undergoing respiratory spirometry. He takes a maximal inspiration and maximally exhales. Which of the following measurements will best illustrate this process?
Vital capacity
The maximum voluntary ventilation is the maximal ventilation over the course of 1 minute.
41 of 192
What are the most likely effects of the release of vasopressin from the pituitary?
Increased water permeability of the distal tubule cells of the kidney
ADH (vasopressin) results in the insertion of aquaporin channels in apical membrane of the distal tubule and collecting ducts.
40 of 192
Which of the following hormones is mainly responsible for sodium - potassium exchange in the salivary ducts?
Aldosterone
Aldosterone is responsible for regulating ion exchange in salivary glands. It acts on a sodium / potassium ion exchange pump.It is a mineralocorticoid hormone derived from the zona glomerulosa of the adrenal gland.
43 of 192
Which of the following is the main site of dehydroepiandrosterone release?
Zona reticularis of the adrenal gland
………………………………..
Adrenal cortex mnemonic: GFR - ACD
DHEA possesses some androgenic activity and is almost exclusively released from the adrenal gland.
44 of 192
A 63 year old female is referred to the surgical clinic with an iron deficiency anaemia. Her past medical history includes a left hemi colectomy but no other co- morbidities. At what site is most dietary iron absorbed?
Duodenum
Iron is best absorbed from the proximal small bowel (duodenum and jejunum) in the Fe state. Iron is transported across the small bowel mucosa by a divalent membrane transporter protein (hence the improved absorption of Fe ). The intestinal cells typically store the bound iron as ferritin. Cells requiring iron will typically then absorb the complex as needed.
45 of 192
A 56 year old man has long standing chronic pancreatitis and develops pancreatic insufficiency. Which of the following will be absorbed normally?
Folic acid
Pancreatic lipase is required for digestion of fat, Proteases facilitate protein and B12 absorption. Folate digestion is independent of the pancreas.
46 of 192
Which vitamin is involved in the formation of collagen?
Vitamin C
Vitamin C is needed for the hydroxylation of proline during collagen synthesis.
47 of 192
A 28 year old man is shot in the abdomen and haemorrhages. Which of the following substances will produce vasoconstriction in response to this process?
Angiotensin II
Renin does not cause vasoconstriction. Angiotensin I is biologically inactive.
Aldosterone will increase blood pressure but does not have direct vasospastic effects.
48 of 192
A 73 year old lady is admitted for a laparoscopic cholecystectomy. During her pre- operative assessment it is noted that she is receiving furosemide for the treatment of hypertension. Where is the site of action of this diuretic?
Ascending limb of the loop of Henle
……………………………………………..
Action of furosemide = ascending limb of the loop of Henle
Furosemide and bumetanide are loop diuretics that act by inhibiting the Na-K-Cl cotransporter in the thick ascending limb of the loop of Henle, reducing the absorption of NaCl.
49 of 192
Which of the following blood gas results would fit with metabolic acidosis with a compensatory respiratory alkalosis?
pH 7.32, PCO 3.8, PaO 22.2 (FiO 40%), Bicarbonate 19.1, Base excess -7.9
51 of 192
Which of the following best accounts for the mechanism of action of glucocorticoids?
Binding of intracellular receptors that migrate to the nucleus to then affect gene transcription
Glucocorticoids exert their effects by binding intracellular receptors that are then transported to the nucleus where they affect gene transcription. There are some questions in the MRCS now that seem to test common pharmacology and so we have decided to include this. A detailed knowledge of the mechanisms by which these effects occur is not needed.
50 of 192
Which of the following is not well absorbed following a gastrectomy?
Vitamin c
Zinc
Vitamin B12(Right)
Copper
Molybdenum
…………………………………
Vitamin B12. The others are unaffected
53 of 192
Which of the following statements related to the coagulation cascade is true?
The intrinsic pathway is the main pathway in coagulation
Heparin inhibits the activation of Factor 8
The activation of factor 8 is the point when the intrinsic and the extrinsic pathways meet
Tissue factor released by damaged tissue initiates the extrinsic pathway(Right)
Thrombin converts plasminogen to plasmin
……………………………………….
The extrinsic pathway is the main path of coagulation. Heparin inhibits the activation of factors 2,9,10,11. The activation of factor 10 is when both pathways meet. Thrombin converts fibrinogen to fibrin. During fibrinolysis plasminogen is converted to plasmin to break down fibrin.
52 of 192
A healthy man has a blood pressure of 120/80 mmHg and an intra cranial pressure of 17 mmHg. What is the approximate cerebral perfusion pressure?
76 mmHg
Cerebral perfusion pressure= Mean arterial pressure - intra cranial pressure
The mean arterial pressure can be calculated as:
MAP= Diastolic pressure+ 0.333(Systolic pressure- Diastolic pressure)
In this situation the MAP = 93.
The ICP is subtracted from this value; 93 - 17 = 76
54 of 192
The pressure within the pleural space is negative with respect to atmospheric pressure, except for which of the following?
During a Valsalva manoeuvre
During a Valsalva manoeuvre, the intra pleural pressure rises owing to extrinsic compression.
55 of 192
Which of the blood gas results listed below is most likely to fit with a patient who has acute respiratory acidosis?
pH 7.19, pCO 10.2, pO 16 (FiO 85%), Bicarbonate 23.8, Base excess -2.2 mmol
56 of 192
A patient has an arterial blood gas sample taken and the following result is obtained:
pH 7.48
pO 10.1
Bicarbonate 30
pCO 4.5
Chloride 10meq
What is the most likely cause?
Metabolic alkalosis
This would be a typical result of prolonged vomiting.
57 of 192
Which of the following substances is released from the sympathetic nervous system to stimulate the adrenal medulla?
Acetyl choline
In the autonomic nervous system, noradrenaline is the commonly used neurotransmitter. However, in the adrenal medulla, Acetylcholine is released to stimulate adrenaline release.
58 of 192
A 65 year old man is admitted for a below knee amputation. He is taking digoxin. Clinically the patient has an irregularly irregular pulse. What would you expect to see when you examine the jugular venous pressure?
Absent a waves
Jugular venous pressure
Absent a waves = Atrial fibrillation
Large a waves = Any cause of right ventricular hypertrophy, tricuspid stenosis
Cannon waves (extra large a waves) = Complete heart block
Prominent v waves = Tricuspid regurgitation
Slow y descent = Tricuspid stenosis, right atrial myxoma
Steep y descent = Right ventricular failure, constrictive pericarditis, tricuspid
regurgitation
This patient has atrial fibrillation and is most likely to have absent a waves.
61 of 192
Which of the following is not a feature of normal cerebrospinal fluid?
It has a pressure of between 10 and 15 mmHg.
It usually contains a small amount of glucose.
It may normally contain up to 5 red blood cells per mm .(Right)
It may normally contain up to 3 white blood cells per mm .
None of the above
………………………………………………
It should not contain red blood cells.
60 of 192
Which of the following is not an effect of somatostatin?
It stimulates pancreatic acinar cells to release lipase(Right)
It decreases gastric acid secretion
It decreases gastrin release
It decreases pepsin secretion
It decreases glucagon release
…………………………………………
It inhibits pancreatic enzyme secretion.
59 of 192
Which of the following is not secreted by the parietal cells?
Hydrochloric acid
Mucus (Right)
Magnesium
Intrinsic factor
Calcium
………………………………..
Chief of Pepsi cola = Chief cells secrete PEPSInogen
Parietal cells: secrete HCl, Ca, Na, Mg and intrinsic factor
Chief cells: secrete pepsinogen
Surface mucosal cells: secrete mucus and bicarbonate
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Which of the following is responsible for the rapid depolarisation phase of the myocardial action potential?
Rapid sodium influx
63 of 192
Which one of the following cells secretes the majority of tumour necrosis factor in humans?
Macrophages
64 of 192
Where are the arterial baroreceptors located?
Carotid sinus and aortic arch
65 of 192
A 47 year old lady is diagnosed as suffering from a phaeochromocytoma. From which of the following amino acids are catecholamines primarily derived?
Tyrosine
Catecholamine hormones are derived from tyrosine, it is modified by a DOPA decarboxylase enzyme to become dopamine and thereafter via two further enzymic modifications to noradrenaline and finally adrenaline.
66 of 192
Adult lung volumes. Which statement is false?
In restrictive lung disease the FEV1/FVC ratio is increased
Residual volume is increased in emphysema
Functional residual capacity is measured by helium dilution test
The tidal volume is approximately 340mls in females
The vital capacity is increased in Guillain Barre syndrome(Right)
…………………………………………………
FEV1/FVC is normal or >80% in restrictive lung disease such as pulmonary fibrosis. The ratio is reduced in obstructive airways disease.
The functional residual capacity, residual volume and the total lung capacity cannot be measured with spirometry. They can only be measured by helium dilution.
The vital capacity is reduced in:
1. Pulmonary fibrosis/infiltration/oedema/effusions
2. Weak respiratory muscles e.g. MG, GBS, myopathies
3. Skeletal abnormalities e.g. chest wall abnormalities
67 of 192
What is the most significant event to contribute to wound healing immediately following injury?
Platelet degranulation
Many of these events contribute to healing. However, platelet degranulation is the earliest phase and results in haemostasis, the main event in then allowing the release of cytokines to attract other cells types to the wound and co-ordinate healing.
68 of 192
Which receptor does noradrenaline mainly bind to?
α 1 receptors
Noradrenaline is the precursor of adrenaline. It is a powerful α 1 stimulant (although it will increase myocardial contractility). Infusions will produce vasoconstriction and an increase in total peripheral resistance. It is the inotrope of choice in septic shock.
69 of 192
Where does spironolactone act in the kidney?
Distal convoluted tubule
70 of 192
A man is admitted after a period of prolonged self, induced starvation. Naso gastric feeding is planned. Which of the following is least likely to occur?
His haemoglobin will have decreased affinity for oxygen
The process of starvation may lower DPG levels, in practice this is unlikely to occur early as it is generated during glycolysis. Altered metabolism in starvation may be more acidotic and this would also tend to impair oxygen carriage.
71 of 192
Which of the following statements are not typically true in hypokalaemia?
It may occur as a result of mechanical bowel preparation
Chronic vomiting may increase renal potassium losses
It may be associated with aciduria
It may cause hyponatraemia
It often accompanies acidosis(Right)
……………………………………………………………
Potassium depletion occurs either through the gastrointestinal tract or the kidney.
Chronic vomiting in itself is less prone to induce potassium loss than diarrhoea as gastric secretions contain less potassium than those in the lower GI tract. If vomiting produces a metabolic alkalosis then renal potassium wasting may occur as potassium is excreted in preference to hydrogen ions. The converse may occur in potassium depletion resulting in acid urine.
Hypokalemia is very commonly associated with metabolic alkalosis. This is due to 2 factors: 1) the common causes of metabolic alkalosis (vomiting, diuretics) directly induce H+ and K loss (via aldosterone) and thus also cause hypokalemia and 2) hypokalemia is a very important cause of metabolic alkalosis by three mechanisms. The initial effect is by causing a transcellular shift in which K leaves and H+ enters the cells, thereby raising the extracellular pH. The second effect is by causing a transcellular shift in the cells of the proximal tubules resulting in an intracellular acidosis, which promotes ammonium production and excretion.
Thirdly, in the presence of hypokalemia, hydrogen secretion in the proximal and distal tubules increases. This leads to further reabsorption of HCO3-. The net effect is an increase in the net acid excretion.
72 of 192
A 16 year old girl develops pyelonephritis and is admitted in a state of septic shock. Which of the following is not typically seen in this condition?
Increased cardiac output
Increased systemic vascular resistance(Right)
Oliguria may occur
Systemic cytokine release
Tachycardia
………………………………………………
Cardiogenic Shock:
e.g. MI, valve abnormality
increased SVR (vasoconstriction in response to low BP)
increased HR (sympathetic response)
decreased cardiac output
decreased blood pressure
Hypovolaemic shock:
blood volume depletion
e.g. haemorrhage, vomiting, diarrhoea, dehydration, third-space losses during major operations
increased SVR
increased HR
decreased cardiac output
decreased blood pressure
Septic shock:
occurs when the peripheral vascular dilatation causes a fall in SVR similar response may occur in anaphylactic shock, neurogenic shock
reduced SVR
increased HR
normal/increased cardiac output
decreased blood pressure
The SVR is reduced in sepsis and for this reason a vasopressor such as noradrenaline may be used if hypotension and oliguria remain a concern despite administration of adequate amounts of intravenous fluids.
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A 45 year old man is undergoing a small bowel resection. The anaesthetist decides to administer an intravenous fluid which is electrolyte rich. Which of the following most closely matches this requirement?
Hartmans
Hartmans solution is the most electrolyte rich. However, both pentastarch and gelofusine have more macromolecules.
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A 17 year old lady with long standing anorexia nervosa is due to undergo excision of a lipoma. Which of the following nutritional deficiencies is most likely to be implicated in poor collagen formation as the wound heals?
Deficiency of ascorbic acid
Vitamin C is involved in the cross linkage of collagen and impaired wound healing is well described in cases of vitamin C deficiency.
76 of 192
Which of the following statements relating the fluid physiology of a physiologically normal 70 Kg adult male is false?
He will have more water per unit of body weight than a female of similar weight
Plasma will comprise 25% of his body weight(Right)
Interstitial fluid will account for up to 24% of body water
Approximately 65% of total body water is intracellular
60% of his body weight is composed of water
…………………………………………………………….
The 60-40-20 rule:
60% total body weight is water
40% of total body weight is intracellular fluids
20% of body weight is extracellular fluids
Plasma typically accounts for 4-6% of body weight in healthy individuals.
Males typically have more water per unit weight than females, as females have a higher fat content.
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A 69 year old man has been living in sheltered accommodation for many months, with inadequate nutrition notices that his night vision is becoming impaired. Deficiency of which vitamin is responsible?
Vitamin A
Loss of vitamin A will result in impair rhodopsin synthesis and results in poor night vision.
77 of 192
Which of the following statements relating to blood transfusions in surgical patients is false?
Packed red cells typically have a haematocrit of between 55 and 75%
Clotting factor activity in whole blood decreases in samples stored for longer than 7 days
After 3 weeks of storage blood has a pH of 6.9
Gamma irradiated blood products are not required routinely
Patients should be transfused to achieve a target haemoglobin of 10 g/dl and a haematocrit of 30%(Right)
………………………………………………..
Patients can generally be managed without transfusion as long as the Hb is 7 or greater. The exact level depends upon patient factors such as co-morbidities. Old blood functions less effectively and should not be used during massive transfusions.
80 of 192
Which of the following mechanisms best accounts for the release of adrenaline?
Release from the adrenal medulla in response to sympathetic stimulation from the splanchnic nerves
The adrenal gland releases adrenaline in response to increased sympathetic discharge from preganglionic sympathetic fibres of the splanchnic nerves. These cause the chromafin cells of the medulla to release adrenaline (which is preformed) by exocytosis.
79 of 192
The acute phase response to injury does not typically include:
Pyrexia
Decreased albumin
Hepatic sequestration of cations
Increased transferrin(Right)
Increased serum amyloid A
…………………………………………………
The acute phase response includes:
Acute phase proteins
Reduction of transport proteins (albumin, transferrin)
Hepatic sequestration cations
Pyrexia
Neutrophil leucocytosis
Increased muscle proteolysis
Changes in vascular permeability
81 of 192
A 43 year old lady is admitted with cholestasis secondary to a stone impacted at the level of the ampulla of vater. Which of the following tests is most likely to be predictive of bleeding diathesis at the time of ERCP in this particular case?
Prothrombin time’
PT: Vitamin K dependent factors 2, 7, 9, 10
APTT: Factors 8, 9, 11, 12
Jaundice will impair the production of vitamin K dependent clotting factors. This is most accurately tested by measuring the prothrombin time. APTT can be affected by vitamin K deficiency (due to factor 9 deficiency), however this occurs to a lesser extent and is normally associated with severe liver disease. The bleeding time is a measure of platelet function.
82 of 192
Which of the following hormonal agents will increase secretions of water and electrolytes in pancreatic juice?
Secretin
Secretin causes secretion of water and electrolytes
Cholecystokinin causes enzyme secretion
While secretin will typically increase electrolyte and water volume of secretions, the enzyme content is increased by cholecystokinin. Somatostatin will decrease the volume of secretions. Aldosterone will tend to conserve electrolytes.
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A 73 year old lady is diagnosed with hyperaldosteronism. From which of the following structures is aldosterone released?
Zona glomerulosa of the adrenal cortex
Aldosterone serves to conserve sodium and water. It is produced in the zona glomerulosa of the adrenal cortex.
84 of 192
Which of the following inhibits gastric acid secretion?
Nausea
Nausea inhibits gastric secretion via higher cerebral activity and sympathetic innervation.
85 of 192
A 22 year old man is undergoing a daycase excision of a sebaceous cyst. He is needle phobic and as the surgeon approaches with the needle the patient begins to hyperventilate. He soon develops circumoral parasthesia and muscular twitching. Which of the following is the most likely explanation for this event?
Reduction in ionised calcium levels
50% of plasma calcium is ionised. Hyperventilation will induce a state of alkalosis which will lower ionised plasma calcium levels.
86 of 192
Which of the following statements relating to gastric acid secretions are untrue?
In parietal cells carbonic anhydrase generates hydrogen ions which are then actively secreted
The cephalic phase is abolished following truncal vagotomy
The intestinal phase accounts for 60% of gastric acid produced(Right)
Histamine acts in a paracrine manner on H receptors
H receptor antagonists will not completely abolish gastric acid production
………………………………………………………
The intestinal phase of gastric acid secretion accounts for only 10% of gastric acid produced.
88 of 192
A 34 year old lady develops septic shock and features of the systemic inflammatory response syndrome as a complication of cholangitis. Which of the following is not a typical feature of this condition?
Body temperature less than 36 C or greater than 38 C
Respiratory rate >20
Lactate <4 mmol/L(Right)
High levels of tumour necrosis factor α
WCC >12,000 mm3
……………………………………………
Septic shock will typically result in end organ hypoperfusion and as a result lactate levels will often be high. In the surviving sepsis campaign it is suggested that elevated lactate levels are an independent indicator for vasopressor support in patient with sepsis. The WCC may be paradoxically low in severe sepsis, although it is most often elevated.
87 of 192
Which of the following stimulates gastric acid secretion?
Histamine
……………………………………
Gastrin: From G cells: stimulates gastric acid production
Pepsin: Digestion of protein, secretion occurs simultaneously with gastrin
Secretin: From mucosal cells in the duodenum and jejunum: inhibits gastric acid, stimulates bile and pancreatic juice production
Gastric inhibitory peptide: (produced in response to fatty acids) inhibits gastrin release and acid secretion from parietal cells
Cholecystokinin: From mucosal cells in the duodenum and jejunum (produced in response to fatty acids) inhibits acid secretion from parietal cells, causes gallbladder contraction and relaxation of sphincter of Oddi
Somatostatin: From D cells
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Release of somatostatin from the pancreas will result in which of the following?
Decrease in pancreatic exocrine secretions
Octreotide reduces exocrine pancreatic secretions so is used to treat high output pancreatic fistulae (though parenteral feeding is most effective). Other uses include variceal bleeding and treatment of acromegaly.
Inhibits growth hormone and insulin release (when released from pancreas).
Somatostatin is also released by the hypothalamus causing a negative feedback response on growth hormone.
90 of 192
Which of the following is least likely to be associated with hypercalcaemia?
Thiazides
Antacids
Coeliac disease(Right)
Sarcoidosis
Zolinger-Ellison syndrome
…………………………………………………..
Mnemonic for the causes of hypercalcaemia:
CHIMPANZEES
C alcium supplementation
H yperparathyroidism
I atrogentic (Drugs: Thiazides)
M ilk Alkali syndrome
P aget disease of the bone
A cromegaly and Addison’s Disease
N eoplasia
Z olinger-Ellison Syndrome (MEN Type I)
E xcessive Vitamin D
E xcessive Vitamin A
S arcoidosis
Patients with coeliac disease tend to develop hypocalcaemia due to malabsorption of calcium by the bowel.
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Which of the following does not cause a normal anion gap acidosis?
Pancreatic fistula
Acetazolamide
Uraemia(Right)
Ureteric diversion
Renal tubular acidosis
………………………………………………..
Normal Gap Acidosis: HARDUP
H - Hyperalimentation/hyperventilation
A - Acetazolamide
R - Renal tubular acidosis
D - Diarrhoea
U - Ureteral diversion
P - Pancreatic fistula/parenteral saline
Uraemia will typically cause a high anion gap acidosis. It is one of the unmeasured anions.
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Which one of the following would cause a rise in the carbon monoxide transfer factor (TLCO)?
Pulmonary haemorrhage
Transfer factor
raised: asthma, haemorrhage, left-to-right shunts, polycythaemia
low: everything else
Where alveolar haemorrhage occurs the TLCO tends to increase due to the enhanced uptake of carbon monoxide by intra-alveolar haemoglobin.
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An arterial blood gas sample is taken and the following results obtained;
PaO 8kPa
PaCO 4kPa
pH 7.4
With which of the following are these values most consistent?
Residing at 4500M for 48 hours
The patient has low oxygen tension and low carbon dioxide. The pH is normal so there is compensation for a long standing condition in which oxygenation is reduced. There is neither alkalosis, nor hypoventilation as the carbon dioxide is low. At very high altitude, the low oxygen tension can exceed the anaerobic threshold and carbon dioxide levels increase.
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Which of the following is not a characteristic of the proximal convoluted tubule in the kidney?
Up to 95% of filtered amino acids will be reabsorbed at this site
It is a risk of damage in a patient with compartment syndrome due to a tibial fracture
It is responsible for absorbing more than 50% of filtered water
Its secretory function is most effective at low systolic blood pressures (typically less than 100mmHg)(Right)
Glucose is reabsorbed by a process of facilitated diffusion
………………………………………
The proximal convoluted tubule may undergo necrosis in situations such as compartment syndrome. It is responsible for reabsorbing up to two thirds of filtered water. Low systolic blood pressures (below the renal autoregulatory range) are a risk factor for acute tubular necrosis. Within the autoregulatory range the absolute value of systolic BP has little effect.
96 of 192
A 39 year old lady has recurrent attacks of biliary colic. What is the approximate volume of bile to enter the duodenum per 24 hours?
500 mL
Between 500 mL and 1.5 L of bile enters the small bowel daily. Most bile salts are recycled by the enterohepatic circulation. When the gallbladder contracts the lumenal pressure is approximately 25cm water, which is why biliary colic may be so painful.
95 of 192
At which of the following sites is the most water absorbed?
Jejunum
Water absorption in the gastrointestinal tract predominantly occurs in the small bowel (jejunum and ileum). The colon is an important site of water absorption, however, its overall contribution is relatively small. The importance of the colonic component to water absorption may increase following extensive small bowel resections.
97 of 192
A 24 year old man is involved in a road traffic accident. His right leg is trapped for 6 hours whilst he is moved. On examination his foot is insensate and a dorsalis pedis pulse is only weakly felt. Which of the biochemical abnormalities listed below is most likely to be present?
Hyperkalaemia
In this scenario the patient will have a compartment syndrome, delayed diagnosis and muscle death. The effect of muscle death will result in the release of potassium. It is also highly likely that there will be a degree of renal impairment, the result of which is that the serum potassium is likely to be high.
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A 45 year old man sustains a closed head injury. He is initially alert, however, his level of consciousness deteriorates on arrival at hospital. An intra cranial pressure monitor is inserted. What is the normal intracranial pressure?
<15mm Hg
The normal intracranial pressure is between 7 and 15 mm Hg. The brain can accommodate increases up to 24 mm Hg, thereafter clinical features will become evident.
98 of 192
A 55-year-old man with a history of type 2 diabetes mellitus, bipolar disorder and chronic obstructive pulmonary disease has bloods taken during a pre operative assessment of an inguinal hernia repair:
Na+ 125 mmol/l
K+ 3.8 mmol/l
Bicarbonate 24 mmol/l
Urea 3.7 mmol/l
Creatinine 92 μmol/l
Due to his smoking history a chest x-ray is ordered which is reported as normal. The Consultant asks you what is the most likely cause for the hyponatraemia?
Carbamazepine
SIADH - drug causes: carbamazepine, sulfonylureas, SSRIs, tricyclics
Lithium can cause diabetes insipidus but this is generally associated with a high sodium. Lithium only tends to cause raised antidiuretic hormone levels following a severe overdosage.
100 of 192
Which substance can be used to achieve the most accurate measurement of the glomerular filtration rate?
Inulin
Creatinine declines with age due to decline in renal function and muscle mass.
Glucose, protein (amino acids) and PAH are reabsorbed by the kidney.
101 of 192
Which of the following statements relating to cerebrospinal fluid is untrue?
The choroid plexus is only present in the lateral ventricles(Right)
Total CSF volume is 100-150ml
CSF pressure is usually 10-15mmHg
The cerebral aqueduct connects the third and fourth ventricles
The foramen of Luschka are paired and lie laterally in the fourth ventricle
…………………………………………
The choroid plexus lies in all ventricles.
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A 73 year old man presents to pre operative clinic for an elective total hip replacement. He is on furosemide for hypertension. His investigations reveal to the following results:
Na 120
Urine Na 10 (low)
Serum osmolality 280 (normal)
What is the most likely cause?
Hypotonic hypovolaemic hyponatraemia
The blood results reflect extra-renal sodium loss. The body is trying to preserve the sodium by not allowing any sodium into the urine (hence the low Na in the urine).
Note with renal sodium loss the Urinary sodium is high.
102 of 192
A 74-year-old woman with thyroid cancer is admitted due to shortness of breath.
What is the best investigation to assess for possible compression of the upper airways?
Flow volume loop
Flow volume loop is the investigation of choice for upper airway compression.
103 of 192
Which of the following drugs does not cause pseudohaematuria?
Rifampicin
Quinine
Noradrenaline(Right)
Levodopa
Phenytoin
…………………………………………………..
Rifampicin, phenytoin, levodopa, methyldopa, and quinine all cause pseudohaematuria.
104 of 192
A 19 year old man is attacked outside a club and beaten with a baseball bat. He sustains a blow to the right side of his head. He is brought to the emergency department and a policy of observation is adopted. His glasgow coma score deteriorates and he becomes comatose. Which of the following haemodynamic parameters is most likely to be present?
Hypertension and bradycardia
Hypertension and bradycardia are seen prior to coning. The brain autoregulates its blood supply by controlling systemic blood pressure.
105 of 192
An elderly lady who presented with weight loss and malabsorption was found to have amyloid of the small bowel. On presentation she was found to have osteomalacia and was hypocalcaemic. Over the past seven days she has received total parenteral nutrition with adequate calcium replacement. Despite this she remained hypocalcaemic. Deficiency of which of the following electrolytes is most likely to account for this process?
Magnesium
Patients with malabsorption may develop magnesium deficiency, although her TPN feeds may have contained magnesium it may not have been sufficient to correct her losses. Sodium, phosphate and potassium would not have this effect on serum calcium.
106 of 192
Which of the following drugs does not interfere with the laboratory analysis of serum cortisol levels?
Dexamethasone(Right)
Prednisolone
Hydrocortisone IV
Hydrocortisone PO
Hydrocortisone IM
………………………………………………
Prednisolone and it’s metabolites can chemically mimic cortisol in radio- immunoassay techniques of laboratory analysis.
Dexamethasone can be given as glucorticoid replacement during testing for addisons or adrenal insufficiency as it does not interfere with cortisol levels. For example, if you have a patient with polymyalgia rheumatica and they are on long term prednisolone, you can replace the prednisolone with dexamethasone to undertake a short synacthen test.
107 of 192
A 55 year old male is diagnosed with carcinoma of the head of the pancreas. He reports that his stool sticks to the commode and will not flush away. Loss of which of the following enzymes is most likely to be responsible for this problem?
Lipase
Loss of lipase is one of the key features in the development of steatorrhoea which typically consists of pale and offensive stools that are difficult to flush away.
108 of 192
Which of the following substances related to thyroid function has its secretion inhibited by increased plasma T3 and T4?
Thyroid stimulating hormone
TSH release is inhibited by negative feedback.
110 of 192
Which one of the following is associated with increased lung compliance?
Emphysema
109 of 192
Which of the following areas is predominantly concerned with thermoregulation?
Hypothalamus
The hypothalamus is primarily concerned with thermoregulation. It may relay to the cerebral cortex to induce behavioural adaptation to facilitate the thermoregulatory process.
111 of 192
Which of the following is not a major function of the spleen in adults?
Iron reutilisation
Storage of platelets
Storage of monocytes
Haematopoeisis in haematological disorders
Storage red blood cells(Right)
……………………………………………
The reservoir function of the spleen is less marked in humans than other animals (e.g. pigs) and in normal individuals it can sequester between 5 and 10% of the red cell mass. The other stated processes are major splenic functions and this accounts for the answer provided.
112 of 192
A 55 year old man undergoes a laparotomy and repair of incisional hernia. Which of the following hormones is least likely to be released in increased quantities following the procedure?
Insulin(Right)
ACTH
Glucocorticoids
Aldosterone
Growth hormone
…………………………………………..
Insulin and thyroxine are often have reduced levels of secretion in the post operative period. This, coupled with increased glucocorticoid release may cause difficulty in management of diabetes in individuals with insulin resistance.
114 of 192
Which one of the following reduces the secretion of renin?
Beta-blockers
113 of 192
Which of the following stimulates prolactin release or action?
Thyrotropin releasing hormone
TRH stimulates prolactin release. Dopamine suppresses the release of prolactin.
115 of 192
A 22 year old lady receives intravenous morphine for acute abdominal pain. Which of the following best accounts for its analgesic properties?
Binding to μ opioid receptors within the CNS
4 Types of opioid receptor:
δ (located in CNS)- Accounts for analgesic and antidepressant effects
k (mainly CNS)- analgesic and dissociative effects
μ (central and peripheral) - causes analgesia, miosis, decreased gut motility
Nociceptin receptor (CNS)- Affect of appetite and tolerance to μ agonists.
118 of 192
A patient has an arterial blood gas sample which provides the following result:
pH 7.20
pO 7.5
Bicarbonate 22
pCO 8.1
Chloride 10meq
What is the most likely cause?
Type II respiratory failure
This is a sign of acute type 2 respiratory failure (non compensated). This is the result of carbon dioxide retention.
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The oxygen-haemoglobin dissociation curve is shifted to the left in:
With decreased 2,3-DPG in transfused red cells
……………………………………………
S shaped curve
The curve is shifted to the left when there is a decreased oxygen requirement by the tissue. This includes:
1. Hypothermia
2. Alkalosis
3. Reduced levels of DPG:
DPG is found in erythrocytes and is reduced in non exercising muscles, i.e. when there is reduced glycolysis.
4. Polycythaemia
116 of 192
A 77 year old man presents to pre operative clinic for a total knee replacement. He is on furosemide for hypertension. He is known to have multiple myeloma. He is found to have the following test results:
Na 120
Serum osmolality 280 (normal)
Urine osmolality normal
Urine Na normal
What is the most likely cause?
Pseudohyponatraemia
Hyperlipidaemia and multiple myeloma are known to cause a pseudohyponatraemia, this is due to raised protein.
117 of 192
A homeless 42 year old male had an emergency inguinal hernia repair 24 hours previously. He has a BMI of 15. He has been put on a feeding regime of 35 kcal/kg/day with no additional medications. The nursing staff contact you as he has become confused and unsteady. On examination the patient is disorientated to place, has diplopia and nystagmus. What is the most likely diagnosis?
Wernickes encephalopathy
Triad of Wernicke encephalopathy:
Acute confusion
Ataxia
Ophthalmoplegia
This patient has received a carbohydrate rich diet without any thiamine or vitamin B co strong replacement. This has led to Wernickes encephalopathy, which classically presents with confusion, ataxia and ophthalmoplegia. Characteristically it is associated with chronic alcoholism, however it is also known to occur post bariatric surgery.
122 of 192
Which one of the following serum proteins is most likely to increase in a patient with severe sepsis?
Ferritin
Ferritin can be markedly increased during acute illness. The other parameters tend to decrease during an acute phase response.
121 of 192
A 23 year old man has a routine ECG performed. Which part of the tracing obtained represents atrial repolarisation?
wave
T wave
Q-T Interval
P-R interval
None of the above(Right)
………………………………………….
The process of atrial repolarisation is generally not visible on the ECG strip. It occurs during the QRS complex.
120 of 192
A 72-year-old woman is admitted to the acute surgical unit with profuse vomiting.
Admission bloods show the following:
Na+ 131 mmol/l
K+ 2.2 mmol/l
Urea 3.1 mmol/l
Creatinine 56 micro mol/l
Glucose 4.3 mmol/l
Which one of the following ECG features is most likely to be seen?
U waves
…………………………
Hypokalaemia - U waves on ECG
J waves are seen in hypothermia whilst delta waves are associated with Wolff Parkinson White syndrome.
124 of 192
Which of the following is not an effect of cholecystokinin?
It causes gallbladder contraction
It increases the rate of gastric emptying(Right)
It relaxes the sphincter of oddi
It stimulates pancreatic acinar cells
It has a trophic effect on pancreatic acinar cells
……………………………………………….
it decreases the rate of gastric emptying.
125 of 192
A 24 year old man is injured in a road traffic accident. He becomes oliguric and his renal function deteriorates. Which of the options below would favor acute tubular necrosis over pre renal uraemia?
No response to intravenous fluids
In acute tubular necrosis there is no response to intravenous fluids because the damage occurs from within the renal system rather than as a result of volume depletion.
123 of 192
Which part of the jugular venous waveform is associated with the closure of the tricuspid valve?
c wave
JVP: C wave - closure of the tricuspid valve
The c wave of the jugular venous waveform is associated with the closure of the tricuspid valve.
126 of 192
Which statement about peristalsis is true?
Longitudinal smooth muscle propels the food bolus through the oesophagus(Right)
Secondary peristalsis occurs when there is no food bolus in the oesophagus
Food transfer from the oesophagus to the stomach is 4 seconds
Circular smooth muscle is not involved in peristalsis
Peristalsis only occurs in the oesophagus
……………………………………
127 of 192
What is the main component of colloid in the thyroid gland?
Thyroglobulin
It is a high molecular weight protein that acts as a storage form of thyroid hormones.
135 of 192
Which of the following is not linked to excess glucocorticoids?
Osteonecrosis
Osteoporosis
Hypokalaemia
Hyponatraemia(Right)
Growth retardation in children
……………………………………..
There are many adverse effects associated with excess glucocorticoids. Thinning of the skin, osteonecrosis and osteoporosis are all common. Steroids are associated with retention of sodium and water. Potassium loss may occur and hypokalaemic alkalosis has been reported.
131 of 192
Which of the following is the equivalent of cardiac preload?
End diastolic volume
Preload is the same as end diastolic volume. When it is increased slightly there is an associated increase in cardiac output (Frank Starling principle). When it is markedly increased e.g. over 250ml then cardiac output falls.
128 of 192
Which of the following is least likely to cause a prolonged prothrombin time?
Cholestatic jaundice
Disseminated intravascular coagulation
Prolonged antibiotic treatment
Liver disease
Acquired factor 12 deficiency (Right)
………………………………………
Vitamin K deficiency results from cholestatic jaundice and prolonged antibiotic therapy. Acquired factor 12 deficiency causes prolonged APTT.
132 of 192
A 33 year old female is admitted for varicose vein surgery. She is fit and well. After the procedure she is persistently bleeding. She is known to have menorrhagia.
Investigations show a prolonged bleeding time and increased APTT. She has a normal PT and platelet count. What is the most likely cause?
von Willebrands disease
Bleeding post operatively, epistaxis and menorrhagia may indicate a diagnosis of vWD. Haemoarthroses are rare. The bleeding time is usually normal in haemophilia (X-linked) and vitamin K deficiency.
129 of 192
A 73 year old female is referred to the surgical clinic with an iron deficiency anaemia. As part of the diagnostic work up the doctor requests a serum ferritin level. Which of the conditions listed is most likely to lead to a falsely elevated result?
Locally perforated sigmoid colonic adenocarcinoma
A locally perforated colonic tumour will typically cause an intense inflammatory response and if peritonitis is not present clinically then at the very least a localised abscess. This inflammatory process is the most likely (from the list) to falsely raise the serum ferritin level. Angiodysplasia and dieulafoy lesions are mucosal arteriovenous malformations and unlikely to result in considerable inflammatory activity.
130 of 192
A 48 year old man undergoes a right hemicolectomy for a large caecal polyp. In the immediate post operative period which of the physiological processes described below is least likely to occur?
Glycogenolysis
Increased production of acute phase proteins
Increased cortisol production
Bronchoconstriction(Right)
Release of nitric oxide by vessels
133 of 192
A 43 year old man has a nasogastric tube inserted. The nurse takes a small aspirate of the fluid from the stomach and tests the pH of the aspirate. What is the normal intragastric pH?
2
The intragastric pH is usually 2. Administration of proton pump inhibitors can result in almost complete abolition of acidity
137 of 192
Which of the following drugs causes hyperkalaemia?
Heparin
Both unfractionated and low-molecular weight heparin can cause hyperkalaemia.
This is thought to be caused by inhibition of aldosterone secretion. Salbutamol is a recognised treatment for hyperkalaemia.
134 of 192
A 54-year-old woman is admitted to the Surgical Admissions Unit with abdominal pain. Blood tests taken on admission show the following:
Magnesium 0.40 mmol/l (normal value 0.7-1.0 mmol/l)
Which one of the following factors is most likely to be responsible for this result?
Diarrhoea
136 of 192
A 25-year-old man who has been morbidly obese for the past five years is reviewed in the surgical bariatric clinic. In this patient, release of which of the following hormones would increase appetite?
Ghrelin
Obesity hormones
leptin decreases appetite
ghrelin increases appetite
Whilst thyroxine can increase appetite it does not fit with the clinical picture being described.
138 of 192
A 39 year old lady undergoes a laparoscopic cholecystectomy as a daycase. The operation is more difficult than anticipated and the surgeon places a drain to the liver bed. In recovery 1.5 litres of blood is seen to enter the drain. Which of the following substances is the first to be released in this situation?
Renin
The decrease in blood pressure will be sensed by the juxtaglomerular cells in the kidney. This will cause renin secretion.
139 of 192
Which of the following statements relating to the regulation of renal blood flow is untrue?
In a healthy 70Kg male, the glomerular filtration rate will be the same at a systolic blood pressure of 120mmHg as a systolic blood pressure of 95 mmHg
Over 90% of the blood supply to the kidney is distributed to the cortex
The kidney receives approximately 25% of the total cardiac output at rest
A decrease in renal perfusion pressure will cause the juxtaglomerular cells to secrete renin
Systolic blood pressures of less than 65mmHg will cause the mesangial cells to secrete aldosterone(Right)
…………………………………………………
The kidney autoregulates its blood supply over a range of systolic blood pressures.
Drop in arterial pressure is sensed by the juxtaglomerular cells and renin is released leading to the activation of the renin-angiontensin system. Mesangial cells are contractile cells that are located in the tubule and have no direct endocrine function.
140 of 192
Which of the following features does not put a patient at risk of refeeding syndrome?
Thyrotoxicosis
Diuretics increase the risk of re-feeding syndrome through a process of increasing the risk of depletion of key electrolytes.
146 of 192
A 34 year old man presents with a peptic ulcer. Which of the following is responsible for the release of gastric acid?
Parietal cells
Parietal cells are responsible for the release of gastric acid. Brunners glands are found in the duodenum.
142 of 192
A 52 year old man develops septic shock following a Hartmans procedure for perforated diverticular disease. He is started on an adrenaline infusion. Which of the following is least likely to occur?
Coronary artery vasospasm
It’s cardiac effects are mediated via β 1 receptors. The coronary arteries which have β 2 receptors are unaffected.
141 of 192
Intra cranial pressure is governed by the principles of the Monroe-Kellie doctrine.
To which of the following does this concept not apply?
A 2 month old child(Right)
A 2 year old child
A 5 year old child
A 10 year old child
An adult
………………………………………
The Monroe-Kelly Doctrine assumes that the cranial cavity is a rigid box. In children with non fused fontanells this is not the case.
144 of 192
Which of these substances is not released from the islets of Langerhans?
Pancreatic polypeptide
Glucagon
Secretin(Right)
Somatostatin
Insulin
…………………………….
Secretin is released from mucosal cells in the duodenum and jejunum.
143 of 192
Which of the following does not cause hyperkalaemia?
Haemolysis
Burns
Familial periodic paralysis
Type 4 renal tubular acidosis
Severe malnutrition(Right)
…………………………………………..
‘Machine’ - Causes of Increased Serum K
M - Medications - ACE inhibitors, NSAIDS
A - Acidosis - Metabolic and respiratory
C - Cellular destruction - Burns, traumatic injury
H - Hypoaldosteronism, haemolysis
I - Intake - Excessive
N - Nephrons, renal failure
E - Excretion - Impaired
Familial periodic paralysis has subtypes associated with hyper and hypokalaemia.
151 of 192
Which of the following will increase the volume of pancreatic exocrine secretions?
Cholecystokinin
Cholecystokinin will often increase the volume of pancreatic secretions.
145 of 192
Which of the following does not lead to relaxation of the lower oesophageal sphincter?
Metoclopramide(Right)
Botulinum toxin type A
Nicotine
Alcohol
Theophylline
………………………………………..
Metoclopramide acts directly on the smooth muscle of the LOS to cause it to contract.
Theophylline is a phosphodiesterase inhibitor (mimics action of prostaglandin E1) which causes relaxation of the LOS.
149 of 192
Which opioid receptor does morphine attach to?
mu
Pethidine and other conventional opioids attach to this receptor.
147 of 192
A 43 year old lady is diagnosed with primary hyperparathyroidism. Her serum PTH levels are elevated. An endocrine surgeon performs a parathyroidectomy. How long will it take for the serum PTH levels to fall if the functioning adenoma has been successfully removed?
10 minutes
PTH has a very short half life usually less than 10 minutes. Therefore a demonstrable drop in serum PTH should be identified within 10 minutes of removing the adenoma. This is useful clinically since it is possible to check the serum PTH intraoperatively prior to skin closure and explore the other glands if levels fail to fall.
148 of 192
Which of the following inhibits the secretion of insulin?
Adrenaline
Inhibition of insulin release:
Alpha adrenergic drugs
Beta blockers
Sympathetic nerves
150 of 192
Where is the majority of iron found in the body?
Haemoglobin
Approximately 70% of body iron is found bound to haemoglobin.
152 of 192
Which of the following does not cause an increased anion gap acidosis?
Uraemia
Paraldehyde
Diabetic ketoacidosis
Ethylene glycol
Acetazolamide(Right)
………………………………………………..
Causes of increased anion acidosis: MUDPILES
M - Methanol
U - Uraemia
D - DKA/AKA
P - Paraldehyde/phenformin
I - Iron/INH
L - Lactic acidosis
E - Ethylene glycol
S - Salicylates
154 of 192
Which of the substances below is derived primarily from the zona reticularis of the adrenal gland?
Sex hormones
153 of 192
Which of the following statements about blood clotting is untrue?
Platelet adhesion to disrupted endothelium is dependent upon von Willebrand factor
Protein C is a vitamin K dependent substance
The bleeding time provides an assessment of platelet function
The prothrombin time tests the extrinsic system
Administration of aprotinin during liver transplantation surgery prolongs survival(Right)
…………………………………………………………
Although aprotinin reduces fibrinolysis and thus bleeding, it is associated with increased risk of death and was withdrawn in 2007. Protein C is dependent upon vitamin K and this may paradoxically increase the risk of thrombosis during the early phases of warfarin treatment.
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A patient is seen in clinic complaining of abdominal pain. Routine bloods show:
Na+ 142 mmol/l
K+ 4.0 mmol/l
Chloride 104 mmol/l
Bicarbonate 19 mmol/l
Urea 7.0 mmol/l
Creatinine 112 μmol/l
What is the anion gap?
23 mmol/L
The anion gap may be calculated by using (sodium + potassium) - (bicarbonate + chloride)
= (142 + 4.0) - (104 + 19) = 23 mmol/L
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A 48 year old woman suffers blunt trauma to the head and develops respiratory compromise. As a result she develops hypercapnia. Which of the following effects is most likely to ensue?
Cerebral vasodilation
Hypercapnia will tend to produce cerebral vasodilation. This is of considerable importance in patients with cranial trauma as it may increase intracranial pressure.
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A 53 year old man is on the intensive care unit following an emergency abdominal aortic aneurysm repair. He develops abdominal pain and diarrhoea and is profoundly unwell. His abdomen has no features of peritonism. Which of the following arterial blood gas pictures is most likely to be present?
pH 7.20, pO 9.0, pCO 3.5, Base excess -10, Lactate 8
This man is likely to have a metabolic acidosis secondary to a mesenteric infarct.
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The Cori cycle is important in lactate metabolism in the septic surgical patient. It is used to describe a pathway in which glucose is metabolised anaerobically to lactate in one tissue and the lactate is converted back to glucose in another. Which one of the following relies on this cycle to meet all of its energy needs?
Erythrocyte
Erythrocytes lack a mitochondria and therefore they generate energy via glycolytic pathways only. All the other cell types have mitochondria and will therefore use the Krebs cycle unless true anaerobic conditions prevail.
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Which of these fluids is not an intravenous colloid?
Gelofusine
Dextran 40
Human albumin solution
Hydroxyethyl starch
Bicarbonate 8.4%(Right)
………………………………………………….
Bicarbonate is a crystalloid.
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Cortisol is predominantly produced by which of the following?
Zona fasciculata of the adrenal(Right)
Zona glomerulosa of the adrenal
Zona reticularis of the adrenal
Adrenal medulla
Posterior lobe of the pituitary
…………………………………………
Relative Glucocorticoid activity:
Hydrocortisone = 1
Prednisolone = 4
Dexamethasone = 25
Cortisol is produced by the zona fasciculata of the adrenal gland.
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A 34 year old male donates a unit of blood. It is stored at 4 C. After 72 hours which of the following clotting factors will be most affected?
Factor VIII
Factors V and VIII are sensitive to temperature which is the reason why FFP is frozen soon after collection.
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A 44 year old lady presents with jaundice. Following a minor ward based surgical procedure she develops troublesome and persistent bleeding. Deficiency of which of the vitamins listed below is responsible?
Vitamin K
Patients who are jaundiced usually have impaired absorption of vitamin K. This can result in loss of the vitamin K dependent clotting factors and troublesome bleeding.
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A 23 year old man presents with blunt abdominal trauma and a splenic bleed is suspected. He is commenced on an infusion of tranexamic acid. Which of the following best describes its mechanism of action?
Inhibition of plasmin
Tranexamic acid inhibits plasmin and this prevents fibrin degradation.
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A 34 year old lady has just undergone a parathyroidectomy for primary hyperparathyroidism. The operation is difficult and all 4 glands were explored. The wound was clean and dry at the conclusion of the procedure and a suction drain inserted. On the ward she becomes irritable and develops stridor. On examination, her neck is soft and the drain empty. Which of the following treatments should be tried initially?
Administration of intravenous calcium gluconate
Exploration of the parathyroid glands may result in impairment of the blood supply. Serum PTH levels can fall quickly and features of hypocalcaemia may ensue, these include neuromuscular irritability and laryngospasm. Prompt administration of intravenous calcium gluconate can be lifesaving. The absence of any neck swelling and no blood in the drain would go against a contained haematoma in the neck (which should be managed by removal of skin closure).
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What is the approximate volume of pancreatic secretions in a 24 hour period?
1500ml
Typically the pancreas secretes between 1000 and 1500ml per day.
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A patient loses 1.6L of fresh blood from their abdominal drain. Which of the following will not decrease?
Cardiac output
Renin secretion(Right)
Firing of carotid baroreceptors
Firing of aortic baroreceptors
Blood pressure
…………………………………………………….
Renin secretion will increase as systemic hypotension will cause impairment of renal blood flow. Although the kidney can autoregulate its own blood flow over a range of systemic blood pressures a loss of 1.6 L will usually produce an increase in renin secretion.
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What is the typical stroke volume in a resting 70 Kg man?
70ml
Stroke volumes range from 55-100ml.
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Secretions from which of the following will contain the highest levels of potassium?
Rectum
The rectum has the potential to generate secretions rich in potassium. This is the rationale behind administration of resins for hyperkalaemia and the development of hypokalaemia in patients with villous adenoma of the rectum.
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An otherwise fit 30 year old male donates 500ml of blood. Which of the processes outlined below is most likely to occur?
Activation of the renin angiotensin system
The loss of 500ml (assuming a 70 Kg male) will usually be sufficient to activate the renin angiotensin system. It is unlikely that it would cause any other physiological disturbance.
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Which of the following does not decrease the functional residual capacity?
Obesity
Pulmonary fibrosis
Muscle relaxants
Laparoscopic surgery
Upright position(Right)
…………………………………..
Increased FRC:
Erect position
Emphysema
Asthma
Decreased FRC:
Pulmonary fibrosis
Laparoscopic surgery
Obesity
Abdominal swelling
Muscle relaxants
When the patient is upright the diaphragm and abdominal organs put less pressure on the lung bases, allowing for an increase in the functional residual capacity (FRC). Other causes of increased FRC include:
Emphysema
Asthma
In addition to those listed above, causes of reduced FRC include:
Abdominal swelling
Pulmonary oedema
Reduced muscle tone of the diaphragm
Age
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Which of the following haemodynamic changes is not seen in hypovolaemic shock?
Decreased cardiac output
Increased heart rate
Reduced left ventricle filling pressures
Reduced blood pressure
Reduced systemic vascular resistance(Right)
……………………………………………………………….
Cardiogenic Shock:
e.g. MI, valve abnormality
increased SVR (vasoconstriction in response to low BP)
increased HR (sympathetic response)
decreased cardiac output
decreased blood pressure
Hypovolaemic shock:
blood volume depletion
e.g. haemorrhage, vomiting, diarrhoea, dehydration, third-space losses during major operations
increased SVR
increased HR
decreased cardiac output
decreased blood pressure
Septic shock:
occurs when the peripheral vascular dilatation causes a fall in SVR similar response may occur in anaphylactic shock, neurogenic shock
reduced SVR
increased HR
normal/increased cardiac output
decreased blood pressure
SVR will typically increase
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Which of the following does not stimulate insulin release?
Gastrin
Atenolol(Right)
Protein
Secretin
Vagal cholinergic action
……………………………………….
Beta blockers inhibit the release of insulin.
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A 32 year old man has a glomerular filtration rate of 110ml / minute at a systolic blood pressure of 120/80. If his blood pressure were to fall to 100/70 what would glomerular filtration rate be?
110ml / minute
The proposed drop in blood pressure falls within the range within which the kidney autoregulates its blood supply. GFR will therefore remain unchanged.
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A 23 year old man has taken an opiate overdose. Of the following structures, which will be most affected by opiates to produce a reduction in respiratory rate?
Medullary respiratory centre
Opiates typically affect the medullary respiratory centre to depress respiratory activity.
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What is the substrate of renin?
Angiotensinogen
Renin hydrolyses angiotensinogen to form angiotensin I.
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Which of the following physiological changes do not occur following tracheostomy?
Alveolar ventilation is increased.
Anatomical dead space is reduced by 50%.
Work of breathing is increased.(Right)
Proportion of ciliated epithelial cells in the trachea may decrease.
Splinting of the larynx may lead to swallowing difficulties.
…………………………………………………………
Work of breathing is decreased which is one of the reasons it is a popular option for weaning ventilated patients. Humidified air in this setting helps to reduce the viscosity of mucous that forms.
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A 45 year old man undergoes a sub total colectomy and formation of end ileostomy. What is the most likely sodium content per litre of ileostomy fluid?
120 mmol
Investigators in the 1960’s dehydrated and measured the sodium content of ileostomy effluent and determined this concentration. Not an experiment many would care to repeat!
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The oxygen-haemoglobin dissociation curve is shifted to the right in which of the following scenarios?
Chronic iron deficiency anaemia
…………………………………………………………
Mnemonic to remember causes of right shift of the oxygen dissociation curve:
CADET face RIGHT
C O2
A cidosis
2,3-DPG
E xercise
T emperature
The curve is shifted to the right when there is an increased oxygen requirement by the tissue. This includes:
Increased temperature
Acidosis
Increased DPG:
DPG is found in erythrocytes and is increased during glycolysis. It binds to the Hb molecule, thereby releasing oxygen to tissues. DPG is increased in conditions associated with poor oxygen delivery to tissues, such as anaemia and high altitude.
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An over enthusiastic medical student decides to ask you questions about ECGs. Rather than admitting your dwindling knowledge on this topic, you bravely attempt to answer her questions! One question is what component of the ECG represents ventricular repolarization?
T wave
The T wave represents ventricular repolarization. The common sense approach to remembering this, is to acknowledge that ventricular repolarization is the last phase of cardiac contraction and should therefore correspond the the last part of the QRS complex.
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A 56 year old male presents to the acute surgical take with severe abdominal pain. He is normally fit and well. He has no malignancy. The biochemistry laboratory contacts the ward urgently, his corrected calcium result is 3.6 mmol/l. What is the medication of choice to treat this abnormality?
IV Pamidronate
IV Pamidronate is the drug of choice as it most effective and has long lasting effects. Calcitonin would need to be given with another agent, to ensure that the hypercalcaemia is treated once its short term effects wear off. IV zoledronate is preferred in scenarios associated with malignancy.
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Which of the conditions listed below is most likely to account for the following arterial blood gas result:
pH 7.49
pO 8.5
Bicarbonate 22
pCO 2.4
Chloride 12meq
Respiratory alkalosis
The hyperventilation results in decreased carbon dioxide levels, causing a respiratory alkalosis (non compensated).
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A 34 year old man receives morphine following an appendicectomy. He develops constipation as a result. Which of the following best accounts for this process?
Stimulation of Mu receptors
4 Types of opioid receptor:
δ (located in CNS)- Accounts for analgesic and antidepressant effects
k (mainly CNS)- analgesic and dissociative effects
μ (central and peripheral) - causes analgesia, miosis, decreased gut motility
Nociceptin receptor (CNS)- Affect of appetite and tolerance to μ agonists.
Constipation is a common side effect of morphine treatment and stimulation of Mu receptors accounts for this process.
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A 28 year old man undergoes an ileocaecal resection to treat terminal ileal Crohns disease. Post operatively he attends the clinic and complains of diarrhoea. His CRP is within normal limits and small bowel enteroclysis shows no focal changes. Which of the following interventions is most likely to be beneficial?
Oral cholestyramine
The question is about high output diarrhoea following terminal ileal resection and the most likely cause is malabsorption of bile salts. The administration of cholestyramine (bile salt binding agent) will counter this and thats why its the correct answer.
Malabsorption of bile salts is a common cause of diarrhoea following ileal resection. A normal small bowel study and CRP effectively excludes active Crohns disease and therefore immunomodulator drugs are not appropriate.
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What is the main event involved in the neovascularization of the immature wound bed following surgery?
Endothelial cell proliferation
Angiogenesis is a key event in wound healing and occurs as a result of endothelial cell proliferation.
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There is decreased secretion of which one of the following hormones in response to major surgery:
Insulin
Endocrine parameters reduced in stress response:
Insulin
Testosterone
Oestrogen
Insulin is often released in decreased quantities following surgery.
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A 23 year old is stabbed in the groin and develops hypovolaemic shock. What is the most likely finding on analysis of his urine?
Increased specific gravity
Hypovolaemic shock is likely to compromise renal blood flow especially if blood pressure falls below the range at which the kidney is able to autoregulate its blood flow. The result of this will be an increase of the specific gravity as water retention occurs in an attempt to maintain circulating volume.
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A 43 year old lady is recovering on the intensive care unit following a Whipples procedure. She has a central venous line in situ. Which of the following will lead to the y descent on the waveform trace ?
Emptying of the right atrium
JVP
3 Upward deflections and 2 downward deflections
Upward deflections
a wave = atrial contraction
c wave = ventricular contraction
v wave = atrial venous filling
Downward deflections
x wave = atrium relaxes and tricuspid valve moves down
y wave = ventricular filling
The y descent represents the emptying of the atrium and the filling of the right ventricle.
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A 45 year old male has alcoholic cirrhosis and decompensated liver failure, which of the following clotting factors is least likely to be affected?
Factor V
Factor VII
Factor IX
Factor VIII(Right)
Factor XI
……………………………………………….
Factor VIII is synthesised in the endothelial cells of the liver rather than the liver itself and therefore is less prone to the effects of hepatic dysfunction.
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Deficiency of which vitamin is most likely to explain the presentation of a 3 year old child with Rickets?
Vitamin D
Vitamin D is needed to help mineralise bone. When this is deficient, mineralisation is inadequate and deformities may result.
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von Willebrand factor is involved in the stabilization of which of the clotting factors listed below?
Factor VIII
…………………………………………….
vWF stabilizes factor VIII
If you answered this incorrectly check you did not select factor VII by mistake!
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Which part of the ECG represents atrial depolarization?
P wave
The P wave represents atrial depolarization. Note that atrial repolarization is obscured within the QRS complex.
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Which of the following drugs increases the rate of gastric emptying in the vagotomised stomach?
Erythromycin
Vagotomy seriously compromises gastric emptying which is why either a pyloroplasty or gastro-enterostomy is routinely performed at the same time.
Chloramphenicol has no effect on gastric emptying. Ondansetron slows gastric emptying slightly. Metoclopramide increases the rate of gastric emptying but its effects are mediated via the vagus nerve. Erythromycin enhances gastric emptying by acting via the motilin receptor in the gut.
