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
62 of 192
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.
73 of 192
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.
74 of 192
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.
75 of 192
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.
