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Respiratory Physiology Questions 1. Increased baroreceptor discharge acts via the medulla to: a. b. c. d. e. 2. c. d. e. 50% is in the dissolved form The Haldane effect is the fact that oxygenation of the blood increases its ability to carry CO2 Ionic dissociation of carbonic acid requires the presence of carbonic anhydrase to be a fast process An increase in pCO2 in blood shifts the oxygen dissociation curve to the left Approximately 30% of the venous-arterial difference is attributable to the carbamino compounds Regarding conduction in the heart a. b. c. d. e. 5. Erythropoietin secretion rises after 2 – 3 days Nifedipine alleviates the symptoms of mountain sickness Alveolar pCO2 levels rise pCO2 levels fall because of decreased oxygen content of the air Initially the O2Hb dissociation curve shifts to the left Regarding CO2 transport in blood a. b. 4. heart rate stroke volume vessel diameter blood pressure renin secretion On Climbing Everest a. b. c. d. e. 3. Increase Increase Increase Increase Increase Stimulation of right vagus inhibits the AV node The rate of discharge of the SAN is independent of temperature Depolarisation of ventricular muscle starts on the right The speed of conduction is fastest in ventricular muscle The SA node and AV node exhibit the same speed of conduction The alveolar gas equation a. b. c. d. e. Is also known as Bohr’s equation Can be used to calculate anatomical dead space Is influenced by diet Is independent of PiO2 Requires sampling of gas to determine PaCO2 6. Regarding ventilation during exercise a. b. c. d. e. 7. Oxygen transport a. b. c. d. e. 8. d. e. b. c. d. e. In healthy individuals, anatomical dead space is less than physiologic dead space The relative change in blood flow from apex to base is less than relative change in the ventilation Ventilation/perfusion differences are due to gravity Ventilation/perfusion ratio is low at the base All of the above For the chemical control of respiration a. b. c. d. e. 11. The autonomic control centre is located in the midbrain Brainstem respiratory neurons only discharge during inspiration Arterial PaO2 must be below 80mmHg to produce increased discharge from peripheral chemoreceptor Medullary chemoreceptors monitor O2 concentration in the CSF In metabolic alkalosis ventilation is depressed Regarding ventilation/perfusion differences in the lung a. 10. The oxygen dissociation curve shifts left with a fall in pH More oxygen is supplied to tissues by a fall in 2,3DPG levels 2,3 DPG levels are increased by ascent to 7,000 metres 2,3 DPG levels in stored blood increase Oxygen dissociation curve shifts right with a drop in temperature With regards to ventilation a. b. c. 9. Pulmonary blood flow is increased from 5.5l/min to 55l/min Abrupt increase in ventilation at onset of exercise is due to increased respiratory rate Increases in ventilation are proportionate to increase CO2 production CO2 excretion increases from 200ml/min to up to 8000ml/min There is a fall in blood pH during moderate exercise The carotid bodies respond to changes of pH, pO2 , pCO2 The aortic bodies respond to changes of pH, pO2 , pCO2 pO2 is only detected by the central chemoreceptors Severe hypoxia strongly stimulates the central chemoreceptors The central chemoreceptors respond to changes in plasma pH In the cardiac cycle a. b. c. d. e. Right ventricular contraction occurs before left Phase II commences with the opening of the AV valves Phase IV is isovolumetric relaxation During inspiration, the pulmonary valve closes before the aortic The duration of systole is more variable than diastole 12. Cerebral circulation a. b. c. d. e. 13. An arterial blood gas taken from a patient breathing room air at sea level shows a pCO2 20, pO2 60, pH 7.52. Assuming a normal respiratory quotient, calculate the alveolar pO2 a. b. c. d. e. 14. Stimulating pulmonary stretch receptors Stimulating central chemoreceptors Inhibiting peripheral chemoreceptors Stimulating J receptors in alveolar walls Increasing CSF pH As a percentage of total blood volume, which of the following values are correct a. b. c. d. e. 17. Capillary pressure at the arteriole end is 15mmHg Hydrostatic pressure exceeds oncotic pressure throughout the capillary Capillary pressure at the venule end is 5mmHg Interstitial colloid osmotic pressure is usually negligible Capillary filtration coefficient decreases with capillary permeability CO2 can increase respiration by: a. b. c. d. e. 16. 80mmHg 85mmHg 150mmHg 130mmHg 125mmHg Regarding Starlings forces a. b. c. d. e. 15. Is highly variable with posture Is constant across approximately 100-200mmHg Is variable due to the “closed box” nature of the cranium Is approximately 750ml/min Has the same flow/weight ratio as the kidney 40% is in the pulmonary circulation 13% is in the systemic arteries 20% is in the systemic arterioles and capillaries 30% is in the veins None of the above are correct Beta-1 receptor mediated increase in cardiac firing rate occurs a. b. c. d. e. G protein related increased K+ conductance G protein related increased Ca++ conductance G protein related decreased K+ conductance cAMP related increased Ca++ conductance cAMP related K+ conductance 18. Vagal stimulation of SA node a. b. c. d. e. 19. With respect to central nervous system control of the heart a. b. c. d. e. 20. Leads to increased conductance of Ca++ into the cell Leads to increased conductance of K+ into the cell Leads to raised intracellular cAMP Decreases the slope of the prepotential of the SA node Inhibits the B-1 receptor directly Sympathetic stimulation can increase cardiac out put nine-fold from the resting state In the absence of parasympathetic input, sympathetic inhibition of the heart results in a 30% decrease in heart rate Vagal stimulation can override sympathetic stimulation Sympathetic input is predominantly to the SA node, while parasympathetic input is predominantly to the AV node All of the above Blood pressure a. b. c. d. e. Fluctuates in the aorta between 180 and 20mmHg Is approaching 0mmHg at the right atrium Is half in the pulmonary arteries of that in the aorta Is greater in large veins than vena cava Drops most significantly at capillary level Respiratory Physiology Dec 06 Answers 1. C 2. E 3. E 4. E 5. C 6. D 7. C 8. E 9. D 10. A 11. C 12. D 13. D 14. D 15. B 16. B 17. D 18. D 19. B 20. B