841. With regard to contraction and relaxation of skeletal muscle, all the following are true except
A. Contraction involves the release of potassium from the terminal cisterns
B. Relaxation involves the release of calcium from troponin
C. Prior to contraction, increased sodium and potassium conduction occurs in the end-plate membrane
D. Relaxation involves cessation of the interaction between actin and myosin
E. Contraction involves inward spread of depolarisation along T tubules

842. Regarding nerve fibres
A. Type C myelinated fibres in the dorsal root conduct impulses concerning pain and temperature
B. Type A alpha unmyelinated fibres conduct impulses concerning proprioception
C. Type A beta unmyelinated fibres conduct impulses concerning light touch
D. Type A gamma unmyelinated fibres conduct impulses to muscle spindles
E. Type B myelinated fibres are located in preganglionic autonomic region

843. With regard to chemoreceptors, all the following are correct except
A. The medullary chemoreceptors respond to a change in blood PC02
B. The medullary chemoreceptors respond to blood [H+]
C. The predominant peripheral chemoreceptors are located in the carotid and aortic bodies
D. The peripheral chemoreceptors respond to P02
E. The peripheral chemoreceptors respond to blood [H+]

844. Functions of the lung include all of the following except
A. Synthesis of phospholipids
B. Synthesis of protein
C. Carbohydrate metabolism
D. Inactivation of bradykinin
E. Removal of dopamine

845. Hypoxaemia is caused by all of the following except
A. Anaemia
B. Pulmonary fibrosis
C. Left to right shunt
D. Residing at high altitude
E. Hypoventilation

846. Vital capacity in an average sized male is equal to
A. 3600 mL (approx)
B. Tidal volume plus inspiratory reserve volume
C. Total lung capacity minus residual volume
D. Functional residual capacity plus inspiratory capacity
E. Expiratory reserve volume plus tidal volume and inspiratory capacity

847. Regarding the cardiac cycle
A. In tachycardia, the duration of systole is shortened relatively more than diastole
B. The v-wave is caused by the bulging of the tricuspid valve into the atria
C. The third heart sound is due to rapid ventricular emptying
D. The end-diastolic ventricular volume is 180 mL (approx)
E. Isovolumetric ventricular relaxation occurs after closure of the aortic and pulmonary valves

848. The action potential of cardiac pacemaker cells
A. Is not affected by calcium current
B. Is mainly due to sodium influx
C. Shows a decreased prepotential slope with sympathetic stimulation
D. Exhibits a prepotential initially caused by decreased potassium efflux
E. Show no spontaneous rhythmicity

849. All of the following statements regarding the atrial natriuretic peptide (ANP) are true except
A. It causes natriuresis
B. It lowers blood pressure
C. Circulating ANP has a short half life
D. ANP has the greatest affinity for the ANPR-B receptor on the glomerulus
E. It is released when atrial muscle is stretched

850. Arteriolar constriction is caused by
A. Kinins
B. Decreased noradrenergic discharge
C. Circulating angiotensin I
D. Circulating Na/K ATPase inhibitor
E. Decreased pH

NOTE
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