Coronary blood flow to the left ventricle increases during A. Early s

1.	Coronary blood flow to the left ventricle increases during A. Early systole. B. Myocardial hypoxia. C. Hypothermia. D. Stimulation of sympathetic nerves to the heart. E. Arterial hypertension.
Answer» A. False It falls; coronary vessels are compressed by the contracting myocardium. B. True A fall in P_O2 has a potent vasodilator effect on coronary vessels. Adenosine released from hypoxic myocardium is also a potent vasodilator. C. False The fall in metabolic rate and cardiac output in hypothermia reduce cardiac work and lead to a reduction in coronary blood flow. D. True Sympathetic stimulation increases the rate and force of contraction; the resulting increase in the rate of production of vasodilator metabolites dilates coronary vessels. E. True Myocardial work and metabolism are increased in hypertension.

Coronary blood flow to the left ventricle increases during A. Early systole. B. Myocardial hypoxia. C. Hypothermia. D. Stimulation of sympathetic nerves to the heart. E. Arterial hypertension.

Answer»

A. False It falls; coronary vessels are compressed by the contracting myocardium.

B. True A fall in P_O2 has a potent vasodilator effect on coronary vessels. Adenosine released from hypoxic myocardium is also a potent vasodilator.

C. False The fall in metabolic rate and cardiac output in hypothermia reduce cardiac work and lead to a reduction in coronary blood flow.

D. True Sympathetic stimulation increases the rate and force of contraction; the resulting increase in the rate of production of vasodilator metabolites dilates coronary vessels.

E. True Myocardial work and metabolism are increased in hypertension.

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