Epinephrine and norepinephrine exert which of the following effects on the heart?

Question

Quizplus · Accepted Answer

Epinephrine and norepinephrine both act on adrenergic receptors in the heart, leading to an increase in the force of myocardial contraction (inotropy) and an increase in heart rate (chronotropy). They also increase conduction velocity and shorten refractory periods in the atrioventricular junction, thus increasing the risk of arrhythmias. However, the overall effect on the heart is to increase cardiac output. Choice A is incorrect because epinephrine and norepinephrine increase, not decrease, heart rate. Choices C and D are incorrect because they increase, not decrease, conduction velocity and shorten, not lengthen, the refractory period of the atrioventricular junction.

Epinephrine and Norepinephrine Exert Which of the Following Effects on the Heart