QuestionJuly 30, 2026

How does the sympathetic nervous system affect the heart? It returns the heart to resting state contraction It causes the release of norepinephrine, which increases the rate of depolarization It releases hormones for muscle lengthening, which slows heart rate It causes an increase in the plateau phase

How does the sympathetic nervous system affect the heart? It returns the heart to resting state contraction It causes the release of norepinephrine, which increases the rate of depolarization It releases hormones for muscle lengthening, which slows heart rate It causes an increase in the plateau phase
How does the sympathetic nervous system affect the heart?
It returns the heart to resting state contraction
It causes the release of norepinephrine, which increases the rate of
depolarization
It releases hormones for muscle lengthening, which slows heart rate
It causes an increase in the plateau phase

Solution
4.3(297 votes)

Answer

B. It causes the release of norepinephrine, which increases the rate of depolarization Explanation The sympathetic nervous system plays a crucial role in regulating the body's "fight or flight" response. It’s part of the autonomic nervous system that stimulates various physiological activities to cope with stress or danger. Regarding its effect on the heart, the sympathetic nervous system releases norepinephrine, which binds to beta-adrenergic receptors. This process increases the rate of depolarization in pacemaker cells of the heart, thereby accelerating heart rate and boosting contraction strength. This physiological response is designed to deliver oxygen and nutrients more quickly to tissues during heightened activity or stress. Among the listed options: - The first option is incorrect because returning the heart to resting state contraction is primarily controlled by the parasympathetic nervous system. - The second option is correct because norepinephrine indeed increases the heart's depolarization rate. - The third and fourth options are incorrect because the sympathetic nervous system does not release hormones for muscle lengthening or increase the plateau phase.

Explanation

The sympathetic nervous system plays a crucial role in regulating the body's "fight or flight" response. It’s part of the autonomic nervous system that stimulates various physiological activities to cope with stress or danger. Regarding its effect on the heart, the sympathetic nervous system releases norepinephrine, which binds to beta-adrenergic receptors. This process increases the rate of depolarization in pacemaker cells of the heart, thereby accelerating heart rate and boosting contraction strength. This physiological response is designed to deliver oxygen and nutrients more quickly to tissues during heightened activity or stress.<br /><br />Among the listed options:<br />- The first option is incorrect because returning the heart to resting state contraction is primarily controlled by the parasympathetic nervous system.<br />- The second option is correct because norepinephrine indeed increases the heart's depolarization rate.<br />- The third and fourth options are incorrect because the sympathetic nervous system does not release hormones for muscle lengthening or increase the plateau phase.<br /><br />
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