Multiple Choice
Which of the following is NOT a function of the parasympathetic nervous system?
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14. The Autonomic Nervous System
Parasympathetic Nervous System
Multiple Choice
Which action of the parasympathetic nervous system would decrease heart rate?
A
Release of epinephrine from the adrenal medulla into the bloodstream
B
Activation of beta-1 adrenergic receptors in the heart
C
Stimulation of sympathetic cardiac nerves releasing norepinephrine onto the SA node
D
Activation of the vagus nerve releasing acetylcholine onto the sinoatrial (SA) node
Verified step by step guidance1
Understand that the parasympathetic nervous system primarily decreases heart rate by releasing the neurotransmitter acetylcholine onto the sinoatrial (SA) node, which is the heart's natural pacemaker.
Recognize that the vagus nerve is the main parasympathetic nerve that innervates the heart and releases acetylcholine to slow down the heart rate.
Contrast this with the sympathetic nervous system actions, such as the release of norepinephrine or epinephrine, which increase heart rate by activating beta-1 adrenergic receptors on the heart.
Identify that activation of beta-1 adrenergic receptors and stimulation of sympathetic cardiac nerves are sympathetic responses that increase heart rate, not parasympathetic actions.
Conclude that the correct parasympathetic action to decrease heart rate is the activation of the vagus nerve releasing acetylcholine onto the SA node, which slows the pacemaker activity and reduces heart rate.
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