Multiple Choice
Which of the following is released by all somatic motor neurons at their synapses and always has an excitatory effect on skeletal muscle?
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14. The Autonomic Nervous System
Neurotransmitters of the ANS
Multiple Choice
Neurotransmitters released by sympathetic postganglionic fibers going to the heart would cause __________.
A
an increase in rate and force
B
an increase in rate and a decrease in force
C
a decrease in both rate and force
D
a decrease in rate and an increase in force
Verified step by step guidance1
Understand the role of the sympathetic nervous system: The sympathetic nervous system is part of the autonomic nervous system responsible for the 'fight or flight' response, which generally prepares the body for action.
Identify the neurotransmitter involved: Sympathetic postganglionic fibers typically release norepinephrine, a neurotransmitter that affects heart function.
Consider the effect of norepinephrine on the heart: Norepinephrine binds to adrenergic receptors in the heart, primarily beta-1 receptors, which are known to increase heart rate and contractility (force of contraction).
Analyze the options given: Based on the effect of norepinephrine, the correct choice would be the one that describes an increase in both the rate and force of heart contractions.
Conclude the reasoning: The sympathetic nervous system, through norepinephrine, increases the heart's rate and force, aligning with the 'fight or flight' response to prepare the body for increased activity.
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