Discuss the chronotropic effects of the sympathetic and parasympathetic nervous systems on the heart
What will be an ideal response?
The sympathetic nervous system releases a neurotransmitter, norepinephrine, which has a positive chronotropic effect on the heart. Due to the influence of the sympathetic nervous system, the sinoatrial (SA) node fires more quickly and the calcium ion concentration in the cardiac muscle cells increases. Both effects increase stroke volume, heart rate, and cardiac output. The parasympathetic nervous system releases a neurotransmitter, acetylcholine, from the vagus nerves (CN X). Acetylcholine has a negative chronotropic effect on the heart by slowing the rate of the sinoatrial (SA) node. Thus, heart rate and cardiac output decreases.
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