How does the autonomic nervous system regulate heart rate?

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Multiple Choice

How does the autonomic nervous system regulate heart rate?

Autonomic input adjusts how fast the heart beats by changing the pace at which the SA node fires and how quickly the AV node conducts impulses. When the sympathetic system is activated, norepinephrine acts on β1 receptors to increase heart rate and the force of contraction, speeding up the pacemaker activity. The parasympathetic system, mainly through the vagus nerve, releases acetylcholine onto muscarinic receptors, which slows SA node firing and reduces AV conduction, lowering heart rate. The heart has a baseline rate set by the intrinsic conduction system, but autonomic tone shifts this rate up or down to meet the body’s needs.

Autonomic input adjusts how fast the heart beats by changing the pace at which the SA node fires and how quickly the AV node conducts impulses. When the sympathetic system is activated, norepinephrine acts on β1 receptors to increase heart rate and the force of contraction, speeding up the pacemaker activity. The parasympathetic system, mainly through the vagus nerve, releases acetylcholine onto muscarinic receptors, which slows SA node firing and reduces AV conduction, lowering heart rate. The heart has a baseline rate set by the intrinsic conduction system, but autonomic tone shifts this rate up or down to meet the body’s needs.

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