How do the sympathetic and parasympathetic nervous systems regulate heart rate and blood pressure?

Question

The autonomic nervous system, composed of the sympathetic and parasympathetic divisions, regulates heart rate and blood pressure to maintain homeostasis. The sympathetic nervous system (SNS) increases heart rate and blood pressure in response to stress or physical activity through the release of norepinephrine. This stimulates the beta-1 adrenergic receptors on the heart, increasing heart rate (chronotropy) and force of contraction (inotropy). The parasympathetic nervous system (PNS), through the vagus nerve, decreases heart rate by releasing acetylcholine, which acts on muscarinic receptors. Together, these systems provide a dynamic balance, with the SNS increasing activity during stress and the PNS promoting relaxation and recovery.

Answer 1

The ANS regulates HR and BP via the SNS and PNS to maintain homeostasis. The SNS increases HR and BP in response to stress or activity by releasing norepi, which stimulates beta-1 adrenergic receptors on the heart, enhancing chronotropy (HR) and inotropy (contractility). The PNS, via the vagus nerve, decreases HR by releasing ACh, which acts on muscarinic receptors to slow HR. These systems work in opposition, with the SNS promoting activation during stress and the PNS promoting relaxation.

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