Define and discuss the difference between the sympathetic and parasympathetic nervous systems and how they impact heart rate.

Parasympathetic and Sympathetic Nervous Systems Student’s Name Institution Course Instructor Date The Parasympathetic Nervous System (PNS) and the Sympathetic Nervous System (SNS) The autonomic nervous system acts on peripheral nerves to regulate involuntary physiological functions, and it consists of the SNS and PNS. The SNS prepares the body for stress or emergencies by triggering physiological changes. It is often called the “flight or fright” system in the body. On the other hand, the PNS promotes relaxation and recuperation by counteracting the effects of the SNS (Giunta et al., 2024). It is often referred to as the “rest and digest” system. Since it usually follows the activation of the SNS, this system has to conserve energy and facilitate recovery from fright or flight. Heart rate regulation depends on the interaction between sympathetic and parasympathetic regulation. Even though these nervous systems play vital roles in body homeostasis, they have contrasting effects on heart rate regulation. When an individual encounters a lion in the bush, the SNS is activated first, and then the PNS will be activated when the individual manages to flee for safety. When the SNS is activated, norepinephrine binds with its receptors. The binding increases depolarization, leading to a faster heart rate (Kasahara et al., 2021). Conversely, when the PNS is activated, acetylcholine binds to muscarinic receptors, decreasing the depolarization rate and resulting in a slower heart rate. Impact of Age and Disease The effectiveness ness of the autonomic nervous system is altered with age. As an individual age, there is a notable decline in parasympathetic tone. This means older people will have a higher resting heart rate than young adults and children. The sensitivity of nerve receptors decreases, and there is a...