The organs of the body, including the heart, stomach and intestines, liver, and kidneys, as well as gland and muscles, are regulated by the autonomic nervous system (ANS), the branch of the peripheral nervous system. The ANS adjusts the functioning of organs according to both external and internal stimuli; it aids in maintaining homeostasis via the control of different activities such as circulation, hormone secretion, respiration, excretion, and digestion. In its turn, The ANS has two subsystems, called the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS) that are interrelated. This paper describes the way of how PNS affects blood pressure, namely, the physiology and the impact of external factors.
Mostly, the PNS is considered to be slowly activated and regulates gland and organ during the rest. Although peptides, such as cholecystokinin, can also act as neurotransmitters, the PNS mainly uses acetylcholine (ACh) as a neurotransmitter, which affects types of receptors, namely, the nicotinic cholinergic and muscarinic receptors (“Functions of the Autonomic Nervous System,” n.d). When the preganglionic nerve is stimulated, it releases ACh at the ganglion that connects with the nicotinic receptors of the postganglionic neurons. Then, the postganglionic nerve produces ACh to incite the muscarinic receptors of the needed organ.
As a result, in addition to decreased sweating, increased peristalsis, pupil constriction, among others, decreased blood pressure is observed primarily through reduced contractility of the heart and its ability to relax and fill. It is worth noting that muscarinic receptors primarily affect the heart through two receptors, that is, M2 and M3; the first is located in the heart, while the second is situated across the whole body (“Autonomic Nervous System,” n.d.). In addition, to decrease blood pressure, the PNS also triggers reducing total peripheral resistance through the relaxation of blood vessels. Finally, the factors that activate the PNS include the resting state of the body, the baroreceptor reflex, sexual response, and using drugs.
References
Autonomic nervous system – Introduction. Vital Scan.
Functions of the autonomic nervous system. Lumen Learning.