Discussion about Autonomic Nervous System
The autonomic nervous system is considered to be a critical component of the peripheral nervous system, and it is primarily involved in regulating the involuntary physiologic processes in the human body such as respiration, heart rate, digestion, sexual arousal, and blood pressure among others (Saladin, 2018). The autonomic nervous system is usually composed of three anatomically distinct divisions: parasympathetic, enteric, and sympathetic nervous systems (Saladin, 2018). While the parasympathetic nervous system (PNS) contains the efferent fibers provide motor output to the central nervous system (CNS), the sympathetic nervous system (SNS), on the other hand, includes the afferent fibers that usually provide sensory input to the central nervous (Saladin, 2018). A postganglionic neuron with a cell body in the periphery that innervates target tissues and a preganglionic neuron with a cell body in the CNS is the only two-neuron series that usually make-up the SNS and PNS motor pathways. The enteric nervous system (ENS) has a web-like and extensive structure that is generally capable of effectively functioning independently from the rest of the nervous system (Bankenahally & Krovvidi, 2016). The ENS is chiefly responsible for regulating the digestive processes, and it primarily contains over 100 million neurons of over 15 morphologies, which are higher than the sum of all other peripheral ganglia.
A state of overall elevated activity and attention, also known as a “fight or flight” response, is achieved due to the activation of the sympathetic nervous system (Bankenahally & Krovvidi, 2016). During the occurrence of this process, several activities tend to take place in the human body such as cessation of the gastrointestinal peristalsis, increase in heart rate and blood pressure and glycogenolysis ensue among others, and almost every living tissue in the human body tends to innervated by the sympathetic nervous system (Bankenahally & Krovvidi, 2016). The parasympathetic nervous system is responsible for promoting the “rest and digest” processes in the human body, such as lowering the blood pressure, restarting the gastrointestinal peristalsis/digestion, and reducing heart rate (Waxenbaum, Vamsi, Matthew, 2020). The parasympathetic nervous system primarily innervates the head, the external genitalia, and viscera, which are notably vacant in much of the skin and the musculoskeletal system, thus the reason as to why it is significantly smaller than the sympathetic nervous system (Waxenbaum, Vamsi, Matthew, 2020). The enteric nervous system primarily comprises of the reflex pathways that are responsible for effectively controlling blood flow, food absorption or secretion, and the digestive functions of the muscle contractions or relaxations.