Final answer:
The parasympathetic nervous system is a component of the autonomic nervous system that originates in the brainstem nuclei and sacral spinal cord, with ganglia located near target organs, and controls 'rest and digest' responses.
Step-by-step explanation:
Parasympathetic Nervous System Overview
The parasympathetic nervous system is one part of the autonomic nervous system (ANS), which regulates involuntary physiological processes. This division helps control the 'rest and digest' responses in the body. The characteristic features of parasympathetic nervous system include a craniosacral origin in the central nervous system (CNS), where the preganglionic neurons are located in brainstem nuclei and sections of the sacral spinal cord. The preganglionic neurons then project to ganglia that are typically located near or within the target organs, hence the ganglion location is intramural or in proximity to the organs they innervate.
Within the autonomic nervous system's operational framework, a typical pathway involves a preganglionic neuron synapsing with a postganglionic neuron, which in turn influences a target organ. The balance between the sympathetic and parasympathetic nervous systems dictates the body's physiological state, with the parasympathetic system countering the sympathetic 'fight or flight' response.
Specifically, the parasympathetic nervous system directly controls the digestive system, as its activation promotes functions associated with conserving energy and digestion. The outflow of parasympathetic fibers is from the brainstem and sacral spinal cord, which differentiates it from the sympathetic nervous system that uses the thoracolumbar outflow from the spinal cord.