Parasympathetic Part of the Autonomic Nervous System

The parasympathetic part of the autonomic nervous system (pars parasympathica, pna; synonym: parasympathetic nervous system) is a section of the autonomic nervous system that innervates internal organs, blood vessels, and glands. Provides trophic and homeostatic innervation of internal organs, reduces their functional activity. The central sections of the parasympathetic nervous system are located in the midbrain and medulla oblongata, and the peripheral ones are in the autonomic ganglia located in the walls of the innervated organs or near them. Parasympathetic nerve fibers innervate the smooth muscles of internal organs, the heart, glands, and blood vessels. The main transmitter of the parasympathetic nervous system is acetylcholine. Stimulation of the parasympathetic nervous system leads to a slowdown in the heartbeat, dilation of blood vessels, increased tone and motility of the gastrointestinal tract, and stimulation of glandular secretion.

The parasympathetic (or visceral) part of the autonomic (autonomic) nervous system (PNS) is a section of the autonomic (autonomous) nervous system that innervates the internal organs, glands, blood vessels and muscles of the body. The PNS regulates the functions of internal organs (primarily the functions of the cardiovascular and respiratory systems, as well as the functions of the digestive and excretory systems).

The central part of the PNS is located in the brain stem, in the lateral horns (lateral nuclei) of the IX, X, XI and XII pairs of cranial nerves. Their nerve cells form parasympathetic centers in the lateral parts of the medulla oblongata, pons and midbrain. These centers control the functioning of internal organs, ensuring their rest, restoration and preparation for active activity.

The PNS also includes the peripheral part, which consists of several nerve fibers and endings located in various organs of the body. These fibers transmit signals from the central nervous system to internal organs to regulate their functions.