The organism consists of functionally closed systems, the processes of which do not reflect the environment, but build our own inner world independently of the outside world.

This independent structure of our organism is largely controlled by the autonomic nervous system. It has the task of ensuring that functionally related organs know about each other in order to be able to coordinate their activities. For example, if one organ's performance increases, the energy supply of another must be restricted, i.e., a redistribution of resources must be initiated.

What is special about the autonomic nerves?

In contrast to the sensorimotor nerves, the nerve fibers of the autonomic nervous system do not touch the cells whose activity they influence. Instead they immerse, for example, the muscle cells of the blood vessels in a "bath" of active substances (transmitters). If the concentration of the active substances is high enough, it causes a change in the tension of the muscle cells and thus increases or decreases blood pressure. The autonomic nerves do their job, so to speak, in passing.

It is also noticeable that the autonomic nervous system is a listening organism. The number of afferent (i.e., perceptual reporting) nerve cells and fibers is unusually large. In comparison, actions and effects are determined by much less efferent nerve cells and fibers.

The parasympathetic or sympathetic part of the autonomic nervous system only intervenes in matters that affect the entire organism.

You see, the autonomic nervous system is very socially organized. On the one hand it listens, on the other hand it stimulates and motivates the target groups, but still leaves them free.

Freely adapted from J.W. Rohen, Morphology of the Human Organism, 2002, p.316ff