What is the nervous system
How does the nervous system work?
The nervous system contains billions of nerve cells called neurons. In the brain alone there are around 100 billion. Each individual nerve cell consists of a body and various processes. The shorter extensions (dendrites) act like antennas: through them the cell body receives signals, for example from other nerve cells. The signals are passed on via the long extension (axon), which can be over a meter long.
Depending on the location of the nerve tracts in the body, a distinction is made between a central and a peripheral nervous system. The central nervous system () comprises nerve tracts in the brain and spinal cord. It is securely embedded in the skull and the vertebral canal in the spine. The peripheral nervous system () includes all other nerve tracts in the body.
Regardless of the situation, one speaks of a voluntary and an involuntary nervous system. The voluntary nervous system () controls all processes that you are aware of and that you can voluntarily influence. These are, for example, targeted movements of arms, legs and other parts of the body.
The vegetative nervous system (autonomous nervous system) regulates the processes in the body that cannot be controlled with one's will. It is constantly active and regulates, for example, breathing, heartbeat and metabolism. To do this, it receives signals from the brain and sends them to the body. In the opposite direction, the autonomic nervous system transmits messages from the body to the brain, for example how full the bladder is or how fast the heart is beating. The autonomic nervous system can very quickly adapt the function of the body to other conditions. For example, when a person is warm, the system increases blood flow to the skin and increases perspiration to cool the body.
Both the central and peripheral nervous systems contain voluntary and involuntary parts. In the central nervous system, however, the two parts are strongly intertwined, while in other areas of the body they are usually separate.
The vegetative involuntary nervous system is divided into three areas:
- The sympathetic nervous system
- The parasympathetic nervous system
- The visceral nervous system ()
The sympathetic and parasympathetic nervous system (and) usually act as an opponent in the body: It prepares the organism for physical and mental performance. It ensures that the heart beats faster and stronger, widens the airways so that you can breathe better and inhibits the bowel movements.
It takes care of the body's functions at rest: it activates digestion, stimulates various metabolic processes and ensures relaxation. but they do not always work in the opposite direction; the two systems also complement each other for some functions.
The enteric nervous system describes the intestine's own nervous system, which largely independently regulates the movement of the intestine during digestion.
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