The autonomic nervous system: the sympathetic, parasympathetic, and enteric nervous system
The human body has to adapt to changing conditions ever: increases as the ambient temperature to activate the sweat glands - people exert themselves physically, gets the heart rate.
Responsible for this vital adjustments is called the autonomic nervous system. It is divided into three different nervous systems: A distinction
Functionally one can sympathetic and parasympathetic as so-called antagonist understand that is their effects on various organs are often contradictory.
The sympathetic nervous system puts the body in a state of higher Attention and readiness to flee.
A person who is exposed to an immediate stress situation or hazard (for example, by a wild animal), will attempt to flee. For that he needs more blood to the muscles in order to escape. The heart has to work accordingly with a higher pump frequency.
His sympathetic works in the highest activity. The person begins to sweat, because the sympathetic nervous system activates the sweat glands. His lungs are working harder to create more oxygen into the blood.
In this example, the activation of the sympathetic nervous system thus means increased attention. The body and the mind are placed on alert by the sympathetic nervous system.
The nerve cells of the sympathetic nervous system originate in the thoracic and lumbar spinal cord. Their processes lead partly in neighboring cell clusters, called ganglia. The ganglia are connected with each other up and down, so right and left perlschnurartiges structure is formed from the spinal cord. The activated sympathetic nervous system is in the ganglia the neurotransmitter noradrenaline free and sends it to the target organs. Once there is norepinephrine binds to specific docking sites (alpha and beta receptors) and stimulates the organs.
The parasympathetic nervous system brings man into a hibernation - it ensures, for example, that the heart rate and blood pressure drop and digestion activity increases.
As the sympathetic and the parasympathetic nervous system is not at a specific location in the body, but is distributed throughout the body.
The neurons of the parasympathetic nervous system origin are either in the brain stem, or in the sacral spinal cord (i.e., in the lower region of the spine). About 75 percent of all nerve fibers of the parasympathetic nervous system originate in the brain stem. They regulate the function
The parasympathetic nerve fibers that originate in the sacral spinal cord that control the colon, the genitals and the urinary bladder.
Once higher centers activate (for example, the hypothalamus) the parasympathetic nerve cells release in the brain stem and sacral neurotransmitter acetylcholine free and send him to the ganglion toward the target organs.
When the parasympathetic ganglia are near or even within the institutions. The incoming acetylcholine stimulates the ganglia in turn to also release acetylcholine. This neurotransmitter acts directly on the organ and leads, for example, to the fact that the pupils become narrower.
The enteric nervous system is a complex network of nerve cells that almost the entire Gastrointestinal tract pervades. One can the enteric nervous system "Brain of the digestive tract" See, as it works completely independently of the central nervous system (brain and spinal cord).
For example, if a part of the intestine stretched through the tract, the enteric nervous system refers to this information. Then it forwards the signals to the muscles of the intestine, which then contracts and then relaxing. Through these bowel movements the chyme is mixed and transported further. The medical term for this is peristalsis.
The enteric nervous system regulates itself independently of external influences - the sympathetic and the parasympathetic nervous system can affect it, however. The sympathetic nervous system inhibits the digestion, the parasympathetic nervous system stimulates them.