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Anatomical features of the autonomic nervous system
02-09-2009
Anatomical features
The autonomic nervous system
Vegetative (autonomous) nervous system of the nervous system that regulates the body of the internal organs, glands of internal and external secretion, blood and lymph vessels, trophism tissue and homeostasis. Functioning on a subconscious level, she quickly and continuously respond to disturbances that threaten the permanence of the internal environment.
For me nowadays, the term autonomic nervous system originates from the work of Bichat (Bishat, 1800).
In 1898, Langley proposed to call the autonomic nervous system «autonomous, including in the name of the concept of independence of the central nervous system.
Due to the fact that the autonomic nervous system participates in the innervation of internal organs, it is called the visceral nervous system. This term is suggested Gaskell in 1916
Currently identify two of the functional level of the autonomic nervous system:
1) autonomic nervous system is the true sympathetic and parasympathetic (in literature called segmental nervous system) provides the autonomic innervation of individual body segments and related
internal organs;
2) nadsegmentarnaya (center), autonomic nervous system (brain stem reticular formation, hypothalamus, thalamus, amygdala, limbic system, cerebral cortex) performs the union of all the segmental apparatus, subjecting their activities overall functional objectives of the whole organism.
Sympathetic nervous system
As part of the sympathetic nervous system and differentiate intracerebral extracelebral part.
1) Intracerebral part of the sympathetic nervous system represented by nerve cells (nuclei Jacobson), located in the lateral horns of the spinal cord between I-m breast-II lumbar segments (D1L2). The location is sympathetic clusters of cells depart thin pulpy sympathetic fibers entering the appropriate front-roots of the spinal cord and with them coming out of it.
Spinal division of the sympathetic nervous system has the features of segmental or Metam ep Noah organization. Autonomic neurons of the spinal cord integrates sensory information from the internal organs and other
sources.
2) extracelebral part. In order to spread throughout the body, initially sympathetic fibers are encapsulated in small clusters of nerve cells, called ganglia. That is, in the sympathetic nervous system, there is an additional link between the spinal cord and terminal working body (effector). Ganglia form a chain, which is called the sympathetic trunk
(tguncus sympathicus).
Sympathetic trunk (doubles: right and left) situated along the lateral surface of the spine from the sacrum to the great foramen, and, basically, has 24 pairs of sympathetic ganglia: 3 neck. 12 thoracic, 5 lumbar and 4 sacral. From the ganglia of the sympathetic trunk are postganglionic fibers that end in the internal organs.
In the thoracic sympathetic trunk border postganglionic fibers form the major and minor splanchnic nerves. These nerves form the solar plexus (plexus solagis), which depart from the set of branches to the internal organs. The solar plexus is located in the upper abdomen, before he was called ventral brain.
In both the core functions of the sympathetic portion of autonomic nervous system is the trophic (e is involved in the process of catabolism), regulates the oxidative processes, the consumption of nutrients, blood flow to the muscles and the heart and increases heart rate, activates a vasoconstrictor, increases pupil and orbital fissure (enhances vision), relaxes the smooth muscles of the bronchi and zheludochnokishechnogo tract, delayed urination, causing constipation.
The main neurotransmitter of sympathetic nerves is one of the catecholamines norepinephrine, which serves as a mediator in the central nervous system.
Parasympathetic nervous system
The bodies of parasympathetic neurons lie in the sacral spinal cord and brain stem (cerebral part).
Cerebral portion includes srednemozgovoy department, which lies in the nuclei of the oculomotor nerve (III pair), located at the bottom of the aqueduct at the level of the upper hills of the roof of the midbrain (pupillary center) and through the oculomotor nerve provides a narrowing of the pupil and accommodation eyes.
By the cerebral part of the department also includes a diamond-shaped, located in the medulla oblongata. The bulk of the vegetative fibers of the rhomboid department is part of a major nerve trunk, called the vagus nerve (A pair). Its numerous branches carry out all the parasympathetic innervation of the heart, lungs and gastrointestinal tract:
slow rhythm of cardiac contractions, promote digestion and absorption of food. Therefore, the parasympathetic system on its main function anabolic (store energy).
Sacred are located in the lateral horns S2S4 kpesttsovyh segments of the spinal cord. Oversees the functions of the pelvic organs (bladder, rectum).
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