The autonomic nervous system

The autonomic nervous systemAutonomic nervous system (synonym: independent, visceral nervous system - nervous system, Innervate the internal organs, blood vessels, smooth muscles, glands of internal and external secretion and skin, as well as participating in innervation AIDS voluntary movements and sensitivity. The autonomic nervous system is divided into two major departments - the sympathetic and parasympathetic.
Sympathetic spinal centers, from which begin peripheral sympathetic fibers, located in the side horns spinal cord from VIII III cervical to the lumbar segment. From located here clusters sympathetic cells thin fibers who ventral roots of the spinal cord and together with them coming out of the spinal cord (Fig). Coming to the site (the ganglion) the sympathetic trunk, these fibers come in and over in his cell, which begins a new peripheral neuron going to the working body.
Sympathetic fiber to the node are called preduslovi, or preganglionarnah, and going from cell site to the periphery - poluslova, or postganglionarnyh. Preganglionarnah fibers covered with white myelin sheath and form white connecting branches. Postganglionarnyh fiber coming from a host that does not have a myelin sheath to form gray connecting branches. Sympathetic trunks, located on both sides of the spine, consist of 2-3 cervical nodes, 12 thoracic, 2-5 lumbar, 2-5 sacral and one unpaired PC, which closed chains of nodes sympathetic trunks. It should be stated that not all the preganglionarnah fiber end up in the cells of the nodes of the sympathetic trunk, part of them are not interrupted in the nodes, and goes to the periphery, to end in one of predposlednij nodes (celiac plexus, nizhnebureiskaya plexus and others). Part of the preganglionarnah fiber passes through these sites without a break, reaching working body, the walls of which are located here clusters sympathetic cells and they make a break. Thus, the sympathetic innervation of internal organs and other devices depends on reflex system performance that originate in the horns lateral thoracic and lumbar regions of the spinal cord.
The sympathetic system extends the pupil, causes increased heart rate and blood pressure, expands the small bronchi, reduces the sphincter of the bladder and rectum. At rise of tone of sympathetic system is marked tendency to constipation.
Parasympathetic innervation is the nerve cells in the sacral region of the spinal cord and brain stem, first and regulate the activity of the organs located in the pelvis (bladder, rectum and genitals), and the cells of the Department nerviruet other organs through the vagus, language-pharyngeal, intermediate and oculomotor nerves, vegetative cores in the medulla, lid bridge (saralieva), the midbrain.
The effect of parasympathetic nervous system in many ways the opposite of the action of the sympathetic system the parasympathetic system narrows the pupil, slows down heartfelt activity, reduces blood pressure. If you raise the tone of the parasympathetic nervous system marked tendency to spasm small bronchi, frequent urination and defecation. Reflex activity of the sympathetic and parasympathetic nervous system, regulating the vital functions of the organism, provides adapting it to the conditions of external environment.
Control over the activity of these two systems (sympathetic and parasympathetic) is the Central autonomic computing, located in the hypothalamus area of the brain. Hypothalamic region regulates the following: blood pressure, blood, breath, thermoregulation, regulation trophism, different types of metabolism, sleep and wakefulness. In turn, the state of the hypothalamic region depends on the functional activity of certain areas of a bark of the big hemispheres of a brain. Disorders of the autonomic nervous system have different clinical picture, depending on the defeat of one or another of its departments. Often there are: headache, vegetative neurosis, Raynaud's disease, ganglionic, solar plexitis.

communication sympathetic fibers with the spinal cord scheme
Fig. 2. Communication sympathetic fibers with the spinal cord (scheme): 1 - funiculus post.; 2 - sulcus medianus post.; 3 - canalis centralis; 4 - comlssura anterior grisea; 5 - fissura medlana ant.; 6 - funiculus ant.; 7 - cornu ant.; 8 - n. spinalis; 9 - r. communicans albus (fibrae praeganglionares to ganglion praevertebrale); 10 - r. communicans albus (fibrae praeganglionares to ganglion tr. sympathici); 11 - fibrae postganglionares from gangl. tr. sympathici; 12 and 16 - fibrae postganglionares; 13 - body (gut); 14 - gangl. praevertebrale; 15 - fibrae praeganglionares to gangl. praevertebrale; 17 - gangl. tr. sympatlilci; 18 - r. interganglionaris; 19 - afferent fibers (viscerotomy); 20 - r. communicans griseus (fibrae postganglionares); 21 and 27 - skin; 22 to 26 - muscle; 23 - r. ventralis; musculoskeletal fiber cells of the anterior horn of the spinal cord; 25 - r. dorsalis; 28 - afferent fibres; 29 - gangl. spinale; 30 - radix dorsalis; 31 - radix ventralis; 32 - funiculus lateralis; 33 - cornu post.; 34 - cornu lat. (s. tractus intermediolateralis).