The nervous system of the human body and animals is divided into two types - this is the somatic and autonomic nervous system. The somatic nervous system is under the conscious control of a person and can obey him, and the autonomic nervous system, on the contrary, is not subject to man, and is under his unconscious control.
The somatic system has a dual function. She receives environmental information through her senses - such as the eyes, which have special receptors. Signals from these receptors enter sensory channels into the central nervous system. The somatic system also sends signals from the central nervous system through the motor channels to the skeletal muscles, causing this movement.
The autonomic nervous system is the part of the nervous system that regulates vascular tone, lymphatic and blood vessels, the work of the endocrine glands and internal secretions, as well as all internal organs.
The ANS keeps the constancy of the environment (homeostasis) in the body at the right level and performs an adaptive-trophic function. Thanks to the autonomous nervous system, the functions of the internal organs and the entire human body adapt to changes in the external environment and affect its mental and physical activity.
The autonomic nervous system (autonomous) is divided into two departments: peripheral and central. The peripheral section includes nerves, nerve fibers and branches that exit from the centers of the system in the spinal cord and brain, plexuses of these nerve fibers and nerves, ganglia (autonomic nodes), sympathetic trunks, which consist of ganglia with connecting nerves and branches, and autonomic nodes of the parasympathetic division of the ANS.
The central department of the ANS is divided into segmental (lower) and suprasegmental (higher) vegetative centers. Segmental centers are located both in the spinal cord and in the brain. The suprasegmental centers of the ANS are concentrated only in the cerebral cortex, mainly in the parietal and frontal lobe, olfactory brain, cerebellum, hypothalamus, subcortical structures, etc.
The autonomic nervous system has two types - parasympathetic and sympathetic. They are distinguished by the location of their effector and central neurons and reflex arcs, as well as their influence on the work of innervated structures.
In the parasympathetic division of the nervous system, central neurons are located in the spinal cord, in its sacral segments (segments 2-4), but most of these neurons are located in the brain stem and depart from it with mixed cranial nerves. In the sympathetic nervous system, central neurons are located in the spinal cord in gray matter from the eighth cervical segment to two to three lumbar. The sympathetic nerves depart only from the spinal cord along the ventral (anterior) roots in the composition of the spinal nerves. Thanks to the parasympathetic nerves that serve the bronchi, they narrow, the sympathetic nerves, on the contrary, expand the bronchi.
The autonomic nervous system is responsible for the implementation of all vital functions and processes in the body, and is also partially responsible for reproduction, which is very important in procreation. Also, the ANS provides normal regulation of the heart rate, body temperature, blood pressure, monitors the activity of various biochemical processes in the body. At the slightest change in internal or external conditions, the autonomic system triggers compensatory and controlling mechanisms, which at the right time change the tone of blood vessels, control respiration, and activate mental activity.