The central nervous system includes the spinal cord and brain. The first looks like a slightly flattened back strand. And the brain, located in the cranial cavity, consists of two hemispheres, a trunk and cerebellum.
The physiology of the central nervous system controls the relationship between the body and the environment, human reactions to various stimuli. Also thanks to her, the coordination of organs and parts of the body takes place. In general, its activity is based on reflexes, since the body reacts to the slightest changes in its surrounding or in the internal environment.
The central nervous system conducts nerve connections with the body as a whole through the cranial nerves (there are 12 pairs of them) and the spinal roots (there are 31 of them). From muscles, skin, partially limbs and internal organs, “information” to the spinal cord is transmitted through afferent nerves coming from the posterior roots. And the “information” from the skeletal muscles enters it through the efferent nerves coming from the posterior roots. The presence or absence of reflexes indicates how the spinal cord works, whether it performs a reflex function. Its damage entails a violation of the transmission of all impulses (both afferent and efferent). Nerve paths go from the spinal cord to the brain and back, which pass through the entire brain stem, they partially break off or end in it. Oculomotor, auditory and optic nerves are embedded in the midbrain. Metabolism, blood circulation, and nutrition are controlled in the diencephalon through the connection of perceptions (internal and external) with the endocrine and cardiovascular systems. The cerebral cortex includes a huge number of neurons. These are cells of various shapes, which are located in several layers and are interconnected using processes. Each part of the cortex has a different composition of cells, this is due to the function that it performs.
The entire central nervous system, all its departments in each act of human behavior work as a whole, thereby forming a functional system. From the position of such an understanding, it is obvious that any reaction, any reflex is preceded by considerable work. At each point in time, the central nervous system depends on the needs of the body. First of all, they are motivated by an objective premise - a change in the environment inside the body. From the point of view of neurophysiology, this mechanism occurs through activation through the subcortical centers of the cerebral cortex. They send the impulses that the body most needs at the moment. The central nervous system seeks to satisfy the dominant motivation. To this end, she synthesizes all the available information about the state of the external and internal environment of the body, and then implements a behavioral act.
Damage to the central nervous system occurs for many reasons. These are congenital malformations, and circulatory disorders, the impact of trauma, the influence of tumor or inflammatory processes. The brain and spinal cord develop with defects if the following dangerous factors affect the fetus: the mother carries infectious diseases during pregnancy, injuries, radiation exposure, exposure to toxic substances, alcoholism of both parents or one of them. Not the least role in the occurrence of deviations is played by heredity.
Particularly severe defects occur when the above factors affect the fetus in the early months of pregnancy. Among them, the first place is occupied by hydrocephalus (too much cerebrospinal fluid accumulates in the ventricles of the brain ) and microcephaly (underdeveloped brain and skull). Affect the defeat of this system and malformations of the spine and bones of the skull.