The structure of the nervous system is a lesson from human anatomy

The general plan of the structure of the nervous system is described by its two components: central and peripheral. The head and spinal cord belong to the central nervous system, and the cranial, cerebral, autonomic and spinal nerves are the basis of the peripheral.

Man, like all other living organisms, is able to react to chemical and physical changes in the environment.

There are factors of the external environment (touch, sound, light, and smell), which by means of special sensitive cells are transformed into nerve impulses. Those, in turn, are represented by a series of electrical and chemical changes directly in the nerve fiber. The received impulses are transmitted along the afferent fibers to the brain and spinal cord, where necessary commands are developed for transmission along the efferent (motor) fibers to the muscles responsible for the executive function.

The structure and functions of the nervous system are aimed at integrating external influences with the body's ability to adapt to it.

The structure of the nervous system can not be fully considered without the characteristics of its structural unit - the neuron, which is a nerve cell and consists of a body, a nucleus, dendrites (branched processes) and an axon (one long process). The principle of the neuron's work is that the nerve impulses pass through the dendrites to the body of the cell, then through the axon it goes to the effector or other cells.

Between themselves neurons are connected through the processes with the help of a synapse, the role of which is to filter the nerve impulses. He is capable of missing one impulse and of detaining others.

Neurons can refer to different groups that determine their specific function. Thus, neurons of one group perform an analytic function and are responsible for the fragmentation of the nerve impulse. The second group is responsible for the synthesis and determination of impulses coming from other senses. There is also a third group that keeps the consequences from previous impacts and compares the arising effects with those having traces.

The center of management of a complex network of nerves distributed throughout the human body is the spinal cord, which looks like a long white "rope", finger-thick, up to 45 cm long and weighing about 30 g, and is located in the vertebral canal. It consists of two components - gray matter (accumulation of nerve cells) and white matter (nerve fibers).

Left and right of the spinal cord branch in the "form of branches from the trunk of the tree" spinal nerves. They are directed to different parts of the human body and provide interrelation with the central nervous system. Control of a certain "site" of the body is carried out by a separate such nerve.

The spinal nerve consists of a posterior, or sensitive, and anterior, or motional, bundles. The first type of fiber originates from the receptors of the skin, tendons, muscles, joints, internal organs and sensory organs. It is in the receptors that neural signals appear that contain information about events occurring both in the body itself and from outside. On the back fibers, these signals enter the spinal cord, and thence to the brain, where they are sorted, processed, evaluated and forward signals are sent in response to other signals to the muscles, internal organs and vessels.

The structure of the nervous system can include the autonomic nervous system, which is responsible for metabolism and the work of internal organs. A feature of this system is independent functioning and at the same time subordination to the central nervous system.

In its influence on internal organs, the autonomic nervous system consists of parasympathetic and sympathetic systems. Their relationship is quite complicated, because often they have the opposite effect on the same organ, thanks to which a certain balance in the body is achieved.

The structure of the nervous system includes the cerebral cortex, which has a thickness of about 3 mm and a total area of about quarter of a square meter. This part of the organ has six layers, the cells of which are closely interrelated with each other. The total number of these cells is about 15 billion pieces.

Structure of the nervous system Will not be considered fully without such a phenomenon as a reflex, which is the reaction of the body to internal and external effects through the central nervous system. The reflexes to the conditioned (the body's ability to adapt to changing environmental conditions) and unconditioned (innate reaction to stimuli from the outside) are subdivided. Unconditioned reflexes do not require certain conditions for their development, but conditioned reflexes arise under the influence of various phenomena that are vitally important for a person.