general plan of the structure of the nervous system is described by two of its components: central and peripheral.Brain and spinal cord are the central nervous system and the cranial, spinal and autonomic nerves are peripheral basis.
man, like all other living organisms, able to respond to chemical and physical changes in the environment.
There are environmental factors (touch, sound, light, and odor), which by means of special sensory cells are converted into nerve impulses.Those, in turn, presents a series of electrical and chemical changes in the nerve fibers directly.These pulses are transmitted by afferent fibers in the brain and spinal cord, where they produced the necessary commands for the transmission of the efferent (motor) fibers to the muscles responsible for the executive function.
structure and function of the nervous system are aimed at the integration of external influence to the ability of the body to adapt to it.
structure of the nervous system can not be considered fully, without the characteristics of its structural units - the neurons that is nerve cell consists of a body, the nucleus, dendrites (branched appendages) and the axon (a long process).The principle of operation of the neuron - the dendrites of nerve impulses travel to the cell body, then through the axon is sent to effectors or other cells.
between neurons are connected via processes using synapse, whose role is to filter nerve impulses.He is able to skip some pulses and detain others.
Neurons can relate to different groups that determine their specific function.Thus, one group of neurons operate analytic function and are responsible for the crushing of a nerve impulse.The second group is responsible for the synthesis and determination of impulses from the other senses.There is a third group, which holds the consequences of previous actions, and compares the impacts arising from the existing tracks.
Control Center complex network of nerves distributed throughout the human body is the spinal cord, which has the form of a long white "rope", thick as a finger, up to 45 cm and weighing about 30 grams, and is located in the spinal canal.It consists of two components - the gray matter (neuronal cell cluster) and white matter (nerve fiber).
left and right of the spinal cord branch out into "branches of a tree trunk" spinal nerves.They are sent to different parts of the human body and provide interconnections to the central nervous system.Control over a certain "portion" of the body is carried out in such a specific nerve.
spinal nerve consists of a back, or sensitive, and front or motor, sheaves.The first type of fibers originates from the receptors of the skin, tendons, muscles, joints, internal organs and sensory organs.It is in the receptors appear nerve signals, which contain information about events taking place in the body and outside.Rear-fiber data signals are sent to the spinal cord, and from there - to the brain, where they are sorted, processed, evaluated and anterior fibers are sent in response to other signals to the muscles, internal organs and blood vessels.
structure of the nervous system may include, and the autonomic nervous system, which is responsible for metabolism and function of internal organs.A special feature of this system is independent functioning and thus the subordination of the central nervous system.
According to its influence on the internal organs of the autonomic nervous system consists of sympathetic and parasympathetic systems.Their relationships are quite complex, since they often have the opposite effect to the one and the same body, due to which achieved a certain balance in the body.
structure of the nervous system including the cerebral cortex, which has a thickness of about 3 mm and a total area of ​​approximately a quarter sq.m.This part of the body has six layers of cells, which are closely linked with each other.The total number of these cells is about 15 bln. Pieces.
structure of the nervous system be considered not entirely without such a phenomenon, as a reflex, which is the body's response to internal and external influences via the central nervous system.Subsections conditioned reflexes (the body's ability to adapt to changing environmental conditions) and unconditioned (innate response to stimuli from the outside).Unconditioned reflexes do not require certain conditions for its development, and contingencies - occur under the influence of various phenomena that are vital for human beings.
