Than we were engaged, our nervous system invisibly participates in each our action. It is the most difficult and major network of management and communication in a human body.
The Nervous system is extremely important for sight and hearing, sensation of a pain and pleasure, the impellent control, regulation of such functions of an organism, as digestion and breath, and also for development of thinking, speech, memory and skills of decision-making.
"ррсюёшьш Іыхьхэ=рьш" nervous system millions interconnected cages - nejronov, carrying out the same function, as wires in the difficult electric car are. nejrony accept signals in one part of nervous system and transfer them in its other part where these signals can arrive on others nejrony or cause any action, for example, reduction of muscular fibres.
Nejrony - very fragile cages which can be easily damaged or destroyed as a result of a trauma, an infection, pressure, chemical influence or an oxygen lack. Moreover, as destroyed nejrony are not restored, such infringements are fraught with serious consequences. The nervous system is broken on two interdependent parts. One of them - the central nervous system (TSNS) - consists from head and a spinal cord. The second - peripheral nervous system (PNS) - includes all nervous fabrics outside of the central nervous system. Both peripheral, and central nervous systems consist of a number of components.
At peripheral nervous system two departments: external, or somatic, nervous system, and internal - vegetative nervous system.
The Somatic system plays a double role. Vopervyh, it collects the information from sense organs and sends it to the central nervous system. Secondly, it transmits signals from the central nervous system to skeletal muscles in reply to the received information, thereby causing movement.
the Realized and not realised actions
The Vegetative nervous system is responsible for regulation of functions of an internal and glands, including heart, a stomach, kidneys and a pancreas. The somatic nervous system consists of two basic components - touch and motor systems. The information on an external world is perceived by sense organs, for example, the eyes having special retseptornye cages. Other similar cages perceive signals of a pain, touch and skin temperature. Signals from these receptors are transferred in TSNS on sensitive nervous fibres. Set of such signals, which intensity reaches millions impulses a second, gives us the necessary information on an external world.
On sensitive nervous fibres the information arrives in TSNS, and therefrom commands are transferred to those or other muscles on impellent nervous fibres.
Both sensitive, and impellent nervous fibres are a part touch and motor nejronov. All nejrony consist of a body of a cage and of some spending fibres. Sensitive and impellent fibres PNS - the longest fibres corresponding nejronov. Bodies of cages of sensitive nervous fibres are near to head or a spinal cord, and motor nejronov - in head or a spinal cord.
The Impellent and sensitive fibres bearing the messages from this or that body or a site of an organism and back, gather in a bunch - a nerve. It is considered that different nerves "яш=р¦=" a concrete site or body. In total, from TSNS 43 steams of nerves depart: 12 steams of craniocereberal nerves from a brain and 31 steams from two parties of a spinal cord.
Craniocereberal nerves feed sense organs and muscles in a skull though very important nerve such - wandering - is responsible for work of digestive organs, heart and pulmonary respiratory ways. Some craniocereberal nerves (for example, an eye optic nerve) consist only of sensitive fibres.
Spinal nerves depart here and there from a spinal cord and always contain both impellent, and sensitive fibres. They feed all sites of our body located below a neck. Each such nerve fastens to a spinal cord two backs, in one of them are impellent, and in the second - sensitive fibres.
the Central nervous system
Head and a spinal cord form the central processor of nervous system which by means of sensitive fibres receives the information from sense organs and receptors, filters and analyzes it, and then on impellent fibres sends the commands causing corresponding reaction in muscles and glands. Such problem under the analysis or data processing can be concerning simple for certain functions of a spinal cord, but the brain, as a rule, carries out very much a complex analysis with participation of thousand various nejronov.
the Spinal cord
The spinal cord is almost cylindrical column of nervous fabrics in length 40 sm, located in a backbone of the person between a brain and the bottom department of a back. It carries out two major functions.
First, he plays a role dvustoronne go a spending way between a brain and PNS. It is reached by means of touch and motor nejronov, whose long bunches of fibres depart from different sites of a brain. They last on various distances along a spinal cord, and their terminations, the most remote from a brain, adjoin to fibres or bodies of cages touch or motor nejronov PNS. Signals can be transferred through intervals - sinapsy - between peripheral and spinal nejronami. The second function of a spinal cord is connected with management of simple reflex actions. This problem carry out nejrony, whose fibres last on short distances upwards and downwards on a spinal cord, and takyozhe intermediate nejrony, transmitting signals directly between touch and motor nejronami.
The Brain consists of three basic parts, or departments. Its trunk is continuation
Spinal cord also serves as a support of the big brain arch - a brain responsible
For the most part of conscious thinking. The cerebellum more low settles down. Though many
Touch and motor nejrony, accordingly, terminate and begin in the head
Brain, the majority brain nejronov are intermediate, into whose problem enters
Filtration, the analysis and information storage.
One of the major functions of a brain is storing of the information received from sense organs. Subsequently this information can be caused and used at decision-making. For example, the painful sensation is remembered at a contact of a hot plate, and later memory will influence the decision, whether it is necessary to concern other plates.
Speech and decision-making
For the majority of the realised actions the top part, or a cerebral cortex answers. Its one shares participate in perception of the information, others are responsible for speech and language, and the others serve as the beginning to impellent spending ways and operate movements.
Between these motorno-touch and speech sites of a cerebral cortex are assotsiirovannye the sites consisting of millions interconnected nejronov. They are connected with reasonings, emotions and decision-making. The cerebellum fastens to a brain trunk at once under a brain and basically is responsible for impellent activity. It sends signals which cause involuntary movements in the muscles, allowing to keep a pose and balance, and together with impellent sites of a brain provides coordination telodvizheny.
The trunk of a brain consists of a number of the various structures, carrying out different a problem, and the major among them are "чхэ=Ё№" supervising work of lungs, heart and blood vessels. Here such functions as blinking and vomiting are supervised. Other structures play a role of relaying stations, transmitting signals from a spinal cord or craniocereberal nerves.
Though gipotalamus is one of the smallest elements of a trunk of a brain, it supervises chemical, hormonal and temperature balance of an organism.
Actually nejrony - not a unique kind of cages which can be found out in nervous system: at it in considerable quantities there are also other cages - nevroglii (that means "ъыхщ эхЁтр"). Their problem - to connect, protect, feed and support nejrony.
Nejrony happen different forms and the sizes, but all of them have identical base structure. As well as all cages, at them have a kernel (or "чхэ=Ё") in a spherical part nejrona, a cage named a body. A number thin kornevidnyh fibres - dsndritov from here disperses. The cage also leaves one long fibre - akson. At the termination akson it is divided into a number of the shoots which are coming to an end with several tiny small knots.
Each small knot is in immediate proximity from dendrita another nejrona, but does not concern it. This interval is called "ёшэряё" and signals are transferred through these intervals by means of the chemical substances named transferring substances of a nerve. When the signal reaches small knots on the end aksona, it can "яхЁхяЁ№уэѕ=і" through sinaps on dendrit next nejrona and to continue the travel.
It is necessary to supply All central nervous system with enough of the blood bearing oxygen and nutrients. Besides, it has two sheetings. The first - from a bone: the brain takes places in a cranium, and a spinal cord - in a backbone. The second consists of three covers from the fiber fabric, named soft brain covers. They completely cover head and a spinal cord. Through a time head and a spinal cord the spinal liquid playing a role of the shock-absorber proceeds.