Nervous system

The nervous system controls activity of all systems and bodies and provides communication of an organism with external environment.

Structure of a nervous system

Structural unit of a nervous system is the neuron – a nervous cell with shoots. In general, the structure of a nervous system represents set of the neurons which are constantly contacting with each other by means of special mechanisms – synapses. On functions and structure the following types of neurons differ:

• Sensitive or receptor;
• Effector – motor neurons which direct an impulse to executive bodies (effectors);
• Switching or inserted (konduktorny).

Conditionally the structure of a nervous system can be divided into two big departments – somatic (or animalny) and vegetative (or autonomous). The somatic system preferential is responsible for communication of an organism with external environment, providing the movement, sensitivity and reduction of skeletal muscles. The vegetative system influences growth processes (breath, a metabolism, allocation, etc.). Both systems have very close interrelation, only the autonomic nervous system is more independent and does not depend on a will of the person. For this reason it still call autonomous. The autonomous system on sympathetic and parasympathetic shares.

All nervous system consists from central and peripheral. Treats the central part back and the brain, and peripheral system represents the departing nerve fibrils from a head and spinal cord. If to look at a brain in a section, it is visible that it consists of white and gray matter.

Gray matter is accumulation of nervous cells (with initial departments of the shoots departing from their bodies). Separate groups of gray matter call still kernels.

White matter consists of the nerve fibrils covered with a myelin cover (shoots of nervous cells of which gray matter is formed). In back and a brain nerve fibrils form conduction paths.

Peripheral nerves share on motive, sensitive and mixed, depending on of what fibers they consist (motive or sensitive). Bodies of neurons whose shoots consist of sensory nerves, are in nerve knots out of a brain. Bodies of motor neurons are in motive kernels of a brain and front horns of a spinal cord.

Functions of a nervous system

The nervous system makes various impact on bodies. Three main functions of a nervous system are:

• Starting, defiant or stopping function of body (gland secretion, reduction of a muscle, etc.);
• Vasomotor, allowing to change width of a gleam of vessels, regulating thereby inflow of blood to body;
• Trophic, lowering or raising a metabolism, and, therefore, consumption of oxygen and nutrients. It allows to coordinate constantly a functional condition of body and its oxygen requirement and nutrients. When on motive fibers to the working skeletal muscle the impulses causing its reduction go, also impulses, the excitometabolic and expanding vessels at the same time arrive that allows to provide a power possibility of performance of muscular work.

Diseases of a nervous system

Together with closed glands the nervous system plays a crucial role in functioning of an organism. It is responsible for harmonious work of all systems and bodies of a human body and combines back, a brain and peripheral system. Physical activity and sensitivity of a body is maintained thanks to nerve terminations. And thanks to vegetative system the cardiovascular system and other bodies is inverted.

Therefore disturbance of functions of a nervous system influences work of all systems and bodies.

All diseases of a nervous system can be divided on infectious, hereditary, vascular, traumatic and chronically progressing.

Hereditary diseases happen genomic and chromosomal. The most known and widespread chromosomal disease is the Down syndrome. This disease the following signs are characteristic: disturbance from a musculoskeletal system, endocrine system, shortage of mental capacities.

Infectious diseases arise owing to influence of bacteria, fungi and parasites. It is possible to rank measles, encephalitis, malaria as diseases of this group, etc. The main symptoms at these diseases are: consciousness disturbance, headache, fervescence, vomiting, nausea.

Traumatic defeats of a nervous system arise owing to bruises and injuries, or when squeezing a head or spinal cord. Such diseases, as a rule, are followed by vomiting, nausea, memory loss, disorders of consciousness, an anesthesia.

Vascular diseases preferential develop against the background of atherosclerosis or a hypertension. It is possible to refer chronic vascular and brain insufficiency, disturbance of cerebral circulation to this category. Are characterized by the following symptoms: attacks of vomiting and nausea, headache, disturbance of a physical activity, sensitivity reduction.

Chronically progressing diseases, as a rule, develop owing to disturbance of exchange processes, influence of an infection, organism intoxication, or because of anomalies of a structure of a nervous system. It is possible to carry a sclerosis, a myasthenia to such diseases, etc. These diseases usually gradually progress, reducing operability of some systems and bodies.

Origins of diseases of a nervous system:

• Viruses (herpes, measles, mumps, chicken pox, HIV);
• Brain bruises;
• Vascular disorders;
• Parasites and fungi (toxoplasmosis, cryptococcosis, malaria);
• Brain tumors.

Also placental way of transfer of diseases of a nervous system during pregnancy (a cytomegalovirus, a rubella), and also on peripheral system (poliomyelitis, rage, herpes, an encephalomeningitis) is possible.

In addition, negatively influences a nervous system endocrine, heart, renal diseases, defective food, chemical and medicines, heavy metals.