Significance of the nervous system. Functions of the nervous system

Each organ or system in the human body plays a role. At the same time, they are all interconnected. The importance of the nervous system can not be overestimated. It is responsible for the correlation between all organs and their systems and for the functioning of the organism as a whole. At school, early acquaintance with such a multifaceted concept as the nervous system begins. 4 th grade are still small children who can not deeply understand many difficult scientific concepts.

Structural Units

The main structural and functional units of the nervous system (NS) are neurons. They are complex excitable secreting cells with processes and perceive nervous excitement, process it and transmit it to other cells. Neurons can also have a modulating or inhibitory effect on target cells. They are part of the bio- and chemoregulation of the body. From a functional point of view, neurons are one of the foundations of the organization of the nervous system. They combine several other levels (molecular, subcellular, synaptic, supercellular).

Neurons consist of a body (soma), a long process (axon) and small branching processes (dendrites). In different parts of the nervous system they have a different shape and magnitude. In some of them, the length of the axon can reach 1.5 m. From one neuron, up to 1000 dendrites leave. According to them, excitation spreads from the receptors to the cell body. Axon impulses are transmitted to effector cells or other neurons.

In science there is the concept of "synapse". The axons of the neurons, approaching other cells, begin to branch and form numerous endings on them. Such places are called synapses. Axons form them not only on nerve cells. Synapses are on muscle fibers. These organs of the nervous system are present even on cells of endocrine glands and blood capillaries. Nerve fibers are glial-coated processes of neurons. They perform a conductive function.

Nerve endings

These are specialized formations located at the tips of the processes of nerve fibers. They provide information in the form of an impulse. Nerve endings participate in the formation of transmitting and receiving terminal devices of different structural organization. According to their functional purpose, they are:

• synapses that transmit a nerve impulse between nerve cells;

• receptors (afferent endings) that guide information from the place of action of the factor of the internal or external environment;

• effectors that transmit a pulse from nerve cells to other tissues.

Activity of the nervous system

The nervous system (HC) is an integral set of several interconnected structures. It promotes harmonious regulation of the activity of all organs and provides a response to changes in conditions. The nervous system of a person, the photo of which is presented in the article, connects the motor activity, sensitivity and work of other regulatory systems (immune, endocrine). Activities of the National Assembly are related to:

• anatomical penetration into all organs and tissues;

• establishing and optimizing the relationship between the body and the external environment (ecological, social);

• Coordination of all exchange processes;

• management of organ systems.

Structure

Anatomy of the nervous system is very complicated. It contains many structures, different in structure and purpose. The nervous system, the photo of which indicates its penetration into all organs and tissues of the body, plays an important role as a receiver of internal and external stimuli. To do this, special sensor structures are designed, which are located in so-called analyzers. They include special nervous devices that are capable of perceiving incoming information. These include the following:

• proprioceptors that collect information on the state of muscles, fascia, joints, bones;

• exteroceptors located in skin integuments, mucous membranes and sensory organs, capable of perceiving irritation factors received from the environment;

• interoceptors located in internal organs and tissues and responsible for making biochemical changes.

The main significance of the nervous system

The work of the National Assembly is closely connected both with the surrounding world and with the functioning of the organism itself. With its help, information is perceived and analyzed. Thanks to it, the stimuli of the internal organs and the signals coming from outside are recognized. The nervous system is responsible for the body's response to the information received. It is due to its interaction with the humoral mechanisms of regulation that man's adaptability to the surrounding world is ensured.

The value of the nervous system is to ensure the coordination of individual parts of the body and maintain its homeostasis (equilibrium state). Thanks to her work, the organism adapts to any changes, called adaptive behavior (state).

Basic functions of the National Assembly

Functions of the nervous system are quite numerous. The main ones are the following:

• regulation of vital functions of tissues, organs and their systems in normal mode;

• integration (integration) of the body;

• preservation of the relationship between a person and the environment;

• control over the condition of individual organs and the body as a whole;

• maintenance of activation and maintenance of a tonus (working condition);

• the definition of people's activities and their mental health, which are the basis of social life.

The nervous system of a person, the photo of which is presented above, provides such thought processes:

• Perception, assimilation and processing of information;

• analysis and synthesis;

• formation of motivation;

• comparison with existing experience;

• goal setting and planning;

• action correction (error correction);

• evaluation of performance;

• formation of judgments, conclusions and conclusions, general (abstract) concepts.

In addition to the nervous system, the nervous system also performs a trophic function. Thanks to it, the biologically active substances released by the body ensure the vital activity of the innervated organs. Organs that are deprived of such recharge, eventually atrophy and die. Functions of the nervous system are very important for a person. With changes in existing environmental conditions with their help, the organism adapts itself to new circumstances.

The processes taking place in the National Assembly

The human nervous system, the scheme of which is fairly simple and understandable, is responsible for the interaction of the organism and the environment. To ensure its implementation, such processes are carried out:

• transduction, which is the transformation of stimulation into nervous excitation;

• transformation, during which the incoming excitation with one characteristics is converted into an output stream with other properties;

• distribution of excitation in different directions;

• modeling, which is the construction of an image of irritation, replacing the source itself;

• modulation, altering the nervous system or its activity.

The value of the human nervous system also consists in the interaction of the organism with the external environment. This gives rise to various responses to any kinds of stimuli. The main types of modulation:

• Excitation (activation), consisting in an increase in the activity of the nervous structure (this state is dominant);

• inhibition, inhibition, which consists in a decrease in the activity of the nervous structure;

• a temporary neural connection, which is the creation of new ways of transmitting stimulation;

• plastic adjustment, which is represented by sensitization (improvement of transmission of excitation) and by gabituation (impairment of transmission);

• activation of the organ providing a reflex response of the human body.

The tasks of the National Assembly

The main tasks of the nervous system:

• Reception - capturing changes in the internal or external environment. It is carried out by sensory systems with the help of receptors and represents the perception of mechanical, thermal, chemical, electromagnetic and other types of stimuli.

• Transduction - the conversion (encoding) of the incoming signal into a nervous excitation, which is a stream of pulses with characteristics characteristic of irritation.

• Implementation of the exercise, which involves the delivery of excitation along the nerve pathways to the necessary areas of the NS and to the effector (executive organs).

• Perception - the creation of a nervous model of irritation (construction of its sensory image). This process forms a subjective picture of the world.

• Transformation - transformation of excitation from sensory into effector. Its purpose is to implement the response of the organism to the occurred change in the environment. In this case, a descending excitation is transmitted from the higher CNS to the lower regions or to the PNS (working organs, tissues).

• Assessment of the results of NA activities through feedback and afferentation (sensory information transfer).

Structure of the National Assembly

The human nervous system, the scheme of which is presented above, is subdivided in structural and functional terms. The work of the National Assembly can not be fully understood without understanding the functions of its main types. Only having studied their purpose, one can realize the complexity of the whole mechanism. The nervous system is divided into:

• Central (CNS), which carries out reactions of varying complexity, called reflexes. She perceives stimuli received from the external environment and from the organs. It includes the head and spinal cord.

• Peripheral (PNS), connecting the CNS with organs and limbs. Its neurons are far from the brain and spinal cord. It is not protected by bones, therefore it is subject to mechanical damages. Only due to the normal functioning of the PNS, the coordination of human movements is possible. This system is responsible for responding to danger and stressful situations. Thanks to her in such situations, the pulse rate increases and the level of adrenaline rises. Diseases of the peripheral nervous system affect the work of the central nervous system .

PNS consists of bundles of nerve fibers. They go far beyond the spinal cord and brain and are sent to different organs. They are called nerves. The PNS includes ganglia (nodes). They are a cluster of nerve cells.

Diseases of the peripheral nervous system are divided according to such principles: topographic-anatomical, etiological, pathogenesis, pathomorphology. These include:

• radiculitis;

• plexites;

• Funiculars;

• mono-, poly- and multi-neurites.

On the etiology of diseases, they are divided into infectious (microbial, viral), toxic, allergic, discirculatory, dismetabolic, traumatic, hereditary, idiopathic, compression-ischemic, vertebrogenic. Diseases of the PNS can be primary (leprosy, leptospirosis, syphilis) and secondary (after childhood infections, mononucleosis, with nodular periarteritis). On pathomorphology and pathogenesis they are divided into neuropathy (radiculopathy), neuritis (radiculitis) and neuralgia.

Properties of the nervous system

Reflex activity is largely determined by the properties of nerve centers, which represent a combination of CNS structures. Their coordinated activity ensures the regulation of various body functions or reflex acts. Nerve centers have several common properties, determined by the structure and function of the synaptic formations (contact between neurons and other tissues):

• One-sidedness of the excitation process. It propagates along the reflex arc in one direction.

• Irradiation of excitation, which consists in the fact that with a significant increase in the strength of the stimulus, the area of neurons involved in this process increases.

• Summation of excitation. This process is facilitated by the presence of a huge number of synaptic contacts.

• High fatigue. With prolonged repeated irritation, the reflex reaction weakens.

• Synaptic delay. The time of the reflex reaction depends entirely on the speed of movement and the time of propagation of excitation through the synapse. In humans, one such delay is about 1 ms.

• A tone that represents the presence of background activity.

• Plasticity, which is a functional ability to significantly modify the overall picture of reflex reactions.

• Convergence of nerve signals, which determines the physiological mechanism of the path of passage of afferent information (constant flow of nerve impulses).

• Integration of cell functions in nerve centers.

• The property of a dominant neural focus characterized by increased excitability, ability to excite and summarize.

• Cephalization of the nervous system, consisting in the movement, coordination of the body's activity in the main sections of the central nervous system and the concentration of regulation functions in them.