The meaning of the nervous system. Functions of the nervous system

Meaning nervous system huge in the human body. After all, it is responsible for the relationship between each organ, organ systems and functioning human body. The activity of the nervous system is determined by the following:

Establishing and establishing relationships between the outside world (social and ecological environment) and the body.
Anatomical penetration into every organ and tissue.
Coordinating each metabolic process flowing inside the body.
Managing the activities of apparatuses and organ systems, combining them into one whole.

The importance of the human nervous system

In order to perceive internal and external stimuli, the nervous system has sensory structures located in the analyzers. These structures will include certain devices capable of receiving information:

Proprioceptors. They collect all information regarding the condition of muscles, bones, fascia, joints, and the presence of fiber.
Exteroceptors. They are located in human skin, sensory organs, and mucous membranes. Capable of perceiving irritating factors, obtained from the environment external environment.
Interoreceptors. Located in tissues and internal organs. Responsible for the perception of biochemical changes received from the external environment.

Basic meaning and functions of the nervous system

It is important to note that with the help of the nervous system perception and analysis of information about stimuli from outside world and internal organs. She is also responsible for responses to these irritations.

The human body, the subtlety of its adaptation to changes in the surrounding world, is accomplished primarily through the interaction of humoral and nervous mechanisms.

The main functions include:

The definition and activities of man, which constitute the basis of his social life.
Regulation of the normal functioning of organs, their systems, tissues.
Integration of the body, its unification into a single whole.
Maintaining the relationship between the whole body and environment. If environmental conditions change, the nervous system adapts to these conditions.

In order to accurately understand the importance of the nervous system, it is necessary to delve into the meaning and main functions of the central and peripheral nervous systems.

The importance of the central nervous system

It is the main part of the nervous system of both humans and animals. Its main function is the implementation of various levels of complexity of reactions called reflexes.

Thanks to the activity of the central nervous system, the brain is able to consciously reflect changes in the external conscious world. Its meaning is that it regulates various kinds reflexes, capable of perceiving stimuli received both from internal organs and from the external world.

The importance of the peripheral nervous system

The PNS connects the central nervous system to the limbs and organs. Its neurons are located far beyond the central nervous system - the spinal cord and brain.

It is not protected by bones, which can lead to mechanical damage or the harmful effects of toxins.

Thanks to the proper functioning of the PNS, the body's movements are coordinated. This system is responsible for conscious control of the actions of the entire organism. Responsible for responding to stressful situations and danger. Increases heart rate. In case of excitement, it increases the level of adrenaline.

It is important to remember that you should always take care of your health. After all, when a person leads healthy image life, sticks to correct mode day, he does not burden his body in any way and thereby remains healthy.

Each organ or system in the human body plays its role. Moreover, they are all interconnected. The importance of the nervous system cannot be overestimated. It is responsible for the correlation between all organs and their systems and for the functioning of the body as a whole. At school, they begin early to become familiar with such a multifaceted concept as the nervous system. 4th grade – these are still young children who cannot deeply understand many complex 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 transfer it to other cells. Neurons can also exert modulatory or inhibitory effects on target cells. They are integral part 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, supracellular).

Neurons consist of a body (soma), a long process (axon), and small branching processes (dendrites). In different parts of the nervous system they have different shape and size. In some of them, the length of the axon can reach 1.5 m. Up to 1000 dendrites extend from one neuron. Through them, excitation spreads from the receptors to the cell body. The axon carries impulses to effector cells or other neurons.

In science there is a concept “synapse”. The axons of 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. There are synapses on muscle fibers. These organs of the nervous system are present even on gland cells internal secretion and blood capillaries. Nerve fibers are processes of neurons covered with glial sheaths. They perform a conducting function.

Nerve endings

These are specialized formations located at the tips of nerve fiber processes. They provide information transmission in the form of an impulse. Nerve endings participate in the formation of transmitting and receiving end apparatuses of different structural organizations. By functional purpose highlight:

Synapses, which transmit nerve impulses between nerve cells;

Receptors (afferent endings) that direct information from the site of action of an internal or external environmental factor;

Effectors that transmit impulses from nerve cells to other tissues.

Activity of the nervous system

The nervous system (NS) is an integral collection of several interconnected structures. It promotes the coordinated regulation of the activities of all organs and ensures a response to changing conditions. The human nervous system, a photo of which is presented in the article, binds together motor activity, sensitivity and functioning of other regulatory systems (immune, endocrine). The activities of the NS are related to:

Anatomical penetration into all organs and tissues;

Establishing and optimizing the relationship between the body and the surrounding external environment (ecological, social);

Coordinating all metabolic processes;

Management of organ systems.

Structure

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

Proprioceptors, which collect information regarding the condition of muscles, fascia, joints, bones;

Exteroceptors located in skin, mucous membranes and sensory organs capable of perceiving irritating factors received from the external environment;

Interoreceptors located in internal organs and tissues and responsible for the adoption of biochemical changes.

Basic meaning of the nervous system

The work of the nervous system is closely connected both with the surrounding world and with the functioning of the body itself. With its help, information is perceived and analyzed. Thanks to it, irritants of internal organs and signals coming from outside are recognized. The nervous system is responsible for the body's reactions to received information. It is thanks to its interaction with humoral regulatory mechanisms that a person’s adaptability to the surrounding world is ensured.

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

Basic functions of the NS

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

Regulation of the vital functions of tissues, organs and their systems in a normal manner;

Unification (integration) of the body;

Preserving the relationship between man and the environment;

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

Ensuring activation and maintenance of tone (working condition);

Determining the activities of people and their mental health, which are the basis of social life.

The human nervous system, the photo of which is presented above, provides the following 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);

Performance evaluation;

Formation of judgments, conclusions and conclusions, general (abstract) concepts.

In addition to signaling, the nervous system also performs a trophic function. Thanks to it, biologically excreted by the body active substances ensure the vital activity of innervated organs. Organs that are deprived of such nourishment atrophy and die over time. The functions of the nervous system are very important for humans. When changes existing conditions environment, with their help the body adapts to new circumstances.

Processes occurring in the NS

The human nervous system, the diagram of which is quite simple and understandable, is responsible for the interaction of the body and the environment. To ensure this, the following processes are carried out:

Transduction, which is the transformation of irritation into nervous excitation;

Transformation, during which the incoming excitation with one characteristics is converted into an outgoing flow with other properties;

Distribution of excitation in different directions;

Modeling, which is the construction of an image of irritation that replaces its source itself;

Modulation that changes the nervous system or its activity.

The importance of the human nervous system also lies in the interaction of the body with the external environment. In this case, various responses to any type of stimulus arise. Main types of modulation:

Excitation (activation), which consists in increasing the activity of the nervous structure (this state is dominant);

Inhibition, depression (inhibition), consisting of a decrease in the activity of the nervous structure;

Temporary neural connection, which represents the creation of new pathways for the transmission of excitation;

Plastic restructuring, which is represented by sensitization (improved transmission of excitation) and habituation (deterioration of transmission);

Activation of the organ that provides the reflex reaction of the human body.

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 sensory systems with the help of receptors and represents the perception of mechanical, thermal, chemical, electromagnetic and other types of stimuli.

Transduction is the transformation (coding) of an incoming signal into nervous excitation, which is a stream of impulses with characteristics characteristic of irritation.

Implementation of conduction, which consists in the delivery of excitation along the nerve pathways in required areas NS and to effectors (executive organs).

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

Transformation is the transformation of excitation from sensory to effector. Its goal is to implement the body’s response to the environmental change that has occurred. In this case, there is a transfer of descending excitation from the higher parts of the central nervous system to the lower ones or to the PNS (working organs, tissues).

Assessment of the result of the activity of the nervous system using feedback and afferentation (transmission of sensory information).

NS structure

The human nervous system, the diagram of which is presented above, is divided structurally and functionally. The work of a neural network cannot be fully understood without understanding the functions of its main types. Only by studying their purpose can one understand the complexity of the entire mechanism. The nervous system is divided into:

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

Peripheral (PNS), connecting the central nervous system with organs and limbs. Its neurons are located far from the brain and spinal cord. It is not protected by bones, so it is susceptible to mechanical damage. Only thanks to the normal functioning of the PNS is coordination of human movements possible. This system is responsible for the body's response to danger and stressful situations. Thanks to it, in such situations, the pulse quickens and the level of adrenaline increases. Diseases of the peripheral nervous system affect the functioning of the central nervous system.

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

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

Radiculitis;

Plexites;

Funiculitis;

Mono-, poly- and multineuritis.

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

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

One-sidedness of the excitation process. It spreads 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 expands.

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

High fatigue. With prolonged repeated stimulation, 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.

Tone, which represents the presence of background activity.

Plasticity, which is functionality significantly modify big picture reflex reactions.

Convergence of nerve signals that determines physiological mechanism pathways for the passage of afferent information (a constant flow of nerve impulses).

Integration of cell functions in nerve centers.

The property of a dominant nerve focus, characterized by increased excitability, the ability to excite and summation.

Cephalization of the nervous system, which consists in moving, coordinating the activity of the body in the main sections of the central nervous system and concentrating the regulatory function in them.

STRUCTURE OF THE NERVOUS SYSTEM

Central and peripheral nervous system. The human nervous system consists of central and peripheral parts. The central part includes the brain and spinal cord, the peripheral part includes nerves and ganglia.

The nervous system is made up of neurons and other cells nerve tissue. There are sensory, executive and mixed nerves.

Signals travel through sensory nerves to the central nervous system. They inform the brain about the state internal environment and events occurring in the surrounding world. Executive nerves carry signals from the brain to organs, controlling their activities. Mixed nerves include both sensory and executive nerve fibers.

The brain is located in the skull. The cell bodies of neurons in the brain are located in the gray matter of the cortex and nuclei scattered among the white matter of the brain. White matter consists of nerve fibers connecting various centers of the brain and spinal cord.

All parts of the brain perform conduction and reflex functions. In the frontal lobes of the cerebral cortex, activity goals are formed and an action program is developed; through the lower parts of the brain, its “orders” are sent to the organs, and through feedback signals are sent from the authorities about the implementation of these “orders” and their effectiveness.

Spinal cord - located in the spinal canal. At the top, the spinal cord passes into the brain, at the bottom it ends at the level of the second lumbar vertebra, a bundle of nerves extending from it, reminiscent of a horse's tail.

The spinal cord is found in the cerebrospinal fluid. It acts as a tissue fluid, ensuring a constant internal environment, and protects the spinal cord from shocks and shocks.

The cell bodies of the spinal cord neurons are concentrated in the gray columns, which occupy the central part of the spinal cord and stretch along the entire spine.

There are ascending nerve pathways along which nerve impulses go to the brain, and descending nerve pathways along which excitation goes from the brain to the centers of the spinal cord.

The spinal cord performs reflex and conductive functions.

Connection between the spinal cord and the brain. The centers of the spinal cord work under the control of the brain. The impulses coming from it stimulate the activity of the spinal cord centers and maintain their tone. If the connection between the spinal cord and the brain is disrupted, which happens when the spine is damaged, shock occurs. In shock, all reflexes, the centers of which lie below the spinal cord lesions, disappear, and voluntary movements become impossible.

Somatic and autonomous (vegetative) departments. Functionally, the nervous system forms two sections: somatic and autonomic.

Somatic the department regulates human behavior in the external environment; it is associated with the work of skeletal muscles, which are controlled by the desires and will of a person.

Autonomous department regulates the functioning of smooth muscles, internal organs, blood vessels. He weakly submits to volitional control and acts according to a program formed as a result natural selection and fixed heredity of the organism.

The autonomous department consists of two sub-departments - sympathetic And parasympathetic, which operate on the principle of complementarity. Thanks to their joint work, the optimal mode of operation of the internal organs is established for each specific situation.

FUNCTIONS AND IMPORTANCE OF THE NERVOUS SYSTEM

The nervous system ensures the relative constancy of the internal environment of the body.

Metabolism in every body occurs continuously. Some substances are consumed and excreted from the body, others come from outside.

The brain, and with it the endocrine glands, automatically maintain a balance between the intake and use of substances, ensuring that vital signs fluctuate within acceptable limits.

Thanks to the nervous system, the body maintains homeostasis, the relative constancy of the internal environment: acid-base balance, quantity mineral salts, oxygen and carbon dioxide, decomposition products and nutrients, in blood - value blood pressure and body temperature.

The nervous system coordinates the work of all organs.

The nervous system is responsible for coordinated activity various organs and systems, as well as for the regulation of body functions. It determines the order of contraction of muscle groups, the intensity of breathing and cardiac activity, and monitors and corrects the results of the action. The nervous system is responsible for sensitivity, motor activity and the functioning of the endocrine and immune systems.

Higher nervous activity ensures the most perfect adaptation of the body to the external environment. In humans, it provides higher mental functions: cognitive, emotional and volitional processes, speech, thinking, consciousness, ability to labor activity and creativity.

Through direct connections there are “orders” of the brain addressed to the organs, and through feedback connections there are signals to the brain from the organs, informing how successfully these “orders” have been carried out. The subsequent action will not take place until the previous one is completed and a positive effect is achieved.

Parasympathetic innervation (supply of nerves) of all organs and tissues is carried out by branches

The nervous system ensures the survival of the organism as a whole.

To survive, the body needs to receive information about objects in the external world. When entering life, a person constantly encounters certain objects, phenomena, and situations. Some of them are necessary for him, some are dangerous, others are indifferent.

With the help of the senses, the nervous system recognizes objects in the external world, evaluates them, remembers and processes the received information aimed at satisfying emerging needs.

OUR NERVOUS SYSTEM LOVES:

1. Fresh air.
2. Movement (long walks).
3. Positive emotions(feeling of joy, change of impressions).
4. Long sleep (9-10 hours).
5. Alternation of physical and mental labor.
6. Water procedures.
7. Simple food: Bread coarse, cereals (buckwheat, oatmeal), legumes, fish, meat and offal (liver, heart, kidneys), dried porcini mushrooms.
8. Vitamins of group “B” and Nicotinic acid.

OUR NERVOUS SYSTEM DOESN'T LIKE:

1. Stress(arising as a result of long-term negative emotions, fasting, prolonged exposure to the hot sun).
2. Noise- anyone annoying.
3. Infections and mechanical damage(diseases of the ears, teeth, squeezing pimples, insect bites - ticks, head contusion).

In order to perceive internal and external stimuli, the nervous system has sensory structures located in the analyzers. These structures will include certain devices capable of receiving information:

1. Proprioceptors. They collect all information regarding the condition of muscles, bones, fascia, joints, and the presence of fiber.

2. Exteroceptors. They are located in human skin, sensory organs, and mucous membranes. Able to perceive irritating factors received from the surrounding environment.

3. Interoreceptors. Located in tissues and internal organs. Responsible for the perception of biochemical changes received from the external environment.

Basic meaning and functions of the nervous system

It is important to note that with the help of the nervous system, perception and analysis of information about stimuli from the external world and internal organs is carried out. She is also responsible for responses to these irritations.

The human body, the subtlety of its adaptation to changes in the surrounding world, is accomplished primarily through the interaction of humoral and nervous mechanisms.

The main functions include:

1. Definition of a person’s mental health and activities, which are the basis of his social life.

2. Regulation of the normal functioning of organs, their systems, tissues.

3. Integration of the body, its unification into a single whole.

4. Maintaining the relationship of the whole organism with the environment. If environmental conditions change, the nervous system adapts to these conditions.

In order to accurately understand the importance of the nervous system, it is necessary to delve into the meaning and main functions of the central and peripheral nervous systems.

The importance of the central nervous system

It is the main part of the nervous system of both humans and animals. Its main function is the implementation of various levels of complexity of reactions called reflexes.

Thanks to the activity of the central nervous system, the brain is able to consciously reflect changes in the external conscious world. Its significance is that it regulates various kinds of reflexes and is able to perceive stimuli received both from internal organs and from the external world.

The importance of the peripheral nervous system

The PNS connects the central nervous system to the limbs and organs. Its neurons are located far beyond the central nervous system - the spinal cord and brain.

It is not protected by bones, which can lead to mechanical damage or harmful effects of toxins

It is important to remember that you should always take care of your health. After all, when a person leads a healthy lifestyle, adheres to the correct daily routine, he does not burden his body in any way and thereby remains healthy.

Nervous system

Functions of the nervous system. The nervous system performs following functions:

· Sensory – perceiving, transmitting and processing information, the nervous system communicates with the external and internal environment and ensures adaptation to living conditions;

· Motor – regulates motor functions organs and systems of the human body;

· Integrative – ensures fast and coordinated interaction between organs, thanks to which the human body functions as a single whole;

· Mental – the central part of the nervous system is the substrate of higher mental manifestations– consciousness, speech, thinking, memory, learning, with the help of which people communicate with each other and understand the environment.

Overall plan structure of the nervous system. The nervous system is topographically divided into central And peripheral , and functionally – on somatic And vegetative . The central nervous system (CNS) includes the spinal cord and brain, and the peripheral nervous system includes nerves and ganglia.

The central nervous system is formed by neurons and neuroglia. In the head and spinal cord neurons can be arranged in the form

· Clusters called nuclei (for example, the nuclei of the cranial nerves);

· Clusters called nerve centers. These centers are necessary for the implementation of a certain reflex or regulation of a particular function (for example, the breathing center in medulla oblongata);

· Networks, that is, diffusely (for example, neurons of the reticular formation);

Parallel horizontal layers (for example, in the cortex cerebral hemispheres and cerebellum);

· Vertical columns (for example, in the cerebral cortex).

The processes of central neurons within the brain form its pathways and connections in neural networks. The processes of neurons located outside the brain form peripheral nerves.

The central nervous system analyzes information coming from the external and internal environment of the body, and forms its response to this information.

Ganglia of the peripheral nervous system are also clusters of neurons surrounded by neuroglial cells. There are spinal and cranial ganglia.

Nerves are formed by long processes of neurons. The peripheral nerves include 12 pairs of cranial nerves and 31 pairs of spinal nerves. The cranial nerves innervate mainly the structures of the head and neck, except vagus nerve, which innervates internal organs. Spinal nerves innervate the muscles of the trunk and limbs. Some nerves carry information from receptors to the central nervous system and are called sensory, or afferent . Other nerves transmit signals from the central nervous system to all organs and systems of the body and are called motor, or efferent . Most peripheral nerves are mixed: they contain both afferent and efferent fibers.

Somatic nervous system provides tone, body posture, motor reactions and innervation of the skin.

Vegetative, or autonomic nervous system regulates the functioning of internal organs. It is associated with the maintenance of homeostasis, metabolism, growth and development of the body, neuroendocrine regulation and trophic innervation of skeletal muscles, skin and the nervous system itself. The autonomic nervous system is divided into sympathetic and parasympathetic divisions.

Both the somatic nervous system and the autonomic nervous system have central and peripheral sections. Central department located in the spinal cord and brain and is represented by nuclei, and the peripheral section is located outside the central nervous system and is represented by nerves.

31.Structure and physiological functions neuron.

A neuron is a cell soms(body) from which several short processes extend - dendrites With spines at the ends there is one long process - axon, which branches to form collaterals. Collaterals and spines are necessary to increase the area of contact of one neuron with other neurons

The neuron has a specialized plasma membrane, conducting impulses. The cytoplasm of a neuron, like any eukaryotic cell, contains a nucleus and organelles. Peculiarity internal structure neuron is that in the neuroplasm of the latter, in addition to the usual organelles, there are special structures - neurofibrils. The cytoplasm of a neuron also contains pigment substances on which the color of the neuron depends. In addition, the neuron contains a large number of mitochondria and their volume varies depending on functional activity, endoplasmic reticulum.

The soma and dendrites of a neuron do not have a myelin sheath (the myelin sheath is formed by a fat-like substance white), therefore in the brain mass they have grey colour. The substance they form is called gray matter brain Axons covered with a myelin sheath form white matter The brain is a collection of pathways. The myelin sheath of the axon is not continuous; at certain intervals it is interrupted - these places are called Ranvier interceptions. The portion of the soma from which the axon arises is called axon hillock. The axon hillock does not have a myelin sheath.

Depending on the number of processes, all neurons are divided into

1. bipolar, which have one axon and one dendrite and are located in the retina of the eye and in the sound-receiving apparatus inner ear;

2. polypolar – have one axon and many dendrites, located in the brain;

3. false unipolar - one process departs from the soma, which then at some distance is divided into two: an axon and a relatively long dendrite; located in peripheral ganglia;

4. unipolar - have one process, are present in the human body only in the prenatal period.

Depending on the shape of the soma, neurons are divided into

1. pyramidal - the catfish has the shape of a pyramid;

2. star-shaped - the catfish has the appearance of a star;

3. spindle-shaped - the catfish has the appearance of a spindle.

The main function of neurons is the reception, transformation and transmission of information, which is encoded in the form of electrical potentials propagating along the processes of the neuron - action potentials (AP). The neuron has an electrically excitable membrane that is negatively charged relative to the surrounding extracellular fluid. Membrane charge – membrane potential , or resting potential (RP), - is not the same for different neurons and depends on a number of factors. The membrane charge is created due to different concentrations of sodium, potassium, and chlorine ions inside and outside the cell. When excited, a neuron generates an AP, or nerve impulse. In this case, depolarization of the membrane occurs, and currents appear in the dendrites and soma directed towards the axon hillock. In the area of the axon hillock, a nerve impulse is generated, which spreads along the axon. If the axon is covered with a myelin sheath, then the AP causes excitation only at the nodes of Ranvier; if the axon is not covered with a sheath, then the AP causes excitation at each adjacent point of the fiber. The speed of PD propagation depends on

1. axon diameter - the thicker the axon, the higher the speed of propagation;

2. the presence of a myelinated membrane;

3. PP values - the higher the PP, the higher the propagation speed;

4. PD values – the higher the PD, the higher the propagation speed.

A neuron works as a signal transducer: it sums up many incoming stimuli and forms its response on this basis. A neuron does not generate a single impulse, but a series of several impulses that occur at a certain frequency. This frequency conversion is one of the main ways of encoding information in the nervous system.

Functionally, all neurons are divided into

1. afferent (sensitive), carrying information from the external and internal environment to the central nervous system;

2. efferent (motor), carrying an information response from the central nervous system to the organs;

3. associative (intercalary) – neurons that connect afferent and efferent cells with each other.

To transmit and process information, neurons interact with each other and with cells executive bodies through special contacts - synapses . The synapse is divided into a presynaptic membrane, a synaptic cleft, and a postsynaptic membrane. According to the nature of their influence on the cell, synapses are divided into excitatory and inhibitory, and according to the method of signal transmission - electrical and chemical. In humans, only chemical synapses are present. Substances that transmit signals through synaptic contact are called mediators . These include acetylcholine, adrenaline, serotonin, histamine, norepinephrine, gamma-aminobutyric acid(GABA). Mediators pass through the presynaptic membrane, bind to receptors on the postsynaptic membrane, thereby changing it membrane potential(resting potential - PP ). Thus, at synapses, a chemical signal is converted into an electrical signal.

Synaptic contacts can be: axosomatic, axodendritic, axo-axonal and dendro-dendritic. The synapses between the axon terminal and the muscle are called neuromuscular, or end plates.

The formation of new synapses underlies the property of the nervous system - plasticity. The development of the child’s brain, learning and memory processes depend on this property.

Nerve fibers

Nerve fibers- processes of nerve cells (neurons) that have a membrane and are capable of conducting nerve impulses.

The main component of the nerve fiber is the process of the neuron, which forms, as it were, the axis of the fiber. For the most part this is an axon. The nerve process is surrounded by a membrane of complex structure, together with which it forms a fiber. The thickness of the nerve fiber in the human body, as a rule, does not exceed 30 micrometers.

Nerve fibers are divided into pulpy (myelinated) and non-myelinated (non-myelinated). The former have a myelin sheath covering the axon, the latter lack a myelin sheath.

Myelin fibers predominate in both the peripheral and central nervous systems. Nerve fibers lacking myelin are located predominantly in the sympathetic division of the autonomic nervous system. At the point where the nerve fiber departs from the cell and in the area of its transition into the final branches, the nerve fibers can be devoid of any membranes, and then they are called bare axial cylinders.

Depending on the nature of the signal carried through them, nerve fibers are divided into motor autonomic, sensory and motor somatic.

The structure of nerve fibers

Myelinated nerve fiber contains the following elements(structures):
1) an axial cylinder located in the very center of the nerve fiber,
2) the myelin sheath covering the axial cylinder,
3) Schwann shell.

The axial cylinder consists of neurofibrils. The pulpy membrane contains a large amount of lipoid substances known as myelin. Myelin ensures the speed of nerve impulses. The myelin sheath does not cover the entire axial cylinder, forming gaps called nodes of Ranvier. In the area of the nodes of Ranvier, the axial cylinder of the nerve fiber is adjacent to the superior Schwann membrane.

The fiber space located between two nodes of Ranvier is called a fiber segment. In each such segment, the nucleus of the Schwann membrane can be seen on stained preparations. It lies approximately in the middle of the segment and is surrounded by the protoplasm of the Schwann cell, the loops of which contain myelin. Between the nodes of Ranvier, the myelin sheath is also not continuous. In its thickness, so-called Schmidt-Lanterman notches are found, running in an oblique direction.

Schwann membrane cells, as well as neurons with processes, develop from the ectoderm. They cover the axial cylinder of the nerve fiber of the peripheral nervous system, similar to how glial cells cover the nerve fiber in the central nervous system. As a result, they may be called peripheral glial cells.

In the central nervous system, nerve fibers do not have Schwann sheaths. The role of Schwann cells here is performed by elements of oligodendroglia. An unmyelinated (unmyelinated) nerve fiber is devoid of a myelin sheath and consists only of an axial cylinder and a Schwann sheath.

Function of nerve fibers

Main function nerve fibers – transmission of nerve impulses. Currently, two types of nerve transmission have been studied: pulsed and non-pulse. Impulse transmission is provided by electrolyte and neurotransmitter mechanisms. The speed of nerve impulse transmission in myelinated fibers is much higher than in nonmyelinated fibers. In its implementation vital role belongs to myelin. This substance is capable of isolating a nerve impulse, resulting in signal transmission along nerve fiber occurs spasmodically, from one interception of Ranvier to another.

Pulseless transmission is carried out by axoplasmic current along special axon microtubules containing trophogens - substances that have a trophic effect on the innervated organ.

The human nervous system is very important in ensuring all functions of the body. It is responsible for its connection with the environment, for the exchange of information between organs and parts of the body and their coordinated work.

Structure of the central nervous system

The nervous system consists of large quantity cells - neurons. They have branches and are connected by them. Together they look like a web and are called nerves. The groups of these cells that form the spinal cord and brain are called the central nervous system (CNS).

Human central nervous system

Brain

The brain is the most important part of the body and the central nervous system. All information received by a person is processed here. Its structure is very complex. It consists of two hemispheres that are responsible for such important processes, How:

emotions and feelings;
hearing;
vision;
touch;
taste and smell;
speech;
visual recognition;
behavior;
movement;
thinking.

Below the hemispheres is the wrinkled-looking cerebellum. A trunk also extends from them, which connects the brain and spinal cord. The trunk consists of oblong, middle and intermediate sections.

The cerebral hemispheres are divided into right and left and have sections:

frontal;
parietal;
occipital;
temporal.

Brain regions

Each zone is responsible for certain processes in the body and performs its own functions. For example, frontal lobes guide human behavior and complex thinking. The occipital region is responsible for vision, the temporal region is responsible for hearing and smell.

Spinal cord

The spinal cord resembles a long cord as thick as your little finger. It is located inside the vertebrae. Its main function is to transmit information along nerves from the whole body to the brain and back. It acts as an intermediate link and is very important for the body.

The spinal cord and brain are the main organs of the human nervous system

Peripheral nervous system and information transmission

Neurons are found throughout the human body and are connected to all muscles, internal organs, skin and even the eyes. These connections are called the peripheral nervous system. It is she who transmits information to the spinal cord and brain and back to tissues, muscles or organs. Information comes in the form of signals - impulses.
The movement of the impulse can be seen in simple example. When a person touches something hot, a signal is sent from the skin to the brain. There it is identified as a danger and a response message is sent to the hand - “pull it away!” This happens very quickly, in less than a second.

The autonomic nervous system is distinguished in the peripheral part. She is responsible for transferring information between internal organs. Thanks to her, they work as one mechanism.

The Importance of Staying Healthy

Brain health is greatly affected by disorders bad feeling and fatigue and poison from alcoholic drinks and tobacco. All this leads to headaches, illnesses, thinking disorders and the death of neurons.
If one nerve cell dies, then a new one is no longer born. To perform all functions, the remaining cells have to work harder. Therefore, it is very important to maintain a healthy lifestyle and “feed” your brain properly. You need to not only eat right, but also go for walks. fresh air, exercise and relax.
In Russian schools, physical education classes in spring and autumn are held outside. This helps too nerve cells be saturated with oxygen. It is also important to maintain a positive attitude towards life and other people.