Textbook: Anatomy of the central nervous system. Structure and functions of the human nervous system The central nervous system is represented by

1. Basic functions of the central nervous system.

2. Methods for studying the functions of the central nervous system.

3. The concept of reflex, classification of reflexes.

4. Basic properties of nerve centers.

5. Basic principles of the coordination activities of the central nervous system.

6. Spinal cord.

7. Medulla oblongata.

8. Midbrain.

9. Reticular formation of the brain stem.

10. Diencephalon.

11. Limbic system.

12. Strio-pallidal system.

Functions of the central nervous system. The human body is a complex, highly organized system consisting of functionally interconnected cells, tissues, organs and their systems.

This relationship (integration) of functions, their coordinated functioning, is ensured by the central nervous system (CNS). The central nervous system regulates all processes occurring in the body, therefore, with its help, the most adequate changes in the work of various organs occur, aimed at ensuring one or another of its activities.

The following can be distinguished main functions of the central nervous system:

1) integration - combining the functions of the body, it has 3 main forms. A neural form of integration, when the unification of functions occurs due to the central and peripheral parts of the nervous system. For example, the sight and smell of food, being conditioned reflex stimuli, lead to the occurrence of a motor food-procuring reaction, the secretion of saliva, gastric juice, etc. In this case, the integration of behavioral, somatic and vegetative functions of the body occurs. Humoral form of integration, when the combination of different functions of the body occurs mainly due to humoral factors. For example, hormones of different endocrine glands can exert their influence either simultaneously (increasing the effects of each other) or sequentially (the production of one hormone is accompanied by an increase in the function of another gland: ACTH – glucocorticoids, TSH – thyroid hormones). In turn, the released hormones have an activating effect on a number of functions. For example, adrenaline simultaneously enhances the work of the heart, increases ventilation of the lungs, increases blood sugar, i.e. leads to the mobilization of the body's energy resources. And finally, the mechanical form of integration, i.e. For the full performance of a particular function, the structural integrity of the organ is necessary. If the arm is injured (bone fracture), then the function of the limb is significantly affected. The same is observed with damage to internal organs, when structural changes lead to dysfunction.

2) Coordination is the coordinated activity of various organs and systems, which is ensured by the central nervous system. Simple and complex forms of movements, movement of the body in space, maintaining posture and position, human labor activity, and a number of general biological adaptive reactions can be achieved through the coordination activity of the central nervous system.

3) Regulation of body functions and preservation of many homeostatic constants is one of the most important functions of the central nervous system. This form of regulation is based on various reflexes, self-regulation, and the formation of functional systems that ensure the achievement of a useful adaptive result to the changing conditions of the external and internal environment of the body. The regulatory influence of the central nervous system can be in the form of triggering (start of activity), corrective (change in the activity of an organ in one direction or another) or trophic in the form of changes in the level of blood supply, the intensity of metabolic processes. Trophic influence is exerted by both autonomic and somatic nerves.

4) Correlation – ensuring the processes of interrelation between individual organs, systems and functions.

5) Establishing and maintaining a connection between the body and the environment.

6) The central nervous system ensures the cognitive and labor activity of the body. It functions as a regulator of behavior necessary in specific conditions of existence. This ensures adequate adaptation to the surrounding world.

Methods for studying the functions of the central nervous system. The intensive development of the physiology of the central nervous system has led to a transition from descriptive methods of studying the functions of various parts of the brain to experimental methods. Many methods used to study CNS function are used in combination with each other.

1) Destruction method, using this method, it is possible to establish which functions of the central nervous system are lost after surgery and which are preserved. This methodological technique has long been used in experimental research. However, destruction and extirpation are gross interventions, and they are accompanied by significant changes in the functions of the central nervous system and the body as a whole. In recent decades, the most widespread method has been the local electrolytic destruction of individual nuclei and structures of the brain using the stereotactic principle. The essence of the latter is that electrodes are guided into the deep structures of the brain using stereotactic atlases. Such brain atlases have been developed for different animals and for humans. According to the corresponding atlases, using a stereotactic device, electrodes and cannulas can be implanted into various nuclei of the brain (and also destroyed locally).

2) The transection method - makes it possible to study the significance in the activity of one or another department of the central nervous system, influences coming from its other departments. Transection is performed at various levels of the central nervous system. Complete transection, for example, of the spinal cord or brain stem separates the overlying parts of the central nervous system from the underlying ones and makes it possible to study reflex reactions that are carried out by nerve centers located below the transection site. Transection and local damage to individual nerve centers is performed not only under experimental conditions, but also in a neurosurgical clinic as a therapeutic measure.

3) The stimulation method makes it possible to study the functional significance of various formations of the central nervous system. With stimulation (chemical, electrical, etc.) of certain brain structures, one can observe the emergence, features of manifestation and the nature of the spread of excitation processes. Currently, the most widely used methods are stimulating individual nuclear formations of the brain, or using microelectrode technology - individual neurons.

4) Electrographic methods. These methods for studying the functions of the central nervous system include:

A) electroencephalography is a method for recording the total electrical activity of various parts of the brain. For the first time, recording of the electrical activity of the brain was carried out by V.V. Pravdich-Neminsky using electrodes immersed in the brain. Berger recorded brain potentials from the surface of the skull and called the recording of brain potential fluctuations an electroencephalogram (EEG).

The frequency and amplitude of EEG oscillations can change, but at each moment in time certain rhythms predominate in the EEG, which Berger called alpha, beta, theta and delta rhythms. The alpha rhythm is characterized by an oscillation frequency of 8-13 Hz, amplitude  50 μV. This rhythm is best expressed in the occipital and parietal areas of the cortex and is recorded under conditions of physical and mental rest with eyes closed. If you open your eyes, the alpha rhythm is replaced by a faster beta rhythm. The beta rhythm is characterized by an oscillation frequency of 14-50 Hz and an amplitude of up to V μV. The theta rhythm is an oscillation with a frequency of 4-8 Hz and an amplitude of  100-150 µV. This rhythm is recorded during shallow sleep, during hypoxia and light anesthesia. The delta rhythm is characterized by slow oscillations of potentials with a frequency of 0.5-3.5 Hz and an amplitude of 250-300 μV. This rhythm is recorded during deep sleep, during deep anesthesia, and in a comatose state.

The EEG method is used in the clinic for diagnostic purposes. This method has found particularly wide application in neurosurgical clinics to determine the location of brain tumors. In a neurological clinic, this method is used to determine the localization of an epileptic focus, and in a psychiatric clinic, for diagnosing mental disorders. In the surgical clinic, EEG is used to test the depth of anesthesia.

B) The method of local potential removal, when biocurrents are recorded from certain nuclear formations either in an acute experiment, or after preliminary implantation of electrodes - in a chronic experiment. Potential tapping using microelectrodes where the activity of individual neurons is recorded. Potential removal can be intracellular or extracellular.

C) The method of evoked potentials, when the electrical activity of certain brain structures is recorded during stimulation of receptors, nerves, and subcortical structures. There are primary (PO) and late or secondary (SE) evoked potentials. The VP method is used in neurology and neurophysiology. Currently, the stereotactic method is widely used in the neurosurgical clinic for the following purposes: destruction of brain structures in order to eliminate states of hyperkinesis, phantom pain, some mental disorders, epileptic disorders, etc., identifying pathological epileptogenic foci; to destroy these tumors; coagulation of cerebral aneurysms.

5) Study of reflexes (for example, knee, Achilles, abdominal, etc.).

6) Pharmacological methods using neuroactive substances of mediator or peptide nature, hormones and medicinal substances that have a specific effect on receptors (for example, mimetics - adreno, choline or blockers of these receptors) of the central nervous system.

7) Biochemical methods.

CNS - what is it? The structure of the human nervous system is described as an extensive electrical network. Perhaps this is the most accurate metaphor possible, since current actually runs through thin filament threads. Our cells themselves generate microdischarges in order to quickly deliver information from receptors and sensory organs to the brain. But the system does not function randomly; everything is subject to a strict hierarchy. That is why they highlight

Departments of the central nervous system

Let's take a closer look at this system. And yet, what is the central nervous system? Medicine provides a comprehensive answer to this question. This is the main part of the nervous system of chordates and humans. It consists of structural units - neurons. In invertebrates, this entire structure looks like a cluster of nodules that have no clear subordination to each other.

The human central nervous system is represented by a ligament of the brain and spinal cord. In the latter, the cervical, thoracic, lumbar and sacrococcygeal regions are distinguished. They are located in the corresponding parts of the body. Almost all peripheral nerve impulses are carried to the spinal cord.

The brain is also divided into several parts, each of which has a specific function, but their work is coordinated by the neocortex, or cerebral cortex. So, anatomically they distinguish:

  • brain stem;
  • medulla;
  • hindbrain (pons and cerebellum);
  • midbrain (lamina quadrigeminalis and cerebral peduncles);
  • forebrain

Each of these parts will be discussed in more detail below. This structure of the nervous system was formed in the process of human evolution so that he could ensure his existence in new living conditions.

Spinal cord

It is one of two organs of the central nervous system. The physiology of its work is no different from that in the brain: with the help of complex chemical compounds (neurotransmitters) and the laws of physics (in particular, electricity), information from small branches of nerves is combined into large trunks and either implemented in the form of reflexes in the corresponding part of the spinal cord, or enters the brain for further processing.

Located in the hole between the arches and vertebral bodies. It is protected, like the head membrane, by three membranes: hard, arachnoid and soft. The space between these tissue sheets is filled with fluid, which nourishes the nervous tissue and also acts as a shock absorber (dampens vibrations during movements). The spinal cord begins from the opening in the occipital bone, at the border with the medulla oblongata, and ends at the level of the first and second lumbar vertebrae. Next are only the membranes, cerebrospinal fluid and long nerve fibers (“cauda equina”). Conventionally, anatomists divide it into departments and segments.

On the sides of each segment (corresponding to the height of the vertebra) sensory and motor nerve fibers called roots extend. These are long processes of neurons, the bodies of which are located directly in the spinal cord. They are a collector of information from other parts of the body.

Medulla

The medulla oblongata is also involved in activities. It is part of a formation such as the brain stem and is in direct contact with the spinal cord. There is a conventional boundary between these anatomical formations - this is the decussation. It is separated from the bridge by a transverse groove and a section of the auditory tract that runs in the rhomboid fossa.

In the thickness of the medulla oblongata there are nuclei of the 9th, 10th, 11th and 12th cranial nerves, fibers of the ascending and descending nerve tracts and the reticular formation. This area is responsible for performing protective reflexes such as sneezing, coughing, vomiting and others. It also keeps us alive by regulating breathing and heartbeat. In addition, the medulla oblongata contains centers for regulating muscle tone and maintaining posture.

Bridge

Together with the cerebellum, it is the posterior part of the central nervous system. What is this? A collection of neurons and their processes located between the transverse sulcus and the exit point of the fourth pair of cranial nerves. It is a roller-shaped thickening with a depression in the center (it contains blood vessels). The fibers of the trigeminal nerve emerge from the middle of the bridge. In addition, the superior and middle cerebellar peduncles extend from the pons, and in the upper part of the pons are the nuclei of the 8th, 7th, 6th and 5th pairs of cranial nerves, a section of the auditory tract and the reticular formation.

The main function of the bridge is to transmit information to the higher and lower parts of the central nervous system. Many ascending and descending pathways pass through it, which end or begin their path in different parts of the cerebral cortex.

Cerebellum

This is the department of the central nervous system (CNS), which is responsible for coordinating movements, maintaining balance and maintaining muscle tone. It is located between the pons and the midbrain. To obtain information about the environment, it has three pairs of legs through which nerve fibers pass.

The cerebellum acts as an intermediate collector of all information. It receives signals from sensory fibers of the spinal cord, as well as from motor fibers starting in the cortex. After analyzing the data obtained, the cerebellum sends impulses to the motor centers and corrects the position of the body in space. All this happens so quickly and smoothly that we do not notice its work. All our dynamic automatisms (dancing, playing musical instruments, writing) are the responsibility of the cerebellum.

Midbrain

There is a department in the human central nervous system that is responsible for visual perception. This is the midbrain. It consists of two parts:

  • The lower one represents the legs of the brain, in which the pyramidal tracts pass.
  • The upper one is the quadrigeminal plate, on which, in fact, the visual and auditory centers are located.

The formations in the upper part are closely connected with the diencephalon, so there is not even an anatomical border between them. Conventionally, we can assume that this is the posterior commissure of the cerebral hemispheres. In the depths of the midbrain there are the nuclei of the third cranial nerve - the oculomotor nerve, and in addition to this there is also the red nucleus (it is responsible for controlling movements), the substantia nigra (initiates movements) and the reticular formation.

The main functions of this area of ​​the central nervous system:

  • orientation reflexes (reaction to strong stimuli: light, sound, pain, etc.);
  • vision;
  • pupil reaction to light and accommodation;
  • friendly turn of the head and eyes;
  • maintaining skeletal muscle tone.

Diencephalon

This formation is located above the midbrain, just below the corpus callosum. It consists of the thalamic part, the hypothalamus and the third ventricle. The thalamic part includes the thalamus itself (or thalamus), epithalamus and metathalamus.

  • The thalamus is the center of all types of sensitivity; it collects all afferent impulses and redistributes them into the appropriate motor pathways.
  • The epithalamus (epiphysis, or pineal body) is an endocrine gland. Its main function is the regulation of human biorhythms.
  • The metathalamus is formed by the medial and lateral geniculate bodies. The medial bodies represent the subcortical center of hearing, and the lateral bodies represent the center of vision.

The hypothalamus controls the pituitary gland and other endocrine glands. In addition, it partially regulates the autonomic nervous system. We have to thank him for the speed of metabolism and maintaining body temperature. The third ventricle is a narrow cavity that contains the fluid necessary to nourish the central nervous system.

Cortex of the hemispheres

Neocortex CNS - what is it? This is the youngest section of the nervous system, phylo - and ontogenetically it is one of the last to be formed and consists of rows of cells densely layered on top of each other. This area occupies about half of the total space of the cerebral hemispheres. It contains convolutions and grooves.

There are five parts of the cortex: frontal, parietal, temporal, occipital and insular. Each of them is responsible for their own area of ​​work. For example, the frontal lobe contains the centers of movement and emotion. In the parietal and temporal are the centers of writing, speech, small and complex movements, in the occipital are visual and auditory, and the insular lobe corresponds to balance and coordination.

All information that is perceived by the endings of the peripheral nervous system, be it smell, taste, temperature, pressure or anything else, enters the cerebral cortex and is carefully processed. This process is so automated that when it is stopped or disrupted due to pathological changes, the person becomes disabled.

Functions of the central nervous system

For such a complex formation as the central nervous system, its corresponding functions are also characteristic. The first of them is integrative-coordination. It implies the coordinated work of various organs and systems of the body to maintain a constant internal environment. The next function is the connection between a person and his environment, the body’s adequate reactions to physical, chemical or biological stimuli. In addition, this includes social activities.

The functions of the central nervous system also cover metabolic processes, their speed, quality and quantity. For this purpose, there are separate structures, such as the hypothalamus and pituitary gland. Higher mental activity is also possible only thanks to the central nervous system. When the cortex dies, the so-called “social death” is observed, when the human body still retains vitality, but as a member of society he no longer exists (he cannot speak, read, write and perceive other information, as well as reproduce it).

It is difficult to imagine humans and other animals without the central nervous system. Its physiology is complex and not yet fully understood. Scientists are trying to understand how the most complex biological computer ever existed works. But this is like “a bunch of atoms studying other atoms,” so progress in this area is not yet sufficient.

The nervous system ensures the vital activity of the organism as a whole in relation to the external and internal environment. The main functions of the nervous system are:

Fast and accurate transmission of information about the state of the external and internal environment - sensory function ;

Analysis and integration all information ;

Organization of adaptive response to external signals - motor function ;

Regulation of the activity of internal organs and the internal environment - visceral function ;

Regulation and coordination of the activities of all organs and systems in accordance with changing conditions of the external and internal environment.

Nervous system unites human organism into a single whole , regulates And coordinates functions of all organs and systems, maintains a constant internal environment body ( homeostasis), establishes relationships body with the external environment .

For the nervous system characteristic accurate focus nerve impulses, large conduction speed information, fast adaptability to changing environmental conditions. The human nervous system creates the basis for mental activity, analysis and synthesis of information entering the body (thinking, speech, complex forms of social behavior).

These complex and vital tasks are solved with the help of neurons that perform the function of perception, transmission, processing and storage of information. Signals (nerve impulses) from human organs and tissues and from the external environment acting on the surface of the body and sensory organs travel through the nerves to the spinal cord and brain. Complex information processing processes occur in the human brain. As a result, response signals go from the brain along the nerves to the organs and tissues, causing a reaction in the body, which manifests itself in the form of muscle or secretory activity. In response to impulses received from the brain, contraction of skeletal muscles or muscles occurs in the walls of internal organs, blood vessels, as well as the secretion of various glands - salivary, gastric, intestinal, sweat and others (secretion of saliva, gastric juice, bile, hormones by the endocrine glands) .

From the brain to the working organs (muscles, glands), nerve impulses also follow chains of neurons. The body's response to influences from the external environment or changes in its internal state, carried out with the participation of the nervous system, is called a reflex (from the Latin reflexus - reflection, response). The path consisting of chains of neurons along which a nerve impulse passes from sensory nerve cells to the working organ is called a reflex arc. For each reflex arc, the first neuron can be identified - sensitive, or bringing, which perceives influences, forms a nerve impulse and brings it to the central nervous system. The following neurons (one or more) are interneurons, conductor neurons located in the brain. Interneurons conduct nerve impulses from the afferent, sensitive neuron to the last, efferent, efferent neuron. The last neuron carries a nerve impulse from the brain to the working organ (muscle, gland), puts this organ into operation, causes an effect, and is therefore also called an effector neuron.


The main functions of the central nervous system are:

Uniting all parts of the body into a single whole and their regulation;

Controlling the state and behavior of the body in accordance with environmental conditions and its needs.

The main and specific function of the central nervous system is the implementation of simple and complex highly differentiated reflective reactions, called reflexes.

In higher animals and humans lower and middle parts of the central nervous system — spinal cord, medulla oblongata, midbrain, diencephalon and cerebellum — regulate the activities of individual organs and systems of a highly developed organism, carry out communication and interaction between them, ensure the unity of the organism and the integrity of its activities .

Higher department of the central nervous system — cerebral cortex and nearby subcortical formations- mostly regulates the connection and relationship of the organism as a whole with the environment .

Practically all departments central and peripheral nervous system participate in information processing , coming through external and internal, located on the periphery of the body and in the organs themselves receptors . With higher mental functions, with human thinking and consciousness the work of the cerebral cortex and subcortical structures included in forebrain .

The main principle of the functioning of the central nervous system is the process regulation, physiological control functions, which are aimed at maintaining the constancy of the properties and composition of the internal environment of the body. The central nervous system ensures optimal relationships between the body and the environment, stability, integrity, and the optimal level of vital activity of the body. .

Distinguish two main types of regulation: humoral and nervous .

Humoral management process involves change in physiological activity body under the influence of chemicals , which are delivered by body fluids. The source of information transfer is chemical substances - utilizons, metabolic products ( carbon dioxide, glucose, fatty acids), informons, endocrine gland hormones, local or tissue hormones.

Nervous the regulatory process involves control of changes in physiological functions along nerve fibers with help potential excitement influenced by the transfer of information.

In organism nervous and humoral mechanisms work as a single system neurohumoral control. This is a combined form, where two control mechanisms are used simultaneously; they are interconnected and interdependent.

Nervous the system is a collection of nerve cells, or neurons.

According to localization they distinguish:

1) central department - brain and spinal cord;

2) peripheral - processes of nerve cells in the brain and spinal cord.

According to functional features they distinguish:

1)somatic department that regulates motor activity;

2) vegetative , regulating the activity of internal organs, endocrine glands, blood vessels, trophic innervation of muscles and the central nervous system itself.

Functions of the nervous system:

1) integrative-coordination function. Provides functions various organs and physiological systems, coordinates their activities with each other;

2) ensuring close ties human body with the environment at the biological and social levels;

3) regulation of the level of metabolic processes in various organs and tissues, as well as in itself;

4) ensuring mental activity higher departments of the central nervous system.

central nervous system(CNS) - the main part of the nervous system of animals and humans, consisting of a collection of nerve cells (neurons) and their processes; It is represented in invertebrates by a system of closely interconnected nerve nodes (ganglia), in vertebrates and humans - by the spinal cord and brain.

The main and specific function of the central nervous system is the implementation of simple and complex highly differentiated reflective processes, called. In higher animals and humans, the lower and middle sections of the central nervous system -, and - regulate the activity of individual organs and systems of a highly developed organism, carry out communication and interaction between them, ensure the unity of the organism and the integrity of its activities. The higher department of the central nervous system - the cerebral cortex and the nearest subcortical formations - mainly regulates the connection and relationship of the body as a whole with the environment.

Main structural features and functions

The central nervous system is connected to all organs and tissues through the peripheral nervous system, which in vertebrates includes cranial nerves extending from the brain and spinal nerves - from, intervertebral nerve ganglia, as well as the peripheral part of the autonomic nervous system - nerve ganglia, with them (preganglionic, from the Latin ganglion) and the nerve fibers extending from them (postganglionic). Sensory, or afferent, nerve adductor fibers are carried to the central nervous system from the peripheral ones; along the efferent efferent (motor and autonomic) nerve fibers, excitation from the central nervous system is directed to the cells of the executive working apparatus (muscles, glands, blood vessels, etc.). In all parts of the central nervous system there are afferent neurons that perceive stimuli coming from the periphery, and efferent neurons that send nerve impulses to the periphery to various executive effector organs. Afferent and efferent cells with their processes can contact each other and form a two-neuron reflex arc that carries out elementary reflexes (for example, tendon reflexes). But, as a rule, intercalary nerve cells, or interneurons, are located in the reflex arc between the afferent and efferent neurons. Communication between different parts of the central nervous system is also carried out using many processes of afferent, efferent and intercalary neurons of these parts, forming intracentral short and long pathways. The CNS also includes cells that perform a supporting function in it, and also participate in the metabolism of nerve cells.

Explanation of the picture

I. Cervical nerves.
II. Thoracic nerves.
III. Lumbar nerves.
IV. Sacral nerves.
V. Coccygeal nerves.
-/-
1. Brain.
2. Diencephalon.
3. Midbrain.
4. Bridge.
5. .
6. Medulla oblongata.
7. Spinal cord.
8. Cervical thickening.
9. Transverse thickening.
10. "Ponytail"

The main part of the nervous system of vertebrates and humans is the central nervous system. It is represented by the brain and spinal cord and consists of many clusters of neurons and their processes. The central nervous system performs many important functions, the main one of which is the implementation of various reflexes.

What is the CNS?

As we evolved, the regulation and coordination of all vital processes of the body began to occur at a completely new level. Improved mechanisms began to provide a very fast response to any changes in the external environment. In addition, they began to remember the effects on the body that occurred in the past and, if necessary, retrieve this information. Similar mechanisms formed the nervous system that appeared in humans and vertebrates. It is divided into central and peripheral.

So what is the CNS? This is the main department that not only unites, but also coordinates the work of all organs and systems, and also ensures continuous interaction with the external environment and maintains normal mental activity.

Structural unit

A similar path includes:

  • sensory receptor;
  • afferent, associative, efferent neurons;
  • effector

All reactions are divided into 2 types:

  • unconditional (innate);
  • conditional (acquired).

The nerve centers of a large number of reflexes are located in the central nervous system, but the reactions, as a rule, are closed outside its boundaries.

Coordination activities

This is the most important function of the central nervous system, implying the regulation of the processes of inhibition and excitation in the structures of neurons, as well as the implementation of responses.

Coordination is necessary for the body to perform complex movements that involve numerous muscles. Examples: performing gymnastic exercises; speech accompanied by articulation; the process of swallowing food.

Pathologies

It is worth noting that the central nervous system is a system whose dysfunction negatively affects the functioning of the entire organism. Any failure poses a health hazard. Therefore, when the first alarming symptoms appear, you should consult a doctor.

The main types of central nervous system diseases are:

  • vascular;
  • chronic;
  • hereditary;
  • infectious;
  • received as a result of injuries.

Currently, about 30 pathologies of this system are known. The most common diseases of the central nervous system include:

  • insomnia;
  • Alzheimer's disease;
  • cerebral palsy;
  • Parkinson's disease;
  • migraine;
  • lumbago;
  • meningitis;
  • myasthenia gravis;
  • ischemic stroke;
  • neuralgia;
  • multiple sclerosis;
  • encephalitis.

Pathologies of the central nervous system arise as a result of lesions in any of its departments. Each of the ailments has unique symptoms and requires an individual approach to choosing a treatment method.

Finally

The task of the central nervous system is to ensure the coordinated functioning of each cell of the body, as well as its interaction with the outside world. Brief description of the central nervous system: it is represented by the brain and spinal cord, its structural unit is the neuron, and the main principle of its activity is reflex. Any disturbances in the functioning of the central nervous system inevitably lead to disruptions in the functioning of the entire body.