Nervous structures. The human nervous system from A to Z: Structure and Functions. Structure and types of the nervous system: structural classification

In order for human behavior to be successful, it is necessary that it internal states, the external conditions in which the person is, and the practical actions taken by him corresponded to each other. At the physiological level, the function of combining (integrating) all of the above factors is provided by nervous system. Its device has access to both internal organs and the external environment. Its function is to connect them and control the organs * of movement.

Thus, main function of the nervous system- integration of external influence with the corresponding adaptive reaction of the organism.

The entire nervous system is divided into central and peripheral. The central nervous system consists of the forebrain, midbrain, hindbrain and spinal cord. It is in these main parts of the central nervous system that the most important structures that are directly related to mental processes, states and properties of a person are located: the thalamus, hypothalamus, bridge, cerebellum and medulla oblongata. From the spinal cord and brain, nerve fibers diverge throughout the body - this is peripheral nervous system. It connects the brain with the sense organs and with the executive organs - the muscles and glands.

All living organisms have the ability to respond to physical and chemical changes in the environment. The stimuli of the external environment (light, sound, smell, touch, etc.) are transformed

PRINCIPLES AND LAWS OF HIGHER NERVOUS ACTIVITY

The processes of inhibition and excitation are subject to the following laws.

The law of irradiation of excitation. Very strong stimuli with prolonged exposure to the body cause irradiation - the spread of excitation over a significant part of the cerebral cortex. Only optimal stimuli of medium strength cause strictly localized foci of excitation, which is the most important condition for successful activity.

The law of concentration of excitation. Excitation that has spread from a certain point to other areas of the cortex, over time, is concentrated in the place of its primary occurrence. This law underlies the main condition of our activity - attention. When excitation is concentrated in certain areas of the cerebral cortex, its functional interaction with inhibition occurs, which ensures normal analytical and synthetic activity.

The law of mutual induction of nervous processes. On the periphery of the focus of one nervous process, a process with the opposite sign always occurs. If the process of excitation is concentrated in one area of the cortex, then the process of inhibition inductively arises around it. The more intense the concentrated excitation, the more intense and widespread the process of inhibition. Along with simultaneous induction, there is a successive induction of nervous processes - a successive change of nervous processes in the same parts of the brain.

STRUCTURE OF THE NERVOUS SYSTEM

Structural unit of the nervous system is a nerve cell neuron. It consists of a cell body, a nucleus, branched processes - dendrites, along which nerve impulses go to the cell body, and one long process - axon. It carries the nerve impulse from the cell body to other cells or effectors.

The processes of two neighboring neurons are connected by a special formation - synapse. It plays an essential role in filtering nerve impulses: it passes some impulses and delays others. Neurons are connected to each other and carry out joint activities.

The central nervous system is made up of brain and spinal cord. The brain is divided into brain stem and anterior brain. The brain stem is made up of medulla oblongata and midbrain. The forebrain is divided into intermediate and finite.

All parts of the brain have their own functions. Thus, the diencephalon consists of the hypothalamus - the center of emotions and vital needs, the limbic system, and the thalamus.

Humans are especially developed cerebral cortex - organ of higher mental functions. It has a thickness of 3-4 mm, and its total area is on average 0.25 square meters. m. The bark consists of six layers. The cells of the cerebral cortex are interconnected. There are about 15 billion of them.

Different cortical neurons have their own specific function. One group of neurons performs the function of analysis, the other group performs synthesis, combines impulses coming from various or-

sensory organs and brain regions. There is a system of neurons that keeps traces of previous influences and compares new influences with existing traces.

According to the features of the microscopic structure, the entire cortex divided into several dozen structural units - fields, and according to the location of its parts - into four lobes: 1) occipital; 2) temporal; 3) parietal; 4) frontal.

The human cerebral cortex is a holistically working organ, although some of its parts are functionally specialized: 1) the occipital region of the cortex performs complex visual functions; 2) frontotemporal - speech; 3) temporal - auditory.

The largest part of the motor cortex of the human cerebral cortex is associated with regulation of the movement of labor and speech organs.

All parts of the cerebral cortex are interconnected; they are also connected to the underlying parts of the brain, which carry out the most important vital functions. The human brain contains all the structures that arose at various stages of the evolution of living organisms. They contain the "experience" accumulated in the process of the entire evolutionary development. This testifies to the common origin of man and animals.

As the organization of animals at various stages of evolution becomes more complex, the importance of the cerebral cortex grows more and more. If, for example, the cerebral cortex of a frog is removed, the frog hardly changes its behavior. Deprived of the cerebral cortex, the dove flies, maintains balance, but already loses a number of vital functions. A dog with a removed cerebral cortex becomes completely unadapted to the environment.

Generally excitation is a property of living organisms, an active response of excitable tissue to irritation. For the nervous system, excitation - main function. The cells that form the nervous system have the property of conducting excitation from one area where it arose to other areas and to neighboring cells. Thus, excitement is a carrier of information about properties coming from outside.

Braking is an active process, inextricably linked with excitation, leading to a delay in the activity of nerve centers or working organs. In the first case, braking is called vaetsyatsentralnoy, vtorom-peripheral.

Only a normal ratio of excitation and inhibition processes provides behavior that is adequate (corresponding) to the environment. The imbalance between these processes, the predominance of one of them causes significant disturbances in the mental regulation of conduction.

Braking happens external and internal. Thus, if an animal is suddenly affected by some new strong irritant, then the previous activity of the animal at the moment will slow down. This is external (unconditional) inhibition. In this case, the appearance of a focus of excitation, according to the law of negative induction, causes inhibition of other parts of the cortex.

One of the types of internal, or conditional, inhibition is extinction of the conditioned reflex, if it is not reinforced by an unconditioned stimulus (extinguishing inhibition). This type of inhibition causes the cessation of previously developed reactions if they become useless under new conditions.

are fused by special sensitive cells (receptors) into nerve impulses - a series of electrical and chemical changes in the nerve fiber. Nerve impulses are transmitted along sensitive (afferent) nerve fibers to the spinal cord and brain. Here, the corresponding command impulses are generated, which are transmitted along the motor (efferent) nerve fibers to the executive organs (muscles, glands). These executive bodies are called effectors.

The activity of the nervous system is directly subordinated to the work of the brain. Consider the activity of the human cerebral cortex.

The activity of the cerebral cortex is subject to a number of principles and laws. The main ones were first established I. P. Pavlov. At present, some provisions of the teachings of IP Pavlov have been clarified and developed, and some parts have been revised. However, in order to master the basics of modern neurophysiology, it is necessary to familiarize yourself with the fundamental provisions of the doctrine.

As established by I.P. Pavlov, the main fundamental principle of the work of the cerebral cortex is analytic-synthetic principle. Orientation in the environment is associated with isolating its individual properties, aspects, features (analysis) and combining, linking these features with what is beneficial or harmful to the body (synthesis).

Synthesis - is the closure of connections, and analysis- this is an increasingly subtle separation of one stimulus from another. The analytical and synthetic activity of the cerebral cortex is carried out by the interaction of two nervous processes: arousal and braking.

3 1 . REFLEX AS THE MAIN MECHANISM OF NERVOUS ACTIVITY

main mechanism nervous activity is a reflex. Reflex- this is the body's reaction to external or internal influences through the central nervous system.

Term "reflex" was introduced into physiology by the French scientist Rene Descartes in the 17th century But to explain mental activity, it was applied only in 1863 by the founder of Russian materialistic physiology M. I. Sechenov. Developing the teachings of I. M. Sechenov, I. P. Pavlov experimentally researched features of the functioning of the reflex.

All reflexes are divided into two groups: conditional £^ and unconditional.

™ " Unconditioned reflexes - these are innate reactions of the body to vital stimuli (food, smell, taste, danger, etc.). They do not require any conditions for their development (for example, the blink reflex, salivation at the sight of food).

Unconditioned reflexes are a natural reserve of ready-made stereotypical reactions of the body. They arose as a result of a long evolutionary development of this species of animals. Unconditioned reflexes are the same in all individuals of the same species, this is the physiological mechanism of instincts. But the behavior of higher animals and humans is characterized not only by innate, i.e. unconditioned, reactions, but also by such reactions that are acquired by a given organism in the process

SYSTEMICITY IN THE WORK OF THE CORK

Nerve endings are located throughout the human body. They carry the most important function and are an integral part of the entire system. The structure of the human nervous system is a complex branched structure that runs through the entire body.

The physiology of the nervous system is a complex composite structure.

The neuron is considered the basic structural and functional unit of the nervous system. Its processes form fibers that are excited when exposed and transmit an impulse. The impulses reach the centers where they are analyzed. After analyzing the received signal, the brain transmits the necessary reaction to the stimulus to the appropriate organs or parts of the body. The human nervous system is briefly described by the following functions:

providing reflexes;
regulation of internal organs;
ensuring the interaction of the organism with the external environment, by adapting the body to changing external conditions and stimuli;
interaction of all organs.

The value of the nervous system is to ensure the vital activity of all parts of the body, as well as the interaction of a person with the outside world. The structure and functions of the nervous system are studied by neurology.

Structure of the CNS

Anatomy of the central nervous system (CNS) is a collection of neuronal cells and neuronal processes of the spinal cord and brain. A neuron is a unit of the nervous system.

The function of the central nervous system is to provide reflex activity and process impulses coming from the PNS.

The anatomy of the central nervous system, the main node of which is the brain, is a complex structure of branched fibers.

The higher nerve centers are concentrated in the cerebral hemispheres. This is the consciousness of a person, his personality, his intellectual abilities and speech. The main function of the cerebellum is to ensure coordination of movements. The brain stem is inextricably linked to the hemispheres and the cerebellum. This section contains the main nodes of the motor and sensory pathways, which ensures such vital body functions as the regulation of blood circulation and breathing. The spinal cord is the distribution structure of the CNS, it provides branching of the fibers that form the PNS.

The spinal ganglion (ganglion) is the site of concentration of sensitive cells. With the help of the spinal ganglion, the activity of the autonomic division of the peripheral nervous system is carried out. Ganglia or nerve nodes in the human nervous system are classified as PNS, they perform the function of analyzers. The ganglia do not belong to the human central nervous system.

Structural features of the PNS

Thanks to the PNS, the activity of the entire human body is regulated. The PNS is made up of cranial and spinal neurons and fibers that form ganglia.

The structure and functions of the human peripheral nervous system are very complex, so any slightest damage, for example, damage to the vessels in the legs, can cause serious disruption of its work. Thanks to the PNS, control is exercised over all parts of the body and the vital activity of all organs is ensured. The importance of this nervous system for the body cannot be overestimated.

The PNS is divided into two divisions - the somatic and autonomic systems of the PNS.

The somatic nervous system performs a double job - collecting information from the sense organs, and further transferring this data to the central nervous system, as well as ensuring the motor activity of the body, by transmitting impulses from the central nervous system to the muscles. Thus, it is the somatic nervous system that is the instrument of human interaction with the outside world, since it processes the signals received from the organs of vision, hearing and taste buds.

The autonomic nervous system ensures the performance of the functions of all organs. It controls the heartbeat, blood supply, and respiratory activity. It contains only motor nerves that regulate muscle contraction.

To ensure the heartbeat and blood supply, the efforts of the person himself are not required - it is the vegetative part of the PNS that controls this. The principles of the structure and function of the PNS are studied in neurology.

Departments of the PNS

The PNS also consists of an afferent nervous system and an efferent division.

The afferent section is a collection of sensory fibers that process information from receptors and transmit it to the brain. The work of this department begins when the receptor is irritated due to any impact.

The efferent system differs in that it processes impulses transmitted from the brain to effectors, that is, muscles and glands.

One of the important parts of the autonomic division of the PNS is the enteric nervous system. The enteric nervous system is formed from fibers located in the gastrointestinal tract and urinary tract. The enteric nervous system controls the motility of the small and large intestines. This department also regulates the secretion secreted in the gastrointestinal tract and provides local blood supply.

The value of the nervous system is to ensure the work of internal organs, intellectual function, motor skills, sensitivity and reflex activity. The central nervous system of a child develops not only in the prenatal period, but also during the first year of life. The ontogenesis of the nervous system begins from the first week after conception.

The basis for the development of the brain is formed already in the third week after conception. The main functional nodes are indicated by the third month of pregnancy. By this time, the hemispheres, trunk and spinal cord have already been formed. By the sixth month, the higher parts of the brain are already better developed than the spinal region.

By the time the baby is born, the brain is the most developed. The size of the brain in a newborn is approximately one eighth of the weight of the child and fluctuates within 400 g.

The activity of the central nervous system and PNS is greatly reduced in the first few days after birth. This may be in the abundance of new irritating factors for the baby. This is how the plasticity of the nervous system is manifested, that is, the ability of this structure to rebuild. As a rule, the increase in excitability occurs gradually, starting from the first seven days of life. The plasticity of the nervous system deteriorates with age.

CNS types

In the centers located in the cerebral cortex, two processes simultaneously interact - inhibition and excitation. The rate at which these states change determines the types of the nervous system. While one section of the CNS center is excited, the other is slowed down. This is the reason for the peculiarities of intellectual activity, such as attention, memory, concentration.

Types of the nervous system describe the differences between the speed of the processes of inhibition and excitation of the central nervous system in different people.

People may differ in character and temperament, depending on the characteristics of the processes in the central nervous system. Its features include the speed of switching neurons from the process of inhibition to the process of excitation, and vice versa.

Types of the nervous system are divided into four types.

The weak type, or melancholic, is considered the most prone to the occurrence of neurological and psycho-emotional disorders. It is characterized by slow processes of excitation and inhibition. A strong and unbalanced type is a choleric. This type is distinguished by the predominance of excitatory processes over inhibition processes.
Strong and mobile - this is the type of sanguine. All processes occurring in the cerebral cortex are strong and active. Strong, but inert, or phlegmatic type, characterized by a low rate of switching of nervous processes.

Types of the nervous system are interconnected with temperaments, but these concepts should be distinguished, because temperament characterizes a set of psycho-emotional qualities, and the type of the central nervous system describes the physiological features of the processes occurring in the central nervous system.

CNS protection

The anatomy of the nervous system is very complex. The CNS and PNS suffer from the effects of stress, overexertion, and malnutrition. Vitamins, amino acids and minerals are necessary for the normal functioning of the central nervous system. Amino acids take part in the work of the brain and are the building material for neurons. Having figured out why and what vitamins and amino acids are needed for, it becomes clear how important it is to provide the body with the necessary amount of these substances. Glutamic acid, glycine and tyrosine are especially important for humans. The scheme of taking vitamin-mineral complexes for the prevention of diseases of the central nervous system and PNS is selected individually by the attending physician.

Damage to bundles of nerve fibers, congenital pathologies and anomalies in the development of the brain, as well as the action of infections and viruses - all this leads to disruption of the central nervous system and PNS and the development of various pathological conditions. Such pathologies can cause a number of very dangerous diseases - immobilization, paresis, muscle atrophy, encephalitis and much more.

Malignant neoplasms in the brain or spinal cord lead to a number of neurological disorders. If you suspect an oncological disease of the central nervous system, an analysis is prescribed - the histology of the affected departments, that is, an examination of the composition of the tissue. A neuron, as part of a cell, can also mutate. Such mutations can be detected by histology. Histological analysis is carried out according to the testimony of a doctor and consists in collecting the affected tissue and its further study. With benign formations, histology is also performed.

There are many nerve endings in the human body, damage to which can cause a number of problems. Damage often leads to a violation of the mobility of a part of the body. For example, an injury to the hand can lead to pain in the fingers and impaired movement. Osteochondrosis of the spine provoke the occurrence of pain in the foot due to the fact that an irritated or transmitted nerve sends pain impulses to receptors. If the foot hurts, people often look for the cause in a long walk or injury, but the pain syndrome can be triggered by damage to the spine.

If you suspect damage to the PNS, as well as any related problems, you should be examined by a specialist.

The human nervous system is similar in structure to the nervous system of higher mammals, but differs in a significant development of the brain. The main function of the nervous system is to control the vital activity of the whole organism.

Neuron

All organs of the nervous system are built from nerve cells called neurons. A neuron is capable of receiving and transmitting information in the form of a nerve impulse.

Rice. 1. Structure of a neuron.

The body of a neuron has processes by which it communicates with other cells. The short processes are called dendrites, the long ones are called axons.

The structure of the human nervous system

The main organ of the nervous system is the brain. It is connected to the spinal cord, which looks like a cord about 45 cm long. Together, the spinal cord and brain make up the central nervous system (CNS).

Rice. 2. Scheme of the structure of the nervous system.

Nerves leaving the CNS make up the peripheral part of the nervous system. It consists of nerves and nerve nodes.

Reflex

This is the body's response to irritation from an external or internal environment.

The main form of activity of the nervous system is a reflex (from the English reflection - reflection).

An example of a reflex is pulling the hand away from a hot object. The nerve ending perceives high temperature and transmits a signal about it to the central nervous system. In the central nervous system, a response impulse arises, going to the muscles of the arm.

Rice. 3. Scheme of the reflex arc.

Sequence: sensory nerve - CNS - motor nerve is called the reflex arc.

Brain

The brain is characterized by a strong development of the cerebral cortex, in which the centers of higher nervous activity are located.

The features of the human brain sharply separated it from the animal world and allowed it to create a rich material and spiritual culture.

What have we learned?

The structure and functions of the human nervous system are similar to those of mammals, but differ in the development of the cerebral cortex with the centers of consciousness, thinking, memory, and speech. The autonomic nervous system controls the body without the participation of consciousness. The somatic nervous system controls the movement of the body. The principle of activity of the nervous system is reflex.

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1. Structure and functions of the nervous system. Glia.

2. Reflex. Reflex arc. Classification of reflexes.

3. Age features of the brain and spinal cord.

1. Structure and functions of the nervous system. glia

The nervous system regulates and coordinates the activity of all organs and systems, determining the integrity of the functioning of the body. Thanks to it, the body is connected with the external environment and its adaptation to constantly changing conditions. The nervous system is the material basis of a person's conscious activity, his thinking, behavior, and speech.

The central nervous system includes the brain and spinal cord. Both of them are evolutionarily, morphologically and functionally interconnected and pass into each other without a sharp boundary.

Functions of the nervous system

1. Provides communication of the body with the external environment.

2. Provides the interconnection of all parts of the body with each other.

3. Provides regulation of trophic functions, i.e. regulates metabolism.

4. The nervous system, in particular the brain, is the substratum of mental activity.

Functionally, the nervous system is divided into somatic and autonomous (vegetative), anatomically - into the central nervous system and the peripheral nervous system.

The somatic nervous system regulates the work of skeletal muscles and provides sensitivity to the human body. The autonomic (vegetative) nervous system regulates metabolism, the functioning of internal organs and smooth muscles.

The autonomic nervous system innervates all internal organs. It also provides trophic innervation to skeletal muscles, other organs and tissues, and the nervous system itself.

The peripheral nervous system is formed by numerous paired nerves, nerve plexuses and nodes. Nerves deliver impulses from the CNS directly to the working organ - the muscle - and information from the periphery to the CNS.

The main elements of the nervous system are nerve cells (neurons). Confirmation of the cellular theory of the structure of the nervous system was obtained using electron microscopy, which showed that the membrane of a nerve cell resembles the main membrane of other cells. It appears continuous throughout the surface of the nerve cell and separates from other cells. Each nerve cell is an anatomical, genetic and metabolic unit, just like the cells of other body tissues. The human nervous system contains about 100 billion nerve cells. Since each nerve cell is functionally connected to thousands of other neurons, the number of possible variants of such connections is close to infinity. The nerve cell should be considered as one of the levels of organization of the nervous system, linking the molecular, synaptic, subcellular levels with the supracellular levels of channel neural networks, nerve centers and functional systems of the brain that organize behavior.

The structure of a neuron. The body of the neuron, which is connected with the processes, is the central part of the neuron and provides nutrition to the rest of the cell. The body is covered by a stratified membrane, which is two layers of lipids with opposite orientations that form a matrix that encloses proteins. The body of a neuron has a nucleus or nuclei containing genetic material.

The nucleus regulates protein synthesis throughout the cell and controls the differentiation of young nerve cells. The cytoplasm of the neuron body contains a large number of ribosomes. Some ribosomes are located freely in the cytoplasm one at a time or form clusters. Other ribosomes attach to the endoplasmic reticulum, which is an internal system of membranes, tubules, and vesicles. Ribosomes attached to membranes synthesize proteins, which are then transported out of the cell. Accumulations of the endoplasmic reticulum with ribosomes embedded in it constitute a formation characteristic of neuronal bodies - Nissl's substance. Accumulations of the smooth endoplasmic reticulum, in which ribosomes are not embedded, make up the Golgi reticular apparatus; it is assumed to be important for the secretion of neurotransmitters and neuromodulators. Lysosomes are membrane-bound accumulations of various hydrolytic enzymes. Important organelles of nerve cells are mitochondria - the main structures of energy production. The inner mitochondrial membrane contains all the enzymes of the citric acid cycle, the most important link in the aerobic pathway for glucose breakdown, which is ten times more efficient than the anaerobic pathway. Nerve cells also contain microtubules, neurofilaments and microfilaments, which differ in diameter. Microtubules (diameter 300 nm) run from the body of the nerve cell to the axon and dendrites and represent an intracellular transport system. Neurofilaments (diameter 100 nm) are found only in nerve cells, especially in large axons, and also form part of its transport system. Microfilaments (diameter 50 nm) are well expressed in the growing processes of nerve cells; they are involved in some types of interneuronal connections.

Dendrites are tree-branching processes of a neuron, its main receptive field, which collects information that comes through synapses from other neurons or directly from the environment. When moving away from the body, branching of the dendrites occurs: the number of dendritic branches increases, and their diameter narrows. On the surface of the dendrites of many neurons (pyramidal neurons of the cortex, Purkinje cells of the cerebellum, etc.) there are spines. The spinous apparatus is an integral part of the dendrite tubule system: dendrites contain microtubules, neurofilaments, the Golgi reticular apparatus, and ribosomes. Functional maturation and the beginning of active activity of nerve cells coincides with the appearance of spines; prolonged cessation of the flow of information to the neuron leads to resorption of the spines. The presence of spines increases the receptive surface of the dendrites.

An axon is a single, usually long output process of a neuron that serves to quickly conduct excitation. At the end, it can branch into a large (up to 1000) number of branches.

Nerve cells perform a series common functions aimed at maintaining the organization's own processes. This is the exchange of substances environment, the formation and expenditure of energy, the synthesis of proteins, etc. In addition, nerve cells perform their own specific functions of perceiving, processing and storing information. Neurons are able to perceive information, process (encode) it, quickly transmit information along specific pathways, organize interaction with other nerve cells, store information and generate it. To perform these functions, neurons have a polar organization with separation of inputs and outputs and contain a number of structural and functional parts.

Classification of neurons. Neurons are divided into the following groups: according to the mediator released at the endings of axons, adrenergic, cholinergic, serotonergic, etc. neurons are distinguished.

Depending on the department of the central nervous system, neurons of the somatic and autonomic nervous systems are isolated.

According to the direction of information, the following neurons are distinguished:

Afferent, perceiving with the help of receptors information about the external and internal environment of the body and transmitting it to the overlying parts of the central nervous system;

Efferent, transmitting information to the working organs - effectors (nerve cells innervating effectors are sometimes called effector);

Interneurons (interneurons) that provide interaction between CNS neurons.

By influence, excitatory and inhibitory neurons are distinguished. By activity, background-active and "silent" neurons are distinguished, which are excited only in response to stimulation. Background-active neurons differ in the general pattern of impulse generation, since some neurons discharge continuously (rhythmically or arrhythmically), others - in bursts of impulses. The interval between pulses in a burst is milliseconds, between bursts is seconds. Background-active neurons play an important role in maintaining the tone of the central nervous system and especially the cerebral cortex.

According to the perceived sensory information, neurons are divided into mono- and bipolysensory. Monosensory neurons are the hearing center in the cerebral cortex. Bisensory neurons are found in the secondary zones of the analyzers in the cortex (neurons of the secondary zone of the visual analyzer in the cerebral cortex respond to light and sound stimuli). Polysensory neurons are neurons of the associative zones of the brain, the motor cortex; they respond to irritations of receptors of the skin, visual, auditory and other analyzers.

Nerve cells are interconnected by numerous connections: the terminal branches of the axon of one neuron come into contact with the dendrites of another neuron, or the branches of the axon braid the entire body of another neuron. The places where neurons meet closely are called synapses.

Synapses are structural formations that ensure the transmission of excitation from a nerve cell to a nerve cell or from a nerve cell to cells of a working organ. The term "synapse" was proposed by the English physiologist C. Sherrington.

Any synapse consists of 3 parts - the presynaptic section, the synaptic cleft and the postsynaptic section.

The presynaptic part consists of the terminal part of the axon covered by the presynaptic membrane. Inside are vesicles - vesicles containing a chemical substance - a mediator.

The synaptic cleft is filled with a fluid similar in composition to blood plasma.

The postsynaptic section is represented by the postsynaptic membrane, which contains chemoreceptors that are sensitive to certain mediators.

The synapse contains a large number of mitochondria.

The electrical impulse of excitation, walking along the axon, reaches the synaptic vesicles, as a result, subsidence and rupture occur. Acetylcholine leaves the vesicles, which enters the synaptic cleft through the pores of the presynaptic membrane and enters into chemical interaction with the receptors of the postsynaptic membrane. As a result, the movement of potassium cations stops and the movement of sodium cations increases significantly, they move inside the nerve fiber and a negative charge appears on the surface of the postsynaptic membrane - depolarization occurs. In the form of a wave of excitation, it is transmitted to another nerve cell.

Neuroglia, or glia, was first identified as a separate group of elements of the nervous system in 1871 by R. Virchow. Neuroglia cells fill the space between neurons, accounting for 40% of the brain volume. As a person ages, the number of neurons in the brain decreases and the number of glial cells increases. Glial cells are 3-4 times smaller than nerve cells in size, their number is huge and increases with age (the number of neurons decreases). The bodies of neurons, like their axons, are surrounded by glial cells. Glial cells perform several functions: supporting, protective, insulating, exchange (supplying neurons with nutrients). Microglial cells are capable of phagocytosis, a rhythmic change in their volume (the contraction period is 1.5 minutes, the relaxation period is 4 minutes). Cycles of volume changes are repeated every 2–20 hours. It is believed that pulsation promotes the promotion of axoplasm in neurons and affects the flow of intercellular fluid. Excitation processes in

neurons and electrical phenomena in glial cells seem to interact.

Glia performs the following functions:

Ensures the normal activity of individual neurons and the entire brain;

Provides reliable electrical insulation of the bodies of neurons, their processes, synapses to exclude inadequate interaction between neurons during the propagation of excitation through the neural circuits of the brain trophic function.

2. Reflex. Reflex arc. Classification of reflexes

The activity of the nervous system is based on a reflective or reflex character, that is, a reflex.

Reflex - a response of the body that occurs to various stimuli of the external or internal environment and is carried out with the help of the central nervous system.

In the 17th century, R. Descartes singled out involuntary movements as a group of reflected actions that arise as a result of the nervous system reflecting stimuli that affect the body. Expressed as final responses.

The anatomical path along which the reflex is carried out is called the reflex arc (Fig. 5.3). It has 5 links:

1) receptor - formations that perceived irritation

2) afferent or sensory, sensitive, centripetal path

3) nerve center - part of the central nervous system

4) efferent, or motor, motor centrifugal path

5) working body or effector

The reflex is carried out not according to a linear scheme, but according to the type of reflex ring (according to Anokhin). The sixth link is added - the feedback afferent connection.

The formed connection provides the nerve centers with information about the state of the working organ and this makes it possible to make the necessary adjustments to the formation of the reflex act.

Reflex arcs can be of different complexity:

Monosynaptic (two-neuron);

Polysynaptic (3 or more neurons).

3. Age features of the brain and spinal cord

In a newborn, the spinal cord is 14 cm long, by two years - 20 cm, by 10 years - 29 cm. The mass of the spinal cord in a newborn is 5.5 g, by two years - 13 g, by 7 years - 19 g. in a newborn, two thickenings are well expressed, and the central canal is wider than in an adult. In the first two years, there is a change in the lumen of the central canal. The volume of white matter increases faster than the volume of gray matter.

Sensitivity has great value in the life of an organism. Through sensitivity (sensation), the body's connection with the external environment and orientation in it are established. Sensitivity must be considered from the point of view of the doctrine of analyzers.

The analyzer is a complex nervous mechanism that perceives irritation, conducts it to the brain and analyzes, that is, decomposes it into separate elements. The analyzer has a perceiving conductor apparatus (nerve conductors) located on the periphery and a central apparatus located in the cerebral cortex. The cortical section of the analyzer carries out the analysis and synthesis of various stimuli of the external world and the internal environment of the body. There are visual, auditory, olfactory, gustatory and skin analyzers.

The peripheral apparatus of the analyzer is called the receptor. Receptors perceive irritation and process it into a nerve impulse. There are exteroreceptors that perceive irritations from the external environment, interoreceptors that perceive irritations from the internal organs of the body, and proprioreceptors that perceive irritations from muscles, tendons, and joints. Impulses in proprioceptors arise in connection with a change in the tension of tendons, muscles and orient the body in relation to the position of the body in space and movement. The type of sensitivity is associated with the type of receptors. Pain, temperature and tactile sensitivity is associated with exteroreceptors and refers to superficial sensitivity.

The feeling of movement and position of the torso and limbs in space (muscle-articular feeling), the feeling of pressure and weight, vibration sensitivity are associated with proprioreceptors and are related to deep sensitivity. There are also complex types sensitivity: a sense of localization of irritation, stereognosis (recognition of objects by touch) and others.

The closest connection of the nervous system with all the vital functions of the body is achieved due to the fact that various organs, parts of the body and entire physiological systems are, as it were, projected into certain nerve centers. So, for example, in the sensitive areas of the cerebral cortex, there are special areas where sensitive impulses from the legs, torso, arms, and face are projected. This principle of somatotopic projection (projection of body parts) can also be traced in many subcortical formations of the brain. At the level of the spinal cord, the somatotopic projection has a peculiar shape: body parts are presented segment by segment. These segments schematically look like transverse stripes on the body, longitudinal stripes on the limbs, and concentric circles on the face. Each segment of the body corresponds to a segment of the spinal cord.

In the functioning of the nervous system, signs of hierarchy are observed: the same function is preliminarily regulated by lower centers, over which higher ones are built. Such a multi-level regulation significantly increases the reliability of the nervous system and at the same time is a reflection of its evolutionary history.

Age features of the brain.

The mass of the brain in a newborn is on average 390 g. By the end of the first year of life, it doubles, and by the age of 3-4 it triples. After 7 years, the weight increases slowly and reaches its maximum value by the age of 20-29 (1355 g for men and 1220 g for women). Up to about 60 years, the mass of the brain does not change significantly, and after 60 years there is a slight decrease.

By the time of birth, most of the nuclei of the brain stem are well developed, the processes of their neurons are myelinated. The structures of the midbrain are insufficiently differentiated by the time of birth. Nuclei such as the red nucleus, the substantia nigra mature in the postnatal period, forming the descending pathways of the extrapyramidal system. The diencephalon in a newborn is relatively well developed. By the time of birth, specific and nonspecific nuclei of the thalamus are differentiated, due to which all types of sensitivity are formed. The final maturation of the thalamic nuclei ends at about 13 years of age. By the age of 2–3 years, most of the hypothalamic nuclei have already been formed, but their final functional maturation occurs by the age of 15–16.

Intensive development of the structures of the cerebellum occurs during puberty. In a one-year-old child, the mass of the cerebellum is 90 g. By the age of 7, it reaches the mass of the cerebellum of an adult (130 g).

ANATOMY AND PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM.

HIGHER NERVOUS ACTIVITY. CONDITIONAL REFLEXES

2. Parts of the brain

2.1. Cerebral hemispheres (lobes, furrows, convolutions, gray and white

substance)

2.2. The structure of the brain stem (medulla oblongata, hindbrain, middle

2.3. The structure of the diencephalon (thalamus, epithalamus, metata-

lamus, hypothalamus)

2.4. Cortex

1. Spinal cord (topography and structure)

The spinal cord is the oldest part of the central nervous system. The spinal cord in appearance is a long, cylindrical, flattened cord from front to back with a narrow central canal inside.

The length of the spinal cord of an adult is on average 43 cm, weight - about 34-38 g, which is approximately 2% of the mass of the brain.

The spinal cord has a segmental structure. At the level of the foramen magnum, it passes into the brain, and at the level of 1-2 lumbar vertebrae, it ends with a cerebral cone, from which the terminal /terminal/filament leaves, surrounded by the roots of the lumbar and sacral spinal nerves. There are thickenings in the places where the nerves originate to the upper and lower extremities. These thickenings are called cervical and lumbar / lumbosacral /. In uterine development, these thickenings are not expressed, the cervical thickening is at the level of the V-VI cervical segments and the lumbosacral thickening in the region of the III-IV lumbar segments. Morphological boundaries between segments of the spinal cord do not exist, so the division into segments is functional.

31 pairs of spinal nerves depart from the spinal cord: 8 pairs of cervical, 12 pairs of thoracic, 5 pairs of lumbar, 5 pairs of sacral and a pair of coccygeal.

Internal structure of the spinal cord

The spinal cord consists of nerve cells and fibers of gray matter, which has the shape of the letter H or a butterfly in a cross section. On the periphery of the gray matter is white matter formed by nerve fibers. At the center of the gray matter is the central canal, which contains the cerebrospinal fluid. The upper end of the canal communicates with the IV ventricle, and the lower end forms the terminal ventricle. In the gray matter, the anterior, lateral and posterior columns are distinguished, and in the transverse section they are, respectively, the anterior, lateral and posterior horns. The anterior horns contain motor neurons, the posterior horns contain sensory neurons, and the lateral horns contain neurons that form the centers of the sympathetic nervous system.

The human spinal cord contains about 13 neurons, of which 3% are motor neurons, and 97% are intercalary. Functionally, spinal cord neurons can be divided into 4 main groups:

1) motor neurons, or motor, - cells of the anterior horns, the axons of which form the anterior roots;

2) interneurons - neurons that receive information from the spinal ganglia and are located in the posterior horns. These neurons respond to pain, temperature, tactile, vibrational, proprioceptive stimuli;

3) sympathetic, parasympathetic neurons are located mainly in the lateral horns. The axons of these neurons exit the spinal cord as part of the anterior roots;

4) associative cells - neurons of the spinal cord's own apparatus, establishing connections within and between segments.

In the middle zone of the gray matter (between the posterior and anterior horns) of the spinal cord there is an intermediate nucleus (Cajal nucleus) with cells whose axons go up or down 1-2 segments, forming a network. There is a similar network at the top of the posterior horn of the spinal cord - this network forms the so-called gelatinous substance and performs the functions of the reticular formation of the spinal cord.

The gray matter of the spinal cord forms the segmental apparatus of the spinal cord. The main function is the implementation of innate reflexes in response to irritation / internal or external /.

The white matter is divided into three cords on each side: anterior, lateral and posterior.

White matter is made up of myelin fibers. The bundles of nerve fibers that connect different parts of the nervous system are called the pathways of the spinal cord. There are three types of pathways.

1. Fibers connecting parts of the spinal cord at different levels.

2. Motor /efferent, descending/ fibers coming from the brain to the spinal cord to connect with the cells of the anterior horns.

3. Sensitive / afferent, ascending / fibers going to the centers of the cerebrum and cerebellum.

All ascending cortical pathways consist of 3 neurons.

The first neurons are located in the sense organs, ending in the spinal cord or in the brain stem.

The second neurons are located in the nuclei of the spinal cord or brain, and end in the nuclei of the thalamus and hypothalamus. These neurons form centripetal ascending pathways.

The third neurons lie in the nuclei of the diencephalon /in the nuclei of the thalamus/ for skin and musculo-articular sensitivity, for visual impulses in the geniculate body, olfactory impulses in the mastoid bodies. The processes of the third neurons end on the cells of the corresponding cortical centers /visual, auditory, olfactory and general sensitivity/.

Among the centrifugal nerve pathways, it is necessary to distinguish cortical-spinal /pyramidal/ and cortical-cerebellar pathways.

The function of the spinal cord is that it serves as a coordinating center for simple spinal reflexes / knee jerk / and autonomic reflexes / bladder contraction /, and also provides a connection between the spinal nerves and the brain.

The spinal cord has two functions: reflex and conduction.

reflex functions. The nerve cells of the body are associated with receptors and working organs. The motor neurons of the brain innervate all the muscles of the trunk, limbs, neck and respiratory muscles - the diaphragm and intercostal muscles.

Own reflex activity of the spinal cord is carried out by segmental reflex arcs.

Conductor functions are performed by ascending and descending paths. These pathways connect certain segments of the spinal cord to each other as well as to the brain.

Blood supply to the spinal cord

The blood supply to the spinal cord is carried out by the vertebral artery, deep cervical artery, intercostal, lumbar, lateral sacral arteries.

Age features

In a newborn, the spinal cord is 14 cm long, by two years - 20 cm, by 10 years - 29 cm. The mass of the spinal cord in a newborn is 5.5 grams, by two years - 13 grams, by 7 years - 19 gr. In a newborn, two thickenings are well expressed, and the central canal is wider than in an adult. In the first two years, there is a change in the lumen of the central canal. The volume of white matter increases faster than the volume of gray matter.

2. Parts of the brain

2.1. Cerebral hemispheres (lobes, convolutions, gray and white matter)

The brain consists of: medulla oblongata, hindbrain, midbrain, diencephalon and terminal brain. The hindbrain is divided into the pons and the cerebellum.

The brain is located in the cranial cavity. It has a convex upper lateral surface and a flattened lower surface - the base of the brain

The mass of the brain of an adult is from 1100 to 2000 grams, from 20 to 60 years, the mass and volume remain maximum and constant, after 60 years it decreases slightly. Neither absolute nor relative brain mass is an indicator of the degree mental development. Turgenev's brain mass 2012 gr., Byron 2238 gr., Cuvier 1830 gr., Schiller 1871 gr., Mendeleev 1579 gr., Pavlov 1653 gr. The brain consists of bodies of neurons, nerve tracts and blood vessels. The brain consists of 3 parts: the cerebral hemispheres, the cerebellum and the brain stem.

The cerebral hemispheres reach their maximum development in humans, which arose later than other departments.

The large brain consists of two hemispheres - the right and left, which are connected to each other by a thick commissure / commissure / - the corpus callosum. The right and left hemispheres are divided by a longitudinal fissure. Under the commissure there is a vault, which consists of two curved fibrous strands, which are interconnected in the middle part, and diverge in front and behind, forming pillars and legs of the vault. In front of the pillars of the vault is the anterior commissure. Between the corpus callosum and the arch is a thin vertical plate of brain tissue - a transparent septum.

The hemispheres have superior lateral, medial, and inferior surfaces. Superolateral convex, medial - flat. Facing the same surface of the other hemisphere, and the lower irregular shape. On three surfaces there are deep and shallow furrows, and between them are convolutions. Furrows are depressions between convolutions. Convolutions - elevations of the medulla.

The surfaces of the cerebral hemispheres are separated from each other by edges. These are the superior margin, the inferior lateral margin, and the inferior vertical margin. In the space between the two hemispheres, the crescent of the cerebrum enters - a large crescent-shaped process, which is a thin plate of the hard shell that penetrates into the longitudinal fissure of the cerebrum without reaching the corpus callosum and separates the right and left hemispheres from each other. The most protruding parts of the hemisphere are called poles: frontal pole, occipital pole and temporal pole. The relief of the surfaces of the cerebral hemispheres is very complex and is due to the presence of more or less deep furrows of the cerebral cortex and the ridge-like elevations located between them - the convolutions of the cerebral cortex. The depth, length of some furrows and convolutions, their shape and direction are very variable.

Each hemisphere is divided into lobes - frontal, parietal, occipital, temporal, insular. The central sulcus / Roland's sulcus / separates the frontal lobe from the parietal, the lateral sulcus / Sylvian sulcus / separates the temporal from the frontal and parietal, the parieto-occipital separates the parietal and occipital lobes. The lateral furrow is laid by the 4th month of intrauterine development, the parieto-occipital and central by the 6th month. In the prenatal period, gyrification occurs - the formation of convolutions. These three furrows appear first and are of great depth. Soon, a couple more parallel to it are added to the central sulcus: one passes in front of the central one and, accordingly, is called precentral, which splits into two - upper and lower. Another furrow is located behind the central and is called postcentral.

The postcentral sulcus lies behind and nearly parallel to the central sulcus. Between the central and postcentral sulci is the postcentral gyrus. At the top, it passes to the medial surface of the cerebral hemisphere, where it connects with the precentral gyrus of the frontal lobe, forming with it the paracentral lobule. On the upper lateral surface of the hemisphere, below, the postcentral gyrus also passes into the precentral gyrus, covering the central sulcus from below. It is parallel to the upper edge of the hemisphere. Above the intraparietal sulcus is a group of small convolutions, called the superior parietal lobule. Below this groove lies the inferior parietal lobule, within which two convolutions are distinguished: supramarginal and angular. The supramarginal gyrus covers the end of the lateral sulcus, and the angular gyrus covers the end of the superior temporal sulcus. The lower part of the inferior parietal lobule and the lower sections of the postcentral gyrus adjacent to it, together with the lower part of the precentral gyrus, hanging over the insular lobe, form the fronto-parietal operculum of the insula.

Lobes of the brain

The dorsal and lateral surface of the cerebral cortex is usually divided into four lobes, which are named after the corresponding bones of the skull: frontal, parietal, occipital, temporal.

The occipital lobe is located behind the parietal-occipital sulcus and its conditional continuation on the upper lateral surface of the hemisphere. Compared to other shares, it is small in size. Posteriorly, the occipital lobe ends at the occipital pole. The sulci and gyri on the superolateral surface of the occipital lobe are very variable. Most often and better than others, the transverse occipital sulcus is expressed, which is, as it were, a continuation of the posterior intraparietal sulcus of the parietal lobe of the brain.

The temporal lobe occupies the lower lateral parts of the hemisphere and is separated from the frontal and parietal lobes by a deep lateral groove. The edge of the temporal lobe covering the insular lobe is called the temporal tegmentum of the insula. The anterior part of the temporal lobe forms the temporal pole. Two sulci are visible on the lateral surface of the temporal lobe, the upper and lower temporal sulci almost parallel to the lateral sulcus. The convolutions of the temporal lobe are oriented along the furrows. The superior temporal gyrus is located between the lateral sulcus above and the superior temporal gyrus below. On the upper surface of this gyrus, hidden in the depths of the lateral sulcus, there are 2-3 short transverse temporal gyrus (Heschl's gyrus), separated by transverse temporal grooves. Between the superior and inferior temporal sulci lies the middle temporal gyrus. The inferolateral edge of the temporal lobe is occupied by the inferior temporal gyrus, bounded above by the sulcus of the same name. The posterior end of this gyrus continues into the occipital lobe.

Above the corpus callosum, separating it from the rest of the hemisphere, is the groove of the corpus callosum. Rounding the back of the corpus callosum, this sulcus goes downward and forward and continues into the hippocampal sulcus or hippocampal sulcus. Above the sulcus of the corpus callosum is the cingulate sulcus. This sulcus begins anterior and inferior to the beak of the corpus callosum, rises up, then turns back and follows parallel to the sulcus of the corpus callosum, ending above and posterior to the ridge of the corpus callosum called the infraparietal sulcus. At the level of the ridge of the corpus callosum, the marginal part branches upward from the cingulate groove, extending upward and backward to the upper edge of the cerebral hemisphere. Between the sulcus of the corpus callosum and the cingulate sulcus is the cingulate gyrus, which encloses the corpus callosum anteriorly, superiorly, and posteriorly. Behind and downward from the ridge of the corpus callosum, the cingulate gyrus narrows, forming the isthmus of the cingulate gyrus.

Between the sulcus of the corpus callosum and the cingulate sulcus is the cingulate gyrus, which encloses the corpus callosum anteriorly, superiorly, and posteriorly. Behind and downward from the ridge of the corpus callosum, the cingulate gyrus narrows, forming the isthmus of the cingulate gyrus.

medial surface of the hemisphere. All lobes of the hemisphere, with the exception of the insular, take part in the formation of its medial surface.

On the medial surface of the occipital lobe there are merging with each other under acute angle, open posteriorly, two deep furrows. This is the parietal-occipital sulcus, which separates the parietal lobe from the occipital, and the spur sulcus, which begins on the medial surface of the occipital pole and goes forward to the isthmus of the cingulate gyrus. The area of the occipital lobe, lying between the parieto-occipital and spur grooves and having the shape of a triangle, with its apex facing the confluence of these grooves, is called a "wedge". The spur groove, clearly visible on the medial surface of the hemisphere, limits the lingual gyrus from above, extending from the occipital pole behind to the lower part of the isthmus of the cingulate gyrus. Below the lingual gyrus is located

collateral groove, already belonging to the lower surface of the hemisphere.

The anterior sections of the lower surface are formed by the frontal lobe of the hemisphere, behind which the temporal pole protrudes, and there are also the lower surfaces of the temporal and occipital lobes, passing one into the other without noticeable boundaries.

On the lower surface of the frontal lobe, somewhat lateral and parallel to the longitudinal fissure of the cerebrum, is the olfactory groove. From below, the olfactory bulb and the olfactory tract are adjacent to it, passing behind into the olfactory triangle, in the region of which the medial and lateral olfactory strips are visible. The area of the frontal lobe between the longitudinal fissure of the cerebrum and the olfactory sulcus is called the direct gyrus. The surface of the frontal lobe, lying lateral to the olfactory sulcus, is divided by shallow orbital sulci into several orbital gyri that are variable in shape, location, and size.

In the posterior part of the lower surface of the hemisphere, a collateral sulcus is clearly visible, lying downward and laterally from the lingual gyrus on the lower surface of the occipital and temporal lobes, laterally from the parahippocampal gyrus. Somewhat anterior to the anterior end of the collateral sulcus is the nasal sulcus, which limits the curved end of the parahippocampal gyrus, the hook, on the lateral side. Lateral to the collateral sulcus lies the medial occipitotemporal gyrus.

Between this gyrus and the lateral occipitotemporal gyrus located outward from it is the occipitotemporal sulcus. The border between the lateral occipital-temporal and inferior temporal gyrus is not the sulcus, but the inferolateral edge of the cerebral hemisphere.

The upper lateral surface of the hemisphere is the frontal lobe located in the anterior part of each hemisphere of the large brain, ending in front with the frontal pole and bounding from below by the lateral (Sylvian) groove, and behind by the deep central groove. A number of brain regions located mainly on the medial surface of the hemisphere and being a substrate for the formation of such general states as wakefulness, sleep, emotions, etc., are called the "limbic system". Since these reactions were formed in connection with the primary functions of smell (in phylogeny), their morphological basis is the parts of the brain that develop from the lower parts of the brain bladder and belong to the so-called olfactory brain. The limbic system consists of the olfactory bulb, the olfactory tract, the olfactory triangle, the anterior perforated substance, located on the lower surface of the frontal lobe (the peripheral part of the olfactory brain), as well as the cingulate and parahippocampal (together with the hook) gyrus, the dentate gyrus, the hippocampus (the central part of the olfactory brain). ) and some other structures. The inclusion of these parts of the brain in the limbic system turned out to be possible due to the common features of their structure (and origin), the presence of mutual connections and the similarity of functional reactions.

The hemispheres are made up of gray and white matter. The layer of gray matter is called the cerebral cortex. The bark covers the remaining formations of the cerebrum in the form of a cloak and is therefore called a cloak. Under the cortex is white matter, and in it islets of gray matter - the basal nuclei, they are called subcortical central, mainly located in the frontal lobe. These include the striatum (caudate and lenticular nucleus), the fence and the amygdala. The striatum / striopallidar system / consists of 2 nuclei: the caudate and lenticular nuclei and separated by a layer of white matter - the internal capsule. In the embryonic period, the striatum is one gray mass, then it is divided.

The caudate nucleus is located near the thalamus, has a horseshoe shape. Consists of head, body and tail. The lenticular nucleus has the shape of a lentil grain, is located lateral to the thalamus and caudate nucleus. The lenticular nucleus is divided into 3 parts, thanks to the white matter. The most lateral is the shell, which has a dark color, and the two lighter parts are called the lateral and medial pale balls.

The nuclei of the striatum are subcortical motor centers, part of the extrapyramidal system, regulating complex automated motor acts. The extrapyramidal system includes the substantia nigra and the red nuclei of the legs of the brain. The striatum regulates the processes of thermoregulation and carbohydrate metabolism. Outside of the lenticular nucleus is a thin plate of gray matter - a fence. The fence is located in the white matter of the hemisphere on the side of the shell, between the latter and the cortex of the insular lobe. The fence contains polymorphic neurons different types. It forms connections mainly with the cerebral cortex. Deep localization and small size of the fence present certain difficulties for its physiological study.

The amygdala is located in the anterior temporal lobe and is part of the limbic system. The white matter of the hemisphere includes the inner capsule and fibers passing adhesions /corpus callosum, anterior commissure, commissure fornix/ and heading to the cortex and basal ganglia. The internal capsule is a thick curved plate of white matter. The internal capsule is divided into 3 sections: 1. anterior leg

internal capsule, 2. posterior leg of the internal capsule, 3. junction of these two sections - knee of the internal capsule. In the knee of the internal capsule, there are cortical-nuclear pathways leading to the motor nuclei of the cranial nerves. In the anterior section there are cortical-spinal fibers located in the precentral gyrus and go to the motor nuclei of the anterior horns of the spinal cord. In the posterior leg are thalamocortical fibers that go to the cortex of the postcentral gyrus. The fibers of conductors of all types of general sensitivity / high temperature, touch, pressure, proprioceptive / are connected to this conducting path. In the posterior sections of the posterior leg are the auditory and visual pathways. Both originate from the subcortical centers of hearing and vision and end in the respective centers.

Thus, the basal nuclei of the brain are the integrative centers for the organization of motor skills, emotions, higher nervous

activities, and each of these functions can be enhanced or inhibited by the activation of individual formations of the basal ganglia. The corpus callosum is a thick, curved plate composed of transverse fibers. In the corpus callosum they are divided: the knee, the beak, between them the trunk, which passes into the roller. The fibers running in the column connect the cortex of the frontal lobes of the right and left hemispheres. Trunk fibers connect the gray matter of the parietal and temporal lobes. In the roller connects the cortex of the occipital lobes. Under the corpus callosum is a vault, which consists of two arcuately curved strands connected by adhesions.

The arch consists of a body, a paired column and paired legs. The legs fuse with the hippocampus to form a fringe. The lateral ventricle is the cavity of the hemispheres / I and II ventricles / and communicates through the interventricular opening with the III ventricle. In each ventricle, a central part is divided, from which blindly ending recesses depart. Three horns extend to other parts of the hemisphere.

Anterior / frontal / horn - in the frontal lobe. The posterior / occipital / horn - in the occipital lobe and the lower / temporal / horn - in the temporal lobe. The lateral ventricles, like the other ventricles of the brain, and the central canal of the spinal cord are lined from the inside with a layer of ependymocytes - cells related to macroglia. Ependymal cells are actively involved in the formation of cerebrospinal fluid and the regulation of its composition.

The rhomboid fossa is a diamond-shaped depression, the long axis of which is directed along the brain. The rhomboid fossa is laterally bounded in its upper section by the superior cerebellar peduncles, and in the lower section by the inferior cerebellar peduncles.

Onto- and phylogenesis of the brain.

The brain develops from an enlarged part of the brain tube, the posterior part turns into the dorsal part from the forebrain. In the process of growth in the anterior part of the brain tube, three brain bubbles are formed by means of constrictions: anterior, middle and posterior / rhomboid /. The diencephalon and telencephalon form from the forebrain. The medulla oblongata and hindbrain /bridge and cerebellum/ are formed from the posterior bladder. The midbrain is not divided and the former name is retained for it. In a newborn, the mass of the brain weighs 370 - 400 grams. During the first year of life, it doubles, and by the age of 6 it increases 3 times. Then there is a slow weight gain, ending at 20-29 years of age. The lancelet does not have a forebrain. In cyclostomes, the forebrain is in its infancy. In bony fish, the forebrain is poorly developed. Amphibians have underdeveloped hemispheres, on the surface of which there are no neurons. The cerebral cortex appears in reptiles. Birds do not have furrows. In mammals, a true bark is formed. The cerebral hemispheres develop from the terminal cerebral bladder of the neural tube, so this section is called the terminal.

Sheaths of the brain and spinal cord.

The brain is surrounded by three membranes:

1. External - solid.

2. Medium - cobweb.

3. Internal - soft / vascular /.

Solid - a dense connective tissue plate, strong, as it is connected by collagen and elastic fibers. The hard shell gives outgrowths to the cranial cavity - processes located between separate parts of the brain - protection from concussions. These outgrowths include the sickle and the cerebellum. The hard shell forms the sinuses, which carry out the outflow of venous blood from the brain. Cobweb - thin, transparent does not penetrate into cracks and furrows. It lies over the furrows, forming tanks. The cobweb is separated from the choroid by the subarachnoid /subarachnoid/ space, which contains cerebrospinal fluid /inside the cisterns/. The soft shell is adjacent to the substance of the brain, lining all the depressions on its surface. In some places, it penetrates into the ventricles of the brain, where it forms the choroid plexuses. The vessels of this membrane are involved in the blood supply to the brain, and the choroid plexuses are involved in the ventricles.

2.2. The structure of the brain stem (oblong, hindbrain, midbrain)

The medulla oblongata is located between the hindbrain and the spinal cord. The length of the medulla oblongata in an adult is 25 mm. It has the shape of a truncated cone or bulb. In the medulla oblongata, ventral, dorsal and 2 lateral surfaces are distinguished, which are separated by grooves. Unlike the spinal cord, it does not have a metomeric, repetitive structure. The gray matter is located in the center, and the nuclei are on the periphery.

The anterior surface is divided by the anterior median fissure, pyramids are located on the sides, formed by bundles of nerve fibers of the pyramidal pathways, partially intersect / cross pyramids /. On the side of the pyramids on each side is an olive, separated from the pyramid by the anterior lateral groove.

The posterior surface is divided by the posterior median sulcus, thickenings are located on the sides - thin and wedge-shaped, bundles of the posterior cords of the spinal cord. In these thickenings, the nuclei of these bundles are located, from which fibers depart, forming a decussation at the level of the medulla oblongata.

Lateral surface - on it on the sides on each side are the anterior and posterior lateral grooves. All these sulci are continuations of the sulci of the same name in the spinal cord. Behind each pyramid are thickenings of an oval shape - olives filled with gray matter. Between the pyramid and the olive in the anterior lateral sulcus, the XII pair of cranial nerves emerge from the medulla oblongata, and the dorsal olives in the posterior lateral sulcus are the roots of the IX, X, XI pairs of cranial nerves.

Top part the back surface has the shape of a triangle and forms the bottom of the IV ventricle. Two cerebellar peduncles run from the medulla oblongata to the cerebellum, where the fibers of the posterior spinal cord and other nerve fibers pass.

The nuclei of the following cranial nerves are located in the medulla oblongata: a pair of VIII cranial nerves - the vestibulocochlear nerve consists of the cochlear and vestibular parts. The cochlear nucleus lies in the medulla oblongata; pair IX - glossopharyngeal nerve; its core is formed by 3 parts - motor, sensory and vegetative. The motor part is involved in the innervation of the muscles of the pharynx and oral cavity, the sensitive part receives information from the taste receptors of the posterior third of the tongue; autonomic innervates the salivary glands; pair X - the vagus nerve has 3 nuclei: autonomic - innervates the larynx, esophagus, heart, stomach, intestines, digestive glands; sensitive receives information from the receptors of the alveoli of the lungs and other internal organs, and motor - provides a sequence of contraction of the muscles of the pharynx, larynx when swallowing; pair XI - accessory nerve; its nucleus is partially located in the medulla oblongata; pair XII - the hypoglossal nerve is the motor nerve of the tongue, its nucleus is mostly located in the medulla oblongata.

Touch functions. The medulla oblongata regulates a number of sensory functions: the reception of skin sensitivity of the face - in the sensory nucleus of the trigeminal nerve; primary analysis of taste reception - in the nucleus of the cochlear nerve; reception of auditory stimuli - in the upper vestibular nucleus. In the posterior superior sections of the medulla oblongata, there are paths of skin, deep visceral sensitivity, some of which switch here to the second neuron (thin and sphenoid nucleus). At the level of the medulla oblongata, the enumerated sensory functions implement the primary analysis of the strength and quality of stimulation, then the processed information is transmitted to the subcortical structures to determine the biological significance of this stimulation.

conductor functions. The white matter of the medulla oblongata consists of short and long bundles of nerve fibers. Short bundles carry out communication between the nuclei of the medulla oblongata, as well as between them and the nuclei of the nearest parts of the brain. Long bundles of nerve fibers represent the ascending and descending pathways of the spinal cord. Brain formations such as the pons, midbrain, cerebellum, thalamus, hypothalamus, and cerebral cortex have bilateral connections with the medulla oblongata. The presence of these connections indicates the participation of the medulla oblongata in the regulation of skeletal muscle tone, autonomic and higher integrative functions, and the analysis of sensory stimuli.

reflex functions. Numerous reflexes of the medulla oblongata are divided into vital and non-vital, however, such a representation is rather arbitrary. Respiratory and vasomotor centers of the medulla oblongata can be classified as vital, because. they close a number of cardiac and respiratory reflexes. Most of the fibers of the pyramidal tract pass into the lateral column of the spinal cord, a smaller, non-crossed part passes into the anterior column of the spinal cord.

Bridge / Bridge of Varolii / The bridge is located above the medulla oblongata and performs sensory, conductive, motor, integrative, reflex functions. It has the form of a transverse fiber, which at the top / in front / borders on the midbrain, and below / behind / - with the medulla oblongata. Length 20–30 mm., Width 20–30 mm. On the sides, the bridge, narrowing, passes into the middle legs of the cerebellum. The bridge consists of an anterior / ventral / part, which is adjacent to the slope of the skull, and a posterior / dorsal / part of the tegmentum of the bridge, facing the cerebellum. In the ventral surface, the basilar /main/ groove is laid, where the artery of the same name lies. The bridge is composed of gray matter on the inside and white matter on the outside. The anterior part mainly consists of white matter - these are longitudinal and transverse fibers. In the dorsal parts of the bridge, ascending sensory pathways follow, and in the ventral, descending pyramidal and extrapyramidal pathways. There are also fiber systems that provide two-way communication between the cerebral cortex and the cerebellum. Directly above the trapezoid body lie the fibers of the medial loop and the spinal loop. Above the trapezoid body, closer to the median plane, is the reticular formation, and even higher is the posterior longitudinal bundle. Laterally and above the medial loop lie the fibers of the lateral loop. In the posterior part there are nuclei: V pair /trigeminal nerve/, abducent /VI pair/, facial /VII pair/, predvernocolitis /VIII pair, as well as fibers of the medial loop, coming from the medulla oblongata, on which the reticular formation of the bridge is located. Pathways pass in the anterior part:

1. Pyramidal path / cortical-spinal /.

2. Pathways from the cortex to the cerebellum.

3. Common sensory pathway that goes from the spinal cord to the thalamus.

4. Ways from the nuclei of the auditory nerve.

Cerebellum.

The cerebellum is located under the occipital lobes of the cerebral hemisphere and lies in the cranial fossa. The maximum width is 11.5 cm, length is 3-4 cm. The cerebellum accounts for about 11% of the weight of the brain. In the cerebellum, there are: hemispheres, and between them - the cerebellar vermis. The surface of the cerebellum is covered with gray matter or cortex, which forms convolutions separated from each other by furrows. In the thickness of the cerebellum is white matter, consisting of fibers that provide intracerebral connections.

The cerebellar cortex is three-layered, consisting of an outer molecular layer, a ganglionic / or Purkinje cell layer / and a granular layer. The cortex contains five types of neurons: granular, stellate, basket, Golgi and Purkinje cells, which have a rather complex system of connections. Between the cerebellum and the pons with the medulla oblongata is the fourth ventricle filled with spinal fluid. In the molecular layer there are 3 types of intercalary neurons: basket cells, short and long stellate cells. The ganglion layer contains Purkinje cells. In the granular layer - granular cells - Golgi cells. The number of granular cells in 1 mm3. equals 2.8 × 10 × 6. The axons of granular cells ascend to the surface, branch in a T-shape, forming parallel fibers. Parallel fibers also form excitatory synapses on the dendrites of basket cells, stellate cells, and Goldki cells.

The nuclei of the cerebellum - in the depths of the cerebellum above the IV cerebral ventricle is located - the nucleus of the tent, cork nucleus, spherical nuclei. The largest nucleus of the cerebellum is the dentate nucleus. In all 4 nuclei, neurons have a similar structure. From the neurons of the nuclei of the cerebellum, its pathways begin. IV ventricle - in the process of development is the remains of the cavity of the rhomboid cerebral bladder. At the bottom, the ventricle communicates with the central canals of the spinal cord, at the top it passes into the cerebral aqueduct of the midbrain, and in the roof region it is connected by three holes with the subarachnoid space of the brain. Its anterior / ventral / wall - the bottom of the IV ventricle - is called the rhomboid fossa. The lower part is formed by the medulla oblongata, and the upper part by the pons and isthmus. Posterior / dorsal / - the roof of the IV ventricle - is formed by the upper and lower cerebral sails and is complemented behind by a plate of the pia mater lined with ependyma. In this area there is a large number of blood vessels, and the choroid plexuses of the IV ventricle are formed. The rhomboid fossa is of great importance, cranial nerves / V - XII / are laid here.

Midbrain.

The midbrain, unlike other parts of the brain, is less complex. It has a roof and legs. The cavity of the midbrain is the aqueduct of the brain. The upper (anterior) border of the midbrain on its ventral surface is the optic tracts and mammillary bodies, on the back - the anterior edge of the bridge. On the dorsal surface, the upper (anterior) border of the midbrain corresponds to the posterior edges (surfaces) of the thalamus, the posterior (lower) - to the level of exit of the roots of the trochlear nerve (IV pair). The roof of the midbrain, which is a plate of the quadrigemina, is located above the aqueduct of the brain. On the preparation of the brain, the roof of the midbrain can be seen only after the removal of the cerebral hemisphere. The roof of the midbrain consists of four elevations - mounds that look like hemispheres, which are separated from each other by two grooves intersecting at right angles. The longitudinal groove is located in the median plane and in its upper (anterior) sections forms a bed for the pineal body, and in the lower it serves as the place from which the bridle of the superior medullary sail begins. The transverse groove separates the superior hillocks from the inferior ones. Thickenings in the form of a roller extend from each of the mounds in the lateral direction - the handle of the mound.

The handle of the superior colliculus is located posterior to the thalamus and goes to the lateral geniculate body, and partly continues into the optic tract. The handle of the inferior colliculus goes to the medial geniculate body. In lower vertebrates, the superior colliculus of the roof of the midbrain serves as the main ending point for the optic nerve and is the main visual center. In a person with the transfer of visual centers to the forebrain, the remaining connection of the optic nerve with the superior colliculus is important only for motor and other reflexes. A similar statement is also true for the lower colliculus of the roof, where

fibers of the auditory loop terminate.

Thus, the roof plate of the midbrain can be considered as a reflex center for various kinds of movements that arise under the influence of visual and auditory stimuli.

Isthmus of the rhomboid brain. The isthmus of the rhomboid brain is a formation formed on the border of the midbrain and rhomboid brain. It includes the superior cerebellar peduncles, the superior medullary velum, and the loop triangle. The superior medullary velum is a thin plate of white matter stretched between the superior cerebellar peduncles on the sides and the cerebellum at the top. Anteriorly (above), the superior medullary velum is attached to the roof of the midbrain, where the bridle of the superior medullary velum ends in a groove between the two lower colliculi. On the sides of the frenulum, the roots of the trochlear nerve emerge from the brain tissue. Together with the superior cerebellar peduncles, the superior medullary velum forms the anterior-superior wall of the roof of the fourth ventricle of the brain. In the lateral sections of the isthmus of the rhomboid brain there is a loop triangle. This is a gray triangle, the boundaries of which are: in front - the handle of the lower mound; behind and above - the superior cerebellar peduncle; on the side - the brain stem, which is separated from the isthmus by a lateral groove on the outer surface of the brain stem. In the region of the triangle, in its depth, lie the fibers of the lateral (auditory) loop.

2.3. The structure of the diencephalon (thalamus, epithalamus, metathalamus)

The diencephalon in the process of embryogenesis develops from the anterior cerebral bladder. Forms the walls of the third cerebral ventricle. The diencephalon is located under the corpus callosum and consists of the thalamus, epithalamus, metathalamus, and hypothalamus. The thalamus is an egg-shaped collection of gray matter. The thalamus is a large subcortical

a formation through which they pass into the cerebral cortex

various afferent pathways. Nerve cells of the thalamus are grouped

are folded into a large number of cores /up to 40/. Topographically, the nuclei are

divided into anterior, posterior, median, medial and lateral

groups. By function, the thalamic nuclei can be differentiated into

specific, nonspecific, associative and motor.

From specific nuclei, information about the nature of sensory

mules enter strictly defined areas of 3-4 layers of the bark. Funk-

the rational basic unit of specific thalamic nuclei

is "relay" neurons that have few dendrites, long

ny axon and perform a switching function. Happened here

dit switching paths going to the cortex from the skin, muscle and other

types of sensitivity. Impaired function of specific nuclei

leads to loss of specific types of sensitivity.

Nonspecific nuclei of the thalamus are associated with many sites

cortex and take part in the activation of its activity, they are referred

to the reticular formation.

Associative nuclei - the main structures of these nuclei are

multipolar, bipolar neurons. To the motor nuclei of the thalamus from

the ventral nucleus is worn, which has input from the cerebellum and basal

ganglia, and at the same time gives projections into the motor zone of the cortex of large

hemispheres. This core is included in the movement regulation system.

The thalamus is the structure in which processing and integration takes place.

tion of almost all signals going to the cerebral cortex, from it

ronov spinal cord, midbrain, cerebellum. Possibility of semi-

read information about the state of many systems of the body allows

him to participate in the regulation and determine the functional state

organism as a whole. This is confirmed by the fact that in the thalamus the eye

lo 120 multifunctional cores.

The thalamus is the subcortical center of all types of sensory

value. In addition to the olfactory one: they approach it and switch

ascending / afferent / conducting paths through which it is transmitted

information from various receptors. From the thalamus come nerve

curl to the cerebral cortex, making up the thalamocortical bundles.

The hypothalamus is a phylogenetic old section of the intermediate

brain, which plays an important role in maintaining the constancy

internal environment and in ensuring the integration of the functions of the vegetative

noah, endocrine and somatic systems. The hypothalamus is involved in

formation of the bottom of the third ventricle. The hypothalamus includes: visual

decussation, optic tract, gray tubercle with funnel, mastoid

body. The structures of the hypothalamus have different origins.

The visual part / visual perception is formed from the telencephalon

cross, optic tract, gray tubercle with funnel, neurohypophysis/, from

diencephalon - olfactory part / mastoid body and sub-

hillock/.

The optic chiasm has the form of a transversely lying roller,

formed by the fibers of the optic nerves (II pair), partially re-

walking to the opposite side (form a cross). This

the roller on each side laterally and posteriorly continues into the viewer

ny tract. The optic tract also lies behind the anterior perforated

substance, goes around the peduncle of the brain from the lateral side and

ends with two roots in the subcortical centers of vision. More

large lateral root approaches the lateral geniculate

body, and a thinner medial root goes to the upper

hillock of the roof of the midbrain.

To the anterior surface of the optic chiasm is adjacent and

the terminal related to the telencephalon (boundary)

lower or final) plate. It closes the anterior section of the pro-

lobular fissure of the large brain and consists of a thin layer of gray matter

a property that in the lateral parts of the plate continues in the substance

the structure of the frontal lobes of the hemispheres.

The optic chiasm (chiasma) is the place in the brain where the

the optic nerves coming from

right and left eyes.

Behind the optic chiasm is a gray tubercle, behind

which lie the mastoid bodies, and on the sides - the visual tracts.

From top to bottom, the gray tubercle passes into a funnel, which connects to the hypo-

physical The walls of the gray tubercle are formed by a thin plate of gray

downward, blindly ending in the deepening of the funnel.

The mastoid bodies are located between the gray tubercle in front and

posterior perforated substance behind. They look like two

large, about 0.5 cm in diameter each, spherical formations

white. White matter is located only outside the mastoid

leg body. Inside there is a gray matter in which metal is secreted

the dial and lateral nuclei of the mastoid body. In the mastoid

lah ends the pillars of the vault. According to their function, the mastoid bodies

belong to the subcortical olfactory centers.

Cytoarchitectonically, there are three areas in the hypothalamus

clusters of nuclei: anterior, middle / medial / and posterior.

The anterior hypothalamus contains the supraoptic

(supervisory) nucleus and paraventricular nuclei. cell processes

of these nuclei form the hypothalamic-pituitary bundle, ending-

located in the posterior lobe of the pituitary gland.

Neurosecretory cells are concentrated in the anterior region,

producing vasopressin and oxytocin, which enter the back

lower lobe of the pituitary gland.

In the middle region are arcuate, gray-tuberous and

other fields where releasing factors are produced, as well as inhibitory

stimulating factors or statins entering the adenohypophysis transmit

transmitting these signals in the form of tropic hormones of the peripheral endocrine

noah gland. The releasing factor promotes the release of thyreo,

luteo, corticotropin, prolactin. Statins inhibit the release of co-

matotropin, melanotropin, prolactin.

The nuclei of the posterior region include scattered large cells,

among which there are clusters of small cells, as well as nuclei of the

prominent body. The nuclei of the mastoid body are subcortical centers

Trami olfactory analyzers.

The pituitary gland contains 32 pairs of nuclei, which are links

extrapyramidal system, as well as the nuclei are subcortical

structures of the limbic system.

Under the third ventricle are the mastoid bodies,

to the subcortical olfactory centers, the gray tubercle and visual

decussation formed by the optic chiasm. At the end

funnel is the pituitary gland. The nuclei of vegetative-

noah nervous system.

The pituitary gland has extensive connections, both with all departments of the central nervous system, and

glands of external secretion / system hypothalamus-pituitary-

adrenal/. Thanks to these extensive multi-functional connections

the hypothalamus acts as the highest subcortical regulator of

changes in substances and body temperature, urination, glandular functions.

Through nerve impulses, the medial region of the hypothalamus

musa controls the activity of the posterior pituitary gland, and through

hormonal mechanisms, the medial hypothalamus controls the

The nervous system controls the activity of all systems and organs and ensures the connection of the body with the external environment.

The structure of the nervous system

The structural unit of the nervous system is the neuron - a nerve cell with processes. In general, the structure of the nervous system is a collection of neurons that are constantly in contact with each other using special mechanisms - synapses. The following types of neurons differ in function and structure:

Sensitive or receptor;
Effector - motor neurons that send an impulse to the executive organs (effectors);
Closing or plug-in (conductor).

Conventionally, the structure of the nervous system can be divided into two large sections - somatic (or animal) and vegetative (or autonomous). The somatic system is primarily responsible for the connection of the body with the external environment, providing movement, sensitivity and contraction of skeletal muscles. The vegetative system affects the growth processes (respiration, metabolism, excretion, etc.). Both systems have a very close relationship, only the autonomic nervous system is more independent and does not depend on the will of a person. That is why it is also called autonomous. The autonomous system is divided into sympathetic and parasympathetic.

The entire nervous system consists of the central and peripheral. The central part includes the spinal cord and brain, and the peripheral system represents the outgoing nerve fibers from the brain and spinal cord. If you look at the brain in section, you can see that it consists of white and gray matter.

Gray matter is an accumulation of nerve cells (with the initial sections of processes extending from their bodies). Separate groups of gray matter are also called nuclei.

White matter consists of nerve fibers covered with myelin sheath (processes of nerve cells from which gray matter is formed). In the spinal cord and brain, nerve fibers form pathways.

Peripheral nerves are divided into motor, sensory and mixed, depending on what fibers they consist of (motor or sensory). The bodies of neurons, whose processes are made up of sensory nerves, are located in ganglions outside the brain. The bodies of motor neurons are located in the motor nuclei of the brain and the anterior horns of the spinal cord.

Functions of the nervous system

The nervous system has different effects on the organs. The three main functions of the nervous system are:

Starting, causing or stopping the function of an organ (secretion of the gland, muscle contraction, etc.);
Vasomotor, which allows you to change the width of the lumen of the vessels, thereby regulating the flow of blood to the organ;
Trophic, lowering or increasing metabolism, and, consequently, the consumption of oxygen and nutrients. This allows you to constantly coordinate the functional state of the body and its need for oxygen and nutrients. When impulses are sent along the motor fibers to the working skeletal muscle, causing its contraction, then impulses are simultaneously received that increase metabolism and dilate blood vessels, which makes it possible to provide the energy for performing muscle work.

Diseases of the nervous system

Together with the endocrine glands, the nervous system plays a crucial role in the functioning of the body. It is responsible for the coordinated work of all systems and organs of the human body and unites the spinal cord, brain and peripheral system. Motor activity and sensitivity of the body is supported by nerve endings. And thanks to the autonomic system, the cardiovascular system and other organs are inverted.

Therefore, a violation of the functions of the nervous system affects the work of all systems and organs.

All diseases of the nervous system can be divided into infectious, hereditary, vascular, traumatic and chronically progressive.

Hereditary diseases are genomic and chromosomal. The most famous and common chromosomal disease is Down's disease. This disease is characterized by the following symptoms: violation of the musculoskeletal system, endocrine system, lack of mental abilities.

Traumatic lesions of the nervous system occur due to bruises and injuries, or when squeezing the brain or spinal cord. Such diseases are usually accompanied by vomiting, nausea, memory loss, disorders of consciousness, loss of sensitivity.

Vascular diseases mainly develop against the background of atherosclerosis or hypertension. This category includes chronic cerebrovascular insufficiency, cerebrovascular accident. Characterized by the following symptoms: attacks of vomiting and nausea, headache, impaired motor activity, decreased sensitivity.

Chronically progressive diseases, as a rule, develop as a result of metabolic disorders, exposure to infection, intoxication of the body, or due to abnormalities in the structure of the nervous system. Such diseases include sclerosis, myasthenia gravis, etc. These diseases usually progress gradually, reducing the performance of some systems and organs.

Causes of diseases of the nervous system:

The placental route of transmission of diseases of the nervous system during pregnancy (cytomegalovirus, rubella), as well as through the peripheral system (poliomyelitis, rabies, herpes, meningoencephalitis) is also possible.

In addition, the nervous system is negatively affected by endocrine, heart, kidney diseases, malnutrition, chemicals and drugs, heavy metals.