home Audience 8 What organs are regulated by the autonomic nervous system. What regulates the autonomic nervous system. sympathetic and parasympathetic

What organs are regulated by the autonomic nervous system. What regulates the autonomic nervous system. sympathetic and parasympathetic

central nervous system and peripheral, represented by those extending from the head and spinal cord nerves, - peripheral nervous system. A section of the brain shows that it consists of gray and white matter.

Gray matter is formed by clusters of nerve cells (with the initial sections of processes extending from their bodies). Separate limited accumulations of gray matter are called nuclei.

Vegetative-vascular dystonia symptoms

This disease is characterized fatigue, weakness, headache, tendency to faint, feeling short of breath, poor adaptation to heat or stuffy rooms, excessive sweating and other disorders.
It's caused pathological changes in work autonomic nervous system.
Autonomic nervous system (ANS) - department of the nervous system, controlling and regulating the work of all internal organs. This is an autonomic nervous system, since its activity is not subject to the will and control of human consciousness. The ANS is involved in the regulation of many biochemical and physiological processes, for example, supports normal body temperature, optimal blood pressure level, is responsible for the processes of digestion, urination, for activity cardiovascular, endocrine, immune systems, etc.

The main divisions of the ANS are: sympathetic and parasympathetic.
Sympathetic division of the ANS responsible for relaxation of the muscles of the digestive tract, Bladder ,

Autonomous, it is also the autonomic nervous system, ANS, is a part of the human nervous system that regulates internal processes, controls almost all internal organs, and is also responsible for adapting a person to new living conditions.

The main functions of the autonomic nervous system

Trophotropic - maintaining homeostasis (the constancy of the internal environment of the body, regardless of changes in external conditions). This function helps to maintain the normal functioning of the body in almost any conditions.

Within its framework, the autonomic nervous system regulates cardiac and cerebral circulation, blood pressure, respectively, body temperature, organic blood parameters (pH, sugar, hormones, and others), the activity of the glands of external and internal secretion, and the tone of the lymphatic vessels.

Ergotropic - ensuring normal physical and mental activities of the body, depending on the specific conditions of human existence at a particular point in time.

In simple words, this function enables the autonomic nervous system to mobilize the body's energy resources to save human life and health, which is necessary, for example, in an emergency situation.

At the same time, the functions of the autonomic nervous system also extend to the accumulation and “redistribution” of energy depending on the activity of a person at a particular point in time, that is, it ensures the normal rest of the body and the accumulation of strength.

Depending on the functions performed, the autonomic nervous system is divided into two sections - parasympathetic and sympathetic, and anatomically - into segmental and suprasegmental.

The structure of the autonomic nervous system. Click on the image to view in full size.

Suprasegmental division of the ANS

This is, in fact, the dominant department, giving commands to the segmental one. Depending on the situation and environmental conditions, it "turns on" the parasympathetic or sympathetic department. The suprasegmental division of the human autonomic nervous system includes the following functional units:

reticular formation of the brain. It contains the respiratory and centers that control the activity of the cardiovascular system, responsible for sleep and wakefulness. It is a kind of "sieve" that controls the impulses entering the brain, primarily during sleep.
Hypothalamus. Regulates the relationship of somatic and vegetative activity. It contains the most important centers that maintain constant and normal for the body indicators of body temperature, heart rate, blood pressure, hormonal levels, as well as controlling feelings of satiety and hunger.
limbic system. This center controls the appearance and extinction of emotions, regulates the daily routine - sleep and wakefulness, is responsible for maintaining the species, eating and sexual behavior.

Since the centers of the suprasegmental part of the autonomic nervous system are responsible for the appearance of any emotions, both positive and negative, it is quite natural that it is quite possible to cope with the violation of autonomic regulation by controlling emotions:

weaken or turn in a positive direction the course of various pathologies;
relieve pain, calm down, relax;
independently, without any medications, cope not only with psycho-emotional, but also with physical manifestations.

This is confirmed by statistical data: approximately 4 out of 5 patients diagnosed with VVD are capable of self-healing without the use of auxiliary drugs or medical procedures.

Apparently, a positive attitude and self-hypnosis help vegetative centers to independently cope with their own pathologies and save a person from unpleasant manifestations of vegetative-vascular dystonia.

Segmental division of the VNS

The segmental vegetative department is controlled by the suprasegmental one, it is a kind of "executive organ". Depending on the functions performed, the segmental division of the autonomic nervous system is divided into sympathetic and parasympathetic.

Each of them has a central and peripheral parts. The central section consists of sympathetic nuclei, located in the immediate vicinity of the spinal cord, and parasympathetic cranial and lumbar nuclei. The peripheral department includes:

branches, nerve fibers, vegetative branches emerging from the spinal cord and brain;
autonomic plexuses and their nodes;
sympathetic trunk with its nodes, connecting and internodal branches, sympathetic nerves;
terminal nodes of the parasympathetic division of the autonomic nervous system.

In addition, some individual organs are "equipped" with their own plexuses and nerve endings, carry out their regulation both under the influence of the sympathetic or parasympathetic department, and autonomously. These organs include the intestines, bladder and some others, and their nerve plexuses are called the third metasympathetic division of the autonomic nervous system.

The sympathetic department is represented by two trunks running along the entire spine - left and right, which regulate the activity of paired organs from the corresponding side. The exception is the regulation of the activity of the heart, stomach and liver: they are controlled by two trunks at the same time.

The sympathetic department in most cases is responsible for exciting processes, it dominates when a person is awake and active. In addition, it is he who "takes responsibility" for controlling all the functions of the body in an extreme or stressful situation - it mobilizes all the forces and all the energy of the body for a decisive action in order to preserve life.

The parasympathetic autonomic nervous system acts in the opposite way to the sympathetic one. It does not excite, but inhibits internal processes, with the exception of those occurring in the organs of the digestive system. It provides regulation when the body is at rest or in a dream, and it is due to its work that the body manages to relax and accumulate strength, stock up on energy.

Sympathetic and parasympathetic divisions

The autonomic nervous system controls all internal organs, and it can both stimulate their activity and relax. The sympathetic NS is responsible for stimulation. Its main functions are as follows:

narrowing or toning of blood vessels, acceleration of blood flow, increased blood pressure, body temperature;
increased heart rate, organization of additional nutrition of certain organs;
slowing down digestion, reducing intestinal motility, reducing the production of digestive juices;
reduces sphincters, reduces the secretion of glands;
dilates the pupil, activates short-term memory, improves attention.

Unlike the sympathetic, the parasympathetic autonomic nervous system "turns on" when the body is resting or sleeping. It slows down the physiological processes in almost all organs, concentrates on the function of accumulating energy and nutrients. It affects organs and systems as follows:

reduces tone, dilates blood vessels, due to which the level of blood pressure, the speed of blood movement through the body decreases, metabolic processes slow down, body temperature decreases;
the heart rate decreases, the nutrition of all organs and tissues in the body decreases;
digestion is activated: digestive juices are actively produced, intestinal motility increases - all this is necessary for the accumulation of energy;
the secretion of the glands increases, the sphincters relax, as a result of which the body is cleansed;
the pupil narrows, attention is scattered, the person feels drowsiness, weakness, lethargy and fatigue.

The normal functions of the autonomic nervous system are maintained mainly due to a kind of balance between the sympathetic and parasympathetic divisions. Its violation is the first and main impetus to the development of neurocirculatory or vegetative-vascular dystonia.

In the human body, the work of all its organs is closely interconnected, and therefore the body functions as a whole. The coordination of the functions of the internal organs is provided by the nervous system. In addition, the nervous system communicates between the external environment and the regulatory body, responding to external stimuli with appropriate reactions.

The perception of changes occurring in the external and internal environment occurs through nerve endings - receptors.

Any irritation (mechanical, light, sound, chemical, electrical, temperature) perceived by the receptor is converted (transformed) into the process of excitation. Excitation is transmitted along sensitive - centripetal nerve fibers to the central nervous system, where an urgent process of processing nerve impulses takes place. From here, impulses are sent along the fibers of centrifugal neurons (motor) to the executive organs that implement the response - the corresponding adaptive act.

This is how a reflex is performed (from the Latin "reflexus" - reflection) - a natural reaction of the body to changes in the external or internal environment, carried out through the central nervous system in response to irritation of the receptors.

Reflex reactions are diverse: this is the narrowing of the pupil in bright light, the release of saliva when food enters the oral cavity, etc.

The path along which nerve impulses (excitation) pass from receptors to the executive organ during the implementation of any reflex is called reflex arc.

The arcs of the reflexes close in the segmental apparatus of the spinal cord and brainstem, but they can also close higher, for example, in the subcortical ganglia or in the cortex.

Based on the foregoing, there are:

central nervous system (brain and spinal cord) and
peripheral nervous system, represented by nerves extending from the brain and spinal cord and other elements that lie outside the spinal cord and brain.

The peripheral nervous system is divided into somatic (animal) and autonomic (or autonomic).

The somatic nervous system mainly carries out the connection of the organism with the external environment: the perception of stimuli, the regulation of movements of the striated muscles of the skeleton, etc.
vegetative - regulates metabolism and the functioning of internal organs: heartbeat, peristaltic contractions of the intestines, secretion of various glands, etc.

The autonomic nervous system, in turn, based on the segmental principle of structure, is divided into two levels:

segmental - includes sympathetic, anatomically associated with the spinal cord, and parasympathetic, formed by accumulations of nerve cells in the midbrain and medulla oblongata, nervous systems
suprasegmental level - includes the reticular formation of the brain stem, hypothalamus, thalamus, amygdala and hippocampus - limbic-reticular complex

The somatic and autonomic nervous systems function in close interaction, however, the autonomic nervous system has some independence (autonomy), controlling many involuntary functions.

CENTRAL NERVOUS SYSTEM

Represented by the brain and spinal cord. The brain is made up of gray and white matter.

Gray matter is a collection of neurons and their short processes. In the spinal cord, it is located in the center, surrounding the spinal canal. In the brain, on the contrary, gray matter is located on its surface, forming a cortex (cloak) and separate clusters, called nuclei, concentrated in white matter.

The white matter is under the gray and is composed of sheathed nerve fibers. Nerve fibers, connecting, compose nerve bundles, and several such bundles form individual nerves.

The nerves through which excitation is transmitted from the central nervous system to the organs are called centrifugal, and the nerves that conduct excitation from the periphery to the central nervous system are called centripetal.

The brain and spinal cord are surrounded by three membranes: hard, arachnoid and vascular.

Solid - external, connective tissue, lines the internal cavity of the skull and spinal canal.
The arachnoid is located under the solid - it is a thin shell with a small number of nerves and blood vessels.
The choroid is fused with the brain, enters the furrows and contains many blood vessels.

Cavities filled with cerebral fluid form between the vascular and arachnoid membranes.

Spinal cord located in the spinal canal and has the appearance of a white cord, stretching from the occipital foramen to the lower back. Longitudinal grooves are located along the anterior and posterior surfaces of the spinal cord, in the center there is a spinal canal, around which gray matter is concentrated - an accumulation of a huge number of nerve cells that form the contour of a butterfly. On the outer surface of the cord of the spinal cord is white matter - an accumulation of bundles of long processes of nerve cells.

The gray matter is divided into anterior, posterior and lateral horns. In the anterior horns lie motor neurons, in the posterior - intercalary, which carry out the connection between sensory and motor neurons. Sensory neurons lie outside the cord, in the spinal nodes along the sensory nerves.

Long processes depart from the motor neurons of the anterior horns - the anterior roots, which form the motor nerve fibers. The axons of sensitive neurons approach the posterior horns, forming the posterior roots, which enter the spinal cord and transmit excitation from the periphery to the spinal cord. Here, excitation switches to the intercalary neuron, and from it to short processes of the motor neuron, from which it is then transmitted along the axon to the working organ.

In the intervertebral foramina, the motor and sensory roots join to form mixed nerves, which then split into anterior and posterior branches. Each of them consists of sensory and motor nerve fibers. Thus, at the level of each vertebra, only 31 pairs of spinal nerves of a mixed type depart from the spinal cord in both directions.

The white matter of the spinal cord forms pathways that stretch along the spinal cord, connecting both its individual segments to each other, and the spinal cord to the brain. Some pathways are called ascending or sensitive, transmitting excitation to the brain, others are descending or motor, which conduct impulses from the brain to certain segments of the spinal cord.

The function of the spinal cord. The spinal cord has two functions:

reflex [show] .
Each reflex is carried out by a strictly defined part of the central nervous system - the nerve center. The nerve center is a collection of nerve cells located in one of the parts of the brain and regulating the activity of any organ or system. For example, the center of the knee-jerk reflex is located in the lumbar spinal cord, the center of urination is in the sacral, and the center of pupil dilation is in the upper thoracic segment of the spinal cord. The vital motor center of the diaphragm is localized in the III-IV cervical segments. Other centers - respiratory, vasomotor - are located in the medulla oblongata.
The nerve center consists of many intercalary neurons. It processes the information that comes from the corresponding receptors, and generates impulses that are transmitted to the executive organs - the heart, blood vessels, skeletal muscles, glands, etc. As a result, their functional state changes. To regulate the reflex, its accuracy, the participation of the higher parts of the central nervous system, including the cerebral cortex, is also necessary.
The nerve centers of the spinal cord are directly connected with the receptors and executive organs of the body. The motor neurons of the spinal cord provide contraction of the muscles of the trunk and limbs, as well as the respiratory muscles - the diaphragm and intercostals. In addition to the motor centers of skeletal muscles, there are a number of autonomic centers in the spinal cord.
conductive [show] .

The bundles of nerve fibers that form the white matter connect the various parts of the spinal cord to each other and the brain to the spinal cord. There are ascending pathways, carrying impulses to the brain, and descending, carrying impulses from the brain to the spinal cord. According to the first, excitation that occurs in the receptors of the skin, muscles, and internal organs is carried along the spinal nerves to the posterior roots of the spinal cord, is perceived by the sensitive neurons of the spinal ganglions, and from here it is sent either to the posterior horns of the spinal cord, or as part of the white matter reaches the trunk, and then the cerebral cortex.

Descending pathways conduct excitation from the brain to the motor neurons of the spinal cord. From here, the excitation is transmitted along the spinal nerves to the executive organs. The activity of the spinal cord is under the control of the brain, which regulates spinal reflexes.

Brain located in the medulla of the skull. Its average weight is 1300 - 1400 g. After the birth of a person, brain growth continues up to 20 years. It consists of five sections: the anterior (large hemispheres), intermediate, middle, hindbrain and medulla oblongata. Inside the brain there are four interconnected cavities - cerebral ventricles. They are filled with cerebrospinal fluid. I and II ventricles are located in the cerebral hemispheres, III - in the diencephalon, and IV - in the medulla oblongata.

The hemispheres (the newest part in evolutionary terms) reach high development in humans, accounting for 80% of the mass of the brain. The phylogenetically older part is the brain stem. The trunk includes the medulla oblongata, the medullary (varoli) bridge, the midbrain and the diencephalon.

Numerous nuclei of gray matter lie in the white matter of the trunk. The nuclei of 12 pairs of cranial nerves also lie in the brainstem. The brain stem is covered by the cerebral hemispheres.

Medulla- a continuation of the dorsal and repeats its structure: furrows also lie on the anterior and posterior surfaces. It consists of white matter (conducting bundles), where clusters of gray matter are scattered - the nuclei from which cranial nerves originate - from IX to XII pairs, including glossopharyngeal (IX pair), vagus (X pair), innervating organs respiration, circulation, digestion and other systems, sublingual (XII pair). At the top, the medulla oblongata continues into a thickening - the pons varolii, and from the sides the lower legs of the cerebellum depart from it. From above and from the sides, almost the entire medulla oblongata is covered by the cerebral hemispheres and the cerebellum.

In the gray matter of the medulla oblongata lie vital centers that regulate cardiac activity, breathing, swallowing, carrying out protective reflexes (sneezing, coughing, vomiting, tearing), secretion of saliva, gastric and pancreatic juice, etc. Damage to the medulla oblongata can be the cause of death due to the cessation heart activity and respiration.

Hind brain includes the pons and cerebellum. The pons of Varolii is limited from below by the medulla oblongata, from above it passes into the legs of the brain, its lateral sections form the middle legs of the cerebellum. In the substance of the pons, there are nuclei from the V to VIII pair of cranial nerves (trigeminal, abducent, facial, auditory).

The cerebellum is located posterior to the pons and medulla oblongata. Its surface consists of gray matter (bark). Under the cerebellar cortex is white matter, in which there are accumulations of gray matter - the nucleus. The entire cerebellum is represented by two hemispheres, the middle part is a worm and three pairs of legs formed by nerve fibers, through which it is connected with other parts of the brain. The main function of the cerebellum is the unconditional reflex coordination of movements, which determines their clarity, smoothness and maintaining body balance, as well as maintaining muscle tone. Through the spinal cord along the pathways, impulses from the cerebellum arrive at the muscles. The activity of the cerebellum is controlled by the cerebral cortex.

midbrain located in front of the pons, it is represented by the quadrigemina and the legs of the brain. In the center of it is a narrow canal (aqueduct of the brain), which connects the III and IV ventricles. The cerebral aqueduct is surrounded by gray matter, which contains the nuclei of the III and IV pairs of cranial nerves. In the legs of the brain, pathways continue from the medulla oblongata and the pons to the cerebral hemispheres. The midbrain plays an important role in the regulation of tone and in the implementation of reflexes, due to which standing and walking are possible. The sensitive nuclei of the midbrain are located in the tubercles of the quadrigemina: the nuclei associated with the organs of vision are enclosed in the upper ones, and the nuclei associated with the organs of hearing are in the lower ones. With their participation, orienting reflexes to light and sound are carried out.

diencephalon occupies the highest position in the trunk and lies anterior to the legs of the brain. It consists of two visual hillocks, supratuberous, hypothalamic region and geniculate bodies. On the periphery of the diencephalon is white matter, and in its thickness - the nuclei of gray matter. Visual hillocks are the main subcortical centers of sensitivity: impulses from all receptors of the body arrive here along ascending paths, and from here to the cerebral cortex. In the hypothalamic part (hypothalamus) there are centers, the totality of which is the highest subcortical center of the autonomic nervous system, which regulates the metabolism in the body, heat transfer, and the constancy of the internal environment. Parasympathetic centers are located in the anterior hypothalamus, and sympathetic centers in the posterior. The subcortical visual and auditory centers are concentrated in the nuclei of the geniculate bodies.

The 2nd pair of cranial nerves - optic nerves - goes to the geniculate bodies. The brain stem is connected to the environment and to the organs of the body by cranial nerves. By their nature, they can be sensitive (I, II, VIII pairs), motor (III, IV, VI, XI, XII pairs) and mixed (V, VII, IX, X pairs).

forebrain consists of strongly developed hemispheres and the middle part connecting them. The right and left hemispheres are separated from each other by a deep fissure, at the bottom of which lies the corpus callosum. The corpus callosum connects both hemispheres through long processes of neurons that form pathways.

The cavities of the hemispheres are represented by the lateral ventricles (I and II). The surface of the hemispheres is formed by gray matter or the cerebral cortex, represented by neurons and their processes, under the cortex lies white matter - pathways. Pathways connect individual centers within the same hemisphere, or the right and left halves of the brain and spinal cord, or different floors of the central nervous system. In the white matter there are also clusters of nerve cells that form the subcortical nuclei of the gray matter. Part of the cerebral hemispheres is the olfactory brain with a pair of olfactory nerves extending from it (I pair).

The total surface of the cerebral cortex is 2000-2500 cm 2, its thickness is 1.5-4 mm. Despite its small thickness, the cerebral cortex has a very complex structure.

The cortex includes more than 14 billion nerve cells, arranged in six layers that differ in shape, size of neurons and connections. The microscopic structure of the cortex was first studied by V. A. Betz. He discovered pyramidal neurons, which were later given his name (Betz cells).

In a three-month-old embryo, the surface of the hemispheres is smooth, but the cortex grows faster than the brain box, so the cortex forms folds - convolutions limited by furrows; they contain about 70% of the surface of the cortex. Furrows divide the surface of the hemispheres into lobes.

There are four lobes in each hemisphere:

frontal
parietal
temporal
occipital.

The deepest furrows are the central one, which runs across both hemispheres, and the temporal one, which separates the temporal lobe of the brain from the rest; the parieto-occipital sulcus separates the parietal lobe from the occipital lobe.

Anterior to the central sulcus (Roland sulcus) in the frontal lobe is the anterior central gyrus, behind it is the posterior central gyrus. The lower surface of the hemispheres and the brain stem is called the base of the brain.

Based on experiments with partial removal of different parts of the cortex in animals and observations on people with affected cortex, it was possible to establish the functions of different parts of the cortex. So, in the cortex of the occipital lobe of the hemispheres is the visual center, in the upper part of the temporal lobe - the auditory. The musculocutaneous zone, which perceives irritations from the skin of all parts of the body and controls the voluntary movements of the skeletal muscles, occupies a portion of the cortex on both sides of the central sulcus.

Each part of the body corresponds to its own section of the cortex, and the representation of the palms and fingers, lips and tongue, as the most mobile and sensitive parts of the body, occupies in a person almost the same area of the cortex as the representation of all other parts of the body combined.

In the cortex there are centers of all sensitive (receptor) systems, representations of all organs and parts of the body. In this regard, centripetal nerve impulses from all internal organs or parts of the body are suitable for the corresponding sensitive areas of the cerebral cortex, where analysis is carried out and a specific sensation is formed - visual, olfactory, etc., and it can control their work.

A functional system consisting of a receptor, a sensitive pathway and a cortical zone where this type of sensitivity is projected, I. P. Pavlov called the analyzer.

The analysis and synthesis of the received information is carried out in a strictly defined area - the zone of the cerebral cortex. The most important areas of the cortex are motor, sensory, visual, auditory, olfactory. The motor zone is located in the anterior central gyrus in front of the central sulcus of the frontal lobe, the zone of skin-muscular sensitivity is located behind the central sulcus, in the posterior central gyrus of the parietal lobe. The visual zone is concentrated in the occipital lobe, the auditory zone is in the superior temporal gyrus of the temporal lobe, and the olfactory and gustatory zones are in the anterior temporal lobe.

In the cerebral cortex, many nervous processes are carried out. Their purpose is twofold: the interaction of the body with the external environment (behavioral reactions) and the unification of body functions, the nervous regulation of all organs. The activity of the cerebral cortex of humans and higher animals was defined by I.P. Pavlov as the highest nervous activity, which is a conditioned reflex function of the cerebral cortex.

Nervous system	Central nervous system
	brain			spinal cord
	large hemispheres	cerebellum	trunk	spinal cord
Composition and structure	Lobes: frontal, parietal, occipital, two temporal. The cortex is formed by gray matter - the bodies of nerve cells. The thickness of the bark is 1.5-3 mm. The area of the cortex is 2-2.5 thousand cm 2, it consists of 14 billion bodies of neurons. White matter is made up of nerve fibers	The gray matter forms the cortex and nuclei within the cerebellum. Consists of two hemispheres connected by a bridge	Educated: diencephalon midbrain bridge medulla oblongata It consists of white matter, in the thickness are the nuclei of gray matter. The trunk passes into the spinal cord	Cylindrical cord 42-45 cm long and about 1 cm in diameter. Passes in the spinal canal. Inside it is the spinal canal filled with fluid. Gray matter is located inside, white - outside. Passes into the brain stem, forming a single system
Functions	Carries out higher nervous activity (thinking, speech, second signaling system, memory, imagination, ability to write, read). Communication with the external environment occurs with the help of analyzers located in the occipital lobe (visual zone), in the temporal lobe (auditory zone), along the central sulcus (musculoskeletal zone) and on the inner surface of the cortex (gustatory and olfactory zones). Regulates the work of the whole organism through the peripheral nervous system	Regulates and coordinates body movements muscle tone. Carries out unconditioned reflex activity (centers of innate reflexes)	Connects the brain with the spinal cord into a single central nervous system. In the medulla oblongata there are centers: respiratory, digestive, cardiovascular. The bridge connects both halves of the cerebellum. The midbrain controls reactions to external stimuli, muscle tone (tension). The diencephalon regulates metabolism, body temperature, connects body receptors with the cerebral cortex	Operates under the control of the brain. Arcs of unconditioned (innate) reflexes pass through it, excitation and inhibition during movement. Pathways - white matter connecting the brain to the spinal cord; is a conductor of nerve impulses. Regulates the work of internal organs through the peripheral nervous system Through the spinal nerves, voluntary movements of the body are controlled

PERIPHERAL NERVOUS SYSTEM

The peripheral nervous system is formed by nerves emerging from the central nervous system, and nerve nodes and plexuses located mainly near the brain and spinal cord, as well as next to various internal organs or in the wall of these organs. In the peripheral nervous system, somatic and autonomic divisions are distinguished.

somatic nervous system

This system is formed by sensory nerve fibers that go to the central nervous system from various receptors, and motor nerve fibers that innervate skeletal muscles. The characteristic features of the fibers of the somatic nervous system are that they are not interrupted anywhere along the entire length from the central nervous system to the receptor or skeletal muscle, they have a relatively large diameter and a high speed of excitation conduction. These fibers make up most of the nerves that emerge from the CNS and form the peripheral nervous system.

There are 12 pairs of cranial nerves that emerge from the brain. The characteristics of these nerves are given in Table 1. [show] .

Table 1. Cranial nerves

Pair	Name and composition of the nerve	The exit point of the nerve from the brain	Function
I	Olfactory	Large hemispheres of the forebrain	Transmits excitation (sensory) from the olfactory receptors to the olfactory center
II	visual (sensory)	diencephalon	Transmits excitation from retinal receptors to the visual center
III	Oculomotor (motor)	midbrain	Innervates the eye muscles, provides eye movements
IV	Block (motor)	Same	Same
V	Trinity (mixed)	Bridge and medulla oblongata	Transmits excitation from the receptors of the skin of the face, mucous membranes of the lips, mouth and teeth, innervates the masticatory muscles
VI	Abductor (motor)	Medulla	Innervates the rectus lateral muscle of the eye, causes eye movement to the side
VII	Facial (mixed)	Same	Transmits excitation from the taste buds of the tongue and oral mucosa to the brain, innervates the mimic muscles and salivary glands
VIII	auditory (sensitive)	Same	Transmits stimulation from inner ear receptors
IX	Glossopharyngeal (mixed)	Same	Transmits excitation from taste buds and pharyngeal receptors, innervates the muscles of the pharynx and salivary glands
X	Wandering (mixed)	Same	Innervates the heart, lungs, most of the abdominal organs, transmits excitation from the receptors of these organs to the brain and centrifugal impulses in the opposite direction
XI	Additional (motor)	Same	Innervates the muscles of the neck and neck, regulates their contractions
XII	Hyoid (motor)	Same	Innervates the muscles of the tongue and neck, causes their contraction

Each segment of the spinal cord gives off one pair of nerves containing sensory and motor fibers. All sensory, or centripetal, fibers enter the spinal cord through the posterior roots, on which there are thickenings - nerve nodes. In these nodes are the bodies of centripetal neurons.

The fibers of the motor, or centrifugal, neurons exit the spinal cord through the anterior roots. Each segment of the spinal cord corresponds to a certain part of the body - metamere. However, the innervation of the metameres occurs in such a way that each pair of spinal nerves innervates three adjacent metameres, and each metamere is innervated by three adjacent segments of the spinal cord. Therefore, in order to completely denervate any metamere of the body, it is necessary to cut the nerves of three neighboring segments of the spinal cord.

The autonomic nervous system is a section of the peripheral nervous system that innervates internal organs: the heart, stomach, intestines, kidneys, liver, etc. It does not have its own special sensitive pathways. Sensitive impulses from organs are transmitted through sensory fibers, which also pass through the peripheral nerves, are common to the somatic and autonomic nervous systems, but make up a smaller part of them.

Unlike the somatic nervous system, autonomic nerve fibers are thinner and conduct excitation much more slowly. On the way from the central nervous system to the innervated organ, they are necessarily interrupted with the formation of a synapse.

Thus, the centrifugal pathway in the autonomic nervous system includes two neurons - preganglionic and postganglionic. The body of the first neuron is located in the central nervous system, and the body of the second is outside it, in the nerve nodes (ganglia). There are many more postganglionic neurons than preganglionic ones. As a result, each preganglionic fiber in the ganglion fits and transmits its excitation to many (10 or more) postganglionic neurons. This phenomenon is called animation.

According to a number of signs, the sympathetic and parasympathetic divisions are distinguished in the autonomic nervous system.

Sympathetic department The autonomic nervous system is formed by two sympathetic chains of nerve nodes (paired border trunk - vertebral ganglia), located on both sides of the spine, and nerve branches that depart from these nodes and go to all organs and tissues as part of mixed nerves. The nuclei of the sympathetic nervous system are located in the lateral horns of the spinal cord, from the 1st thoracic to the 3rd lumbar segments.

The impulses coming through the sympathetic fibers to the organs provide reflex regulation of their activity. In addition to the internal organs, sympathetic fibers innervate blood vessels in them, as well as in the skin and skeletal muscles. They increase and speed up heart contractions, cause a rapid redistribution of blood by constricting some vessels and expanding others.

Parasympathetic department represented by a number of nerves, among which the vagus nerve is the largest. It innervates almost all organs of the chest and abdominal cavity.

The nuclei of the parasympathetic nerves lie in the middle, oblong sections of the brain and sacral spinal cord. Unlike the sympathetic nervous system, all parasympathetic nerves reach the peripheral nerve nodes located in the internal organs or on the outskirts of them. The impulses carried out by these nerves cause weakening and slowing of cardiac activity, narrowing of the coronary vessels of the heart and brain vessels, dilation of the vessels of the salivary and other digestive glands, which stimulates the secretion of these glands, and increases the contraction of the muscles of the stomach and intestines.

The main differences between the sympathetic and parasympathetic divisions of the autonomic nervous system are given in Table. 2. [show] .

Table 2. Autonomic nervous system

Index	Sympathetic nervous system	parasympathetic nervous system
Location of the pregangloonic neuron	Thoracic and lumbar spinal cord	Brain stem and sacral spinal cord
Location of switch to postganglionic neuron	Nerve nodes of the sympathetic chain	Nerves in internal organs or near organs
Postganglionic neuron mediator	Norepinephrine	Acetylcholine
Physiological action	Stimulates the work of the heart, constricts blood vessels, enhances the performance of skeletal muscles and metabolism, inhibits the secretory and motor activity of the digestive tract, relaxes the walls of the bladder	It slows down the work of the heart, dilates some blood vessels, enhances the secretion of juice and motor activity of the digestive tract, causes contraction of the walls of the bladder

Most of the internal organs receive a double autonomic innervation, that is, both sympathetic and parasympathetic nerve fibers approach them, which function in close interaction, having the opposite effect on the organs. This is of great importance in adapting the body to constantly changing environmental conditions.

A significant contribution to the study of the autonomic nervous system was made by L. A. Orbeli [show] .

Orbeli Leon Abgarovich (1882-1958) - Soviet physiologist, student of I.P. Pavlov. Acad. Academy of Sciences of the USSR, Academy of Sciences of the ArmSSR and the Academy of Medical Sciences of the USSR. Head of the Military Medical Academy, Institute of Physiology. I, P. Pavlov of the USSR Academy of Sciences, Institute of Evolutionary Physiology, Vice-President of the USSR Academy of Sciences.

The main direction of research is the physiology of the autonomic nervous system.

L. A. Orbeli created and developed the doctrine of the adaptive-trophic function of the sympathetic nervous system. He also carried out research on the coordination of the activity of the spinal cord, on the physiology of the cerebellum, and on higher nervous activity.

Nervous system	Peripheral nervous system
	somatic (nerve fibers are not interrupted; impulse conduction speed is 30-120 m/s)		vegetative (nerve fibers are interrupted by nodes: the speed of the impulse is 1-3 m / s)
	cranial nerves (12 pairs)	spinal nerves (31 pairs)	sympathetic nerves	parasympathetic nerves
Composition and structure	Depart from various parts of the brain in the form of nerve fibers. Subdivided into centripetal, centrifugal. Innervate the sense organs, internal organs, skeletal muscles	They depart in symmetrical pairs on both sides of the spinal cord. The processes of centripetal neurons enter through the posterior roots; processes of centrifugal neurons exit through the anterior roots. The processes join to form a nerve	They depart in symmetrical pairs on both sides of the spinal cord in the thoracic and lumbar regions. The prenodal fiber is short, as the nodes lie along the spinal cord; the post-nodal fiber is long, as it goes from the node to the innervated organ	Depart from the brain stem and sacral spinal cord. Nerve nodes lie in the walls of or near the innervated organs. The prenodal fiber is long, as it passes from the brain to the organ, the postnodal fiber is short, as it is located in the innervated organ
Functions	They provide communication of the body with the external environment, quick reactions to its change, orientation in space, body movements (purposeful), sensitivity, vision, hearing, smell, touch, taste, facial expressions, speech. Activities are controlled by the brain	Carry out movements of all parts of the body, limbs, determine the sensitivity of the skin. They innervate skeletal muscles, causing voluntary and involuntary movements. Voluntary movements are carried out under the control of the brain, involuntary under the control of the spinal cord (spinal reflexes)	Innervate internal organs. Post-nodal fibers leave the spinal cord as part of the mixed nerve and pass to the internal organs. Nerves form plexuses - solar, pulmonary, cardiac. Stimulate the work of the heart, sweat glands, metabolism. They hinder the activity of the digestive tract, constrict blood vessels, relax the walls of the bladder, dilate the pupils, etc.	They innervate the internal organs, exerting an influence on them opposite to the action of the sympathetic nervous system. The largest nerve is the vagus. Its branches are located in many internal organs - the heart, blood vessels, stomach, since the nodes of this nerve are located there.
			The activity of the autonomic nervous system regulates the work of all internal organs, adapting them to the needs of the whole organism.

Autonomic nervous system ">

autonomic nervous system.

The vegetative (autonomous) nervous system - regulates the activity of internal organs, provides the most important functions of nutrition, respiration, excretion, reproduction, blood and lymph circulation. Its reactions are not directly subordinated to our consciousness. The components of the autonomic nervous system permeate almost all tissues of the body; together with the hormones of the endocrine glands (endocrine glands), it coordinates the work of organs, subordinating it to a common goal - creating optimal conditions for the existence of the body in a given situation and at a given time. .

Nerve cells of the autonomic nervous system are not only found in the brain and spinal cord, they are widely dispersed in many organs, especially in the gastrointestinal tract. They are in the form of numerous nodes (ganglia) located between the organs and the brain. Autonomic neurons form connections with each other, allowing them to work autonomously, a mass of small nerve centers is formed outside the central nervous system, which can take on some relatively simple functions (for example, the organization of undulating bowel contractions). At the same time, the central nervous system continues to exercise general control over the course of these processes and intervene in them.

The autonomic nervous system is divided into sympathetic and parasympathetic parts. With the predominant influence of one of them, the body reduces or, conversely, enhances its work. Both of them are under the control of the higher parts of the central nervous system, which is how their coordinated action is achieved. Autonomic centers in the brain and spinal cord make up the central section of the autonomic nervous system, and its peripheral section is represented by nerves, nodes, autonomic nerve plexuses.

Sympathetic centers are located in the lateral horns of the gray matter of the spinal cord, in its thoracic and lumbar segments. Sympathetic fibers depart from their cells, which, as part of the anterior roots, spinal nerves and their branches, are sent to the nodes of the sympathetic trunk. The right and left sympathetic trunks are located along the entire spinal column. They are a chain of thickenings (nodes) in which the bodies of sympathetic nerve cells are located. Nerve fibers from the centers of the spinal cord approach them. The processes of the cells of the nodes go to the internal organs as part of the autonomic nerves and plexuses.

Sympathetic trunks have cervical, thoracic, lumbar and pelvic regions. The cervical region consists of three nodes, the branches of which form plexuses on the vessels of the head, neck, chest, near the organs and in their walls, including the cardiac plexus. The thoracic region includes 10-12 nodes, their branches form plexuses on the aorta, bronchi, and in the esophagus. Passing through the diaphragm, they are part of the solar plexus. The lumbar sympathetic trunk form 3-5 nodes. Their branches through the solar and other vegetative plexuses of the abdominal cavity reach the stomach, liver, intestines,

A person has a direct impact on the work of many internal organs and systems. Thanks to it, breathing, blood circulation, movement and other functions of the human body are carried out. Interestingly, despite its significant influence, the autonomic nervous system is very "hidden", that is, no one can clearly feel changes in it. But this does not mean that it is not necessary to pay due attention to the role of the ANS in the human body.

The human nervous system: its divisions

The main task of the human NS is to create an apparatus that would connect all the organs and systems of the human body together. Thanks to this, it could exist and function. The basis of the human nervous system is a kind of structure called a neuron (they create contact with each other using nerve impulses). It is important to know that the anatomy of the human NS is a combination of two departments: the animal (somatic) and autonomic (vegetative) nervous systems.

The first was created mainly so that the human body could contact the external environment. Therefore, this system has its second name - animal (i.e., animal), due to the performance of the functions that are inherent in them. The value of the system for a person is no less important, but the essence of its work is completely different - control over those functions that are responsible for respiration, digestion and other roles that are predominantly inherent in plants (hence the second name of the system - autonomous).

What is the human autonomic nervous system?

The ANS carries out its activities with the help of neurons (a set of nerve cells and their processes). They, in turn, work by sending certain signals to various organs, systems and glands from the spinal cord and brain. It is interesting that the neurons of the autonomic part of the human nervous system are responsible for the work of the heart (its contraction), the functioning of the gastrointestinal tract, and the activity of the salivary glands. Actually, this is why they say that the autonomic nervous system organizes the work of organs and systems unconsciously, since initially these functions were inherent in plants, and then already in animals and humans. The neurons that form the basis of the ANS are capable of creating some clusters located in the brain and spinal cord. They were given the names "vegetative nuclei". Also, near the organs and the spine, the vegetative section of the NS is able to form. So, the vegetative nuclei are the central part of the animal system, and the nerve nodes are peripheral. In fact, the ANS is divided into two parts: parasympathetic and sympathetic.

What role does the ANS play in the human body?

Often people cannot answer a simple question: “The autonomic nervous system regulates the work of what: muscles, organs, or systems?”

In fact, it, in fact, is a kind of a kind of "response" of the human body to irritations from the outside and from the inside. It is important to understand that the autonomic nervous system works in your body every second, only its activity is invisible. For example, regulating the normal internal state of a person (blood circulation, respiration, excretion, hormone levels, etc.) is the main role of the autonomic nervous system. In addition, it is able to have the most direct impact on other components of the human body, say, muscles (cardiac, skeletal), various sensory organs (for example, dilation or contraction of the pupil), glands of the endocrine system, and much more. The autonomic nervous system regulates the work of the human body through various influences on its organs, which can be conditionally represented by three types:

Control of metabolism in the cells of various organs, the so-called trophic control;

An indispensable effect on the functions of organs, for example, on the work of the heart muscle - functional control;

Influence on organs by increasing or decreasing their blood flow - vasomotor control.

The composition of the human ANS

It is important to note the main thing: the ANS is divided into two components: parasympathetic and sympathetic. The last of them is usually associated with such processes as, for example, wrestling, running, i.e., strengthening the functions of various organs.

In this case, the following processes are observed: an increase in contractions of the heart muscle (and, as a result, an increase in blood pressure above normal), increased sweating, enlarged pupils, and weak work of intestinal motility. works in a completely different way, i.e., in the opposite way. It is characterized by such actions in the human body, in which it rests and assimilates everything. When it begins to activate the mechanism of its work, the following processes are observed: pupil constriction, reduced sweating, it works more weakly (i.e., the number of its contractions decreases), intestinal motility activates, and blood pressure decreases. The functions of the ANS are reduced to the work of its above-studied departments. Their interconnected work allows you to maintain the human body in balance. In simpler terms, these components of the ANS should exist in a complex, constantly complementing each other. This system works only due to the fact that the parasympathetic and sympathetic nervous systems are able to release neurotransmitters, which connect organs and systems with the help of nerve signals.

Control and verification of the autonomic nervous system - what is it?

The functions of the autonomic nervous system are under the continuous control of several main centers:

Spinal cord. The sympathetic nervous system (SNS) creates elements that are in close proximity to the spinal cord, and its external components are represented by the parasympathetic division of the ANS.
Brain. It has the most direct effect on the work of the parasympathetic and sympathetic nervous systems, regulating the balance throughout the human body.
stem brain. This is a kind of connection that exists between the brain and spinal cord. It is able to control the functions of the ANS, namely its parasympathetic division (blood pressure, respiration, heart rate, and more).
Hypothalamus- part It affects sweating, digestion, heart contractions, etc.
limbic system(in fact, these are human emotions). Located under the cerebral cortex. It affects the work of both departments of the ANS.

Given the above, the role of the autonomic nervous system is immediately noticeable, because its activity is controlled by such important components of the human body.

Functions carried out by the VNS

They originated thousands of years ago, when people learned to survive in the most difficult conditions. The functions of the human autonomic nervous system are directly related to the work of its two main divisions. So, the parasympathetic system is able to normalize the work of the human body after the stress (activation of the sympathetic division of the ANS). Thus, the emotional state is balanced. Of course, this part of the ANS is also responsible for other important roles, such as sleep and rest, digestion and reproduction. All this is carried out due to acetylcholine (a substance that transmits nerve impulses from one nerve fiber to another).

The work of the sympathetic department of the ANS is aimed at activating all the vital processes of the human body: blood flow to many organs and systems increases, the heart rate increases, sweating increases, and much more. It is these processes that help a person survive stressful situations. Therefore, we can conclude that the autonomic nervous system regulates the work of the human body as a whole, in one way or another affecting it.

Sympathetic Nervous System (SNS)

This part of the human ANS is associated with the struggle or response of the body to internal and external stimuli. Its functions are as follows:

Inhibits the work of the intestine (its peristalsis), due to a decrease in blood flow to it;

increased sweating;

When a person does not have enough air, his ANS, with the help of appropriate nerve impulses, expands the bronchioles;

Due to the narrowing of blood vessels, an increase in blood pressure;

Normalizes blood glucose levels by lowering it in the liver.

It is also known that the autonomic nervous system regulates the work of skeletal muscles - this is directly involved in its sympathetic department.

For example, when your body is under stress in the form of fever, the sympathetic division of the ANS immediately works as follows: it transmits the appropriate signals to the brain, and it, in turn, increases sweating or expands the skin pores with the help of nerve impulses. Thus, the temperature is significantly reduced.

Parasympathetic Nervous System (PNS)

This component of the ANS is aimed at creating in the human body a state of rest, calmness, assimilation of all vital processes. His work boils down to the following:

Strengthens the work of the entire gastrointestinal tract, increasing blood flow to it;

It directly affects the salivary glands, stimulating the production of saliva, thereby accelerating intestinal motility;

Reduces pupil size;

Exercises the strictest control over the work of the heart and all its departments;

Reduces the size of the bronchioles when the level of oxygen in the blood becomes normal.

It is very important to know that the autonomic nervous system regulates the work of the muscles of various organs - this issue is also dealt with by its parasympathetic department. For example, contraction of the uterus during arousal or in the postpartum period is associated precisely with the work of this system. A man's erection is subject only to her influence. Indeed, with the help of nerve impulses, blood enters the genitals of a man, to which the muscles of the penis react.

How does stress affect the ANS?

I would like to say right away that it is stress that can cause the ANS to malfunction.
The functions of the autonomic nervous system can be completely paralyzed when such a situation occurs. For example, there was a threat to a person's life (a huge stone falls on him, or a wild animal suddenly appeared in front of him). Someone immediately runs away, while the other will simply freeze in place without the ability to move from the dead center. It does not depend on the person himself, this is how his ANS reacted at the unconscious level. And all this is because of the nerve endings located in the head, the limbic system (responsible for emotions). After all, it has already become clear that the autonomic nervous system regulates the work of many systems and organs: digestion, the cardiovascular apparatus, reproduction, the activity of the lungs and urinary tract. Therefore, in the human body there are many centers that can respond to stress due to the work of the ANS. But do not worry too much, since most of our lives we do not experience strong shocks, so the occurrence of such conditions for a person is rare.

Deviations in human health caused by improper functioning of the ANS

Of course, from the foregoing, it became clear that the autonomic nervous system regulates the work of many systems and organs in the human body. Therefore, any functional violations in its work can significantly disrupt this workflow.

By the way, the causes of such disorders can be either heredity or diseases acquired in the process of life. Often the work of the human ANS is “invisible” in nature, but problems in this activity are already noticeable on the basis of the following symptoms:

Nervous system: the body's inability to lower body temperature without unnecessary help;

Gastrointestinal: vomiting, constipation or diarrhea, inability to swallow food, urinary incontinence and more;

Skin problems (itching, redness, peeling), brittle nails and hair, increased or decreased sweating;

Vision: blurry picture, no tears, difficulty focusing;

Respiratory system: improper response to low or high oxygen levels in the blood;

Heart and vascular system: fainting, palpitations, shortness of breath, dizziness, tinnitus;

Urinary system: any problems in this area (incontinence, frequency of urination);

Reproductive system: inability to achieve orgasm, premature erection.

People suffering from an ANS disorder (vegetative neuropathy) often cannot control its development. It often happens that progressive autonomic dysfunction originates from diabetes. And in this case, it will be enough to clearly control the level of sugar in the blood. If the reason is different, you can simply take control of those symptoms that, to one degree or another, lead to autonomic neuropathy:

Gastrointestinal system: medicines that relieve constipation and diarrhea; various exercises that increase mobility; maintaining a certain diet;

Skin: various ointments and creams that help relieve irritation; antihistamines to reduce itching;

Cardiovascular system: increased fluid intake; wearing special underwear; taking medications that control blood pressure.

It can be concluded that the autonomic nervous system regulates the functional activity of almost the entire human body. Therefore, any problems that have arisen in his work should be noticed and studied by you with the help of highly qualified medical professionals. After all, the value of the ANS for a person is enormous - it is thanks to it that he learned to “survive” in stressful situations.