The autonomic nervous system (synonym: autonomic, visceral nervous system) is a department of the nervous system that innervates internal organs, blood vessels, smooth muscles, internal and external secretion and skin, and also participates in the innervation of the apparatus of voluntary movements and sensitivity. The autonomic nervous system is divided into two large divisions - sympathetic and parasympathetic.

The sympathetic spinal centers, from which the peripheral sympathetic fibers originate, are located in the lateral horns of the spinal cord from the VIII cervical to the III lumbar segment. From the clusters of sympathetic cells located here, thin fibers depart, entering the anterior roots and, together with them, leaving the spinal cord (Fig.). Approaching the node () of the sympathetic trunk, these fibers enter it and end in its cells, from which a new peripheral neuron begins, going to the working organ.

autonomic nervous system. Scheme of the structure and connections (red color - sympathetic nerve cells and fibers, blue - parasympathetic).

Sympathetic fibers to the node are called pre-nodal, or preganglionic, and those going from the cells of the node to the periphery are called post-nodal, or postganglionic. The preganglionic fibers are covered with a white myelin sheath and form white connecting branches. Postganglionic fibers emerging from the node do not have a myelin sheath and form gray connecting branches. Sympathetic trunks, located on both sides, consist of 2-3 cervical nodes, 12 thoracic, 2-5 lumbar, 2-5 sacral and one unpaired - coccygeal, which closes the chains of nodes of sympathetic trunks. It should be pointed out that not all preganglionic fibers end in the cells of the nodes of the sympathetic trunk, some of them are not interrupted in the nodes, but go to the periphery to end in one of the prevertebral nodes (celiac plexus, lower mesenteric plexus, etc.). Part of the preganglionic fibers also passes through these nodes without interruption, reaching the working organ, in the walls of which they take a break in the clusters of sympathetic cells located here. Thus, the sympathetic innervation of the internal organs and other apparatuses depends on the reflex activity of systems originating in the lateral horns of the thoracic and lumbar spinal cord.

The sympathetic system dilates the pupil, causes an increase in heart rate and blood pressure, expands the small bronchi, and helps to reduce the sphincters of the bladder and rectum. With an increase in the sympathetic system, there is a tendency to.

Parasympathetic innervation is carried out by nerve cells located in the sacral spinal cord and in the brain stem, the former regulating the activity of organs located in the small pelvis (bladder, and), and the cells of the head section innervate the rest of the organs through the vagus, glossopharyngeal, intermediate and the oculomotor nerves, the autonomic nuclei of which are located in the medulla oblongata, the pons tegmentum (varolii), and the midbrain.

The action of the parasympathetic nervous system is in many respects opposite to the action of the sympathetic system: the parasympathetic system constricts the pupil, slows down cardiac activity, and lowers blood pressure. With an increase in the tone of the parasympathetic nervous system, there is a tendency to spasm of the small bronchi, frequent urination and defecation. The reflex activity of the sympathetic and parasympathetic nervous system, regulating the vital functions of the body, ensures its adaptation to environmental conditions.

Control over the action of these two systems (sympathetic and parasympathetic) is carried out by the central autonomic apparatus located in the hypothalamic region of the brain. The hypothalamic region regulates the following functions: blood pressure, respiration, regulation, various types of metabolism, sleep and wakefulness. In turn, the state of the hypothalamic region depends on the functional activity of certain areas of the cerebral cortex. Diseases of the autonomic nervous system have a different clinical picture depending on the defeat of one or another of its departments. Often found: migraine,.

Rice. 2. Connection of sympathetic fibers with the spinal cord (scheme): 1 - funiculus post.; 2 - sulcus medianus post.; 3 - canalis centralis; 4 - comlssura anterior grisea; 5 - fissura medlana ant.; 6 - funiculus ant.; 7 - cornu ant.; 8-n. spinalis; 9-r. communicans albus (fibrae praeganglionares to ganglion praevertebrale); 10-r. communicans albus (fibrae praeganglionares to ganglion tr. sympathici); 11 - fibrae postganglionares from gangl. tr. sympathetic; 12 and 16 - fibrae postganglionares; 13 - organ (gut); 14 - gangl. praevertebrale; 15-fibrae praeganglionares to gangl. praevertebrale; 17 - gangl. tr. sympatlilci; 18-r. interganglionaris; 19 - afferent fibers (viscerosensory); 20-r. communicans griseus (fibrae postganglionares); 21 and 27 - leather; 22 to 26 - muscles; 23-r. ventralis; - motor fibers of the cells of the anterior horn of the spinal cord; 25-r. dorsalis; 28 - afferent fibers; 29 - gangl. spinal; 30 - radix dorsalis; 31 - radix ventralis; 32 - funiculus lateralis; 33 - cornu post.; 34 - cornu lat. (s. tractus intermediolateralis).

Autonomic nervous system(from lat. vegetatio - excitement, from lat. vegetativus - vegetable), VNS, autonomic nervous system, ganglionic nervous system(from lat. ganglion - nerve node), visceral nervous system (from lat. viscera - insides), organ nervous system, celiac nervous system, systema nervosum autonomicum(PNA) - part of the nervous system of the body, a complex of central and peripheral cellular structures that regulate the functional level of the body, necessary for an adequate response of all its systems.

The autonomic nervous system is a department of the nervous system that regulates the activity of internal organs, endocrine and external secretion glands, blood and lymphatic vessels. It plays a leading role in maintaining the constancy of the internal environment of the body and in the adaptive reactions of all vertebrates.

Anatomically and functionally, the autonomic nervous system is divided into sympathetic, parasympathetic and metasympathetic. Sympathetic and parasympathetic centers are under the control of the cerebral cortex and hypothalamic centers.

In the sympathetic and parasympathetic divisions there are central and peripheral parts. The central part is formed by the bodies of neurons lying in the spinal cord and brain. These clusters of nerve cells are called vegetative nuclei. Fibers extending from the nuclei, autonomic ganglia lying outside the central nervous system, and nerve plexuses in the walls of internal organs form the peripheral part of the autonomic nervous system.

Sympathetic nuclei are located in the spinal cord. The nerve fibers departing from it end outside the spinal cord in the sympathetic ganglions, from which the nerve fibers originate. These fibers are suitable for all organs.

Parasympathetic nuclei lie in the middle and medulla oblongata and in the sacral part of the spinal cord. Nerve fibers from the nuclei of the medulla oblongata are part of the vagus nerves. From the nuclei of the sacral part, the nerve fibers go to the intestines, the excretory organs.

The sympathetic nervous system enhances metabolism, increases the excitability of most tissues, and mobilizes the body's forces for vigorous activity. The parasympathetic system contributes to the restoration of spent energy reserves, regulates the functioning of the body during sleep.

Under the control of the autonomous system are the organs of blood circulation, respiration, digestion, excretion, reproduction, as well as metabolism and growth. In fact, the efferent division of the ANS carries out the nervous regulation of the functions of all organs and tissues, except for the skeletal muscles, which are controlled by the somatic nervous system.

The location of the ganglia and the structure of the pathways

Neurons nuclei of the central part of the autonomic nervous system - the first efferent neurons on the way from the central nervous system (spinal cord and brain) to the innervated organ. The nerve fibers formed by the processes of these neurons are called prenodal (preganglionic) fibers, since they go to the nodes of the peripheral part of the autonomic nervous system and end in synapses on the cells of these nodes. Preganglionic fibers have a myelin sheath, due to which they are distinguished by a whitish color. They leave the brain as part of the roots of the corresponding cranial nerves and the anterior roots of the spinal nerves.

Reflex arc

The structure of the reflex arcs of the vegetative division differs from the structure of the reflex arcs of the somatic part of the nervous system. In the reflex arc of the autonomic part of the nervous system, the efferent link does not consist of one neuron, but of two, one of which is outside the central nervous system. In general, a simple autonomic reflex arc is represented by three neurons.

The first link of the reflex arc is a sensitive neuron, the body of which is located in the spinal nodes and in the sensory nodes of the cranial nerves. The peripheral process of such a neuron, which has a sensitive ending - a receptor, originates in organs and tissues. The central process, as part of the posterior roots of the spinal nerves or sensory roots of the cranial nerves, goes to the corresponding nuclei in the spinal cord or brain.

The second link of the reflex arc is efferent, since it carries impulses from the spinal cord or brain to the working organ. This efferent pathway of the autonomic reflex arc is represented by two neurons. The first of these neurons, the second in a row in a simple autonomic reflex arc, is located in the autonomic nuclei of the CNS. It can be called intercalary, since it is located between the sensitive (afferent) link of the reflex arc and the second (efferent) neuron of the efferent pathway.

The effector neuron is the third neuron of the autonomic reflex arc. The bodies of effector (third) neurons lie in the peripheral nodes of the autonomic nervous system (sympathetic trunk, autonomic nodes of cranial nerves, nodes of extraorganic and intraorganic autonomic plexuses). The processes of these neurons are sent to organs and tissues as part of organ autonomic or mixed nerves. Postganglionic nerve fibers terminate on smooth muscles, glands, and other tissues with corresponding terminal nerve apparatuses.

Physiology

The General Importance of Autonomic Regulation

The autonomic nervous system adapts the work of internal organs to changes in the environment. The ANS provides homeostasis (the constancy of the internal environment of the body). The ANS is also involved in many behavioral acts carried out under the control of the brain, affecting not only the physical, but also the mental activity of a person.

The role of the sympathetic and parasympathetic divisions

The sympathetic nervous system is activated during stress reactions. It is characterized by a generalized influence, while sympathetic fibers innervate the vast majority of organs.

It is known that parasympathetic stimulation of some organs has an inhibitory effect, while others have an excitatory effect. In most cases, the action of the parasympathetic and sympathetic systems is opposite.

Influence of the sympathetic and parasympathetic divisions on individual organs

Influence of the sympathetic department:

Influence of the parasympathetic department:

• On the heart - reduces the frequency and force of contractions of the heart.
• It does not affect the arteries in most organs, it causes the expansion of the arteries of the genital organs and the brain, the narrowing of the coronary arteries and arteries of the lungs.
• On the intestines - enhances intestinal motility and stimulates the production of digestive enzymes.
• On the salivary glands - stimulates salivation.
• On the bladder - contracts the bladder.
• On the bronchi and breathing - narrows the bronchi and bronchioles, reduces ventilation of the lungs.
• On the pupil - narrows the pupils.

Neurotransmitters and cell receptors

The sympathetic and parasympathetic divisions have different, in some cases, opposite effects on various organs and tissues, and also cross influence each other. The different effects of these sections on the same cells are associated with the specifics of the neurotransmitters they secrete and with the specifics of the receptors present on the presynaptic and postsynaptic membranes of the neurons of the autonomous system and their target cells.

Preganglionic neurons of both parts of the autonomic system secrete acetylcholine as the main neurotransmitter, which acts on nicotinic acetylcholine receptors on the postsynaptic membrane of postganglionic (effector) neurons. Postganglionic neurons of the sympathetic division, as a rule, secrete norepinephrine as a mediator, which acts on adrenoreceptors of target cells. On target cells of sympathetic neurons, beta-1 and alpha-1 adrenoreceptors are mainly concentrated on postsynaptic membranes (this means that in vivo they are mainly affected by norepinephrine), and al-2 and beta-2 receptors - on extrasynaptic sections of the membrane (they are mainly affected by blood adrenaline). Only some postganglionic neurons of the sympathetic division (for example, acting on the sweat glands) secrete acetylcholine.

Postganglionic neurons of the parasympathetic division secrete acetylcholine, which acts on muscarinic receptors on target cells.

Two types of adrenergic receptors predominate on the presynaptic membrane of the postganglionic neurons of the sympathetic division: alpha-2 and beta-2 adrenoreceptors. In addition, on the membrane of these neurons there are receptors for purine and pyrimidine nucleotides (ATP P2X receptors, etc.), nicotinic and muscarinic cholinergic receptors, neuropeptide and prostaglandin receptors, and opioid receptors.

When alpha-2 adrenoreceptors are acted upon by norepinephrine or adrenaline in the blood, the intracellular concentration of Ca 2+ ions decreases, and the release of norepinephrine in the synapses is blocked. A negative feedback loop develops. Alpha-2 receptors are more sensitive to norepinephrine than to epinephrine.

Under the action of norepinephrine and epinephrine on beta-2 adrenoceptors, the release of norepinephrine usually increases. This effect is observed during the usual interaction with the Gs-protein, in which the intracellular concentration of cAMP increases. Beta-two receptors are more sensitive to adrenaline. Since adrenaline is released from the adrenal medulla under the action of norepinephrine of the sympathetic nerves, a positive feedback loop is created.

However, in some cases, activation of beta-2 receptors can block the release of norepinephrine. It has been shown that this may be due to the interaction of beta-2 receptors with G i/o proteins and their binding (sequestration) of G s proteins, which, in turn, prevents the interaction of G s proteins with other receptors.

When acetylcholine acts on the muscarinic receptors of sympathetic neurons, the release of norepinephrine in their synapses is blocked, and when it acts on nicotinic receptors, it is stimulated. Since muscarinic receptors predominate on the presynaptic membranes of sympathetic neurons, activation of the parasympathetic nerves normally reduces the release of noradrenaline from the sympathetic nerves.

On the presynaptic membranes of postganglionic neurons of the parasympathetic division, alpha-2 adrenoceptors predominate. Under the action of norepinephrine on them, the release of acetylcholine is blocked. Thus, sympathetic and parasympathetic nerves mutually inhibit each other.

Development in embryogenesis

• Development of the peripheral (somatic) and autonomic nervous system. The peripheral (somatic) and autonomic nervous system develops from the outer germ layer - the ectoderm. The cranial and spinal nerves in the fetus are laid very early (5-6 weeks). Myelination of nerve fibers occurs later (in the vestibular nerve - 4 months; in most nerves - at 6-7 months).

Spinal and peripheral vegetative nodes are laid simultaneously with the development of the spinal cord. The starting material for them is the cellular elements of the ganglion plate, its neuroblasts and glioblasts, from which the cellular elements of the spinal nodes are formed. Some of them are displaced to the periphery to the localization of the autonomic nerve nodes

Comparative anatomy and evolution of the autonomic nervous system

Insects have a so-called sympathetic or stomodal nervous system. It includes the frontal ganglion, which is located in front of the brain and is connected by paired connectives to the tritocerebrum. The unpaired frontal nerve departs from it, stretching along the dorsal side of the pharynx and esophagus. This nerve connects with several nerve ganglia; nerves extending from them innervate the anterior intestine, salivary glands and aorta.

The autonomic nervous system (ANS) is an autonomous part responsible for the functioning of absolutely all internal organs of a person, adequate metabolism, blood circulation and adaptation to constantly changing environmental conditions.

The anatomy of the ANS is quite complex and confusing; to facilitate its study, it is customary to divide it into several departments, first of all, it is necessary to consider the central and peripheral.

The central part is represented by the nuclei of some pairs of cranial nerves, which lie in the thickness of the tissues of the brain and spinal cord. In the midbrain there are centers responsible for the diameter of the pupil, the work of the eye, in the nervous tissue of the medulla oblongata and the sacral segment of the spinal cord there are fibers responsible for the functioning of the gastrointestinal tract, heart, liver and other organs.

A special place in the central section is occupied by the hypothalamus and the limbic structure. The first has three groups of nuclei, is responsible for the work of all endocrine and external secretion glands, regulates the act of breathing, the tone of arteries and veins. The limbic structure is involved in behavioral responses, with the help of it a person is able to make plans, dream and be awake during the day.

The peripheral section consists of autonomic nerves, plexuses, endings, a sympathetic trunk and parasympathetic ganglia. The first three parts bring the electrical impulse to the desired target, that is, to a certain part of the body, organ, and so on. The next two parts are included in two fundamentally different, but very important divisions of the ANS: parasympathetic and sympathetic.

• The parasympathetic autonomic nervous system transmits its impulses through the production of a special mediator - acetylcholine. Consists of long presynaptic and short postsynaptic fibers. It does not innervate the brain, the smooth muscle wall of the blood vessels, with the exception of some organs, the skeletal muscles, and practically all the sense organs. This department is responsible for the secretion of saliva into the oral cavity, a decrease in heart rate and blood pressure indicators, provides bronchospasm, peristalsis of the small and large intestines, and other necessary functions.
• The sympathetic autonomic nervous system consists of sympathetic chains, ganglia, connected by nerve fibers and located on both sides of the spine, as well as the celiac plexus and mesenteric nodes. In the transmission of nerve impulses, adrenal hormones participate: adrenaline and norepinephrine, therefore, it is activated in stressful situations. It mainly enhances the work of internal organs, but there is an exception, which are discussed below.

Functions

The autonomic nervous system regulates the work of almost every cell in the body and normalizes metabolic processes. If we consider the influence of each of the departments, then we can form a whole list of systems that affect the production of certain biologically active substances. The functions of the autonomic system are also divided into two large parts.

With the functioning of the sympathetic part:

1. From the side of the CCC: the heartbeat quickens, the pressure on the walls of the arteries increases due to a decrease in their lumen, the strength and release of blood into the main vessels (aorta and pulmonary artery) increase;
2. On the part of the respiratory system: it increases the frequency of breathing, expands the bronchi, thereby providing increased ventilation of the lungs and greater delivery of oxygen to organ systems, the secretion of the glands of the ciliated epithelium decreases;
3. From the side of the bladder: the ducts and the wall of the bladder itself relaxes;
4. On the part of the digestive system: the peristalsis of the small and large intestines decreases, the tone of the sphincters of the gastrointestinal tract and the secretion of the accessory glands of the stomach increase, the gallbladder itself and its ducts relax;
5. From the glands of external and internal secretion: the production of both enzymes and hormones increases, respectively, the metabolism is accelerated - protein synthesis, energy supply and other vital processes;
6. On the part of the sense organs: it mainly affects the eye, or rather, dilates the pupil, reduces the oculomotor muscles.

When the parasympathetic department is turned on:

1. From the side of the CCC: a decrease in heart rate up to cardiac arrest, the strength of contractions also decreases, the conduction of impulses slows down, atrioventricular blockade may develop, blood pressure drops;
2. On the part of the respiratory system: the tone of the smooth muscle wall of the bronchi increases, bronchospasm is formed, the secretion of glands secreted from goblet cells increases, the respiratory rate becomes less;
3. From the sensory organs: pupil diameter decreases, oculomotor muscles relax;
4. On the part of the digestive system: the peristalsis of the gastrointestinal tract increases, the tone of the sphincters decreases, the production of secretions from the main and parietal glands of the stomach increases, the gallbladder ducts and the organ itself contract;
5. From the glands of external and internal secretion: metabolism decreases, glycogen is synthesized in the liver to a greater extent, the concentration of glucose in the blood falls, the amount of secreted hormones also falls;
6. From the side of the bladder: the wall of the bladder contracts, the sphincter relaxes, which facilitates urination.

Differences from the somatic nervous system

The somatic nervous system (SNS) is arbitrary, that is, controlled by human consciousness. It is responsible for the contraction of striated muscle tissue, that is, mainly for the motor activity of the musculoskeletal system.

Vegetative NS differs sharply in structure and function. With regard to anatomy, the differences mainly relate to the reflex arcs and the place where the nerve fibers originate. The reflex arc itself in both parts consists of three parts: sensitive, intercalary and executive. In most cases, the sensitive link in both types is common, but the executive link has a different localization. In the case of the ANS, it is located outside the central nervous system, that is, in close proximity to the target organ. The arc of the SNS ends in the spinal cord, in its gray matter.

The nerve fibers of the ANS are smaller in diameter, they are not fully covered by the myelin sheath, they have a lower speed of electrical impulse conduction, therefore, a more powerful irritating factor is needed to conduct it. The axons of neurons are short and interrupted in the ganglia. The SNS is the exact opposite: the fibers are larger, all myelinated, the speed is higher, the axons are continuous and longer.

As for neurotransmitters, the biologically active substance of the somatic nervous system is only acetylcholine, which regulates the transmission of all impulses. The autonomic nervous system is very diverse, its mediators are norepinephrine and adrenaline, histamine, acetylcholine, serotonin, adenosine triphosphoric acid and others.

Formation during embryogenesis

The nervous system itself is formed from the ectoderm. In the third week of fetal growth, sympathetic trunks and nodes begin to form from neuroblasts migrating from the neural tube, at the same time they tend to localize future internal organs. Initially, sympathetic nodes are formed in the intestinal wall, then - in the heart tube. All processes end by the end of the seventh week of embryo development. The parasympathetic nervous system initially appears in the facial region from the same neuroblasts detached from the anterior end of the neural tube.

At the same time, the vegetative centers of the spinal cord develop, they originate from sympathoblasts. Here, embryonic development begins from the thoracic to the lumbar segment.

The formation of higher nervous activity begins with the formation of the brain, and this is the second month of embryogenesis.

It is during this period that the limbic system, the hippocampus, the hypothalamus and the cerebral cortex acquire the necessary structure.

Further differentiation of nerve fibers occurs in conjunction with the growth of the internal organs and body of the fetus.

Possible deviations in work

Since people, especially in the modern world, are always subject to stress, the human nervous system ceases to adequately regulate the processes of the body, and the state of health is sharply reduced.

The most common disorders include autonomic dysfunction syndrome, formerly called vegetative-vascular dystonia. Its symptoms can be indigestion, a change in blood pressure up or down, increased ventilation of the lungs due to an increase in respiratory rate, or, conversely, a subjective feeling of lack of air. Behavior changes dramatically, as the autonomic nervous system is responsible for mood, perception of the surrounding world and adaptation.

The patient may become apathetic, suspicious, his behavior and views on certain things will change. The main problem in diagnosis is the similarity of the clinical picture of autonomic dysfunction with other serious pathologies of the gastrointestinal tract, heart, blood vessels, endocrine glands and other organs. Treatment is mainly carried out by a neurologist, psychotherapist and psychiatrist, they build the correct therapy regimen and partly help the patient cope with emotional experiences.

The autonomic (autonomous) nervous system regulates all the internal processes of the body: the functions of internal organs and systems, glands, blood and lymphatic vessels, smooth and partially striated muscles, sensory organs (Fig. 6.1). It provides homeostasis of the body, i.e. the relative dynamic constancy of the internal environment and the stability of its basic physiological functions (blood circulation, respiration, digestion, thermoregulation, metabolism, excretion, reproduction, etc.). In addition, the autonomic nervous system performs an adaptive-trophic function - the regulation of metabolism in relation to environmental conditions.

The term "autonomic nervous system" reflects the control of the involuntary functions of the body. The autonomic nervous system is dependent on the higher centers of the nervous system. There is a close anatomical and functional relationship between the autonomic and somatic parts of the nervous system. Autonomic nerve conductors pass through the cranial and spinal nerves. The main morphological unit of the autonomic nervous system, as well as the somatic one, is the neuron, and the main functional unit is the reflex arc. In the autonomic nervous system, there are central (cells and fibers located in the brain and spinal cord) and peripheral (all its other formations) sections. There are also sympathetic and parasympathetic parts. Their main difference lies in the features of functional innervation and is determined by the attitude to the means that affect the autonomic nervous system. The sympathetic part is excited by adrenaline, and the parasympathetic part by acetylcholine. Ergotamine has an inhibitory effect on the sympathetic part, and atropine on the parasympathetic part.

6.1. Sympathetic division of the autonomic nervous system

Central formations are located in the cerebral cortex, hypothalamic nuclei, brain stem, in the reticular formation, and

Rice. 6.1. Autonomic nervous system (diagram).

1 - cortex of the frontal lobe of the brain; 2 - hypothalamus; 3 - ciliary knot; 4 - pterygopalatine node; 5 - submandibular and sublingual nodes; 6 - ear knot; 7 - upper cervical sympathetic node; 8 - large splanchnic nerve; 9 - internal node; 10 - celiac plexus; 11 - celiac nodes; 12 - small splanchnic nerve; 12a - lower splanchnic nerve; 13 - superior mesenteric plexus; 14 - lower mesenteric plexus; 15 - aortic plexus; 16 - sympathetic fibers to the anterior branches of the lumbar and sacral nerves for the vessels of the legs; 17 - pelvic nerve; 18 - hypogastric plexus; 19 - ciliary muscle; 20 - sphincter of the pupil; 21 - pupil dilator; 22 - lacrimal gland; 23 - glands of the mucous membrane of the nasal cavity; 24 - submandibular gland; 25 - sublingual gland; 26 - parotid gland; 27 - heart; 28 - thyroid gland; 29 - larynx; 30 - muscles of the trachea and bronchi; 31 - lung; 32 - stomach; 33 - liver; 34 - pancreas; 35 - adrenal gland; 36 - spleen; 37 - kidney; 38 - large intestine; 39 - small intestine; 40 - bladder detrusor (muscle that ejects urine); 41 - sphincter of the bladder; 42 - gonads; 43 - genitals; III, XIII, IX, X - cranial nerves

also in the spinal cord (in the lateral horns). The cortical representation is not sufficiently elucidated. From the cells of the lateral horns of the spinal cord at the level from C VIII to L V, peripheral formations of the sympathetic division begin. The axons of these cells pass as part of the anterior roots and, having separated from them, form a connecting branch that approaches the nodes of the sympathetic trunk. This is where part of the fibers ends. From the cells of the nodes of the sympathetic trunk, the axons of the second neurons begin, which again approach the spinal nerves and end in the corresponding segments. The fibers that pass through the nodes of the sympathetic trunk, without interruption, approach the intermediate nodes located between the innervated organ and the spinal cord. From the intermediate nodes, the axons of the second neurons begin, heading to the innervated organs.

The sympathetic trunk is located along the lateral surface of the spine and has 24 pairs of sympathetic nodes: 3 cervical, 12 thoracic, 5 lumbar, 4 sacral. From the axons of the cells of the upper cervical sympathetic ganglion, the sympathetic plexus of the carotid artery is formed, from the lower - the upper cardiac nerve, which forms the sympathetic plexus in the heart. The aorta, lungs, bronchi, abdominal organs are innervated from the thoracic nodes, and the pelvic organs are innervated from the lumbar nodes.

6.2. Parasympathetic division of the autonomic nervous system

Its formations begin from the cerebral cortex, although the cortical representation, as well as the sympathetic part, has not been sufficiently elucidated (mainly it is the limbic-reticular complex). There are mesencephalic and bulbar sections in the brain and sacral - in the spinal cord. The mesencephalic section includes the nuclei of the cranial nerves: the third pair is the accessory nucleus of Yakubovich (paired, small cell), which innervates the muscle that narrows the pupil; Perlia's nucleus (unpaired small cell) innervates the ciliary muscle involved in accommodation. The bulbar section consists of the upper and lower salivary nuclei (VII and IX pairs); X pair - the vegetative nucleus that innervates the heart, bronchi, gastrointestinal tract,

his digestive glands, other internal organs. The sacral section is represented by cells in segments S II -S IV, the axons of which form the pelvic nerve that innervates the urogenital organs and the rectum (Fig. 6.1).

Under the influence of both the sympathetic and parasympathetic divisions of the autonomic nervous system are all organs, with the exception of blood vessels, sweat glands and the adrenal medulla, which have only sympathetic innervation. The parasympathetic department is more ancient. As a result of its activity, stable states of organs and conditions for creating reserves of energy substrates are created. The sympathetic part changes these states (i.e., the functional abilities of organs) in relation to the function being performed. Both parts work in close cooperation. Under certain conditions, the functional predominance of one part over the other is possible. In the case of the predominance of the tone of the parasympathetic part, a state of parasympathotonia develops, the sympathetic part - sympathotonia. Parasympathotonia is characteristic of the state of sleep, sympathotonia is characteristic of affective states (fear, anger, etc.).

In clinical conditions, conditions are possible in which the activity of individual organs or body systems is disrupted as a result of the predominance of the tone of one of the parts of the autonomic nervous system. Parasympathotonic manifestations accompany bronchial asthma, urticaria, angioedema, vasomotor rhinitis, motion sickness; sympathotonic - vasospasm in the form of Raynaud's syndrome, migraine, transient form of hypertension, vascular crises in hypothalamic syndrome, ganglionic lesions, panic attacks. The integration of vegetative and somatic functions is carried out by the cerebral cortex, the hypothalamus and the reticular formation.

6.3. Limbico-reticular complex

All activity of the autonomic nervous system is controlled and regulated by the cortical parts of the nervous system (frontal cortex, parahippocampal and cingulate gyrus). The limbic system is the center of emotion regulation and the neural substrate of long-term memory. The rhythm of sleep and wakefulness is also regulated by the limbic system.

Rice. 6.2. limbic system. 1 - corpus callosum; 2 - vault; 3 - belt; 4 - posterior thalamus; 5 - isthmus of the cingulate gyrus; 6 - III ventricle; 7 - mastoid body; 8 - bridge; 9 - lower longitudinal beam; 10 - border; 11 - gyrus of the hippocampus; 12 - hook; 13 - orbital surface of the frontal pole; 14 - hook-shaped bundle; 15 - transverse connection of the amygdala; 16 - front spike; 17 - anterior thalamus; 18 - cingulate gyrus

The limbic system (Fig. 6.2) is understood as a number of closely interconnected cortical and subcortical structures that have common development and functions. It also includes the formation of the olfactory pathways located at the base of the brain, the transparent septum, the vaulted gyrus, the cortex of the posterior orbital surface of the frontal lobe, the hippocampus, and the dentate gyrus. The subcortical structures of the limbic system include the caudate nucleus, the putamen, the amygdala, the anterior tubercle of the thalamus, the hypothalamus, and the nucleus of the frenulum. The limbic system includes a complex interweaving of ascending and descending pathways, closely associated with the reticular formation.

Irritation of the limbic system leads to the mobilization of both sympathetic and parasympathetic mechanisms, which has corresponding vegetative manifestations. A pronounced vegetative effect occurs when the anterior parts of the limbic system are irritated, in particular the orbital cortex, amygdala and cingulate gyrus. At the same time, there are changes in salivation, respiratory rate, increased intestinal motility, urination, defecation, etc.

Of particular importance in the functioning of the autonomic nervous system is the hypothalamus, which regulates the functions of the sympathetic and parasympathetic systems. In addition, the hypothalamus implements the interaction of nervous and endocrine, the integration of somatic and autonomic activity. The hypothalamus contains specific and nonspecific nuclei. Specific nuclei produce hormones (vasopressin, oxytocin) and releasing factors that regulate the secretion of hormones from the anterior pituitary gland.

6.4. Vegetative innervation of the head

Sympathetic fibers that innervate the face, head and neck originate from cells located in the lateral horns of the spinal cord (C VIII -Th III). Most of the fibers are interrupted in the superior cervical sympathetic ganglion, and a smaller part goes to the external and internal carotid arteries and forms periarterial sympathetic plexuses on them. They are joined by postganglionic fibers coming from the middle and lower cervical sympathetic nodes. In small nodules (cell clusters) located in the periarterial plexuses of the branches of the external carotid artery, fibers terminate that are not interrupted at the nodes of the sympathetic trunk. The remaining fibers are interrupted in the facial ganglia: ciliary, pterygopalatine, sublingual, submandibular and auricular. Postganglionic fibers from these nodes, as well as fibers from the cells of the upper and other cervical sympathetic nodes, go to the tissues of the face and head, partly as part of the cranial nerves (Fig. 6.3).

Afferent sympathetic fibers from the head and neck are sent to the periarterial plexuses of the branches of the common carotid artery, pass through the cervical nodes of the sympathetic trunk, partially contacting their cells, and through the connecting branches come to the spinal nodes, closing the arc of the reflex.

Parasympathetic fibers are formed by axons of the stem parasympathetic nuclei, they are directed mainly to the five autonomic ganglia of the face, in which they are interrupted. A smaller part of the fibers goes to the parasympathetic clusters of cells of the periarterial plexuses, where it is also interrupted, and the postganglionic fibers go as part of the cranial nerves or periarterial plexuses. In the parasympathetic part there are also afferent fibers that go in the vagus nerve system and are sent to the sensory nuclei of the brainstem. The anterior and middle sections of the hypothalamic region through the sympathetic and parasympathetic conductors affect the function of the predominantly ipsilateral salivary glands.

6.5. Autonomic innervation of the eye

sympathetic innervation. Sympathetic neurons are located in the lateral horns of segments C VIII -Th III of the spinal cord. (centrun ciliospinale).

Rice. 6.3. Vegetative innervation of the head.

1 - posterior central nucleus of the oculomotor nerve; 2 - accessory nucleus of the oculomotor nerve (nucleus of Yakubovich-Edinger-Westphal); 3 - oculomotor nerve; 4 - nasociliary branch from the optic nerve; 5 - ciliary knot; 6 - short ciliary nerves; 7 - sphincter of the pupil; 8 - pupil dilator; 9 - ciliary muscle; 10 - internal carotid artery; 11 - carotid plexus; 12 - deep stony nerve; 13 - upper salivary nucleus; 14 - intermediate nerve; 15 - knee assembly; 16 - large stony nerve; 17 - pterygopalatine node; 18 - maxillary nerve (II branch of the trigeminal nerve); 19 - zygomatic nerve; 20 - lacrimal gland; 21 - mucous membranes of the nose and palate; 22 - knee-tympanic nerve; 23 - ear-temporal nerve; 24 - middle meningeal artery; 25 - parotid gland; 26 - ear knot; 27 - small stony nerve; 28 - tympanic plexus; 29 - auditory tube; 30 - single way; 31 - lower salivary nucleus; 32 - drum string; 33 - tympanic nerve; 34 - lingual nerve (from the mandibular nerve - III branch of the trigeminal nerve); 35 - taste fibers to the anterior 2/3 of the tongue; 36 - sublingual gland; 37 - submandibular gland; 38 - submandibular node; 39 - facial artery; 40 - upper cervical sympathetic node; 41 - cells of the lateral horn ThI-ThII; 42 - the lower node of the glossopharyngeal nerve; 43 - sympathetic fibers to the plexuses of the internal carotid and middle meningeal arteries; 44 - innervation of the face and scalp. III, VII, IX - cranial nerves. Green color indicates parasympathetic fibers, red - sympathetic, blue - sensitive

The processes of these neurons, forming preganglionic fibers, exit the spinal cord together with the anterior roots, enter the sympathetic trunk as part of the white connecting branches and, without interruption, pass through the overlying nodes, ending at the cells of the superior cervical sympathetic plexus. The postganglionic fibers of this node accompany the internal carotid artery, braiding its wall, penetrate into the cranial cavity, where they connect with the I branch of the trigeminal nerve, penetrate the orbital cavity and end at the muscle that dilates the pupil (m. dilatator pupillae).

Sympathetic fibers also innervate other structures of the eye: tarsal muscles, which expand the palpebral fissure, the orbital muscle of the eye, as well as some structures of the face - sweat glands of the face, smooth muscles of the face and blood vessels.

parasympathetic innervation. The preganglionic parasympathetic neuron lies in the accessory nucleus of the oculomotor nerve. As part of the latter, it leaves the brain stem and reaches the ciliary ganglion (ganglion ciliare), where it switches to postganglionic cells. From there, part of the fibers goes to the muscle that narrows the pupil (m. sphincter pupillae), and the other part is involved in providing accommodation.

Violation of the autonomic innervation of the eye. The defeat of sympathetic formations causes the Bernard-Horner syndrome (Fig. 6.4) with pupil constriction (miosis), narrowing of the palpebral fissure (ptosis), retraction of the eyeball (enophthalmos). It is also possible to develop homolateral anhidrosis, conjunctival hyperemia, depigmentation of the iris.

The development of the Bernard-Horner syndrome is possible with the localization of the lesion at a different level - the involvement of the posterior longitudinal bundle, the paths to the muscle that dilates the pupil. The congenital variant of the syndrome is more often associated with birth trauma with damage to the brachial plexus.

When the sympathetic fibers are irritated, a syndrome occurs that is the opposite of the Bernard-Horner syndrome (Pourfour du Petit) - expansion of the palpebral fissure and pupil (mydriasis), exophthalmos.

6.6. Vegetative innervation of the bladder

The regulation of the activity of the bladder is carried out by the sympathetic and parasympathetic divisions of the autonomic nervous system (Fig. 6.5) and includes retention of urine and emptying of the bladder. Normally, retention mechanisms are more activated, which

Rice. 6.4. Right-sided Bernard-Horner syndrome. Ptosis, miosis, enophthalmos

is carried out as a result of activation of sympathetic innervation and blockade of the parasympathetic signal at the level of segments L I -L II of the spinal cord, while detrusor activity is suppressed and the tone of the muscles of the internal sphincter of the bladder increases.

Regulation of the act of urination occurs when activated

parasympathetic center at the level of S II -S IV and the center of urination in the bridge of the brain (Fig. 6.6). Descending efferent signals send signals that provide relaxation of the external sphincter, suppress sympathetic activity, remove the block of conduction along parasympathetic fibers, and stimulate the parasympathetic center. This results in contraction of the detrusor and relaxation of the sphincters. This mechanism is under the control of the cerebral cortex; the reticular formation, the limbic system, and the frontal lobes of the cerebral hemispheres take part in the regulation.

Arbitrary stop of urination occurs when a command is received from the cerebral cortex to the centers of urination in the brain stem and sacral spinal cord, which leads to a contraction of the external and internal sphincters of the pelvic floor muscles and periurethral striated muscles.

The defeat of the parasympathetic centers of the sacral region, the autonomic nerves emanating from it, is accompanied by the development of urinary retention. It can also occur when the spinal cord is damaged (trauma, tumor, etc.) at a level above the sympathetic centers (Th XI -L II). Partial damage to the spinal cord above the level of the location of the autonomic centers can lead to the development of an imperative urge to urinate. When the spinal sympathetic center (Th XI - L II) is affected, true urinary incontinence occurs.

Research methodology. There are numerous clinical and laboratory methods for studying the autonomic nervous system, their choice is determined by the task and conditions of the study. However, in all cases, it is necessary to take into account the initial vegetative tone and the level of fluctuations relative to the background value. The higher the baseline, the lower will be the response in functional tests. In some cases, even a paradoxical reaction is possible. Beam study

Rice. 6.5. Central and peripheral innervation of the bladder.

1 - cerebral cortex; 2 - fibers that provide arbitrary control over the emptying of the bladder; 3 - fibers of pain and temperature sensitivity; 4 - cross section of the spinal cord (Th IX -L II for sensory fibers, Th XI -L II for motor); 5 - sympathetic chain (Th XI -L II); 6 - sympathetic chain (Th IX -L II); 7 - cross section of the spinal cord (segments S II -S IV); 8 - sacral (unpaired) node; 9 - genital plexus; 10 - pelvic splanchnic nerves;

11 - hypogastric nerve; 12 - lower hypogastric plexus; 13 - sexual nerve; 14 - external sphincter of the bladder; 15 - bladder detrusor; 16 - internal sphincter of the bladder

Rice. 6.6. Regulation of the act of urination

it is better to carry out in the morning on an empty stomach or 2 hours after eating, at the same time, at least 3 times. The minimum value of the received data is taken as the initial value.

The main clinical manifestations of the predominance of the sympathetic and parasympathetic systems are presented in Table. 6.1.

To assess the autonomic tone, it is possible to conduct tests with exposure to pharmacological agents or physical factors. As pharmacological agents, solutions of adrenaline, insulin, mezaton, pilocarpine, atropine, histamine, etc. are used.

Cold test. In the supine position, the heart rate is calculated and blood pressure is measured. After that, the other hand is dipped in cold water (4 °C) for 1 min, then the hand is taken out of the water and the blood pressure and pulse are recorded every minute until they return to the initial level. Normally, this happens after 2-3 minutes. With an increase in blood pressure by more than 20 mm Hg. Art. the reaction is considered pronounced sympathetic, less than 10 mm Hg. Art. - moderate sympathetic, and with a decrease in blood pressure - parasympathetic.

Oculocardial reflex (Dagnini-Ashner). When pressing on the eyeballs in healthy people, the heart rate slows down by 6-12 per minute. If the number of heart rate decreases by 12-16 per minute, this is regarded as a sharp increase in the tone of the parasympathetic part. The absence of a decrease or increase in heart rate by 2-4 per minute indicates an increase in the excitability of the sympathetic department.

solar reflex. The patient lies on his back, and the examiner presses his hand on the upper abdomen until a pulsation of the abdominal aorta is felt. After 20-30 seconds, the heart rate slows down in healthy people by 4-12 per minute. Changes in cardiac activity are assessed in the same way as when evoking an oculocardial reflex.

orthoclinostatic reflex. In a patient lying on his back, the heart rate is calculated, and then they are asked to stand up quickly (orthostatic test). When moving from a horizontal to a vertical position, the heart rate increases by 12 per minute with an increase in blood pressure by 20 mm Hg. Art. When the patient moves to a horizontal position, the pulse and blood pressure return

Table 6.1. Clinical characteristics of the functional state of the autonomic nervous system

Continuation of table 6.1.

are reduced to the initial values ​​within 3 minutes (clinostatic test). The degree of pulse acceleration during an orthostatic test is an indicator of the excitability of the sympathetic division of the autonomic nervous system. A significant slowing of the pulse during the clinostatic test indicates an increase in the excitability of the parasympathetic department.

Adrenaline test. In a healthy person, subcutaneous injection of 1 ml of a 0.1% solution of adrenaline after 10 minutes causes blanching of the skin, increased blood pressure, increased heart rate and increased blood glucose levels. If such changes occur faster and are more pronounced, then the tone of sympathetic innervation is increased.

Skin test with adrenaline. A drop of 0.1% adrenaline solution is applied to the skin injection site with a needle. In a healthy person, blanching with a pink corolla around occurs in such an area.

Atropine test. Subcutaneous injection of 1 ml of a 0.1% solution of atropine in a healthy person causes dry mouth, decreased sweating, increased heart rate and dilated pupils. With an increase in the tone of the parasympathetic part, all reactions to the introduction of atropine are weakened, so the test can be one of the indicators of the state of the parasympathetic part.

To assess the state of the functions of segmental vegetative formations, the following tests can be used.

Dermographism. Mechanical irritation is applied to the skin (with the handle of a hammer, with the blunt end of a pin). The local reaction occurs as an axon reflex. At the site of irritation, a red band appears, the width of which depends on the state of the autonomic nervous system. With an increase in sympathetic tone, the band is white (white dermographism). Wide stripes of red dermographism, a stripe rising above the skin (sublime dermographism), indicate an increase in the tone of the parasympathetic nervous system.

For topical diagnosis, reflex dermographism is used, which is irritated with a sharp object (swiped across the skin with the tip of a needle). There is a strip with uneven scalloped edges. Reflex dermographism is a spinal reflex. It disappears in the corresponding zones of innervation when the posterior roots, segments of the spinal cord, anterior roots and spinal nerves are affected at the level of the lesion, but remains above and below the affected zone.

Pupillary reflexes. Determine the direct and friendly reaction of the pupils to light, the reaction to convergence, accommodation and pain (dilation of the pupils with a prick, pinch and other irritations of any part of the body).

Pilomotor reflex caused by a pinch or by applying a cold object (a test tube with cold water) or a coolant (a cotton wool moistened with ether) to the skin of the shoulder girdle or the back of the head. On the same half of the chest, "goosebumps" appear as a result of contraction of smooth hair muscles. The arc of the reflex closes in the lateral horns of the spinal cord, passes through the anterior roots and the sympathetic trunk.

Test with acetylsalicylic acid. After taking 1 g of acetylsalicylic acid, diffuse sweating appears. With the defeat of the hypothalamic region, its asymmetry is possible. With damage to the lateral horns or anterior roots of the spinal cord, sweating is disturbed in the zone of innervation of the affected segments. With damage to the diameter of the spinal cord, taking acetylsalicylic acid causes sweating only above the site of the lesion.

Trial with pilocarpine. The patient is injected subcutaneously with 1 ml of a 1% solution of pilocarpine hydrochloride. As a result of irritation of the postganglionic fibers going to the sweat glands, sweating increases.

It should be borne in mind that pilocarpine excites peripheral M-cholinergic receptors, which cause an increase in the secretion of the digestive and bronchial glands, constriction of the pupils, an increase in the tone of the smooth muscles of the bronchi, intestines, gall and bladder, uterus, but pilocarpine has the strongest effect on sweating. With damage to the lateral horns of the spinal cord or its anterior roots in the corresponding area of ​​the skin, after taking acetylsalicylic acid, sweating does not occur, and the introduction of pilocarpine causes sweating, since the postganglionic fibers that respond to this drug remain intact.

Light bath. Warming the patient causes sweating. This is a spinal reflex similar to the pilomotor reflex. The defeat of the sympathetic trunk completely eliminates sweating after the use of pilocarpine, acetylsalicylic acid and warming the body.

Skin thermometry. Skin temperature is examined using electrothermometers. Skin temperature reflects the state of skin blood supply, which is an important indicator of autonomic innervation. Areas of hyper-, normo- and hypothermia are determined. The difference in skin temperature of 0.5 °C in symmetrical areas indicates a violation of autonomic innervation.

Electroencephalography is used to study the autonomic nervous system. The method makes it possible to judge the functional state of the synchronizing and desynchronizing systems of the brain during the transition from wakefulness to sleep.

There is a close relationship between the autonomic nervous system and the emotional state of a person, therefore, the psychological status of the subject is studied. To do this, use special sets of psychological tests, the method of experimental psychological testing.

6.7. Clinical manifestations of lesions of the autonomic nervous system

With dysfunction of the autonomic nervous system, various disorders occur. Violations of its regulatory functions are periodic and paroxysmal. Most pathological processes do not lead to the loss of certain functions, but to irritation, i.e. to increased excitability of central and peripheral structures. On the-

disruption in some parts of the autonomic nervous system can spread to others (repercussion). The nature and severity of symptoms are largely determined by the level of damage to the autonomic nervous system.

Damage to the cerebral cortex, especially the limbic-reticular complex, can lead to the development of vegetative, trophic, and emotional disorders. They can be caused by infectious diseases, injuries of the nervous system, intoxication. Patients become irritable, quick-tempered, quickly exhausted, they have hyperhidrosis, instability of vascular reactions, fluctuations in blood pressure, pulse. Irritation of the limbic system leads to the development of paroxysms of pronounced vegetative-visceral disorders (cardiac, gastrointestinal, etc.). Psychovegetative disorders are observed, including emotional disorders (anxiety, anxiety, depression, asthenia) and generalized autonomic reactions.

If the hypothalamic region is affected (Fig. 6.7) (tumor, inflammatory processes, circulatory disorders, intoxication, trauma), vegetative-trophic disorders may occur: sleep and wakefulness rhythm disturbances, thermoregulation disorder (hyper- and hypothermia), ulceration in the gastric mucosa, lower part of the esophagus, acute perforation of the esophagus, duodenum and stomach, as well as endocrine disorders: diabetes insipidus, adiposogenital obesity, impotence.

Damage to the vegetative formations of the spinal cord with segmental disorders and disorders localized below the level of the pathological process

Patients may have vasomotor disorders (hypotension), sweating disorders and pelvic functions. With segmental disorders, trophic changes are noted in the relevant areas: increased dryness of the skin, local hypertrichosis or local hair loss, trophic ulcers and osteoarthropathy.

With the defeat of the nodes of the sympathetic trunk, similar clinical manifestations occur, especially pronounced with the involvement of the cervical nodes. There is a violation of sweating and a disorder of pilomotor reactions, hyperemia and an increase in the temperature of the skin of the face and neck; due to a decrease in the tone of the muscles of the larynx, hoarseness of the voice and even complete aphonia may occur; Bernard-Horner syndrome.

Rice. 6.7. Areas of damage to the hypothalamus (scheme).

1 - damage to the lateral zone (increased drowsiness, chills, increased pilomotor reflexes, pupillary constriction, hypothermia, low blood pressure); 2 - damage to the central zone (violation of thermoregulation, hyperthermia); 3 - damage to the supraoptic nucleus (impaired secretion of antidiuretic hormone, diabetes insipidus); 4 - damage to the central nuclei (pulmonary edema and erosion of the stomach); 5 - damage to the paraventricular nucleus (adipsia); 6 - damage to the anteromedial zone (increased appetite and impaired behavioral responses)

The defeat of the peripheral parts of the autonomic nervous system is accompanied by a number of characteristic symptoms. Most often there is a kind of pain syndrome - sympathalgia. The pains are burning, pressing, bursting, tend to gradually spread beyond the area of ​​primary localization. Pain is provoked and aggravated by changes in barometric pressure and ambient temperature. Changes in the color of the skin due to spasm or expansion of peripheral vessels are possible: blanching, redness or cyanosis, changes in sweating and skin temperature.

Autonomic disorders can occur with damage to the cranial nerves (especially the trigeminal), as well as the median, sciatic, etc. The defeat of the autonomic ganglia of the face and oral cavity causes burning pain in the area of ​​innervation related to this ganglion, paroxysm, hyperemia, increased sweating, in case lesions of the submandibular and sublingual nodes - an increase in salivation.

The autonomic nervous system is a part of the nervous system that innervates the internal organs and blood vessels, that is, organs in which there are smooth muscle elements and glandular epithelium. The state of the autonomic nervous system directly affects the metabolism in organs. The autonomic part of the nervous system got its name from the Latin name "vegetatio" - excitation or "vegeto" - to revitalize, strengthen, animate. Sometimes the name vegetative is translated as vegetable.

For the first time in 1880, this term was used by Bisha. He divided all organs into vegetable and animal. The organs of plant life perform the functions inherent in all living things, including plants: respiration, nutrition, growth, excretion, reproduction. Animal organs, according to Bish, are organs that provide the function of movement in space. These include: the musculoskeletal system, from which the muscles provide active movement.

Vegetative organs act involuntarily, automatically and without rest. Animal organs act voluntarily and require rest.

For the first time, the autonomic nervous system was called autonomous by the English physiologist Langley at the end of the 19th century. He separated it completely from the nervous system. This opinion was wrong. This system does not have absolute autonomy and is under the control of the central nervous system. A major role in the further development of knowledge about the autonomic nervous system was made by domestic scientists, especially neurohistologists, who, using the method of selective staining of nerve elements with methylene blue, obtained a lot of new data on the structure of individual links of the autonomic nervous system. Of particular importance are the works of Lavrentiev, Kolosov, Ivanov I.F., Dolgo-Saburov, Melman, and others.

The isolation of the autonomic (autonomous) nervous system is due to some features of its structure.

focal localization of autonomic nuclei in the central nervous system;

accumulation of bodies of effective neurons in the peripheral nervous system in the form of autonomic ganglia and autonomic plexuses;

the two-neuronality of the efferent link of the autonomic reflex arc, that is, there are at least two neurons along the path from the autonomic nucleus to the working organ.

The autonomic nervous system acts on the organs in two ways: either enhances the function of the organs or weakens their work. Since the same nerve fiber cannot conduct impulses of the opposite action, the autonomic nervous system is divided into sympathetic and parasympathetic parts.

The sympathetic part of the autonomic nervous system mainly enhances the functions of internal organs, performs a trophic function, enhances metabolic processes in cells, increases the secretion of glands, and increases the rhythm of heart contractions.

A playful teenager in the forest stumbled upon a hollow in an old willow, around which wasps hovered. Not being a humanist, our hero covered up with a cobblestone just below the hornet's nest, and the rotten tree hummed. Blinded by rage, the wasps rushed after the offender, and he drapes, hoping to avoid punishment for his trick. At the same time, some changes occur in his body: breathing is frequent and shallow, the heart rate is increased, the pressure is increased, the intestines, kidneys and bladder sharply reduce their function (you can’t really cope with the need on the run), your mouth is dry, the pupils are wide (the eyes of fear are large), the skin is pale, covered with sweat. So, running from a swarm of wasps is like the action of the sympathetic nervous system.

The parasympathetic part of the autonomic nervous system performs protective functions - it slows down the heart rate, constricts the pupil, enhances the motility of the gastrointestinal tract, contributing to a faster removal of contents from it, empties the hollow organs, i.e. its action is diametrically opposed. We will show this with the following example: a young girl, a pupil of the pre-revolutionary Smolny Institute for Noble Maidens, after reading a couple of chapters of a love story, lowered her head on the pillow. She had a sublimely restless feeling in her soul, and she fell asleep with a smile on her lips. Her breathing became deep, her heart beat slower, her blood pressure dropped, her gastrointestinal tract and urinary system became active (morning toilet). So, deep healthy sleep is similar to the parasympathetic nervous system.

There are organs that are innervated only by the sympathetic part of the autonomic nervous system - sweat glands, smooth muscles of the skin, adrenal glands.

Although the sympathetic and parasympathetic parts of the autonomic nervous system are antagonists, at the same time they act as synergists. And only the state of the organ depends on the predominance of some part. As throughout the nervous system, the autonomic nervous system has central and peripheral divisions.

The central division of the autonomic nervous system includes autonomic nuclei lying in the gray matter of the brain and spinal cord and autonomic centers.

The peripheral part of the autonomic nervous system includes nerves (preganglionic and postganglionic nerve fibers), autonomic ganglia and autonomic plexuses - periorganic and intraorganic.

Vegetative nuclei (foci) - accumulations of bodies of vegetative neurocytes. There are 4 autonomic nuclei, three of them are parasympathetic, and one is sympathetic.

parasympathetic nuclei.

Mesencephalic nuclei (medium) are a group of small visceral-type neurocytes located under the aqueduct of the brain. Yakubovich's nuclei or additional nuclei are located on the sides, and the Darkshevich's nucleus is located in the midline.

Bulbar nuclei - these include: a) the superior spinal nucleus, 7 pairs of cranial nerves located in the bridge dorsal to the nucleus of the facial nerve; b) the lower salivary nucleus - (9 pairs) lies in the medulla oblongata between the double nucleus and the nucleus of the olive and the posterior nucleus of the vagus nerve, which lies in the medulla oblongata in the triangle of the same name.

The sacral nucleus - the nuclei of the gray matter of the spinal cord (2-4 sacral segments) is a group of small elongated nerve cells of the lateral **** nucleus.

Sympathetic nuclei .

The thoracolumbar nucleus or thoracolumbar nucleus is an accumulation of nerve cells in the lateral horns of the gray matter of the spinal cord from the 8th cervical to the 2nd lumbar segment inclusive.

The nuclei are dominated by vegetative centers, which are not divided into sympathetic and parasympathetic, but are common, that is, depending on the signal coming from the periphery, they can excite either sympathetic or parasympathetic nuclei.

Vegetative centers are located in different parts of the brain. in the medulla oblongata - these are the vasomotor and respiratory centers, in the hindbrain - the cerebellar cortex, in the midbrain - this is the gray matter of the bottom of the Sylvian aqueduct, in the diencephalon - the nuclei of the hypothalamus, especially the mastoid bodies and the gray tubercle, and in the final brain - the basal nuclei especially the striatum.

Peripheral part of the autonomic nervous system

Autonomic nerves- are processes of nerve cells lying in the central parts of the autonomic nervous system, in the nuclei. Upon exiting the brain and spinal cord, these processes (axons) are sent to the organs either as part of other nerves or in the form of independently formed and visible nerve trunks. On the way from the center to the organ, the fibers of the autonomic nerves are necessarily interrupted in the autonomic nodes. This is the main difference between autonomic nerves and somatic.

The part of the autonomic nerve that carries the nerve impulse from the center to the node is called the prenodal (preganglionic) part.

The part of the autonomic nerve that carries the impulse from the node and transmits it to the working organ is called post-nodal or postganglionic.

Autonomic ganglions- their shape is diverse: rounded, oval, star-shaped, lamellar. The size of the nodes varies widely. Large nerve nodes have a well-defined connective tissue sheath. A large number of vegetative nodes lie on both sides of the spinal column, stretching in the form of a chain, and form the dorsal trunks. They are called paravertebral nodes.

Both sympathetic trunks stretch from the base of the skull to the coccyx and consist of separate sympathetic nodes connected by internodal branches. These nodes are connected to the spinal cord by myelinated fibers. These fibers are preganglionic and are called white connecting branches.

Postganglionic fibers extend from the sympathetic ganglia and connect the sympathetic trunk to the spinal nerves. They are fleshless and are called gray connecting branches. Each sympathetic trunk is divided into 4 sections:

Neck - contains 3 knots

Thoracic - 10-12 knots

Lumbar - 3-5 knots

Sacral - 3-4 knots.

In the region of the coccyx, both sympathetic trunks are connected into one node. Postganglionic fibers from the sympathetic trunk go to the blood vessels, smooth muscles of the skin, to the glands, to the striated muscles, forming a trophic.

In addition to macroscopically identified nodes along the course of the nerves, there are small groups of autonomic nerve cells - microganglia. There are vegetative nodes lying directly at the wall - near-organ or inside the wall - intramural.

Any autonomic node is a cluster of neurons of the autonomic nervous system. With the help of these neurons, the node creates a certain color of nerve impulses and forms a wide variety of reaction states of those organs that it innervates.

In addition to nerve cells, vegetative nodes contain three types of nerve fibers: preganglionic, postganglionic, and centripetal nerve fibers that travel from organs through the vegetative node to the central nervous system. Preganglionic fibers, having entered the nerve ganglion, divide many times. They lose myelin and form numerous plexuses. From these plexuses depart thin threads that are closely adjacent to the dendrites of nerve cells. They are laid in the form of rings, loops, plates and are synapses of the central neuron of the autonomic nervous system with the neurocyte of this node.

Some of the fibers pass in transit, forming internodal connecting branches. In addition to the nodes of the sympathetic trunks, the head nodes (parasympathetic) are well-known: the ciliary node is in the orbit, the pterygo-palatine node is in the same-named fossa of the skull, the submandibular node lies at the edge of the medial pterygoid muscle, the ear node is located under the oval opening of the skull on medial side of the submandibular nerve.

Autonomic plexuses are formed by the terminal branches of the branches of the sympathetic trunk and branches of the vagus nerve. They also contain afferent fibers.