Vegetative nervous system plays no less important role in the functioning of the human body than the central one. Its various departments control the acceleration of metabolism, the renewal of energy reserves, the control of the processes of blood circulation, respiration, digestion and more. Knowledge of what is needed for, what it consists of and how the autonomic nervous system of a person works, for a personal trainer are necessary condition his professional development.
The autonomic nervous system (it is also autonomous, visceral and ganglionic) is part of the entire nervous system of the human body and is a kind of aggregator of central and peripheral nervous formations that are responsible for regulating the functional activity of the body, which is necessary for the appropriate response of its systems to various stimuli. She monitors the work of internal organs, glands of internal and external secretion, as well as blood and lymph vessels. Plays an important role in maintaining homeostasis and an adequate course of adaptation processes of the body.
The work of the autonomic nervous system is in fact not controlled by humans. This suggests that a person is not able, through any effort, to influence the work of the heart or organs. digestive tract... Nevertheless, it is still possible to achieve a conscious influence on many parameters and processes that are controlled by the VNS, in the process of going through a complex of physiological, preventive and treatment procedures using computer technology.
The structure of the autonomic nervous system
Both in structure and in function, the autonomic nervous system is divided into sympathetic, parasympathetic and metasympathetic. The sympathetic and parasympathetic center controls the cerebral cortex and hypothalamic centers. Both the first and second sections have a central and peripheral part. The central part is formed from the bodies of neurons that are located in the brain and spinal cord. Such formations nerve cells are called vegetative nuclei. The fibers that extend from the nuclei, the autonomic ganglia that lie outside the central nervous system, and the nerve plexuses inside the walls of the internal organs form the peripheral part of the autonomic nervous system.
- The sympathetic nuclei are found in the spinal cord. The nerve fibers that branch off from it end outside the spinal cord in sympathetic nodes, and already from them nerve fibers originate that go to the organs.
- The parasympathetic nuclei are located in the midbrain and medulla oblongata, as well as in the sacral part of the spinal cord. Nerve fibers of the nuclei of the medulla oblongata are present in the vagus nerves. The nuclei of the sacral part lead nerve fibers to the intestines and excretory organs.
The metasympathetic nervous system consists of nerve plexuses and small ganglia within the walls of the digestive tract, and Bladder, heart and other organs.
The structure of the autonomic nervous system: 1- Brain; 2- Nerve fibers to the meninges; 3- Pituitary gland; 4- Cerebellum; 5- The medulla oblongata; 6, 7- Parasympathetic fibers of the eyes of the motor and facial nerves; 8- Star knot; 9- Border post; 10- Spinal nerves; 11- Eyes; 12- Salivary glands; 13- Blood vessels; fourteen- Thyroid; 15- Heart; 16- Lungs; 17- Stomach; 18- Liver; 19- Pancreas; 20- Adrenal glands; 21- Small intestine; 22- Colon; 23- Kidneys; 24- Bladder; 25- Genitals.
I- Cervical; II- Chest; III- Lumbar region; IV- Sacrum; V- tailbone; VI- Vagus nerve; VII- Solar plexus; VIII- Superior mesenteric node; IX- Inferior mesenteric node; X- Parasympathetic nodes of the hypogastric plexus.
The sympathetic nervous system speeds up the metabolism, increases the stimulation of many tissues, activates the body's forces for physical activity... The parasympathetic nervous system promotes the regeneration of wasted energy reserves, and also controls the body during sleep. The autonomic nervous system controls the organs of blood circulation, respiration, digestion, excretion, reproduction, and among other things, metabolism and growth processes. By and large, the efferent division of the ANS controls nervous regulation the work of all organs and tissues with the exception of skeletal muscles, which are controlled by the somatic nervous system.
Morphology of the autonomic nervous system
The isolation of the ANS is associated with the characteristic features of its structure. These features usually include: localization of the presence of autonomic nuclei in the central nervous system; the accumulation of bodies of effector neurons in the form of nodes in the composition of the autonomic plexus; two-neurality nervous path from the vegetative nucleus in the central nervous system to the target organ.
Spinal cord structure: 1- Spine; 2- Spinal cord; 3- Articular process; 4- Transverse process; 5- Spinous process; 6- Place of attachment of the rib; 7- Vertebral body; eight- Intervertebral disc; 9- Spinal nerve; 10- Central canal of the spinal cord; 11- Vertebral ganglion; 12- Soft shell; 13- Arachnoid; 14- Hard shell.
The fibers of the autonomic nervous system do not branch out in segments, as, for example, in the somatic nervous system, but from three distant localized sections of the spinal cord - the cranial sterno-lumbar and sacral. As for the previously mentioned divisions of the autonomic nervous system, in the sympathetic part of it, the processes of the spinal neurons are short, and the ganglionic ones are long. V parasympathetic system the opposite is true. The processes of the spinal neurons are longer, and the ganglionic ones are shorter. It is worth noting here that sympathetic fibers innervate all organs without exception, while the local innervation of parasympathetic fibers is largely limited.
Departments of the autonomic nervous system
According to the topographic feature, the ANS is divided into central and peripheral sections.
- Central department. It is represented by parasympathetic nuclei of 3, 7, 9 and 10 pairs of cranial nerves that run in the brain stem (craniobulbar region) and nuclei located in the gray matter of three sacral segments (sacral region). The sympathetic nuclei are located in the lateral horns of the thoracolumbar spinal cord.
- Peripheral department. Submitted by autonomic nerves, branches and nerve fibers emerging from the brain and spinal cord. This also includes the autonomic plexus, the nodes of the autonomic plexus, the sympathetic trunk (right and left) with its nodes, inter-nodal and connecting branches and sympathetic nerves. As well as the terminal nodes of the parasympathetic part of the autonomic nervous system.
Functions of the autonomic nervous system
The main function of the autonomic nervous system is to provide an adequate adaptive response of the body to various stimuli. VNS provides constancy control internal environment, and also takes part in multiple responses under the control of the brain, and these responses can be both physiological and mental character... As for the sympathetic nervous system, it is activated when stress reactions occur. It is characterized by a global effect on the body, while sympathetic fibers innervate most of the organs. It is also known that parasympathetic stimulation of some organs leads to an inhibitory response, while other organs, on the contrary, to an exciting one. In the vast majority of cases, the action of the sympathetic and parasympathetic nervous systems is opposite.
The vegetative centers of the sympathetic division are located in the thoracic and lumbar of the spinal cord, the centers of the parasympathetic section - in the brainstem (eyes, glands and organs innervated by the vagus nerve), as well as in the sacral section of the spinal cord (bladder, lower colon and genitals). Preganglionic fibers of the first and second divisions of the autonomic nervous system run from the centers to the ganglia, where they end in postganglionic neurons.
Preganglionic sympathetic neurons originate in the spinal cord and end either in the paravertebral ganglion chain (in the cervical or abdominal ganglion) or in the so-called terminal ganglia. The transmission of stimulus from preganglionic neurons to postganglionic neurons is cholinergic, that is, it is mediated by the release of the neurotransmitter acetylcholine. Stimulation by postganglionic sympathetic fibers of all effector organs, with the exception of the sweat glands, is adrenergic, that is, it is mediated by the release of norepinephrine.
Now let's look at the effect of the sympathetic and parasympathetic divisions on specific internal organs.
- Impact of the sympathetic division: on the pupils - has a dilating effect. On the arteries - has an expanding effect. On salivary glands- inhibits salivation. On the heart - increases the frequency and strength of its contractions. On the bladder - has a relaxing effect. On the intestines - inhibits peristalsis and the production of enzymes. On the bronchi and breathing - expands the lungs, improves their ventilation.
- The impact of the parasympathetic department: on the pupils - has a constricting effect. It does not affect the arteries in most organs, it causes an expansion of the arteries of the genital organs and the brain, as well as a narrowing of the coronary arteries and arteries of the lungs. On the salivary glands - stimulates salivation. On the heart, it reduces the strength and frequency of its contractions. On the bladder - contributes to its contraction. On the intestines - enhances its peristalsis and stimulates the production of digestive enzymes. On the bronchi and breathing - narrows the bronchi, reduces ventilation of the lungs.
Basic reflexes often run inside specific body(for example, in the stomach), but more complex (complex) reflexes pass through the controlling autonomic centers in the central nervous system, mainly in the spinal cord. These centers are controlled by the hypothalamus, the activity of which is associated with the autonomic nervous system. The cerebral cortex is the most highly organized nerve center that connects the ANS with other systems.
Conclusion
The autonomic nervous system, through its subordinate structures, sets in motion a number of simple and complex reflexes. Some fibers (afferent) conduct stimuli from the skin and pain receptors in organs such as the lungs, gastrointestinal tract, gall bladder, vascular system and genitals. Other fibers (efferent) conduct a reflex response to afferent signals, realizing smooth muscle contractions in organs such as the eyes, lungs, digestive tract, gallbladder, heart, and glands. Knowledge about the autonomic nervous system as one of the elements of the integral nervous system of the human body is an integral part of the theoretical minimum that a personal trainer should have.
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 internal organs is ensured by the nervous system. In addition, the nervous system carries out a connection between external environment and the regulatory body responding to external stimuli with appropriate responses.
The perception of changes in the external and internal environment occurs through the nerve endings - receptors.
Any irritation (mechanical, light, sound, chemical, electrical, temperature) perceived by the receptor is transformed (transformed) into a 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 directed along the fibers of centrifugal neurons (motor) to the executive organs that implement the response - the corresponding adaptive act.
This is how a reflex occurs (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 stimulation of the receptors.
Reflex reactions are diverse: constriction of the pupil in bright light, salivation when food enters the oral cavity, etc.
The path along which nerve impulses (excitation) pass from the receptors to the executive organ during the implementation of any reflex is called a reflex arc.
Arcs of reflexes are closed in the segmental apparatus of the spinal cord and brainstem, but they can be closed even higher, for example, in the subcortical ganglia or in the cortex.
In view of the above, they are distinguished:
- the central nervous system (brain and spinal cord) and
- the peripheral nervous system, represented by nerves extending from the brain and spinal cord and other elements lying outside the spinal cord and brain.
The peripheral nervous system is subdivided into somatic (animal) and autonomic (or autonomous).
- the somatic nervous system carries out mainly the connection of the body with the external environment: the perception of stimuli, regulation of the movements of the striated muscles of the skeleton, etc.
- vegetative - regulates metabolism and the work 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 middle 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 composed of gray and white matter.
The 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, the gray matter is located along its surface, forming the cortex (cloak) and separate clusters, called the nuclei, concentrated in the white matter.
The white matter is underneath the gray and is composed of sheathed nerve fibers. Nerve fibers, connecting, compose nerve bundles, and several of these bundles form separate 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, lining inner cavity skull and spinal canal.
- The arachnoid is located under the hard - it is a thin shell with a small number of nerves and blood vessels.
- The choroid is fused to the brain, extends into the grooves, and contains many blood vessels.
Cavities filled with cerebral fluid are formed between the choroid and arachnoid membranes.
Spinal cord is located in the spinal canal and looks like a white cord extending from the occipital foramen to the lumbar region. Longitudinal grooves are located along the anterior and posterior surfaces of the spinal cord, in the center there is a spinal canal, around which a gray matter is concentrated - an accumulation huge amount nerve cells that form the contour of the butterfly. On the outer surface of the cord of the spinal cord, there is a white matter - an accumulation of bundles of long processes of nerve cells.
In the gray matter, anterior, posterior and lateral horns are distinguished. In the anterior horns, motor neurons lie, in the posterior horns, intercalary ones, which carry out a connection between sensory and motor neurons. Sensory neurons lie outside the cord, in the spinal nodes along the sensory nerves.
Long processes branch off from the motor neurons of the anterior horns - the anterior roots, which form motor nerve fibers. The axons of sensory neurons that form the dorsal roots, which enter the spinal cord and transmit excitation from the periphery to the spinal cord, approach the posterior horns. Here, the excitation switches to the intercalary neuron, and from it to short branches motor neuron, from which it then communicates along the axon to the working organ.
In the intervertebral foramen, the motor and sensory roots join together 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 mixed spinal nerves 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 with each other and the spinal cord with the brain. Some pathways are called ascending or sensory, transmitting excitation to the brain, others - descending or motor, which conduct impulses from the brain to certain segments of the spinal cord.
Spinal cord function. The spinal cord has two functions:
- reflex [show]
.
Each reflex is carried out by a strictly defined area of the central nervous system - the nerve center. The nerve center is called a set of nerve cells located in one of the brain regions and regulating the activity of an organ or system. For example, the center of the knee reflex is 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 information that comes from the corresponding receptors, and impulses are formed that are transmitted to the executive organs - the heart, blood vessels, skeletal muscles, glands, etc. functional state changes. For the regulation of the reflex, its accuracy, the participation of the higher parts of the central nervous system, including the cerebral cortex, is necessary.
The nerve centers of the spinal cord are directly associated with receptors and executive bodies 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 intercostal muscles. In addition to the motor centers of skeletal muscles, the spinal cord contains a number of autonomic centers.
- 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. Distinguish between ascending paths, carrying impulses to the brain, and descending, carrying impulses from the brain to the spinal cord. According to the first, excitation arising in the receptors of the skin, muscles, internal organs is carried out along the spinal nerves to the dorsal roots of the spinal cord, is perceived by sensitive neurons of the spinal cord nodes and from here is sent either to rear horns 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, excitement 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 cerebral section of the skull. Its average weight is 1300 - 1400 g. After the birth of a person, the growth of the brain continues up to 20 years. It consists of five sections: the anterior (large hemispheres), diencephalon, middle, posterior and medulla oblongata. Inside the brain there are four communicating cavities - the 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 oblong.
The hemispheres (the most recent evolutionary part) reach high development in humans, accounting for 80% of the brain mass. The phylogenetically more ancient part is the brain stem. The trunk includes the medulla oblongata, cerebral (varolium) pons, midbrain and diencephalon.
Numerous kernels lie in the white matter of the trunk gray matter... The nuclei of 12 pairs of cranial nerves also lie in the brain stem. The brain stem is covered by the cerebral hemispheres.
Medulla- an extension of the dorsal and repeats its structure: grooves also lie on the front and back surfaces. It consists of white matter (conducting beams), where clusters of gray matter are scattered - the nuclei from which originate cranial nerves- from IX to XII pair, including the glossopharyngeal (IX pair), wandering (X pair), innervating the respiratory, circulatory, digestive and other systems, sublingual (XII pair). Above, the medulla oblongata continues into a thickening - the pons varoli, and the lower legs of the cerebellum extend from the sides of it. Above and from the sides, almost the entire medulla oblongata is covered by the large 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 termination cardiac activity and respiration.
Hind brain includes pons varoli and cerebellum. The pons Varoliyev is bounded 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 V to VIII pairs of cranial nerves (trigeminal, abducens, facial, auditory).
The cerebellum is located posterior to the pons and medulla oblongata. Its surface consists of gray matter (bark). Under the cerebellar cortex there is a white matter, in which there are accumulations of gray matter - the nucleus. The entire cerebellum is represented by two hemispheres, middle part- a worm and three pairs of legs formed by nerve fibers, with the help of which it is connected with other parts of the brain. The main function of the cerebellum is unconditional reflex coordination of movements, which determines their clarity, smoothness and preservation body balance as well as maintaining muscle tone. Through the spinal cord, along the pathways, impulses from the cerebellum are delivered to the muscles. Controls the activity of the cerebellar cortex.
Midbrain located in front of the pons of varoli, it is represented by the quadruple and the legs of the brain. In the center of it passes a narrow channel (aqueduct of the brain), which connects the third and fourth ventricles. The cerebral aqueduct is surrounded by gray matter, in which the nuclei of the III and IV pairs of cranial nerves lie. In the legs of the brain, the pathways from the medulla oblongata and the pons to the cerebral hemispheres continue. The midbrain plays an important role in the regulation of tone and in the implementation of reflexes, thanks to which standing and walking are possible. The sensory nuclei of the midbrain are located in the tubercles of the quadruple: the upper ones contain the nuclei associated with the organs of vision, in the lower ones - the nuclei associated with the organs of hearing. 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. Consists of two visual hillocks, the supra-hillock, sub-hillock region and the geniculate bodies. On the periphery of the diencephalon there is a white matter, and in its thickness there are nuclei of gray matter. The visual hillocks are the main subcortical centers of sensitivity: impulses from all receptors in the body come here along the ascending pathways, and from here to the cerebral cortex. In the hypothalamus (hypothalamus) there are centers, the aggregate of which is the higher subcortical center of the autonomic nervous system, which regulates metabolism in the body, heat transfer, and the constancy of the internal environment. In the anterior parts of the hypothalamus, parasympathetic centers are located, in the posterior - sympathetic. The subcortical visual and auditory centers are concentrated in the nuclei of the geniculate bodies.
The second pair of cranial nerves - the optic ones - is directed to the geniculate bodies. The brain stem is associated with environment and with the organs of the body the 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 highly developed hemispheres and the middle part connecting them. Right and left hemisphere separated from each other by a deep gap, at the bottom of which the corpus callosum lies. The corpus callosum connects both hemispheres through long outgrowths 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 the gray matter or the cerebral cortex, represented by neurons and their processes, under the cortex lies the white matter - the pathways. Pathways connect separate centers within the same hemisphere, or the right and left halves of the brain and spinal cord, or different levels of the central nervous system. In the white matter there are also accumulations 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. In spite of small thickness, the cerebral cortex has a very complex structure.
The cortex contains 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 investigated by V.A. Bets. 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 cerebral box, so the cortex forms folds - convolutions, limited by grooves; they contain about 70% of the surface of the crust. Furrows divide the surface of the hemispheres into lobes.
There are four lobes in each hemisphere:
- frontal
- parietal
- temporal
- occipital.
The deepest grooves are the central, which runs across both hemispheres, and the temporal, which separates the temporal lobe of the brain from the rest; The parieto-occipital groove separates the parietal lobe from the occipital.
In front of 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 brainstem is called the base of the brain.
On the basis of experiments with partial removal of different parts of the cortex in animals and observations of people with affected bark, 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 center. The musculocutaneous zone, which perceives irritations from the skin of all parts of the body and directs the voluntary movements of skeletal muscles, occupies an area of the cortex on both sides of the central sulcus.
Each part of the body corresponds to its own part 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 humans almost the same area of the cortex as the representation of all other parts of the body put together.
In the cortex are the 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.
The functional system, consisting of a receptor, a sensitive pathway and a zone of the cortex, where this type of sensitivity is projected, I.P. Pavlov called an analyzer.
Analysis and synthesis of the information received is carried out in a strictly defined area - the area of the cerebral cortex. The most important zones 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 musculocutaneous 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 in the superior temporal gyrus of the temporal lobe, and the olfactory and gustatory zones in the anterior temporal lobe.
Many nervous processes are carried out in the cerebral cortex. 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 in humans and higher animals was defined by I.P. Pavlov as higher nervous activity, which is a conditioned reflex function of the cerebral cortex.
| Nervous system | Central nervous system | |||
| brain | spinal cord | |||
| large hemispheres | cerebellum | trunk | ||
| Composition and structure | Lobes: frontal, parietal, occipital, two temporal. The bark is formed by gray matter - the bodies of nerve cells. Bark thickness 1.5-3 mm. The area of the cortex is 2-2.5 thousand cm 2, it consists of 14 billion neuron bodies. The white matter is formed by nerve processes |
The gray matter forms the cortex and nuclei inside the cerebellum. Consists of two hemispheres connected by a bridge |
Formed:
It consists of white matter, in the thickness there are cores of gray matter. The trunk goes into the spinal cord |
Cylindrical strand 42-45 cm long and about 1 cm in diameter. Passes through the spinal canal. Inside it is a fluid-filled spinal canal. The gray matter is on the inside, white is on the outside. Passes into the brain stem, forming a single system |
| Functions | Carries out higher nervous activity (thinking, speech, the second signaling system, memory, imagination, the ability to write, read). Communication with the external environment occurs with the help of analyzers located in the occipital lobe (visual zone), in temporal lobe(auditory zone), along the central sulcus (musculocutaneous zone) and on inner surface cortex (gustatory and olfactory zones). Regulates the work of the whole body through the peripheral nervous system |
Muscle tone regulates and coordinates body movements. Carries out unconditional reflex activity (centers congenital 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, binds body receptors with the cerebral cortex |
It functions under the control of the brain. Arcs of unconditioned (innate) reflexes that excite and inhibit during movement pass through it. Pathways - the white matter that connects the brain to the spinal cord; is a conductor of nerve impulses. Regulates the work of internal organs through the peripheral nervous system Spinal nerves control voluntary body movements |
PERIPHERAL NERVOUS SYSTEM
The peripheral nervous system is formed by nerves emanating 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, the somatic and vegetative sections 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 the skeletal muscles. The characteristic features fibers of the somatic nervous system is that they are not interrupted anywhere from the central nervous system to the receptor or skeletal muscle, they have relatively large diameter and high speed of excitation. These fibers make up the majority of the nerves that exit the central nervous system and form the peripheral nervous system.
12 pairs of cranial nerves leave the brain. The characteristics of these nerves are shown in Table 1. [show] .
Table 1. Cranial nerves
| Pair | Name and composition of the nerve | The exit of the nerve from the brain | Function |
| I | Olfactory | Large hemispheres of the forebrain | Transmits excitation (sensitive) from the olfactory receptors to the olfactory center |
| II | Visual (sensitive) | Diencephalon | Transmits excitation from the receptors of the retina to the visual center |
| III | Oculomotor (motor) | Midbrain | Innervates the eye muscles, provides eye movement |
| IV | Block (motor) | Also | Also |
| V | Trigeminal (mixed) | Bridge and medulla oblongata | Transmits excitation from receptors of the skin of the face, mucous membranes of the lips, mouth and teeth, innervates the chewing muscles |
| VI | Abduction (motor) | Medulla | Innervates the straight line lateral muscle eyes, causes eye movement to the side |
| Vii | Facial (mixed) | Also | Transfers to the brain excitement from the taste buds of the tongue and mucous membrane of the mouth, innervates the facial muscles and salivary glands |
| VIII | Auditory (sensitive) | Also | Transmits arousal from receptors in the inner ear |
| IX | Glossopharyngeal (mixed) | Also | Transmits excitement from taste buds and pharyngeal receptors, innervates the muscles of the pharynx and salivary glands |
| X | Wandering (mixed) | Also | Innervates the heart, lungs, most organs abdominal cavity, transmits excitation from the receptors of these organs to the brain and centrifugal impulses in the opposite direction |
| XI | Additional (motor) | Also | Innervates the muscles of the neck and occiput, regulates their contractions |
| XII | Sublingual (motor) | Also | Innervates the muscles of the tongue and neck, causes them to contract |
Each segment of the spinal cord gives off one pair of nerves containing sensory and motor fibers. All sensitive, or centripetal, fibers enter the spinal cord through the dorsal roots, which have thickenings - nerve nodes. In these nodes are the bodies of centripetal neurons.
The fibers of motor, or centrifugal, neurons leave the spinal cord through the anterior roots. Each segment of the spinal cord corresponds to a specific area of the body - a metamere. However, the innervation of the metameres occurs in such a way that each pair 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 adjacent segments of the spinal cord.
The autonomic nervous system is a section of the peripheral nervous system that innervates the internal organs: heart, stomach, intestines, kidneys, liver, etc. It does not have its own special sensitive pathways. Sensitive impulses from organs are transmitted along sensitive fibers, which also pass through the composition peripheral nerves, are common to the somatic and autonomic nervous systems, but constitute a smaller part of them.
In contrast to 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, in the nerve nodes (ganglia). There are many more postganglionic neurons than preganglionic ones. As a result, each preganglionic fiber in the ganglion approaches and transmits its excitation to many (10 or more) postganglionic neurons. This phenomenon is called animation.
For a number of signs in the autonomic nervous system, the sympathetic and parasympathetic divisions are distinguished.
Sympathetic division 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 extend 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.
Impulses flowing through sympathetic fibers to organs provide reflex regulation of their activity. In addition to the internal organs, sympathetic fibers innervate the blood vessels in them, as well as in the skin and skeletal muscles. They strengthen and speed up heartbeats, cause a rapid redistribution of blood by narrowing some vessels and expanding others.
Parasympathetic division represented by a number of nerves, among which the largest is nervus vagus... It innervates almost all organs of the chest and abdominal cavity.
The nuclei of the parasympathetic nerves lie on average, oblong divisions the brain and sacral spinal cord. In contrast to the sympathetic nervous system, all parasympathetic nerves reach the peripheral nerve nodes located in the internal organs or at the approaches to them. The impulses carried out by these nerves cause weakening and slowing down of cardiac activity, narrowing of the coronary vessels of the heart and cerebral vessels, dilation of the vessels of the salivary and other digestive glands, which stimulates the secretion of these glands, 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 shown in table. 2. [show] .
Table 2. Autonomic nervous system
| Index | Sympathetic nervous system | Parasympathetic nervous system |
| Location of the pregangloonary neuron | Thoracic and lumbar spinal cord | Brain stem and sacral spinal cord |
| Place of switching to the postganglionic neuron | Nerve nodes of the sympathetic chain | Nerve nodes 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 inhibits 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 get double vegetative innervation, that is, both sympathetic and parasympathetic nerve fibers are suitable for them, which function in close interaction, having the opposite effect on organs. It has great importance in the adaptation of the body to constantly changing environmental conditions.
L.A. Orbeli made a significant contribution to the study of the autonomic nervous system [show] .
Orbeli Leon Abgarovich (1882-1958) - Soviet physiologist, student of I.P. Pavlov. Acad. USSR Academy of Sciences, ArmSSR Academy of Sciences and USSR Academy of Medical Sciences. Supervisor Military Medical Academy, Institute of Physiology. And, P. Pavlova, 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 conducted research on the coordination of the activity of the spinal cord, on the physiology of the cerebellum, on the higher nervous activity.
| Nervous system | Peripheral nervous system | |||
| somatic (nerve fibers are not interrupted; the speed of the impulse 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 | They depart from various parts of the brain in the form of nerve fibers. They are subdivided into centripetal, centrifugal. Innervate the senses, internal organs, skeletal muscles |
They leave 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 connect to form a nerve |
They leave in symmetrical pairs on both sides of the spinal cord in the thoracic and lumbar regions. The prenodal fiber is short, since the nodes lie along the spinal cord; the postnodal fiber is long, as it goes from the node to the innervated organ |
They move away from the brain stem and sacral spinal cord. Nerve nodes lie in the walls or near the innervated organs. The prenodal fiber is long, since it runs from the brain to the organ, the postnodal fiber is short, since it is located in the innervated organ |
| Functions | They provide the body's connection with the external environment, quick reactions to its change, orientation in space, body movements (purposeful), sensitivity, vision, hearing, smell, touch, taste, facial expressions, speech. The activity is carried out under the control of the brain |
They carry out movements of all parts of the body, limbs, and determine the sensitivity of the skin. Skeletal muscles innervate, causing voluntary and involuntary movements. Voluntary movements are carried out under the control of the brain, involuntary movements under the control of the spinal cord (spinal reflexes) |
Internal organs innervate. Post-nodular fibers leave as part of the mixed nerve from the spinal cord and pass to the internal organs. Nerves form plexuses - solar, pulmonary, cardiac. Stimulates the work of the heart, sweat glands, metabolism. They slow down 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 that is 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 | ||||
A) muscles of the upper and lower limbs,
B) heart and blood vessels,
C) digestive organs,
D) facial muscles,
D) kidneys and bladder,
E) the diaphragm and intercostal muscles.
AT 3. The peripheral nervous system includes:
B) the cerebellum,
C) nerve nodes,
D) the spinal cord,
D) sensory nerves,
E) motor nerves.
AT 4. The cerebellum contains the centers of regulation:
A) muscle tone,
B) vascular tone,
C) posture and body balance,
D) coordination of movements,
D) emotions,
E) inhalation and exhalation.
Matching assignments.
AT 5. Establish a correspondence between an individual neuron function and the type of neuron that performs this function.
FUNCTIONS OF NEURONS TYPES OF NEURONS
1) transmit from one neuron A) sensitive,
on the other in the brain, B) intercalary,
2) transmit nerve impulses from organs B) motor.
feelings in the brain,
3) transmit nerve impulses to muscles,
4) transmit nerve impulses from internal organs to the brain,
5) transmit nerve impulses to the glands.
AT 6. Establish a correspondence between the departments of the nervous system and their functions.
FUNCTIONS PERFORMED NERVOUS SYSTEM DEPARTMENT
1) constricts blood vessels, A) sympathetic,
2) slows down the rhythm of the heart, B) parasympathetic.
3) narrows the bronchi,
4) dilates the pupil.
AT 7. Establish a correspondence between the structure and functions of a neuron and its processes.
STRUCTURE AND FUNCTIONS OF THE NEURON SPECT
1) conducts a signal to the body of the neuron, A) axon,
2) outside covered with myelin sheath, B) dendrite.
3) short and highly branched,
4) participates in the formation of nerve fibers,
5) conducts a signal from the body of the neuron.
AT 8. Establish a correspondence between the properties of the nervous system and its types that possess these properties.
PROPERTIES NERVOUS SYSTEM TYPE
1) innervates the skin and skeletal muscles, A) somatic,
2) innervates all internal organs, B) vegetative.
3) helps to maintain the body's connection
with the external environment,
4) regulates metabolic processes, body growth,
5) actions are controlled by consciousness (arbitrary),
6) actions are not subject to consciousness (autonomous).
AT 9. Establish a correspondence between examples of human nervous activity and the functions of the spinal cord.
EXAMPLES OF NERVOUS ACTIVITIES OF THE SPINAL FUNCTIONS
1) knee reflex, A) reflex,
2) transmission of nerve impulses from the spinal; B) conduction.
brain in the head,
3) extension of the limbs,
4) jerking the hand away from a hot object,
5) transmission of nerve impulses from the brain
to the muscles of the limbs.
AT 10. Establish a correspondence between the structural feature and function of the brain and its department.
STRUCTURAL FEATURES OF THE HEADER DEPARTMENT
AND BRAIN FUNCTIONS
1) contains respiratory center, A) medulla oblongata,
2) the surface is divided into lobes, B) the forebrain.
3) perceives and processes information from
4) regulates the activity of the cardiovascular system,
5) contains the centers of the body's defense reactions - cough
and sneezing.
Sequencing tasks.
AT 11. Establish the correct sequence of the location of the parts of the brain stem, in the direction from the spinal cord.
A) diencephalon,
B) the medulla oblongata,
C) midbrain,
Free answer tasks
Lecture number 5. Autonomic nervous system
The nervous system is divided into somatic (Slide 2) and autonomous (autonomic) (Slide 3).
The somatic nervous system controls the work of skeletal muscles, and the autonomic nervous system regulates the activity of internal organs.
The autonomous and somatic nervous systems act in a friendly manner in the body, at the same time there are many differences between the systems.
Differences between the autonomic and somatic nervous systems
The autonomic nervous system (autonomic) is involuntary, it is not controlled by consciousness, the somatic one is subject to voluntary control.
The autonomic nervous system innervates the internal organs, the glands of the external and internal secretion, circulatory and lymphatic vessels, smooth muscles. Its main function is to maintain the constancy of the internal environment of the body. The somatic nervous system innervates the skeletal muscles.
The reflex arc of both somatic and autonomous reflexes consists of three links: afferent (sensory, sensitive), intercalary and effector (executive) (Slide 4). However, in the autonomic nervous system, the effector neuron is located outside the central nervous system and is located in the ganglia (nodes). The neurons of the autonomic nervous system, which are located in the central nervous system, are called preganglionic neurons, and their processes - preganglionic fibers... The effector neurons that are located in the nodes are called postganglionic neurons, and their processes - respectively postganglionic fibers... In the somatic nervous system, effector neurons are located in the central nervous system (gray matter of the spinal cord).
The fibers of the autonomic nervous system leave the central nervous system only in certain areas of the brain stem, as well as in the thoracolumbar and sacral regions of the spinal cord. In the intraorgan section, the reflex arcs are completely in the organ and have no exits from the central nervous system. The fibers of the somatic nervous system leave the spinal cord segmentally along its entire length (Slide 5).
Structure and function of the autonomic nervous system
In the autonomic nervous system, the sympathetic and parasympathetic departments (Slide 6). Each of them, in turn, has central and peripheral divisions. Central departments are located in the brain stem and spinal cord, the bodies of preganglionic neurons are located in it.
The peripheral section is represented by neuronal processes (pre- and postganglionic fibers), as well as ganglia, in which the bodies of postganglionic neurons are located. In the ganglia of the autonomic nervous system, there are synaptic contacts between pre- and postganglionic neurons.
Many internal organs receive both sympathetic and parasympathetic innervation. As a rule (although not always), the parasympathetic and sympathetic systems exert the opposite influence on tissues and organs.
In the walls of many hollow internal organs (bronchi, heart, intestines) there are nerve nodes that regulate functions at the local level, largely independently of the parasympathetic and sympathetic systems. These nodes combine into a separate part of the autonomic nervous system - metasympathetic(enteral, intraorgan)
Sympathetic division of the autonomic nervous system (Slide 7)
The centers of the sympathetic nervous system are represented by nuclei located in the lateral horns of the gray matter of the spinal cord (from VIII cervical to I - II lumbar segments). The axons of the preganglionic neurons that make up these nuclei exit the spinal cord as part of its anterior roots and end in a pair - or prevertebral ganglia.Paravertebral ganglia are near spinal column, a prevertebral- in the abdominal cavity. In the paravertebral and prevertebral ganglia are postganglionic neurons, the processes of which form postganglionic fibers. These fibers are suitable for the actuators.
The endings of the preganglionic fibers secrete the mediator acetylcholine, and the postganglionic ones - mainly norepinephrine. The exceptions are postganglionic fibers, which innervate the sweat glands, and sympathetic nerves, which dilate the vessels of skeletal muscles. These fibers are called sympathetic cholinergic because acetylcholine is secreted from their endings.
Functions of the sympathetic system.The sympathetic nervous system is activated by stress. In animals, stress implies physical activity (flight or fight response), therefore, the functions of the sympathetic nervous system are aimed at ensuring muscular work.
When the sympathetic nerves are excited, the work of the heart increases, the vessels of the skin and abdominal cavity narrow, and in the skeletal muscles and in the heart they expand. Due to such influences on cardiovascular system increased blood flow in the working organs (skeletal muscles, heart, brain). The musculature of the bronchi relaxes and their lumen increases. An increase in the lumen of the bronchi occurs in response to increased pulmonary ventilation and an increase in the volume of air passing through
through the respiratory tract.
The digestive and urinary functions are inhibited during exercise, therefore motor and secretory activity gastrointestinal tract decreases, there is a contraction of the sphincters of the urinary and gallbladder and relaxation of their bodies. Under the influence of the sympathetic system, the pupil dilates.
The sympathetic nervous system not only regulates the work of internal organs, but also influences metabolic processes in skeletal muscles and in the nervous system. When the sympathetic system is activated, metabolic processes are enhanced. In addition, when it is excited, the activity of the adrenal medulla increases, and adrenaline is released.
The sympathetic division of the autonomic nervous system is a system of anxiety, mobilization of the body's defenses and resources (Slide 8). Its excitement leads to an increase in blood pressure, the release of blood from the depot, the breakdown of glycogen in the liver and the entry of glucose into the blood, an increase in tissue metabolism, and activation of the central nervous system. All these processes are associated with energy expenditure in the body, i.e., the sympathetic nervous system performs ergotropic function.
Parasympathetic division of the autonomic nervous system
The centers of the parasympathetic division of the autonomic nervous system (Slide 9) are the nuclei located in the midbrain (III pair of cranial nerves), the medulla oblongata (VII, IX and X pairs of cranial nerves) and the sacral spinal cord. The preganglionic fibers of the parasympathetic nerves, which are part of the oculomotor nerve, exit from the midbrain (III). Preganglionic fibers emerge from the medulla oblongata, which are part of the facial (VII), glossopharyngeal (IX) and vagus (X) nerves. Preganglionic parasympathetic fibers, which are part of the pelvic nerve, depart from the sacral spinal cord.
The parasympathetic part of the III nerve is responsible for the constriction of the pupil, the VII and IX nerves innervate the salivary and lacrimal glands. The vagus nerve provides parasympathetic innervation to almost all organs of the thoracic and abdominal cavities, with the exception of the small pelvis. The pelvic organs receive parasympathetic innervation from the sacral segments of the spinal cord.
The ganglia of the parasympathetic nervous system are located near or within innervated organs, therefore, in contrast to the sympathetic department, the preganglionic fibers of the parasympathetic section are long, and the postganglionic fibers are short... Acetylcholine is released at the ends of the parasympathetic fibers. Parasympathetic fibers only supply certain parts of the body. Skeletal muscle, brain, smooth muscle of blood vessels, sensory organs and adrenal medulla do not have parasympathetic
innervation.
Functions of the parasympathetic nervous system.The parasympathetic division of the autonomic nervous system is active at rest, its action is aimed at restoration and maintenance the constancy of the composition of the internal environment of the body ( Slide 10 ). Thus, the parasympathetic nervous system performs in the body trophotropic function.
When the parasympathetic nerves are excited, the work of the heart is inhibited, the tone of the smooth muscles of the bronchi increases, as a result of which their lumen decreases, the pupil narrows. The digestive processes (motility and secretion) are also stimulated, thereby ensuring the restoration of the level nutrients in the body, the gallbladder, bladder, rectum are emptied. By acting on the pancreas, the vagus nerve promotes the production of insulin. This in turn leads to a decrease in blood glucose levels, stimulation of glycogen synthesis in the liver and the formation of fats.
Intraorgan department (enteral, metasympathetic)
This section includes intramural (that is, located in the wall of the organ) nerve plexuses of all hollow internal organs, which have their own automatic motor activity: heart, bronchi, bladder, digestive tract, uterus, gallbladder and biliary tract(Slides 11, 12).
The intraorgan department has all the links reflex arc: afferent, intercalary and efferent neurons, which are completely located in the nerve plexuses of internal organs. This department is distinguished by stricter autonomy, i.e. independence from the central nervous system. Sympathetic and parasympathetic nerves form synaptic contacts on the intercalary and efferent neurons of the intraorgan nervous system. Some efferent neurons of the metasympathetic system can be simultaneously parasympathetic postganglionic neurons. All this ensures reliability in the activities of the organs.
Preganglionic fibers of the metsympathetic system secrete
acetylcholine and norepinephrine, postganglionic - ATP and adenosine, acetylcholine, norepinephrine, serotonin, dopamine, adrenaline, histamines
This department of the autonomic nervous system controls the work of smooth muscles, absorbing and secreting epithelium, local blood flow, local endocrine and immune mechanisms. Thus, the metasympathetic system is responsible for the implementation of the simplest motor and secretory functions, and the sympathetic and parasympathetic divisions control and adjust its work, performing more complex functions.
Autonomic nervous system mediators (Slide 13)
Preganglionic neurons of both divisions of the autonomic nervous
systems release the mediator acetylcholine. On the postinaptic membrane of all postganglionic neurons there are H-cholinergic receptors(they are sensitive to nicotine).
At the endings of postganglionic neurons of the parasympathetic
system, acetylcholine is secreted, which acts on M - cholinergic receptors in the tissues. These receptors are sensitive to fly agaric poison
muscarine.
In the endings of sympathetic postganglionic neurons are secreted norepinephrine which acts onα- and β-adrenergic receptors. The effect of the sympathetic nervous system on organs and tissues depends on the type of adrenergic receptors that are located there, and sometimes this effect can be the opposite. For example, vessels with α-adrenergic receptors narrow under the influence of the sympathetic system, and vessels withβ-receptors - expand.
α-adrenergic receptors are mainly found in the smooth muscles of the vessels of the skin, mucous membranes and abdominal organs, as well as in the radial muscle of the eye, intestinal smooth muscles, sphincters of the digestive tract and urinary bladder, in the pancreas, fat cells, platelets.
β- adrenergic receptors located mainly in the heart, smooth muscles of the intestines and bronchi, in adipose tissue, in the vessels of the heart.
Centers for the regulation of autonomous functions (Slide 14)
The centers of the autonomic nervous system described above (in the middle, medulla oblongata and spinal cord) are regulated by the overlying parts of the central nervous system. One of the highest centers for the regulation of autonomous functions is located in
hypothalamus. Stimulation of the nuclei of the posterior group of the hypothalamus
It has reactions similar to irritation of the sympathetic nervous system: dilation of the pupils and eye slits, increased heart rate, vasoconstriction and increased blood pressure, inhibition of the motor activity of the stomach and intestines, an increase in adrenaline and norepinephrine in the blood, glucose concentration. Stimulation anterior nuclei of the hypothalamus leads to effects similar to irritation of the parasympathetic nervous system: narrowing of the pupils and eye slits, slowing heart rate, lowering blood pressure, increasing motor activity of the stomach and intestines, increasing gastric secretion, stimulating insulin secretion and lowering blood glucose levels. The middle group of nuclei of the hypothalamus ensures the regulation of metabolism and water balance, there are centers of hunger, thirst and satiety. In addition, the hypothalamus is responsible for emotional behavior, the formation of sexual and aggressive defensive reactions.
Limbic system centers... These centers are responsible for the formation of an autonomous component of emotional reactions (that is, a change in the work of internal organs during emotional states), eating, sexual, defensive behavior, as well as the regulation of systems that provide sleep
and wakefulness, attention.
Cerebellar centers... Due to the presence of activating and inhibitory mechanisms, the cerebellum can have a stabilizing effect on the activity of internal organs, correcting autonomous reflexes.
Centers of the reticular formation... The reticular formation tones up and increases the activity of other autonomic nerve centers.
Centers of the cerebral cortex... The cerebral cortex carries out the highest integrative (general) control of autonomous functions, exerting downward inhibitory and activating influences on the reticular formation and other subcortical centers.
In general, the overlying parts of the central nervous system, without interfering with the activity of the underlying centers, adjust their work based on the specific situation and state of the organism. Thus, the autonomic nervous system has a hierarchical (subordinate) structure; the lowest elements of this system are the intraorgan nodes, which provide the performance of the simplest functions (for example, the nerve plexuses in the intestinal wall regulate peristaltic contractions), and the highest element is the cerebral cortex.
The nervous system is structurally divided into 2 parts:
- central - spinal cord and brain;
- peripheral - nerves and ganglia.
Nerves are bundles of nerve fibers surrounded by a connective tissue sheath.
Nerve nodes are collections of neuronal bodies outside the central nervous system, such as the solar plexus.
The nervous system is divided into 2 parts according to its functions:
- somatic - controls skeletal muscles, obeys consciousness;
- vegetative (autonomous) - controls the internal organs, does not obey consciousness. It consists of two parts - sympathetic and parasympathetic.
The brain and spinal cord are covered with three membranes - hard, arachnoid and soft. Between the rungs connective tissue in the arachnoid there is a space filled with cerebrospinal fluid. It is also found in the spinal canal of the spinal cord and in the four ventricles of the brain. Its total volume is about 120 ml, it performs nutritional, excretory and support functions.
Tests
1. The somatic nervous system regulates activity
A) heart, stomach
B) endocrine glands
B) skeletal muscle
D) smooth muscles
2. The human peripheral nervous system is formed
A) intercalary neurons
B) the spinal cord
C) nerves and nerve nodes
D) pathways of the brain
3. The somatic nervous system, in contrast to the autonomic, controls the work
A) skeletal muscle
B) heart and blood vessels
B) intestines
D) kidney
4) Which nerves are used to move the impulses that amplify the pulse?
A) sympathetic
B) spinal
B) parasympathetic
D) cranial sensitive
5. The autonomic nervous system regulates muscle function
A) chest
B) limbs
V) abdominal
D) internal organs
6. Vegetative department the human nervous system regulates the work of muscles
A) backs
B) chewing
B) stomach
D) limbs
7. The autonomic (autonomic) nervous system controls activity
A) internal organs
B) analyzers
B) skeletal muscle
D) brain and spinal cord
8) Which part of the nervous system does NOT contain cerebrospinal fluid
A) the ventricles of the brain
B) soft shell
V) arachnoid
D) spinal canal
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