Parts of the nervous system. Human nervous system

Very clear, concise and understandable. Posted as a keepsake.

1. What is the nervous system

One of the components of a person is his nervous system. It is reliably known that diseases of the nervous system negatively affect the physical condition of the entire human body. When there is a disease of the nervous system, both the head and the heart (the “engine” of a person) begin to hurt.

Nervous system is a system that regulates the activities of all human organs and systems. This system provides:

1) functional unity of all human organs and systems;

2) the connection of the whole organism with the environment.

The nervous system also has its own structural unit, which is called a neuron. Neurons - these are cells that have special processes. It is neurons that build neural circuits.

The entire nervous system is divided into:

1) central nervous system;

2) peripheral nervous system.

The central nervous system includes the brain and spinal cord, and the peripheral nervous system includes the cranial and spinal nerves and nerve ganglia extending from the brain and spinal cord.

Also The nervous system can be roughly divided into two large sections:

1) somatic nervous system;

2) autonomic nervous system.

Somatic nervous system associated with the human body. This system is responsible for the fact that a person can move independently; it also determines the connection of the body with the environment, as well as sensitivity. Sensitivity is provided with the help of human senses, as well as with the help of sensitive nerve endings.

Human movement is ensured by the fact that skeletal muscle mass is controlled by the nervous system. Biological scientists call the somatic nervous system animal in another way, since movement and sensitivity are characteristic only of animals.

Nerve cells can be divided into two large groups:

1) afferent (or receptor) cells;

2) efferent (or motor) cells.

Receptor nerve cells perceive light (using visual receptors), sound (using sound receptors), and smells (using olfactory and taste receptors).

Motor nerve cells generate and transmit impulses to specific executive organs. A motor nerve cell has a body with a nucleus and numerous processes called dendrites. A nerve cell also has a nerve fiber called an axon. The length of these axons ranges from 1 to 1.5 mm. With their help, electrical impulses are transmitted to specific cells.

In the membranes of cells that are responsible for the sensation of taste and smell, there are special biological compounds that react to a particular substance by changing their state.

For a person to be healthy, he must first of all monitor the state of his nervous system. Today, people sit a lot in front of the computer, stand in traffic jams, and also find themselves in various stressful situations (for example, a student received a negative grade at school, or an employee received a reprimand from his immediate superiors) - all this negatively affects our nervous system. Today, enterprises and organizations create rest (or relaxation) rooms. Arriving in such a room, the employee mentally disconnects from all problems and simply sits and relaxes in a favorable environment.

Law enforcement officials (police, prosecutors, etc.) have created, one might say, their own system for protecting their own nervous system. Victims often come to them and talk about the misfortune that happened to them. If a law enforcement officer, as they say, takes what happened to the victims to heart, then he will retire disabled, if his heart even survives until retirement. Therefore, law enforcement officers put up a kind of “protective screen” between themselves and the victim or criminal, that is, the problems of the victim or criminal are listened to, but the employee, for example, from the prosecutor’s office, does not express any human involvement in them. Therefore, you can often hear that all law enforcement officers are heartless and very evil people. In fact, they are not like that - they just have this method of protecting their own health.

2. Autonomic nervous system

Autonomic nervous system - this is one of the parts of our nervous system. The autonomic nervous system is responsible for: the activity of internal organs, the activity of endocrine and exocrine glands, the activity of blood and lymphatic vessels, and also, to some extent, the muscles.

The autonomic nervous system is divided into two sections:

1) sympathetic section;

2) parasympathetic section.

Sympathetic nervous system dilates the pupil, it also causes increased heart rate, increased blood pressure, dilates small bronchi, etc. This nervous system is carried out by sympathetic spinal centers. It is from these centers that the peripheral sympathetic fibers begin, which are located in the lateral horns of the spinal cord.

Parasympathetic nervous system is responsible for the activity of the bladder, genitals, rectum, and it also “irritates” a number of other nerves (for example, the glossopharyngeal, oculomotor nerve). This “diverse” activity of the parasympathetic nervous system is explained by the fact that its nerve centers are located both in the sacral part of the spinal cord and in the brain stem. Now it becomes clear that those nerve centers that are located in the sacral part of the spinal cord control the activity of organs located in the pelvis; nerve centers, which are located in the brain stem, regulate the activity of other organs through a number of special nerves.

How is the activity of the sympathetic and parasympathetic nervous system controlled? The activity of these sections of the nervous system is controlled by special autonomic apparatuses located in the brain.

Diseases of the autonomic nervous system. The causes of diseases of the autonomic nervous system are the following: a person does not tolerate hot weather well or, conversely, feels uncomfortable in winter. A symptom may be that when a person is excited, he quickly begins to blush or turn pale, his pulse quickens, and he begins to sweat profusely.

It should also be noted that diseases of the autonomic nervous system occur in people from birth. Many people believe that if a person gets excited and blushes, it means that he is simply too modest and shy. Few would think that this person has any disease of the autonomic nervous system.

These diseases can also be acquired. For example, due to a head injury, chronic poisoning with mercury, arsenic, or due to a dangerous infectious disease. They can also occur when a person is overworked, with a lack of vitamins, or with severe mental disorders and worries. Also, diseases of the autonomic nervous system can be the result of non-compliance with safety regulations in the workplace with hazardous working conditions.

The regulatory activity of the autonomic nervous system may be impaired. Diseases can “masquerade” as other diseases. For example, with a disease of the solar plexus, bloating and poor appetite may be observed; with a disease of the cervical or thoracic nodes of the sympathetic trunk, chest pain may be observed, which can radiate to the shoulder. Such pain is very similar to heart disease.

To prevent diseases of the autonomic nervous system, a person should follow a number of simple rules:

1) avoid nervous fatigue and colds;

2) observe safety precautions in production with hazardous working conditions;

3) eat well;

4) go to the hospital in a timely manner and complete the entire prescribed course of treatment.

Moreover, the last point, timely access to the hospital and complete completion of the prescribed course of treatment, is the most important. This follows from the fact that delaying your visit to the doctor for too long can lead to the most dire consequences.

Good nutrition also plays an important role, because a person “charges” his body and gives it new strength. Having refreshed yourself, the body begins to fight diseases several times more actively. In addition, fruits contain many useful vitamins, which help the body fight disease. Most healthy fruits are in their raw form, since during their preparation many beneficial features may disappear. A number of fruits, in addition to containing vitamin C, also contain a substance that enhances the effect of vitamin C. This substance is called tannin and is found in quince, pears, apples, and pomegranate.

3. Central nervous system

The human central nervous system consists of the brain and spinal cord.

The spinal cord looks like a cord; it is somewhat flattened from front to back. Its size in an adult is approximately 41 to 45 cm, and its weight is about 30 gm. It is “surrounded” by the meninges and is located in the medullary canal. Throughout its entire length, the thickness of the spinal cord is the same. But it has only two thickenings:

1) cervical thickening;

2) lumbar thickening.

It is in these thickenings that the so-called innervation nerves of the upper and lower extremities are formed. Dorsal brain is divided into several departments:

1) cervical region;

2) thoracic region;

3) lumbar region;

4) sacral section.

The human brain is located in the cranial cavity. There are two large hemispheres: the right hemisphere and the left hemisphere. But, in addition to these hemispheres, the trunk and cerebellum are also distinguished. Scientists have calculated that a man's brain is heavier than a woman's brain by an average of 100 gm. They explain this by the fact that most men are much larger than women in their physical parameters, that is, all parts of a man’s body are larger than parts of a woman’s body. The brain actively begins to grow even when the child is still in the womb. The brain reaches its “true” size only when a person reaches twenty years of age. At the very end of a person's life, his brain becomes a little lighter.

The brain has five main sections:

1) telencephalon;

2) diencephalon;

3) midbrain;

4) hindbrain;

5) medulla oblongata.

If a person has suffered a traumatic brain injury, this always has a negative impact on both his central nervous system and his mental state.

If there is a mental disorder, a person may hear voices inside his head that command him to do this or that. All attempts to drown out these voices are unsuccessful and in the end the person goes and does what the voices told him to do.

In the hemisphere, the olfactory brain and the basal ganglia are distinguished. Everyone also knows this humorous phrase: “Get smart,” that is, think. Indeed, the “pattern” of the brain is very complex. The complexity of this “pattern” is determined by the fact that furrows and ridges run along the hemispheres, which form a kind of “convolutions”. Despite the fact that this “pattern” is strictly individual, several common grooves are distinguished. Thanks to these common grooves, biologists and anatomists have identified 5 hemisphere lobes:

1) frontal lobe;

2) parietal lobe;

3) occipital lobe;

4) temporal lobe;

5) hidden share.

The brain and spinal cord are covered with membranes:

1) dura mater;

2) arachnoid membrane;

3) soft shell.

Hard shell. The hard shell covers the outside of the spinal cord. In its shape it most closely resembles a bag. It should be said that the outer dura mater of the brain is the periosteum of the skull bones.

Arachnoid. The arachnoid membrane is a substance that is almost closely adjacent to the hard shell of the spinal cord. The arachnoid membrane of both the spinal cord and the brain does not contain any blood vessels.

Soft shell. The soft membrane of the spinal cord and brain contains nerves and vessels, which, in fact, nourish both brains.

Despite the fact that hundreds of works have been written to study the functions of the brain, its nature has not been fully elucidated. One of the most important riddles that the brain “makes” is vision. Or rather, how and with what help we see. Many people mistakenly assume that vision is the prerogative of the eyes. This is wrong. Scientists are more inclined to believe that the eyes simply perceive signals that the environment around us sends us. The eyes transmit them further “up the chain of command.” The brain, having received this signal, builds a picture, i.e. we see what our brain “shows” us. The issue of hearing should be resolved similarly: it is not the ears that hear. Or rather, they also receive certain signals that the environment sends us.

In general, it will not be long before humanity fully understands what the brain is. It is constantly evolving and developing. The brain is believed to be the "home" of the human mind.

Nervous system consists of winding networks nerve cells, making up various interconnected structures and controlling all the activities of the body, both desired and conscious actions, as well as reflexes and automatic actions; The nervous system allows us to interact with the outside world and is also responsible for mental activity.

The nervous system consists of various interconnected structures that together constitute an anatomical and physiological unit. consists of organs located inside the skull (brain, cerebellum, brain stem) and spine (spinal cord); is responsible for interpreting the condition and various needs of the body based on the information received, in order to then generate commands designed to produce appropriate responses.

consists of many nerves that go to the brain (cerebral pairs) and the spinal cord (vertebral nerves); acts as a transmitter of sensory stimuli to the brain and commands from the brain to the organs responsible for their execution. The autonomic nervous system controls the functions of numerous organs and tissues through antagonistic effects: the sympathetic system is activated during anxiety, and the parasympathetic system is activated during rest.

central nervous system
Includes the spinal cord and brain structures.

In the human body, the work of all its organs is closely interconnected, and therefore the body functions as a single whole. The coordination of the functions of internal organs is ensured by the nervous system, which, in addition, communicates the body as a whole with the external environment and controls the functioning of each organ.

Distinguish central nervous system (brain and spinal cord) and peripheral, represented by nerves extending from the brain and spinal cord and other elements lying outside the spinal cord and brain. The entire nervous system is divided into somatic and autonomic (or autonomic). Somatic nervous the system primarily communicates the body with the external environment: perception of irritations, regulation of movements of the striated muscles of the skeleton, etc., vegetative - regulates metabolism and the functioning of internal organs: heartbeat, peristaltic contractions of the intestines, secretion of various glands, etc. Both of them function in close interaction, but the autonomic nervous system has some independence (autonomy), controlling many involuntary functions.

A cross-section of the brain shows that it consists of gray and white matter. Gray matter is a collection of neurons and their short processes. In the spinal cord it is located in the center, surrounding the spinal canal. In the brain, on the contrary, gray matter is located along its surface, forming a cortex and separate clusters called nuclei, concentrated in the white matter. White matter is located under the gray and is composed of nerve fibers covered with membranes. Nerve fibers, when connected, form nerve bundles, and several such bundles form individual nerves. The nerves through which excitation is transmitted from the central nervous system to the organs are called centrifugal, and the nerves that conduct excitation from the periphery to the central nervous system are called centripetal.

The brain and spinal cord are covered with three membranes: dura mater, arachnoid membrane and vascular membrane. Solid - external, connective tissue, lining the internal cavity of the skull and spinal canal. Arachnoid located under the dura ~ this is a thin shell with a small number of nerves and blood vessels. Vascular the membrane is fused with the brain, extends into the grooves and contains many blood vessels. Between the choroid and arachnoid membranes, cavities filled with brain fluid are formed.

In response to irritation, the nervous tissue enters a state of excitation, which is a nervous process that causes or enhances the activity of the organ. The property of nervous tissue to transmit excitation is called conductivity. The speed of excitation is significant: from 0.5 to 100 m/s, therefore, interaction is quickly established between organs and systems that meets the needs of the body. Excitation is carried out along the nerve fibers in isolation and does not pass from one fiber to another, which is prevented by the membranes covering the nerve fibers.

The activity of the nervous system is reflexive character. The response to stimulation carried out by the nervous system is called reflex. The path along which nervous excitation is perceived and transmitted to the working organ is called reflex arc. It consists of five sections: 1) receptors that perceive irritation; 2) sensitive (centripetal) nerve, transmitting excitation to the center; 3) the nerve center, where excitation switches from sensory neurons to motor neurons; 4) motor (centrifugal) nerve, carrying excitation from the central nervous system to the working organ; 5) a working organ that reacts to the received irritation.

The process of inhibition is the opposite of excitation: it stops activity, weakens or prevents its occurrence. Excitation in some centers of the nervous system is accompanied by inhibition in others: nerve impulses entering the central nervous system can delay certain reflexes. Both processes are excitation And braking - are interconnected, which ensures coordinated activity of organs and the entire organism as a whole. For example, during walking, contraction of the flexor and extensor muscles alternates: when the flexion center is excited, impulses follow to the flexor muscles, at the same time, the extension center is inhibited and does not send impulses to the extensor muscles, as a result of which the latter relax, and vice versa.

Spinal cord is located in the spinal canal and has the appearance of a white cord stretching from the occipital foramen to the lower back. There are longitudinal grooves along the anterior and posterior surfaces of the spinal cord; the spinal canal runs in the center, around which the Gray matter - an accumulation of a huge number of nerve cells that form a butterfly outline. Along the outer surface of the spinal cord there is white matter - a cluster of bundles of long processes of nerve cells.

In the gray matter, anterior, posterior and lateral horns are distinguished. They lie in the anterior horns motor neurons, in the rear - insert, which communicate between sensory and motor neurons. Sensory neurons lie outside the cord, in the spinal ganglia along the sensory nerves. Long processes extend from the motor neurons of the anterior horns - anterior roots, forming motor nerve fibers. Axons of sensory neurons approach the dorsal horns, forming back roots, which enter the spinal cord and transmit excitation from the periphery to the spinal cord. Here the excitation is switched to the interneuron, and from it to the short processes of the motor neuron, from which it is then communicated to the working organ along the axon.

In the intervertebral foramina, the motor and sensory roots are connected, forming mixed nerves, which then split into front and rear branches. Each of them consists of sensory and motor nerve fibers. Thus, at the level of each vertebra from the spinal cord in both directions only 31 pairs leave spinal nerves mixed type. 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 sensitive, transmitting excitation to the brain, others - downward or motor, which conduct impulses from the brain to certain segments of the spinal cord.

Function of the spinal cord. The spinal cord performs two functions - reflex and conduction.

Each reflex is carried out by a strictly defined part of the central nervous system - the nerve center. A nerve center is a collection of nerve cells located in one of the parts of the brain and regulating the activity of an organ or system. For example, the center of the knee reflex is located in the lumbar spinal cord, the center of urination is in the sacral, and the center of pupil dilation is in the upper thoracic segment of the spinal cord. The vital motor center of the diaphragm is localized in the III-IV cervical segments. Other centers - respiratory, vasomotor - are located in the medulla oblongata. In the future, some more nerve centers that control certain aspects of the body’s life will be considered. The nerve center consists of many interneurons. It processes the information that comes from the corresponding receptors and generates impulses that are transmitted to the executive organs - the heart, blood vessels, skeletal muscles, glands, etc. As a result, their functional state changes. To regulate the reflex and 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 connected to the receptors and executive organs of the body. 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.

Another function of the spinal cord is conduction. Bundles of nerve fibers that form white matter connect various parts of the spinal cord to each other and the brain to the spinal cord. There are ascending pathways that carry impulses to the brain, and descending pathways that carry impulses from the brain to the spinal cord. According to the first, excitation arising in the receptors of the skin, muscles, and internal organs is carried along the spinal nerves to the dorsal roots of the spinal cord, perceived by sensitive neurons of the spinal nodes and from here sent either to the dorsal horns of the spinal cord, or as part of the white matter reaches the trunk, and then the cortex cerebral hemispheres. Descending pathways carry excitation from the brain to the motor neurons of the spinal cord. From here, excitation is transmitted along the spinal nerves to the executive organs.

The activity of the spinal cord is controlled by the brain, which regulates spinal reflexes.

Brain located in the brain part of the skull. Its average weight is 1300-1400 g. After a person is born, brain growth continues up to 20 years. It consists of five sections: the anterior (cerebral hemispheres), intermediate, middle "hindbrain and medulla oblongata. Inside the brain there are four interconnected cavities - cerebral ventricles. They are filled with cerebrospinal fluid. The first and second ventricles are located in the cerebral hemispheres, the third - in the diencephalon, and the fourth - in the medulla oblongata. The hemispheres (the newest part in evolutionary terms) reach a high level of development in humans, making up 80% of the mass of the brain. The phylogenetically more ancient part is the brain stem. The trunk includes the medulla oblongata, pons, midbrain and diencephalon. The white matter of the trunk contains numerous nuclei of gray matter. The nuclei of 12 pairs of cranial nerves also lie in the brain stem. The brainstem is covered by the cerebral hemispheres.

The medulla oblongata is a continuation of the spinal cord and repeats its structure: there are also grooves on the anterior and posterior surfaces. It consists of white matter (conducting bundles), where clusters of gray matter are scattered - the nuclei from which cranial nerves originate - from the IX to the XII pairs, including the glossopharyngeal (IX pair), vagus (X pair), innervating the respiratory organs, blood circulation, digestion and other systems, sublingual (XII pair).. At the top, the medulla oblongata continues into a thickening - pons, and from the sides why the lower cerebellar peduncles extend. From above and from the sides, almost the entire medulla oblongata is covered by the cerebral hemispheres and the cerebellum.

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

The hindbrain includes the pons and cerebellum. Pons It is bounded below by the medulla oblongata, from above it passes into the cerebral peduncles, and its lateral sections form the middle cerebellar peduncles. The substance of the pons contains the nuclei of the V to VIII pairs of cranial nerves (trigeminal, abducens, facial, auditory).

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

The cerebral cortex controls the activity of the cerebellum. The midbrain is located in front of the pons and is represented by quadrigeminal And legs of the brain. In its center there is a narrow canal (brain aqueduct), which connects the III and IV 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 cerebral peduncles the pathways from the medulla oblongata continue; pons to the cerebral hemispheres. The midbrain plays an important role in the regulation of tone and in the implementation of reflexes that make standing and walking possible. The sensitive nuclei of the midbrain are located in the quadrigeminal tubercles: the upper ones contain nuclei associated with the organs of vision, and the lower ones contain nuclei associated with the organs of hearing. With their participation, orienting reflexes to light and sound are carried out.

The diencephalon occupies the most high position and lies anterior to the cerebral peduncles. Consists of two visual tuberosities, supracubertal, subtubercular region and geniculate bodies. Along the periphery of the diencephalon there is white matter, and in its thickness there are nuclei of gray matter. Visual tuberosities - the main subcortical centers of sensitivity: impulses from all receptors of the body arrive here along the ascending pathways, and from here to the cerebral cortex. In the sub-hillock part (hypothalamus) there are centers, the totality of which represents the highest subcortical center of the autonomic nervous system, regulating metabolism in the body, heat transfer, and the constancy of the internal environment. The parasympathetic centers are located in the anterior parts of the hypothalamus, and the sympathetic centers in the posterior parts. The subcortical visual and auditory centers are concentrated in the nuclei of the geniculate bodies.

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

Autonomic nervous system. Centrifugal nerve fibers are divided into somatic and autonomic. Somatic conduct impulses to skeletal striated muscles, causing them to contract. They originate from motor centers located in the brainstem, in the anterior horns of all segments of the spinal cord and, without interruption, reach executive bodies. Centrifugal nerve fibers going to internal organs and systems, to all tissues of the body, are called vegetative. Centrifugal neurons of the autonomic nervous system lie outside the brain and spinal cord - in the peripheral nerve nodes - ganglia. The processes of ganglion cells end in smooth muscles, in the heart muscle and glands.

The function of the autonomic nervous system is to regulate physiological processes in the body, to ensure the body's adaptation to changing environmental conditions.

The autonomic nervous system does not have its own special sensory pathways. Sensitive impulses from organs are sent along sensory fibers common to the somatic and autonomic nervous systems. The regulation of the autonomic nervous system is carried out by the cerebral cortex.

The autonomic nervous system consists of two parts: sympathetic and parasympathetic. Nuclei of the sympathetic nervous system located in the lateral horns of the spinal cord, from the 1st thoracic to the 3rd lumbar segments. Sympathetic fibers leave the spinal cord as part of the anterior roots and then enter the nodes, which, connecting in short bundles in a chain, form a paired border trunk located on both sides spinal column. Next, from these nodes, the nerves go to the organs, forming plexuses. Impulses entering the organs through sympathetic fibers provide reflex regulation of their activity. They strengthen and increase heart rate, cause rapid redistribution of blood by narrowing some vessels and dilating others.

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

Most internal organs receive dual autonomic innervation, that is, they are approached by both sympathetic and parasympathetic nerve fibers, which function in close interaction, exerting the opposite effect on the organs. It has great importance in adapting the body to constantly changing environmental conditions.

The forebrain consists of highly developed hemispheres and the middle part connecting them. The right and left hemispheres are separated from each other by a deep fissure at the bottom of which lies the corpus callosum. Corpus callosum connects both hemispheres through long processes of neurons that form pathways. The cavities of the hemispheres are represented lateral ventricles(I and II). The surface of the hemispheres is formed by gray matter or the cerebral cortex, represented by neurons and their processes; under the cortex lies white matter - pathways. Pathways connect individual centers within one hemisphere, or the right and left halves of the brain and spinal cord, or different floors of the central nervous system. The white matter also contains clusters of nerve cells that form the subcortical nuclei of the gray matter. Part of the cerebral hemispheres is the olfactory brain with a pair of olfactory nerves extending from it (I pair).

The total surface of the cerebral cortex is 2000 - 2500 cm 2, its thickness is 2.5 - 3 mm. The cortex includes more than 14 billion nerve cells arranged in six layers. In a three-month-old embryo, the surface of the hemispheres is smooth, but the cortex grows faster than the braincase, so the cortex forms folds - convolutions, limited by grooves; they contain about 70% of the surface of the cortex. Furrows divide the surface of the hemispheres into lobes. Each hemisphere has four lobes: frontal, parietal, temporal And occipital, The deepest grooves are the central ones, separating the frontal lobes from the parietal lobes, and the lateral ones, which delimit the temporal lobes from the rest; The parieto-occipital sulcus separates the parietal lobe from the occipital lobe (Fig. 85). Anterior to the central sulcus in the frontal lobe is the anterior central gyrus, behind it is the posterior central gyrus. The lower surface of the hemispheres and the brain stem is called base of the brain.

To understand how the cerebral cortex functions, you need to remember that the human body has a large number of a variety of highly specialized receptors. Receptors are capable of detecting the most minor changes in the external and internal environment.

Receptors located in the skin respond to changes in the external environment. In muscles and tendons there are receptors that signal to the brain about the degree of muscle tension and joint movements. There are receptors that respond to changes in the chemical and gas composition of the blood, osmotic pressure, temperature, etc. In the receptor, irritation is converted into nerve impulses. Along sensitive nerve pathways, impulses are carried to the corresponding sensitive zones of the cerebral cortex, where a specific sensation is formed - visual, olfactory, etc.

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

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

The activity of analyzers reflects the external material world in our consciousness. This enables mammals to adapt to environmental conditions by changing behavior. Man, learning natural phenomena, the laws of nature and creating tools, actively changes the external environment, adapting it to his needs.

Many neural processes take place in the cerebral cortex. Their purpose is twofold: interaction of the body with the external environment (behavioral reactions) and the unification of body functions, nervous regulation of all organs. The activity of the cerebral cortex of humans and higher animals was defined by I. P. Pavlov as higher nervous activity, representing conditioned reflex function cerebral cortex. Even earlier, the main principles about the reflex activity of the brain were expressed by I. M. Sechenov in his work “Reflexes of the Brain.” However, the modern idea of higher nervous activity created by I.P. Pavlov, who, by studying conditioned reflexes, substantiated the mechanisms of adaptation of the body to changing environmental conditions.

Conditioned reflexes are developed during the individual life of animals and humans. Therefore, conditioned reflexes are strictly individual: some individuals may have them, while others may not. For such reflexes to occur, the action of the conditioned stimulus must coincide in time with the action of the unconditioned stimulus. Only the repeated coincidence of these two stimuli leads to the formation of a temporary connection between the two centers. According to the definition of I.P. Pavlov, reflexes acquired by the body during its life and resulting from the combination of indifferent stimuli with unconditioned ones are called conditioned.

In humans and mammals, new conditioned reflexes are formed throughout life; they are locked in the cerebral cortex and are temporary in nature, since they represent temporary connections of the organism with the environmental conditions in which it is located. Conditioned reflexes in mammals and humans are very complex to develop, since they cover a whole complex of stimuli. In this case, connections arise between different parts of the cortex, between the cortex and subcortical centers, etc. The reflex arc becomes significantly more complex and includes receptors that perceive conditioned stimulation, a sensory nerve and the corresponding pathway with subcortical centers, a section of the cortex that perceives conditioned irritation, second area associated with the center of the unconditioned reflex, center of the unconditioned reflex, motor nerve, working organ.

During the individual life of an animal and a person, countless formed conditioned reflexes serve as the basis for his behavior. Animal training is also based on the development of conditioned reflexes, which arise as a result of combination with unconditioned ones (giving treats or encouraging affection) when jumping through a burning ring, lifting on their paws, etc. Training is important in the transportation of goods (dogs, horses), border protection, hunting (dogs), etc.

Various environmental stimuli acting on the body can cause not only the formation of conditioned reflexes in the cortex, but also their inhibition. If inhibition occurs immediately upon the first action of the stimulus, it is called unconditional. When braking, suppression of one reflex creates conditions for the emergence of another. For example, the smell of a predatory animal inhibits the consumption of food by a herbivore and causes an orienting reflex, in which the animal avoids meeting the predator. In this case, in contrast to unconditional inhibition, the animal develops conditioned inhibition. It occurs in the cerebral cortex when a conditioned reflex is reinforced by an unconditioned stimulus and ensures the animal’s coordinated behavior in constantly changing environmental conditions, when useless or even harmful reactions are excluded.

Higher nervous activity. Human behavior is associated with conditioned-unconditioned reflex activity. Based on unconditioned reflexes, starting from the second month after birth, the child develops conditioned reflexes: as he develops, communicates with people and is influenced by the external environment, temporary connections constantly arise in the cerebral hemispheres between their various centers. The main difference between human higher nervous activity is thinking and speech, which appeared as a result of labor social activity. Thanks to the word, generalized concepts and ideas arise, as well as the ability for logical thinking. As a stimulus, a word evokes a large number of conditioned reflexes in a person. They are the basis for training, education, and the development of work skills and habits.

Based on the development of speech function in people, I. P. Pavlov created the doctrine of first and second signaling systems. The first signaling system exists in both humans and animals. This system, the centers of which are located in the cerebral cortex, perceives through receptors direct, specific stimuli (signals) of the external world - objects or phenomena. In humans, they create the material basis for sensations, ideas, perceptions, impressions of surrounding nature and social environment, and this forms the basis concrete thinking. But only in humans there is a second signaling system associated with the function of speech, with the word audible (speech) and visible (writing).

A person can be distracted from the characteristics of individual objects and find common properties in them, which are generalized in concepts and united by one word or another. For example, the word “birds” summarizes representatives of various genera: swallows, tits, ducks and many others. Likewise, every other word acts as a generalization. For a person, a word is not only a combination of sounds or an image of letters, but first of all a form of representing material phenomena and objects of the surrounding world in concepts and thoughts. With the help of words, general concepts are formed. Through the word, signals about specific stimuli are transmitted, and in this case the word serves as a fundamentally new stimulus - signal signals.

When generalizing various phenomena, a person discovers natural connections between them - laws. A person’s ability to generalize is the essence abstract thinking, which distinguishes him from animals. Thinking is the result of the function of the entire cerebral cortex. The second signaling system arose as a result of a joint labor activity people, in which speech became a means of communication between them. On this basis, verbal human thinking arose and developed further. The human brain is the center of thinking and the center of speech associated with thinking.

The dream and its meaning. According to the teachings of I.P. Pavlov and other domestic scientists, sleep is a deep protective inhibition that prevents overwork and exhaustion of nerve cells. It covers the cerebral hemispheres, midbrain and diencephalon. In

During sleep, the activity of many physiological processes sharply decreases, only the parts of the brain stem that regulate vital functions - breathing, heartbeat - continue to function, but their function is also reduced. The sleep center is located in the hypothalamus of the diencephalon, in the anterior nuclei. The posterior nuclei of the hypothalamus regulate the state of awakening and wakefulness.

Monotonous speech, quiet music, general silence, darkness, and warmth help the body fall asleep. During partial sleep, some “sentinel” points of the cortex remain free from inhibition: the mother sleeps soundly when there is noise, but the slightest rustle of the child wakes her up; soldiers sleep with the roar of guns and even on the march, but immediately respond to the orders of the commander. Sleep reduces the excitability of the nervous system, and therefore restores its functions.

Sleep occurs quickly if stimuli that interfere with the development of inhibition, such as loud music, bright lights, etc., are eliminated.

Using a number of techniques, preserving one excited area, it is possible to induce artificial inhibition in the cerebral cortex (dream-like state) in a person. This condition is called hypnosis. I.P. Pavlov considered it as a partial inhibition of the cortex limited to certain zones. With the onset of the deepest phase of inhibition, weak stimuli (for example, a word) are more effective than strong ones (pain), and high suggestibility is observed. This state of selective inhibition of the cortex is used as therapeutic appointment, during which the doctor instills in the patient that it is necessary to eliminate harmful factors - smoking and drinking alcohol. Sometimes hypnosis can be caused by a strong, unusual stimulus under given conditions. This causes “numbness,” temporary immobilization, and concealment.

Dreams. Both the nature of sleep and the essence of dreams are revealed on the basis of the teachings of I. P. Pavlov: during a person’s wakefulness, excitation processes predominate in the brain, and when all parts of the cortex are inhibited, a complete deep dream. With such sleep there are no dreams. In the case of incomplete inhibition, individual uninhibited brain cells and areas of the cortex enter into various interactions with each other. Unlike normal connections in the waking state, they are characterized by quirkiness. Every dream is a more or less vivid and complex event, a picture, a living image that periodically arises in a sleeping person as a result of the activity of cells that remain active during sleep. According to I.M. Sechenov, “dreams are unprecedented combinations of experienced impressions.” Often, external irritations are included in the content of a dream: a warmly covered person sees himself in hot countries, the cooling of his feet is perceived by him as walking on the ground, in the snow, etc. Scientific analysis of dreams from a materialistic point of view has shown the complete failure of the predictive interpretation of “prophetic dreams.”

Hygiene of the nervous system. The functions of the nervous system are carried out by balancing excitatory and inhibitory processes: excitation at some points is accompanied by inhibition at others. At the same time, the functionality of the nervous tissue is restored in the areas of inhibition. Low mobility contributes to fatigue mental work and monotony - with physical. Fatigue of the nervous system weakens its regulatory function and can provoke the occurrence of a number of diseases: cardiovascular, gastrointestinal, skin, etc.

Most favorable conditions for the normal functioning of the nervous system are created with the correct alternation of work, active rest and sleep. Elimination of physical fatigue and nervous fatigue occurs when switching from one type of activity to another, in which different groups of nerve cells will alternately experience the load. In conditions of high automation of production, the prevention of overwork is achieved by the personal activity of the employee, his creative interest, and the regular alternation of moments of work and rest.

Drinking alcohol and smoking cause great harm to the nervous system.

The human nervous system is a stimulator of the muscular system, which we talked about in. As we already know, muscles are needed to move body parts in space, and we have even studied specifically which muscles are intended for which work. But what powers the muscles? What and how makes them work? This will be discussed in this article, from which you will learn the necessary theoretical minimum to master the topic indicated in the title of the article.

First of all, it is worth informing that the nervous system is designed to transmit information and commands to our body. The main functions of the human nervous system are the perception of changes within the body and the space surrounding it, the interpretation of these changes and the response to them in the form of a certain form (including muscle contraction).

Nervous system– many different nervous structures interacting with each other, providing, along with the endocrine system, coordinated regulation of the work of most of the body’s systems, as well as a response to changing conditions of the external and internal environment. This system combines sensitization, motor activity and the correct functioning of systems such as endocrine, immune and more.

Structure of the nervous system

Excitability, irritability and conductivity are characterized as functions of time, that is, it is a process that occurs from irritation to the appearance of an organ response. The propagation of a nerve impulse in a nerve fiber occurs due to the transition of local foci of excitation to adjacent inactive areas of the nerve fiber. The human nervous system has the property of transforming and generating energies from the external and internal environment and converting them into a nervous process.

Structure of the human nervous system: 1-brachial plexus; 2- musculocutaneous nerve; 3rd radial nerve; 4- median nerve; 5- iliohypogastric nerve; 6-femoral-genital nerve; 7- locking nerve; 8-ulnar nerve; 9 - common peroneal nerve; 10- deep peroneal nerve; 11- superficial nerve; 12- brain; 13- cerebellum; 14- spinal cord; 15- intercostal nerves; 16- hypochondrium nerve; 17 - lumbar plexus; 18-sacral plexus; 19-femoral nerve; 20- genital nerve; 21-sciatic nerve; 22- muscular branches of the femoral nerves; 23- saphenous nerve; 24 tibial nerve

The nervous system functions as a whole with the senses and is controlled by the brain. The largest part of the latter is called the cerebral hemispheres (in the occipital region of the skull there are two smaller hemispheres of the cerebellum). The brain connects to the spinal cord. The right and left cerebral hemispheres are connected to each other by a compact bundle of nerve fibers called the corpus callosum.

Spinal cord- the main nerve trunk of the body - passes through the canal formed by the foramina of the vertebrae and stretches from the brain to the sacral spine. On each side of the spinal cord, nerves extend symmetrically to different parts of the body. The sense of touch is, in general terms, provided by certain nerve fibers, countless endings of which are located in the skin.

Classification of the nervous system

The so-called types of the human nervous system can be represented as follows. The entire integral system is conditionally formed by: the central nervous system - CNS, which includes the brain and spinal cord, and the peripheral nervous system - PNS, which includes numerous nerves extending from the brain and spinal cord. The skin, joints, ligaments, muscles, internal organs and sensory organs send input signals to the central nervous system via PNS neurons. At the same time, outgoing signals from the central nervous system are sent by the peripheral nervous system to the muscles. As visual material, below, the complete human nervous system (diagram) is presented in a logically structured manner.

central nervous system- the basis of the human nervous system, which consists of neurons and their processes. The main and characteristic function of the central nervous system is the implementation of reflective reactions of varying degrees of complexity, called reflexes. The lower and middle parts of the central nervous system - the spinal cord, medulla oblongata, midbrain, diencephalon and cerebellum - control the activities of individual organs and systems of the body, realize communication and interaction between them, ensure the integrity of the body and its correct functioning. The highest department of the central nervous system - the cerebral cortex and the nearest subcortical formations - for the most part controls the connection and interaction of the body as an integral structure with the outside world.

Peripheral nervous system- is a conditionally allocated part of the nervous system, which is located outside the brain and spinal cord. Includes the nerves and plexuses of the autonomic nervous system, connecting the central nervous system to the organs of the body. Unlike the CNS, the PNS is not protected by bones and can be affected by mechanical damage. In turn, the peripheral nervous system itself is divided into somatic and autonomic.

Somatic nervous system- part of the human nervous system, which is a complex of sensory and motor nerve fibers responsible for excitation of muscles, including skin and joints. It also guides the coordination of body movements and the reception and transmission of external stimuli. This system performs actions that a person controls consciously.
Autonomic nervous system divided into sympathetic and parasympathetic. The sympathetic nervous system controls the response to danger or stress, and can, among other things, cause an increase in heart rate, increased blood pressure and stimulation of the senses by increasing the level of adrenaline in the blood. The parasympathetic nervous system, in turn, controls the state of rest, and regulates the contraction of the pupils, the slowing of the heart rate, the dilation of blood vessels and the stimulation of the digestive and genitourinary systems.

Above you can see a logically structured diagram showing the parts of the human nervous system, in order corresponding to the above material.

Structure and functions of neurons

All movements and exercises are controlled by the nervous system. Main structural and functional unit The nervous system (both central and peripheral) is the neuron. Neurons– these are excitable cells that are capable of generating and transmitting electrical impulses (action potentials).

Structure of a nerve cell: 1- cell body; 2- dendrites; 3- cell nucleus; 4- myelin sheath; 5- axon; 6- axon ending; 7- synaptic thickening

The functional unit of the neuromuscular system is the motor unit, which consists of a motor neuron and the muscle fibers it innervates. Actually, the work of the human nervous system, using the process of muscle innervation as an example, occurs as follows.

The cell membrane of the nerve and muscle fiber is polarized, that is, there is a potential difference across it. The inside of the cell contains a high concentration of potassium ions (K), and the outside contains high concentrations of sodium ions (Na). At rest, the potential difference between the internal and outside cell membrane does not lead to the appearance electric charge. This specific value is the resting potential. Due to changes in the external environment of the cell, the potential on its membrane constantly fluctuates, and if it increases and the cell reaches its electrical threshold for excitation, there is a sharp change in the electrical charge of the membrane, and it begins to conduct an action potential along the axon to the innervated muscle. By the way, in large muscle groups, one motor nerve can innervate up to 2-3 thousand muscle fibers.

In the diagram below you can see an example of the path a nerve impulse takes from the moment a stimulus occurs to the receipt of a response to it in each individual system.

Nerves connect to each other through synapses, and to muscles through neuromuscular junctions. Synapse- this is the point of contact between two nerve cells, and - the process of transmitting an electrical impulse from a nerve to a muscle.

Synaptic connection: 1- neural impulse; 2- receiving neuron; 3- axon branch; 4- synaptic plaque; 5- synaptic cleft; 6- neurotransmitter molecules; 7- cellular receptors; 8- dendrite of the receiving neuron; 9- synaptic vesicles

Neuromuscular contact: 1- neuron; 2- nerve fiber; 3- neuromuscular contact; 4- motor neuron; 5- muscle; 6- myofibrils

Thus, as we have already said, the process of physical activity in general and muscle contraction in particular is completely controlled by the nervous system.

Conclusion

Today we learned about the purpose, structure and classification of the human nervous system, as well as how it is related to its motor activity and how it affects the functioning of the whole organism as a whole. Since the nervous system is involved in regulating the activity of all organs and systems of the human body, including, and perhaps primarily, the cardiovascular system, then in the next article in the series about the systems of the human body, we will move on to its consideration.

A person? What functions does the nervous system perform in our body? What is the structure of our body? What is the human nervous system called? What is the anatomy and structure of the nervous system and how does it transmit information? In our body there are many channels through which streams of data, chemicals, electricity... And all this is inside our nervous system. After reading this article, you will gain a basic knowledge of how the human body works.

Nervous system

What is the human nervous system for? Each element of the nervous system has its own function, purpose and purpose. Now sit back, relax and enjoy reading. I see you at the computer, with a tablet or phone in your hand. Imagine the situation: CogniFit Do you know how you managed to do all this? What parts of the nervous system were involved in this? I suggest you answer all these questions yourself after you read this material.

*Ectodermic origin means that the nervous system is located within the outer germ layer of the embryo (human/animal). The ectoderm also includes nails, hair, feathers...

What are the functions of the nervous system? What functions does the nervous system perform in the human body? The main function of the nervous system is to quickly detection and processing signals of all types (both external and internal), as well as coordination and control of all organs of the body. Thus, thanks to the nervous system, we can effectively, correctly and promptly interact with the environment.

2. Function of the nervous system

How does the nervous system work? In order for information to reach our nervous system, receptors are needed. Eyes, ears, skin... They collect the information we perceive and send it throughout the body to the nervous system in the form of electrical impulses.

However, we receive information not only from the outside. The nervous system is also responsible for all internal processes: heartbeat, digestion, bile secretion, etc.

What else is the nervous system responsible for?

Controls hunger, thirst and sleep cycle, and also monitors and regulates body temperature (using ).
Emotions (through) and thoughts.
Learning and memory (via ).
Movement, balance and coordination (using the cerebellum).
Interprets all information received through the senses.
Work of internal organs: pulse, digestion, etc.
Physical and emotional reactions

and many other processes.

3. Characteristics of the Central Nervous System

Features of the Central Nervous System (CNS):

Its main parts are well protected from the external environment. For example, Brain covered by three membranes called the meninges, which in turn are protected by the cranium. Spinal cord also protected by a bone structure - the spine. All vital organs of the human body are protected from the external environment. “I imagine the Brain as a king, sitting on a throne in the middle of a castle and protected by the powerful walls of his fortress.”
Cells located in the central nervous system form two different structures - gray and white matter.
In order to perform its main function (receiving and transmitting information and orders), the central nervous system needs an intermediary. Both the brain and spinal cord are filled with cavities containing cerebrospinal fluid. In addition to the function of transmitting information and substances, it is also responsible for cleansing and maintaining homeostasis.

4.- Formation of the Central Nervous System

During the embryonic phase of development, the nervous system is formed, consisting of the brain and spinal cord. Let's look at each of them:

Brain

Parts of the brain called the primitive brain:

Forebrain: with the help of the telencephalon and diencephalon, it is responsible for memories, thinking, coordination of movements, and speech. In addition, it regulates appetite, thirst, sleep and sexual impulses.
Midbrain: connects the cerebellum and brain stem to the diencephalon. It is responsible for conducting motor impulses from the cerebral cortex to the brain stem and sensory impulses from the spinal cord to the thalamus. Participates in the control of vision, hearing and sleep.
Diamond Brain: with the help of the cerebellum, tubercle and bulb of the medulla oblongata, it is responsible for vital organic processes, such as breathing, blood circulation, swallowing, muscle tone, eye movements, etc.

Spinal cord

With the help of this nerve cord, information and nerve impulses are transmitted from the brain to the muscles. Its length is approximately 45 cm, diameter - 1 cm. Spinal cord white and is quite flexible. Has reflex functions.

Spinal nerves:

Cervical: neck area.
Pectorals: middle of the spine.
Lumbar: lumbar region.
Sacral (sacral): lower spine.
Coccygeal: last two vertebrae.

Classification of the nervous system

The nervous system is divided into two large groups - the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

The two systems differ in function. The central nervous system, to which the brain belongs, is responsible for logistics. She manages and organizes all processes occurring in our body. The PNS, in turn, is like a courier, sending and receiving external and internal information from the central nervous system to the entire body and back with the help of nerves. This is how the interaction between both systems occurs, ensuring the functioning of the whole body.

The PNS is divided into the Somatic and Autonomic (Autonomic) Nervous Systems. Let's look at this below.

6. Central Nervous System (CNS)

In some cases, the functioning of the Nervous System may be disrupted, and deficits or problems in its functioning may arise. Depending on the affected area of the Nervous System, various types of diseases are distinguished.

Central nervous system diseases are diseases in which the ability to receive and process information, as well as control over body functions, is impaired. These include.

Diseases

Multiple sclerosis. This disease attacks the myelin sheath, damaging nerve fibers. This leads to a decrease in the number and speed of nerve impulses, until they stop. The result is muscle spasms, problems with balance, vision and speech.
Meningitis. This infection is caused by bacteria in the meninges (the membranes that cover the brain and spinal cord). The cause is bacteria or viruses. Among the symptoms are heat, strong headache, stiff neck, drowsiness, loss of consciousness and even convulsions. Bacterial meningitis can be treated with antibiotics, but viral meningitis will not be treated with antibiotics.
Parkinson's disease. This chronic nervous system disorder, caused by the death of neurons in the midbrain (which coordinates muscle movement), has no cure and progresses over time. Symptoms of the disease include tremors of the limbs and slowness of conscious movements.
Alzheimer's disease . This disease leads to memory impairment, changes in character and thinking. Its symptoms include confusion, temporal-spatial disorientation, dependence on other people to carry out daily activities, etc.
Encephalitis. This is an inflammation of the brain caused by bacteria or viruses. Symptoms: headache, difficulty speaking, loss of energy and body tone, fever. May lead to seizures or even death.
Disease Huntington ( Huntington): This is a neurological degenerative hereditary disease of the Nervous System. This disease damages cells throughout the brain, leading to progressive impairment and motor problems.
Tourette's syndrome: Detailed information information about this disease can be found on the NIH page. This disease is defined as:

A neurological disorder characterized by repetitive, stereotypical and involuntary movements accompanied by sounds (tics).

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7. Peripheral I Nervous System and its subtypes

As we mentioned above, the PNS is responsible for sending information through the spinal and spinal nerves. These nerves are located outside the central nervous system, but connect both systems. As with the CNS, there are different PNS diseases depending on the area affected.

Somatic Nervous System

Responsible for connecting our body with the external environment. On the one hand, it receives electrical impulses, with the help of which the movement of skeletal muscles is controlled, and on the other hand, it transmits sensory information from various parts body into the Central Nervous System. Diseases of the somatic nervous system are:

Radial nerve palsy: Damage occurs to the radial nerve, which controls the muscles of the arm. This paralysis results in impaired motor and sensory function of the limb and is therefore also known as “floppy hand.”
Carpal Tunnel Syndrome or Carpal Tunnel Syndrome: The median nerve is affected. The disease is caused by compression of the median nerve between the bones and tendons of the wrist muscles. This leads to numbness and immobility of part of the hand. Symptoms: pain in the wrist and forearm, cramps, numbness...
Guillain's syndrome–Barre: The University of Maryland Medical Center defines the disease as “a severe disorder in which the body's defense system (immune system) mistakenly attacks the nervous system. This leads to nerve inflammation, muscle weakness and other consequences.”
Neurology: This is a sensory disorder of the Peripheral Nervous System (attacks of severe pain). Occurs due to damage to the nerves responsible for sending sensory signals to the brain. Symptoms include severe pain, increased sensitivity skin in the area where the damaged nerve passes.

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Autonomic/Autonomic Nervous System

It is associated with the internal processes of the body and does not depend on the cerebral cortex. Receives information from internal organs and regulates them. Responsible, for example, for the physical manifestation of emotions. It is divided into Sympathetic and Parasympathetic NS. Both are associated with internal organs and perform the same functions, but in the opposite form (for example, the sympathetic department dilates the pupil, and the parasympathetic department constricts it, etc.). Diseases affecting the autonomic nervous system:

Hypotension: low blood pressure, in which the organs of our body are not sufficiently supplied with blood. Her symptoms:
- Dizziness.
- Drowsiness and short-term confusion.
- Weakness.
- Disorientation and even loss of consciousness.
- Fainting.
Hypertension: The Spanish Heart Foundation defines it as “a continuous and sustained increase in blood pressure.”

With hypertension, minute blood volume and vascular resistance increase, which leads to an increase in muscle mass heart (left ventricular hypertrophy). This increase in muscle mass is harmful because it is not accompanied by an equivalent increase in blood flow.

Hirschsprung's disease: This is a congenital disease, an abnormality of the autonomic nervous system, affecting the development of the colon. Characterized by constipation and intestinal obstruction due to a lack of nerve cells in the lower colon. As a result, when body waste accumulates, the brain does not receive a signal about it. This leads to bloating and severe constipation. It is treated surgically.

As we have already mentioned, Autonomous NS is divided into two types:

Sympathetic Nervous System: regulates energy consumption and mobilizes the body in situations. Dilates the pupil, reduces salivation, increases heart rate, relaxes bladder.
Parasympathetic Nervous System: responsible for relaxation and accumulation of resources. Constricts the pupil, stimulates salivation, slows the heartbeat, and contracts the bladder.

The last paragraph may surprise you a little. What does contraction of the bladder have to do with relaxation and relaxation? And how is the decrease in salivation related to activation? The fact is that we are not talking about processes and actions that require activity. It's about what happens as a result of a situation that activates us. For example, in an attack on the street:

Our heart rate increases, our mouth becomes dry, and if we feel extreme fear, we may even wet ourselves (imagine what it would be like to run or fight with a full bladder).
When the dangerous situation has passed and we are safe, our parasympathetic system is activated. The pupils return to normal, the pulse decreases, and the bladder begins to function as usual.

8. Conclusions

Our body is very complex. It consists of a huge number of parts, organs, their types and subspecies.

It cannot be otherwise. We are developed beings at the pinnacle of evolution, and we simply cannot consist of simple structures.

Of course, a lot of information could be added to this article, but that was not its purpose. The purpose of this material is to introduce you to basic information about the human nervous system - what it consists of, what its functions are as a whole and of each part separately.

Let's go back to the situation I talked about at the beginning of the article:

You're waiting for someone and decide to go online to see what's new on the CogniFit blog. The title of this article caught your attention, and you opened it to read it. At this time, a car suddenly honked, startling you, and you looked to where you heard the source of the sound. Then we continued reading. After reading the publication, you decided to leave your review and started typing it...

Having learned how the nervous system works, we can already explain all this in terms of the functions of various parts of the nervous system. You can do this yourself and compare with what is written below:

Ability to sit and hold a posture: The central nervous system, thanks to the hindbrain, maintains muscle tone, blood circulation...
Feel in your hands mobile phone: The Peripheral Somatic Nervous System receives information through touch and sends it to the central nervous system.
Process information read: The central nervous system, with the help of the telencephalon, the brain receives and processes the data that we read.
Raise your head and look at the honking car: The Sympathetic Nervous System is activated, using the medulla oblongata or medulla.