The human body is a multi-stage structure, each organ and system of which is closely interconnected with each other and with the environment. And so that this connection is not interrupted even for a split second, a nervous system is provided - a complex network that permeates the entire human body and is responsible for self-regulation and the ability to adequately respond to external and internal stimuli. Thanks to the well-coordinated work of the nervous system, a person can adapt to the factors of the external world: any, even minor, change in the environment causes nerve cells to transmit hundreds of impulses at an incredibly high speed so that the body can instantly adapt to new conditions. Internal self-regulation works in a similar way, in which the activity of cells is coordinated in accordance with current needs.
The functions of the nervous system affect the most important processes of life, without which the normal existence of the body is unthinkable. These include:
- regulation of the work of internal organs in accordance with external and internal impulses;
- coordination of all units of the body, from the smallest cells to organ systems;
- harmonious interaction between humans and the environment;
- the basis of higher psychophysiological processes characteristic of humans.
How does this complex mechanism work? What cells, tissues and organs make up the human nervous system and what is each of its sections responsible for? A brief excursion into the basic anatomy and physiology of the human body will help you find answers to these questions.
Stages of nervous system development
In evolution, the nervous system has undergone several stages of development, which became turning points in the qualitative organization of its activities.
These stages differ in the number and types of neuronal formations, synapses, signs of their functional specialization, and in the formation of groups of neurons interconnected by common functions. There are three main stages of the structural organization of the nervous system: diffuse, nodular, tubular. The diffuse nervous system is the most ancient, found in coelenterates (hydra). Such a nervous system is characterized by a multiplicity of connections between neighboring elements, which allows excitation to freely spread throughout the nervous network in all directions.
This type of nervous system provides wide interchangeability and thereby greater reliability of functioning, but these reactions are imprecise and vague.
The nodal type of nervous system is typical for worms, mollusks, and crustaceans.
It is characterized by the fact that the connections of nerve cells are organized in a certain way, excitation passes along strictly defined paths. This organization of the nervous system turns out to be more vulnerable. Damage to one node causes dysfunction of the entire organism as a whole, but its qualities are faster and more accurate.
The tubular nervous system is characteristic of chordates; it includes features of the diffuse and nodular types. The nervous system of higher animals took all the best: high reliability of the diffuse type, accuracy, locality, speed of organization of nodal type reactions.
The leading role of the nervous system
At the first stage of the development of the world of living beings, interaction between the simplest organisms was carried out through the aquatic environment of the primitive ocean, into which the chemical substances released by them entered. The first oldest form of interaction between the cells of a multicellular organism is chemical interaction through metabolic products entering the body fluids. Such metabolic products, or metabolites, are the breakdown products of proteins, carbon dioxide, etc. This is the humoral transmission of influences, the humoral mechanism of correlation, or connections between organs.
The humoral connection is characterized by the following features:
- lack of an exact address to which a chemical substance entering the blood or other body fluids is sent;
- the chemical spreads slowly;
- the chemical acts in minute quantities and is usually quickly broken down or eliminated from the body.
Humoral connections are common to both the animal and plant worlds. At a certain stage of development of the animal world, in connection with the appearance of the nervous system, a new, nervous form of connections and regulation is formed, which qualitatively distinguishes the animal world from the plant world. The higher the development of an animal’s organism, the greater the role played by the interaction of organs through the nervous system, which is designated as reflex. In higher living organisms, the nervous system regulates humoral connections. Unlike the humoral connection, the nervous connection has a precise direction to a specific organ and even a group of cells; communication is carried out hundreds of times faster than the speed of distribution of chemicals. The transition from a humoral connection to a nervous connection was not accompanied by the destruction of the humoral connection between the cells of the body, but by the subordination of nervous connections and the emergence of neurohumoral connections.
At the next stage of development of living beings, special organs appear - glands, in which hormones are produced, formed from food substances entering the body. The main function of the nervous system is both to regulate the activity of individual organs among themselves, and in the interaction of the body as a whole with its external environment. Any impact of the external environment on the body appears, first of all, on receptors (sensory organs) and is carried out through changes caused by the external environment and the nervous system. As the nervous system develops, its highest department—the cerebral hemispheres—becomes “the manager and distributor of all the activities of the body.”
How are pathologies of the nervous system treated?
As in all other cases, treatment should begin as early as possible. The first step is to contact a neurologist and undergo diagnostics. Standard examination methods:
- general tests;
- MRI;
- CT.
Treatment is usually complex, using different means:
- medicines;
- procedures (physiotherapy);
- physiotherapy;
- surgical intervention.
Structure of the nervous system
The nervous system is formed by nervous tissue, which consists of a huge number of neurons - a nerve cell with processes.
The nervous system is conventionally divided into central and peripheral.
The central nervous system includes the brain and spinal cord, and the peripheral nervous system includes the nerves that arise from them.
The brain and spinal cord are a collection of neurons. In a cross section of the brain, white and gray matter are distinguished. Gray matter consists of nerve cells, and white matter consists of nerve fibers, which are processes of nerve cells. In different parts of the central nervous system, the location of white and gray matter is different. In the spinal cord, gray matter is located inside, and white matter is outside, but in the brain (cerebral hemispheres, cerebellum), on the contrary, gray matter is outside, white matter is inside. In various parts of the brain there are separate clusters of nerve cells (gray matter) located inside the white matter - the nuclei. Clusters of nerve cells are also located outside the central nervous system. They are called nodes and belong to the peripheral nervous system.
Vascular pathologies
Circulatory disorders have a particularly severe impact on the brain, which is very sensitive to a lack of oxygen and nutrients. Therefore, the consequences can be very serious:
- Stroke is the death of part of the brain cells due to a sudden disruption of blood flow (destruction or complete blockage of blood vessels). Very often, patients cannot fully undergo rehabilitation, which results in lifelong disability of group 1.
- Atherosclerosis is the loss of elasticity of blood vessels, the formation of cholesterol deposits and blood clots on the inner surface.
- An aneurysm is a thinning of the walls of blood vessels, the formation of a seal that can rupture, leading to serious consequences. Death is often observed.
Reflex activity of the nervous system
The main form of activity of the nervous system is the reflex. Reflex is the body’s reaction to changes in the internal or external environment, carried out with the participation of the central nervous system in response to irritation of receptors.
With any irritation, excitation from the receptors is transmitted along centripetal nerve fibers to the central nervous system, from where, through the interneuron along centrifugal fibers, it goes to the periphery to one or another organ, the activity of which changes. This entire path through the central nervous system to the working organ, called the reflex arc, is usually formed by three neurons: sensory, intercalary and motor. A reflex is a complex act in which a significantly larger number of neurons take part. Excitation, entering the central nervous system, spreads to many parts of the spinal cord and reaches the brain. As a result of the interaction of many neurons, the body responds to irritation.
Congenital diseases
A number of diseases of the nervous system arise due to gene disorders (mutations). Another common cause is embryonic developmental disorders or injuries received during birth. The most famous pathologies:
- Epilepsy is a disease accompanied by convulsions and seizures.
- Canavan syndrome is a brain disorder that causes delays in intellectual development. Treatment is impossible.
- Tourette's syndrome is a disease in which a person begins to move involuntarily and even shout words. Usually goes away as you get older.
- Spinal muscular atrophy is a lesion of the neuronal cells of the spinal cord, which impairs the development of muscle tissue, which can be fatal.
- Huntington's chorea - tics, dementia. The pathology is genetically predetermined, but begins to manifest itself only in old age.
Spinal cord
The spinal cord is a cord about 45 cm long, 1 cm in diameter, located in the spinal canal, covered with three meninges: dura, arachnoid and soft (vascular).
The spinal cord is located in the spinal canal and is a cord that at the top passes into the medulla oblongata and at the bottom ends at the level of the second lumbar vertebra. The spinal cord consists of gray matter containing nerve cells and white matter consisting of nerve fibers. Gray matter is located inside the spinal cord and is surrounded on all sides by white matter.
In a cross section, the gray matter resembles the letter H. It distinguishes the anterior and posterior horns, as well as the connecting crossbar, in the center of which there is a narrow canal of the spinal cord containing cerebrospinal fluid. In the thoracic region there are lateral horns. They contain the bodies of neurons that innervate internal organs. The white matter of the spinal cord is formed by nerve processes. Short processes connect sections of the spinal cord, and long ones make up the conductive apparatus of bilateral connections with the brain.
The spinal cord has two thickenings - cervical and lumbar, from which nerves extend to the upper and lower extremities. 31 pairs of spinal nerves arise from the spinal cord. Each nerve begins from the spinal cord with two roots - anterior and posterior. The dorsal roots are sensitive and consist of processes of centripetal neurons. Their bodies are located in the spinal ganglia. The anterior roots - motor - are processes of centrifugal neurons located in the gray matter of the spinal cord. As a result of the fusion of the anterior and posterior roots, a mixed spinal nerve is formed. The spinal cord contains centers that regulate the simplest reflex acts. The main functions of the spinal cord are reflex activity and conduction of excitation.
The human spinal cord contains reflex centers for the muscles of the upper and lower extremities, sweating and urination. The function of excitation is that impulses from the brain to all areas of the body and back pass through the spinal cord. Centrifugal impulses from organs (skin, muscles) are transmitted through ascending pathways to the brain. Along descending pathways, centrifugal impulses are transmitted from the brain to the spinal cord, then to the periphery, to the organs. When the pathways are damaged, there is a loss of sensitivity in various parts of the body, a violation of voluntary muscle contractions and the ability to move.
Chapter 1. The nervous system as a unique natural computer
Structure of the nervous system
Imagine that you are in the cabin of an airplane, which, when landing, flies over the city so low that through the window you can see residential areas in which multi-storey buildings stand either separately or huddled together. Now also imagine that in every apartment of such houses floating under the wing of an airplane there is a computer. And, of course, each such computer can communicate with any other computer not only in the city, but throughout the world. So, one nerve cell is a whole computer, and all the computers that you can imagine at the same time are a semblance of our nervous system. And the main thing in this system is not the computer itself - the cell, but its ability to receive and transmit information.
Information from one computer to another can be transferred in two ways: connecting computers to each other using a special cord (in nerve cells this is an anatomical connection) or using the Internet (functional connections of nerve cells). Neuron
(this is the name of a nerve cell) was created solely for the purpose of receiving information and necessarily, without fail, transmitting it further.
If we continue the analogy with computers, then very soon differences will be revealed - this is understandable, a computer is only a similarity to what nature has created in the human body. The power went out and the computer screen went dark. In a natural computer, in addition to biological electricity, there is another way - with the help of chemicals - mediators, neuropeptides.
It must be said that the neuron has a very interesting structure: like any computer, it has a case - a body. And yet, this is not what the neuron is famous for; the main thing about it is its processes. The entire neuron is somewhat reminiscent of a tree, which has a developed crown and trunk. The crown of a tree is formed by branches, and in a neuron these are short processes, they are called dendrites
.
A tree has a trunk, and a neuron has a long process, an axon.
And now about the junction of nerve cells - this is
a synapse
. If two computers are connected with a cord, then the contact between the computer and the cord will be exactly the same synapse in the nervous system.
And now very good news! The nervous system is a self-programming computer! What does this mean for you personally, for example? This means the following: through training and repeated repetition, you, dear reader, can learn anything! If there is a desire, of course. Bears skate in the circus not just for the sake of our pleasure and fun, but also for clarity, so to speak! If we are bears, then us?! And all thanks to the ability of nerve cells to grow new processes and connect with the necessary nerve cells. You need it, no problem, the neuron cell begins this painstaking work of growing new dendrites-branches! You don’t need any more – no problem either, the unnecessary ones disappear.
The more you read and try to remember new things, the longer your brain remains young, the better your memory, your thinking. This is a useful thing - to move your convolutions! By the way, no joke - this is a reliable remedy for dementia in old age!
The emergence of new processes and synapses and the partial disintegration of existing ones underlie learning, adaptation, compensation and restoration of impaired functions.
The body and processes of a neuron even differ in color: the place where there are many nerve cell bodies is gray, but the accumulation of processes is white. The processes united together are already a nerve
, and the accumulation of neuron bodies is
a nerve ganglion
.
The nerve ganglion is an anatomical concept. If several neurons perform the same function, this is already a nerve center.
In order to understand how the nervous system works, let's look at an example. Surely there has been a time in your life when, through carelessness or inexperience, you touched something hot with your hand. Remember, before you had time to think of anything, your hand pulled back on its own. This is the simplest reflex, and this kind of work of the nervous system, when an action is carried out as if by itself, without your thinking, is called reflex.
As you understand, such activity is simply vital.
How is it carried out? The skin contains special nerve endings called receptors that distinguish, for example, a cold touch or a hot touch. A long process of a neuron approaches these receptors, and the neuron itself is located in the central nervous system, in the spinal cord, and specifically in the intervertebral node.
Receptors are able to convert mechanical stimulation into an electrical impulse that runs along the process and reaches the body of the neuron. A neuron receives information and transmits the potential further to the body of another neuron, like one computer to another through an electrical cord. Of course, the neuron, which is located in the spinal cord, also has a long process that goes from the spinal cord directly to the muscle. The muscle perceives the impulse and does what it knows how to do - it contracts. The hand withdraws. The path from skin receptors through the spinal cord to the muscle is called a reflex arc. Essentially, when we pull our hand away from a hot surface, we are thinking with our spinal cord!
Spinal cord
- This is already a department of the central nervous system, and the body takes great care of it. He, like a treasure, is packed in armor made of vertebrae. Very reliable protection, both durable and mobile.
The spinal cord itself is a cylindrical cord 41-45 cm long. The most remarkable thing about it, that is, what is immediately noticeable, are its roots. These roots are very cleverly arranged: they extend from the spinal cylinder in front and behind, and on the side of it they join together, forming the spinal nerve, which in turn passes through the hole between two adjacent vertebrae.
In total, such nerves extending from the lateral surface of the spinal cord, spinal roots,
31 pairs. The functions of the remarkable roots of the spinal cord were discovered through an experiment by two outstanding scientists - the Scot Bell and the Frenchman Magendie. It turned out that cutting the anterior roots leads to the inability to move the limbs, that is, they become completely immobile, paralyzed, but the sensitivity in them remains completely intact. When the dorsal roots are cut, on the contrary, sensitivity in the limbs is lost, but movements in them are preserved.
The spinal cord collects all information from the skin, muscles, blood vessels, intestines, and genitals through these roots. And all this information is processed by the spinal cord without our conscious participation and transmitted to the muscles of the skeleton (arms, legs, torso, everything except the face), and internal organs. The work, one might say, is in full swing, but we don’t feel it at all, and that’s wonderful.
There is another curious detail related to the unconscious, i.e., reflex, activity of the spinal cord. It turns out that we can feel quite alert when our skeletal muscles are toned, that is, not relaxed. And this tone is maintained by special impulses through the motor neurons of the same spinal cord.
Perhaps some of you, dear readers, have noticed that you feel better in sunny weather, for example, but for others, on the contrary, give it some rain, and longer! This phenomenon is called meteosensitivity, and it is realized with the help of special flows of information coming from above, from our personal power plant, the reticular formation, located in the brain and directly related to another part of the nervous system - the part of the autonomic nervous system. Work or don’t work your muscles, and if the reticular formation in our head is lazy and does not have enough strength to send impulses to special motor neurons in the spinal cord, then you won’t find a feeling of vigor during the day, lethargy and laziness result.
And yet, scientists were very curious about what kind of activity is inherent in the spinal cord itself, without the influences of the head, so to speak, regardless of the influences of the brain. To do this, a special experiment was carried out on animals: the brain was separated from the spinal cord. Such an animal has no voluntary movements, it has ceased to feel and breathe. The respiratory function was supported by artificial devices. But some things still remained: the reflex activity of the skeletal muscles was preserved (i.e., the animal could not run away from the scientists, but pulling back a limb is welcome), blood pressure, urination reflexes, defecation, and some sexual intercourse were normal. reflexes.
This is how we quietly approached the definition of the functions inherent in the spinal cord. This is already familiar to us reflexive, i.e. automatic, activity, and, in addition, conductive - from the brain and back.
I hope you have already understood that the central nervous system includes not only the spinal cord, but also the brain, which, like the spinal cord, is reliably protected, completely covered by the skull and has a shock absorption system - a special liquid, cerebrospinal fluid, which circulates between the membranes brain. The connection between the brain and the spinal cord is through the foramen magnum of the skull.
But this is not the whole division of the nervous system - into the central
and
peripheral
.
There is also a division into somatic and vegetative. The somatic nervous
system contains the root "soma" in its name, which means "body". That’s right, this system is mainly responsible for the functioning of the skeletal muscles.
Autonomic nervous system,
on the contrary, it regulates the functioning of internal organs, and with the help of two different, opposite influences, which are successfully carried out by two subsections of the autonomic nervous system - sympathetic and parasympathetic.
The somatic and autonomic nervous systems differ in function, like the animal and plant worlds. Even in the names of these subsystems one hears and writes “soma” (“body”) and “vegetatics” (“plant”). These analogies will help us better understand the subtle differences in their functional activities.
So, only an animal has eyes, ears, a throat, it is alive while it moves, and can find food for itself as long as its body is preserved. This is not the case with a plant - the tree sheds its leaves for the winter, and the life in it is, as it were, packed away until spring. The plant is alive as long as it has roots, and new shoots can grow in place of a broken branch or even a cut trunk.
Somatic nervous system
belongs to the cerebral cortex,
and the autonomic
part belongs to the subcortex, the stem part of the brain. Somatics dominates during the day, and vegetatives dominates at night. That is, the tone of the somatic nervous system during the daytime prevails over the tone of the autonomic nervous system. Knowing this, we can easily understand in the future why some people experience palpitations more often at night.
During the day, the muscles of the body recharge the centers of the autonomic nervous system with energy, thereby allowing it to have the necessary resource for normal functioning. Do I need to add after this how important reasonable physical exercise is! And if, nevertheless, your work, which requires nervous tension, does not leave you the opportunity for physical activity, is it any wonder that at night there is no sleep, and your heart suddenly seizes?
By the way, stress is realized through the somatic nervous system and is triggered when a large focus of excitation occurs in the cerebral cortex. More often these are some difficult or completely unsolvable social problems. At this moment, all other functions of the body seem to be suppressed, while stress very quickly devastates the autonomic nervous system, and these are the energy batteries of the whole body. And then depression is just around the corner - beware of stress!
High aspirations, touchiness, and aggressiveness are not compatible with the rational functioning of the nervous system.
Somatic nervous
The system, unlike the vegetative one, has very strong protection in the form of the skull and spine
.
The autonomic system lives like a vine, resting on the spine and passing next to it. Of course, protection in the form of bone cases is reliable, but over time these cases turn into sarcophagi! The bones of the skull completely lose mobility, the holes between the vertebrae collapse, become smaller, are walled up with cholesterol, and become overgrown with bone formations. But it is through these openings that the arteries go to the brain. And what? The blood supply to the brain and its nutrition deteriorate, the brain simply starves, and the somatic nervous system, under its leadership, begins to function weakly, the heart does not receive support from the head, the autonomic system is also left without energy, since the muscles no longer charge it!
Control in the body becomes headless, and the person, sadly enough, loses to the microflora, which in his body begins to unpack its growth and reproduction programs and blooms wildly! This is how diseases begin.
Only a person can exploit his body so mercilessly, busy with the constant, restless solution of social problems, forgetting that the autonomic nervous system at this time is left without energy and quickly works out. And what does she do in response to such an appeal to her? The tree shedding its leaves for winter, remember? That's right, it's the same with us: the autonomic nervous system, not receiving energy from the muscles, declares stress mode and packs up.
We cannot live with ourselves in peace and harmony, we do not hear the quiet voice of reason - we get, like the tomb of a pharaoh, a sarcophagus of osteochondrosis and depression. It seems like they’re still alive, but there’s no time for love!
Let's remember! Functions of the somatic nervous system
, which provides us with behavior, motor activity, learning, protection, receiving information about the environment through the channels of central analyzers - all this depends on the nutrition of the brain and the quality of its bone protection! It would seem that the neck began to creak when turning the head, well, doctors diagnose osteochondrosis, but our adaptation suffers! But not only chondrosis! And the injuries! Did you fall on your tailbone from a bicycle as a child? Did you hit the wall with your head? That's the same! After injuries, pockets of inflammation remain that can disrupt the flow of blood and lymph.
Somatic nervous system
The somatic nervous system is cross-controlled: the muscles on the left are controlled from the right hemisphere of the cerebral cortex, and the muscles on the right are controlled from the left hemisphere. The somatic nervous system, in addition to innervating the muscles, also affects the organs that are located next to these muscles.
If, for example, you do physical exercises for the muscles of the arms and upper shoulder girdle, then you also nourish your heart! The organs are fed from the same arteries as the muscles located next to them. I hope that from now on you will be imbued with greater respect for physical exercises, and after reading the book to the last page, you will begin to perform these exercises with pleasure!
But the main thing is for you to understand now that with the power of the somatic nervous system, which nourishes the muscles, we can support our internal organs, despite the fact that they are under the jurisdiction of a completely different department of the nervous system - the autonomic one.
This is very important when the nutrition of these organs suffers due to disruptions in brain regulation. Osteochondrosis, for example, does not go away immediately, but the heart should always receive good nutrition.
So, we won’t talk any more about the benefits of therapeutic exercises. Everyone has already understood that reasonable, gentle training should become your daily routine. Doctors don’t talk about this, and it’s clear: they don’t have time, they’re treating diseases. And you and I want to stay healthy as long as you want. Again, we are not talking about sports training, but about reasonable, gentle exercises. This is a fundamental difference, and it is very important, since sport itself can lead to stress, here you cannot do without experienced sports doctors and trainers, but we don’t need that.
Autonomic nervous system
Now it's time to talk about the autonomic nervous system.
It is really responsible for the growth of the body, for receiving energy through the lungs and intestines, for blood circulation, and is connected with the rhythm of the heart. Again, she is in charge of bringing to life, implementing the stress regime, which is launched from the centers of the somatic nervous system for flight and fight.
But we just don’t run, because erosion in the intestines and stomach can appear, and neurodermatitis. But the nature of stress may be different, internal, so to speak. For example, after a traumatic brain injury. Like a damaged telephone: the “damaged” brain begins to give completely wrong commands.
But it is with signals emanating from internal organs that the autonomic nervous system works, regulating vascular tone and the movement of blood and lymph. Moreover, these signals are quiet, of small amplitude, and the brain, in which thoughts about where to get money are always spinning, is unlikely to hear them. Of course, this is a joke, but the science of maintaining the autonomic nervous system and its rational management came to us from the East, from China. This is the doctrine of meridians, biologically active points, as well as a wonderful healing method - acupuncture. Now let’s try to remember some parts of the autonomic nervous system: hypothalamus, pituitary gland, vagus nerve, nerve nuclei in the back of the head (head control), sacral nuclei (return blood to the heart), cardiac plexuses (providing a cardiac impulse), thoracic, celiac, lumbar nerves plexus.
The autonomic nervous system relies on three areas in the brain: the nuclei of the cranial nerves, especially the vagus nerve, the hypothalamus, the pituitary gland, and the pineal gland. The control organs of the autonomic nervous system are symmetrical: the left nuclei control the left organs, the right ones control the right ones.
Autonomic nervous system
to a very large extent depends on the volume of blood that circulates through the vessels, on the quality of the skull, spine, pelvis, on the condition of the throat, sinuses and forehead, lungs, and liver.
This nervous system has two subdivisions : sympathetic and parasympathetic
.
Sympathetic division of the autonomic nervous system
The sympathetic division, in the form of two trunks, runs on both sides of the spine. The left trunk nourishes the organs of the left side, the right – the right. The exceptions are the liver, stomach and heart; they are fed by both sympathetic trunks. Moreover, if the nerves of the spinal cord have protective sheaths, then the sympathetic trunks are “naked” and can literally be pinched and switched off.
The main part of the network of the autonomic nervous system is located in the organs, its nerve centers are removed from the bone case of the skull and spine, live and work in close proximity to the spine, skull, near arteries, veins, in the walls of organs, where, of course, both viruses and bacteria. Those nerve centers that are located in the central nervous system have common protections, the same for everyone: bone sheaths, the blood-brain barrier, and the peripheral centers protect themselves, individually, so to speak. The first is dangerous due to a concussion, and the second is due to flooding (inflammation in the organ disables the nerve plexus located in it).
Now let's digress a little. Just an interesting hypothesis. You must have heard about the mysterious Russian soul? We don’t know what it is, we just feel it. It is in this ability to feel what is not seen or heard that the Eastern mentality lies, and these are well-functioning meridians, biologically active points. Touch. As you remember, this is the autonomic nervous system. Western mentality is about animal analyzers, that is, the somatic nervous system: hearing, vision, smell.
Parasympathetic nervous system
Now remember: in a state of rest, the parasympathetic nervous system dominates. It constricts the pupil, slows the heart rate, dilates blood vessels, lowers blood pressure, enhances the secretion of glands and intestinal motility, and relaxes the sphincters. When stressed, the sympathetic nervous system comes into force, which dilates the pupil, increases the heart rate, constricts blood vessels, increases blood pressure, reduces the secretion of glands, slows down the peristalsis of the intestines and stomach, and contracts the sphincters.
The autonomic nervous system forms a number of plexuses: solar, pericardial, mesenteric, pelvic, which innervate the internal organs. Higher control is carried out from the nuclei of the hypothalamus, the limbicoreticular complex. Management is the integration of mental and somatic functions. By the way, during emotions of fear, anger, anger, the sympathetic nervous system is excited. Now it’s clear why your heart is pounding, your mouth is dry, your pupils are wide? If you need to empty the gallbladder, bladder and rectum, the parasympathetic nervous system is activated, but when blood sugar decreases, the sympathetic nervous system is activated. At the same time, it stimulates the adrenal glands, which release adrenaline into the blood, which, entering the liver, converts glycogen into glucose, and blood sugar levels normalize. The body's performance is directly related to the tone of the sympathetic nervous system: the higher it is, the more active a person is.
Now let's briefly return to the topic of stress. The stress mode is activated when there is a lack of resources to solve current problems in the environment and in the body itself. It occurs when demands are high or when one is aware of one’s troubles. Sometimes it is rage due to humiliation, sometimes it is the inability to achieve a goal. And the more significant this goal is, the greater the stress. Love, hunger, rivalry, as well as beliefs and the desire for comfort - these are all sources of stress, as well as inadequate reactions to signals from reality. This is called stupid behavior. The situation is assessed as hopeless, and the hypothalamus launches a stress program, whether you want this program or not.
And the resources for the survival program (this, by the way, is a huge expenditure of energy) are taken from the cells of the immune, digestive and reproductive systems. Have you probably encountered a situation where, after exams, students start to get sick, like during a flu epidemic? And these protective cells, which provided immunity, went into the energy cauldron of those who regarded passing exams as stressful. The body simply digested these cells to obtain additional energy.
When stressed, the organs that use insulin to absorb glucose from the blood suffer. When stressed, they remain hungry and without energy. And this is immunodeficiency, impotence, erosion of the gastrointestinal tract. If stress is chronic, then diseases of these organs occur.
Chronic stress is stress that is produced by the adrenal hormone cortisol. By the way, aggressiveness is also realized with the help of cortisol. And love.
How do we lose weight when we fall in love, you know? With the help of the stress hormone cortisol, which is also a catalyst for fat metabolism in the cell. Who would argue that love is a disease!
After stress, the liver and heart suffer. The volume of circulating blood decreases, and foci of inflammation appear. The blood becomes thick and does not “get through” into the capillaries. The cells experience cold, hunger and sadness. If you do nothing, you can get seriously ill.
Please limit your desires, tame your pride, fight not with others, but with yourself. Peace in your soul is your concern; maintain it, and it will save strength and strengthen the nervous system. God bless you!
Evolution of the vertebrate brain
The formation of the central nervous system in the form of a neural tube first appears in chordates. In lower chordates, the neural tube is preserved throughout life; in higher chordates, vertebrates, a neural plate is formed on the dorsal side during the embryonic stage, which is immersed under the skin and folded into a tube. In the embryonic stage of development, the neural tube forms three swellings in the anterior part - three brain vesicles, from which parts of the brain develop: the anterior vesicle gives rise to the forebrain and diencephalon, the middle vesicle turns into the midbrain, the posterior vesicle forms the cerebellum and medulla oblongata. These five brain regions are characteristic of all vertebrates.
Lower vertebrates - fish and amphibians - are characterized by a predominance of the midbrain over other parts. In amphibians, the forebrain somewhat enlarges and a thin layer of nerve cells is formed in the roof of the hemispheres - the primary medullary vault, the ancient cortex. In reptiles, the forebrain increases significantly due to accumulations of nerve cells. Most of the roof of the hemispheres is occupied by the ancient cortex. For the first time in reptiles, the rudiment of a new cortex appears. The hemispheres of the forebrain creep onto other parts, as a result of which a bend is formed in the region of the diencephalon. Beginning with ancient reptiles, the cerebral hemispheres became the largest part of the brain.
The structure of the brain of birds and reptiles has much in common. On the roof of the brain is the primary cortex, the midbrain is well developed. However, in birds, compared to reptiles, the total brain mass and the relative size of the forebrain increase. The cerebellum is large and has a folded structure. In mammals, the forebrain reaches its greatest size and complexity. Most of the brain matter is made up of the neocortex, which serves as the center of higher nervous activity. The intermediate and middle parts of the brain in mammals are small. The expanding hemispheres of the forebrain cover them and crush them under themselves. Some mammals have a smooth brain without grooves or convolutions, but most mammals have grooves and convolutions in the cerebral cortex. The appearance of grooves and convolutions occurs due to the growth of the brain with limited dimensions of the skull. Further growth of the cortex leads to the appearance of folding in the form of grooves and convolutions.
Instead of a preface
“All illnesses come from nerves!” Is this true or not? Exaggeration or sad reality? And what kind of diseases are these that are caused by nerves? For clarity, I will allow myself to cite one case from my medical practice.
I work in a clinic, where, as you know, in addition to local doctors, doctors of other specialties - “narrow specialists” - also see patients. This, by the way, is Western technology, when it is not a person who is treated, but his illness, and accordingly, each disease has its own specialist. But we are already accustomed to this and cannot even imagine how it could be otherwise.
So, one day a middle-aged man came to an appointment; after a conflict at work, a stomach ulcer opened up, a rash appeared on his hands, his blood pressure rose, and he couldn’t sleep at all! And instead of sleep, sadness appeared, and anxiety. His stomach was treated by a gastroenterologist, his skin rash by a dermatologist, and his blood pressure by a therapist. And everything would have been fine, as they say, but when the man remembered the conflict, everything was repeated again, and the doctors, sensing something was wrong, referred him to a psychotherapist.
It should be said that the human brain is designed like the most perfect computer; or rather, the computer is designed in a similar way to the nervous system. In the human body, the channels for inputting information are the eyes, ears, skin, there are receptors that react to the biochemical composition of the blood, etc. So, the brain reacts very sensitively to a word, and a rude word can cause a whole storm in the body, just like this happened in our case: the central nervous system responded to psychological stress with a powerful release of biologically active substances as its defense, and one of these substances was histamine, which caused stomach ulcers and neurodermatitis.
Moreover, with each memory of what happened, the brain reacted with a new release of the same active substances, as if it were not a simple memory, but a repeated event.
Yes, this is how our nervous system works: memories are as real to the brain as the events that gave rise to them. To help that man, it was necessary to influence the central nervous system, which triggered a defensive reaction in the form of the release of certain substances that acted on the stomach, and on the skin, and on blood pressure, and on sleep, and on mood, and acting like you understand, not in the most successful way. Which is what was done. Along with sadness, all other illnesses soon disappeared.
It turns out that the nervous system is really the head of everything? Of course, that's why she's a head! And you, of course, have experienced how much it hurts at least once in your life. The central nervous system is, of course, just a part of the nervous system, but without a doubt it is its main part. That is why it is so carefully packed by the skeletal system. And we will talk about this later.
So what needs to be done to maintain the health of our most advanced computer - the nervous system? Well, first of all, it should be said that what a person does not know, he does not own. Secondly, today any of us should have an idea of how the human body works. You need to rely on doctors, but do not forget that they treat diseases, and the science of health is different. And here everyone needs to work for themselves: no one can take responsibility for your own health for you.
Now is the time when doctors share with you, dear reader, all their knowledge and accumulated experience so that you take on the task of maintaining your own health. This is exactly what your humble servant, a psychotherapist, is going to do for you. I hope that this will be not only useful for you, but also interesting. Are you interesting to yourself?
You need to know your own body in order to help it, treat it with care, so that the problems of the body do not overshadow the abilities and needs of the soul for creativity and love. Therefore, do not consider it difficult to find out how the holy of holies of our body - the nervous system - works, how to avoid its breakdowns, and if they do happen, eliminate them. Together with the doctor. We're together right?
Brain
If the spinal cord in all vertebrates is developed more or less equally, then the brain differs significantly in size and complexity of structure in different animals. The forebrain undergoes particularly dramatic changes during evolution. In lower vertebrates, the forebrain is poorly developed. In fish, it is represented by the olfactory lobes and nuclei of gray matter in the thickness of the brain. The intensive development of the forebrain is associated with the emergence of animals onto land. It differentiates into the diencephalon and two symmetrical hemispheres, which are called the telencephalon. Gray matter on the surface of the forebrain (cortex) first appears in reptiles, developing further in birds and especially in mammals. Truly large forebrain hemispheres become only in birds and mammals. In the latter, they cover almost all other parts of the brain.
The brain is located in the cranial cavity. It includes the brainstem and telencephalon (cerebral cortex).
The brainstem consists of the medulla oblongata, pons, midbrain and diencephalon.
The medulla oblongata is a direct continuation of the spinal cord and, expanding, passes into the hindbrain. It basically retains the shape and structure of the spinal cord. In the thickness of the medulla oblongata there are accumulations of gray matter - the nuclei of the cranial nerves. The posterior pons includes the cerebellum and the pons. The cerebellum is located above the medulla oblongata and has a complex structure. On the surface of the cerebellar hemispheres, gray matter forms the cortex, and inside the cerebellum - its nuclei. Like the spinal medulla oblongata, it performs two functions: reflex and conductive. However, the reflexes of the medulla oblongata are more complex. This is reflected in its importance in the regulation of cardiac activity, the condition of blood vessels, respiration, and sweating. The centers of all these functions are located in the medulla oblongata. Here are the centers for chewing, sucking, swallowing, saliva and gastric juice. Despite its small size (2.5–3 cm), the medulla oblongata is a vital part of the central nervous system. Damage to it can cause death due to cessation of breathing and heart activity. The conductor function of the medulla oblongata and the pons is to transmit impulses from the spinal cord to the brain and back.
In the midbrain there are primary (subcortical) centers of vision and hearing, which carry out reflexive orienting reactions to light and sound stimuli. These reactions are expressed in various movements of the torso, head and eyes towards the stimuli. The midbrain consists of the cerebral peduncles and quadrigeminalis. The midbrain regulates and distributes the tone (tension) of skeletal muscles.
The diencephalon consists of two sections - the thalamus and hypothalamus, each of which consists of a large number of nuclei of the visual thalamus and subthalamic region. Through the visual thalamus, centripetal impulses are transmitted to the cerebral cortex from all receptors of the body. Not a single centripetal impulse, no matter where it comes from, can pass to the cortex, bypassing the visual hillocks. Thus, through the diencephalon, all receptors communicate with the cerebral cortex. In the subtubercular region there are centers that influence metabolism, thermoregulation and endocrine glands.
The cerebellum is located behind the medulla oblongata. It consists of gray and white matter. However, unlike the spinal cord and brainstem, the gray matter - the cortex - is located on the surface of the cerebellum, and the white matter is located inside, under the cortex. The cerebellum coordinates movements, makes them clear and smooth, plays an important role in maintaining the balance of the body in space, and also influences muscle tone. When the cerebellum is damaged, a person experiences a decrease in muscle tone, movement disorders and changes in gait, speech slows down, etc. However, after some time, movement and muscle tone are restored due to the fact that the intact parts of the central nervous system take over the functions of the cerebellum.
The cerebral hemispheres are the largest and most developed part of the brain. In humans, they form the bulk of the brain and are covered with cortex over their entire surface. Gray matter covers the outside of the hemispheres and forms the cerebral cortex. The human cerebral cortex has a thickness of 2 to 4 mm and is composed of 6–8 layers formed by 14–16 billion cells, different in shape, size and functions. Under the cortex is a white substance. It consists of nerve fibers connecting the cortex with the lower parts of the central nervous system and the individual lobes of the hemispheres with each other.
The cerebral cortex has convolutions separated by grooves, which significantly increase its surface. The three deepest grooves divide the hemispheres into lobes. In each hemisphere there are four lobes: frontal, parietal, temporal, occipital. The excitation of different receptors enters the corresponding receptive areas of the cortex, called zones, and from here they are transmitted to a specific organ, prompting it to action. The following zones are distinguished in the cortex. The auditory zone is located in the temporal lobe and receives impulses from auditory receptors.
The visual zone lies in the occipital region. Impulses from the eye receptors arrive here.
The olfactory zone is located on the inner surface of the temporal lobe and is connected to the receptors of the nasal cavity.
The sensory-motor zone is located in the frontal and parietal lobes. This zone contains the main centers of movement of the legs, torso, arms, neck, tongue and lips. This is also where the center of speech lies.
The cerebral hemispheres are the highest division of the central nervous system, controlling the functioning of all organs in mammals. The importance of the cerebral hemispheres in humans also lies in the fact that they represent the material basis of mental activity. I.P. Pavlov showed that mental activity is based on physiological processes occurring in the cerebral cortex. Thinking is associated with the activity of the entire cerebral cortex, and not just with the function of its individual areas.
| Brain department | Functions | |
| Medulla | Conductor | Connection between the spinal and overlying parts of the brain. |
| Reflex | Regulation of the activity of the respiratory, cardiovascular, digestive systems:
| |
| Pons | Conductor | Connects the cerebellar hemispheres to each other and to the cerebral cortex. |
| Cerebellum | Coordination | Coordination of voluntary movements and maintaining body position in space. Regulation of muscle tone and balance |
| Midbrain | Conductor | Approximate reflexes to visual and sound stimuli (turns of the head and torso). |
| Reflex |
| |
| Diencephalon | thalamus
hypothalamus
| |
The brain is the “administrator” of the nervous system and human psyche
Previously, it was believed that a person’s “soul” was contained in his heart. With the development of science, humanity gradually began to study what made us human, the crown of the animal world - the brain.
Our mental system is formed through the interaction of the cerebral cortex and the underlying sections (dietum, midbrain, brainstem). Each area is responsible for one or another function. But the most interesting thing is that when one section of neurons fails, its work can be partially replaced by another, which is called neuroplasticity.
The frontal lobe is involved in the formation of emotions, memory, speech and behavior. Evolutionarily, this part is the most developed in Homo sapiens, since it began to develop with the transition of primates to upright walking and the activation of fine motor skills of the upper limbs. Therefore, the frontal lobe is responsible for many functions. To understand what effect the frontal lobe has on a person’s mental state, we should mention the so-called frontal syndrome, which is observed in people with organic brain damage due to external influences, vascular, oncological and other pathologies. They experience disinhibition in behavior, self-control disappears, and a tendency toward brutal, antisocial behavior, as well as outbursts of aggressiveness, appears. In addition to behavior and emotions, memory is impaired, a person cannot concentrate on any task, and the function of cognition of the outside world suffers. In severe cases, the core of the personality is lost - we stop seeing the person as he was before.
There is a part of the brain called the hypothalamus, which is responsible for regulating autonomic functions. It communicates with the endocrine system of the body and is directly connected with the hormone regulator gland – the pituitary gland. The latter secretes special substances that give a signal to the pituitary gland to release hormones: gonadotropic (affecting the gonads), thyroid-tropic (thyroid), adrenocorticotropic (adrenal glands), somatotropic (tissue growth) and prolactin (breast).
Cerebral cortex
The surface of the human cerebral cortex is about 1500 cm2, which is many times greater than the inner surface of the skull. This large surface of the cortex was formed due to the development of a large number of grooves and convolutions, as a result of which most of the cortex (about 70%) is concentrated in the grooves. The largest grooves of the cerebral hemispheres are the central one, which runs across both hemispheres, and the temporal one, which separates the temporal lobe from the rest. The cerebral cortex, despite its small thickness (1.5–3 mm), has a very complex structure. It has six main layers, which differ in the structure, shape and size of neurons and connections. The cortex contains the centers of all sensory (receptor) systems, representatives of all organs and parts of the body. In this regard, centripetal nerve impulses from all internal organs or parts of the body approach the cortex, and it can control their work. Through the cerebral cortex, conditioned reflexes are closed, through which the body constantly, throughout life, very accurately adapts to the changing conditions of existence, to the environment.
