The environment around us - air, water, soil, objects - contain a lot of microorganisms that can harm human health. But thanks to the fact that the immune system guards our well-being, in most cases this does not happen. The immune system “fights” every minute with an army of bacteria and viruses, successfully “fighting off” all these harmful “attacks”.
The human immune system is very complex. It includes several organs connected to each other by a continuous network of lymphatic ducts.
Structure immune system person
The organs of the immune system include:
Bone marrow is located in the spongy substance bone tissue. The total weight of this organ is 2.5–3 kg. Bone marrow is a concentration of stem cells, which are the ancestors of all the formed blood elements we need.
Approximately 50% of the main weight of the bone marrow is a cluster of hematopoietic vessels that ensure the delivery of oxygen and necessary tissues chemical compounds. The porous structure of the vascular wall creates conditions for the penetration of nutrients inside.
There are two different types of bone marrow - red and yellow, between which there is no clearly defined boundary. The basis of red bone marrow is hematopoietic tissue, and yellow bone marrow is made up of adipose tissue. The red marrow produces blood cells, monocytes and B-lymphocytes. Yellow brain in education blood cells is not involved, but in some situations (for example, with blood loss), small foci of hematopoiesis may appear in it.
Over the years, the volume of red bone marrow in bone tissue decreases, and yellow bone marrow, on the contrary, increases. This is due to the fact that from the moment of puberty until old age, the processes of hematopoiesis begin to steadily fade away.
The thymus (thymus gland) is located in the middle chest, in the retrosternal space. The shape of the thymus gland is a little like a fork with two prongs (hence the name thymus gland). At the time of birth, the weight of the thymus is 10–15 grams. In the first three years of life, the thymus gland grows extremely quickly.
From three to twenty years of age, the mass of the thymus remains the same and is about 26-29 grams. Then the involution (reverse development) of the organ begins. In older people, the mass of the thymus does not exceed 15 grams. With age, the structure of the thymus gland also changes - the thymus parenchyma is replaced by adipose tissue. In old people, this organ is 90% fatty.
The thymus gland has a bilobed structure. The upper and lower lobes of the gland have different size and shape. On the outside it is covered with a connective tissue capsule. The connective tissue also penetrates into the thymus, thereby dividing it into lobules. The gland is divided into a cortical layer, in which growth and “instilling working skills” occurs in lymphocytes “born” in the bone marrow, and a medulla, the bulk of which consists of glandular cells.
The process of “reaching maturity” by lymphocytes, which occurs in the thymus gland, is extremely significant for the human immune system. U infants with congenital defects of the thymus - underdevelopment or complete absence of this organ, the functional development of the entire lymphatic system, therefore, life expectancy with this pathology rarely exceeds 12 months.
The spleen is located on the left under the ribs and has the shape of a flattened and elongated hemisphere. In adults, the length of the spleen is 10-14 cm, width 6-10 cm, and thickness 3-4 cm. The weight of the organ in a man 20-40 years old is 192 grams, in a woman - 153 grams. Scientists have found that between 750 and 800 ml of blood passes through the spleen every day. Here, the formation of immunoglobulins of class M and J occurs as a reaction to the arrival of antigens, and the synthesis of factors that stimulate phagocytosis by leukocytes and macrophages. In addition, the spleen is a biological filter for xenobiotics, dead blood cells, bacteria and microflora.
Lymph nodes They act as biological filters in the body for the lymphatic fluid flowing through them. They are located along the flow of lymph through the lymphatic vessels from organs and tissues.
As a rule, lymph nodes occur in groups of two to several dozen nodes. On the outside, the lymph nodes are protected by a capsule, inside of which there is a stroma consisting of reticular cells and fibers. Each lymph node includes from 1-2 to 10 small arteries that supply it with blood.
Accumulations of lymphatic tissue located in the mucous membrane are also called lymphoid formations. Lymphoid formations are present in the pharynx, esophagus, stomach, intestines, respiratory organs, and urinary tract.
Islands of lymphatic tissue in the pharynx are represented by 6 tonsils of the lymphoid pharyngeal ring. Tonsils are a powerful collection of lymphoid tissue. They are uneven on top, which promotes food retention and creates a breeding ground for bacterial growth, which, in turn, serves as a trigger for immunological processes.
Lymphoid formations of the esophagus are lymph nodes deep in the folds of the esophagus. The task of the lymphoid formations of the esophagus is to protect the walls of this organ from foreign tissue and antigens that enter the body with food.
Lymphoid formations of the stomach are represented by B- and T-lymphocytes, macrophages and plasma cells. The lymphatic network of the stomach begins with lymphatic capillaries located in the mucous membrane of the organ. Lymphatic vessels depart from the lymphatic network and pass through the thickness of the muscle layer. Vessels from the plexuses lying between the muscular layers flow into them.
Islands of intestinal lymphatic tissue are represented by Peyer's patches - group lymph nodes, single lymph nodes, diffusely located lymphocytes and the lymphatic apparatus of the appendix.
The appendix or vermiform appendix is an appendage of the cecum and extends from its posterolateral wall. The thickness of the appendix contains large number lymphoid tissue. It is believed that lymphoid tissue The vermiform appendix makes up 1% of all human lymphoid tissue. The cells produced here protect the body from foreign substances entering the digestive tract along with food.
Lymphoid formations respiratory system- these are accumulations of lymphatic tissue in the mucous membrane of the larynx, trachea and bronchi, as well as lymphoid cells diffusely located in the mucosa of the respiratory apparatus, called lymphoid tissue associated with the bronchi. The lymphoid formations of the respiratory system protect the body from foreign particles entering the respiratory organs along with the air flow.
Lymphoid formations urinary tract located in the walls of the ureters and bladder. According to scientists, in infancy the number of lymph nodes in the ureters ranges from 2 to 11, and then increases to 11-14. IN old age the number of lymph nodes again decreases to 6-8. Lymph nodes in the urinary tract protect us from foreign substances that enter the body from the outside through the ascending route.
The human body’s immunity and immune system is a highly precise, well-coordinated mechanism that fights bacteria and xenobiotics. All organs of the human immune system work together, complementing each other. The main task of the immune system and the immune system is to recognize, destroy and remove harmful substances from the body. infectious agents and foreign substances, as well as the resulting mutated cells and decay products.
All substances unknown to the body that penetrate it are called antigens. After the immune system detects an antigen and recognizes it, it begins to produce special cells - antibodies, which bind the antigen and destroy it.
There are two types in humans immune defense– innate and acquired immunity. Innate resistance is a very ancient defense system that all living beings have. Innate immunity is aimed at destroying the cell membrane of a foreigner that has entered the body.
If the destruction of the foreign cell does not occur, another line of defense comes into play - acquired immunity. The principle of its operation is as follows: when bacteria or a foreign substance enters the human body, leukocytes begin to produce antibodies. These antibodies are strictly specific, that is, they correspond to the substance that has entered the body like two adjacent puzzles to each other. Antibodies bind and destroy the antigen, thereby protecting our body from disease.
In some situations, the immune system human body reacts violently to safe factors environment. This condition is called allergy. Substances that provoke the manifestation of allergies are called allergens.
Allergens are divided into external and internal. External allergens are those that enter the body from the environment. This could be some types of food, mold, wool, pollen, etc. The internal allergen is our own tissue, usually with altered properties. This happens, for example, with bee stings, when the affected tissue begins to be identified as foreign.
When an allergen first enters the human body, it usually does not cause any external changes, however, the processes of production and accumulation of antibodies occur. If the allergen enters the body again, an allergic reaction begins, which can occur in different ways: in the form of skin rashes, tissue swelling or an attack of suffocation.
Why don't all people suffer from allergies? There are several reasons for this. Firstly, heredity. Scientists have proven that the tendency to develop allergies is passed on from generation to generation. Moreover, if the mother has allergies, then the child will have an allergy with a probability of 20-70%, and if the father - only 12-40%.
The likelihood of an allergy in a child is especially high if both parents have this disease. In this case, the allergy will be inherited with a probability of 80%. In addition, allergic reactions are more likely to occur in people who were sick a lot in childhood.
Another factor that contributes to the development of allergies in a person is the unfavorable environmental situation in the area of residence. Scientists have proven that in areas with polluted air the number of children with allergies is significantly higher than in areas with a favorable environment. This especially applies to such allergic diseases, How bronchial asthma And allergic rhinitis(hay fever).
And this has scientific explanation: microscopic particles suspended in polluted air irritate the epithelial cells of the mucous membrane respiratory tract, thereby activating them and promoting the release of anti-inflammatory cytokines.
Thus, allergic reactions are another manifestation of the work of the immune system, the very case when, caring for our safety, the immune system, like a loving parent, shows excessive zeal.
The human immune system is a complex of special anatomical structures that provide protection to our body from various pathogenic agents and decay products of their vital activity, as well as substances and tissues that have an antigenic effect foreign to us.
The goal of the immune system is to destroy:
In this way, the biological individuality of our body is achieved, in which there are many ways on the part of the immune system to detect and remove many foreign agents. Such a process in medical practice briefly and clearly called the immune response.
The forms of the immune response are divided into congenital and acquired. The main difference between them is that the immunity acquired by a person is highly specific in relation to a certain type of antigen and allows them to be more quickly and effectively destroyed when they re-enter the body.
Antigens are molecules that cause special specific responses of the body as to a foreign agent.
Thus, people who have had chickenpox (diphtheria or measles) usually develop lifelong immunity to such diseases. When autoimmune reactions occur, such an antigen can already be a cell-molecule produced by our body.
The organ responsible for immunity and hematopoiesis in our body is the bone marrow, in which stem cells are located. They give rise to all types of cells of the immune system and blood. Stem cells have the ability to divide multiple times; due to this function, they belong to a self-sustaining population.
Also, the formed elements of blood are formed in the bone marrow:
Stem cells form the cells of the immune system—plasmocytes and lymphocytes.
The organs of our immune system containing lymphoid tissue protect the constancy of the internal environment of our body throughout life. The cells they produce ensure the fight against foreign organisms and substances.
Components of our immune system other than bone marrow:
All human immune organs are localized in our body not randomly, but in clearly defined places that are protected. Thus, the thymus is located in the chest cavity, and the bone marrow is located in closed medullary cavities.
The tonsils are located at the very beginning of the digestive tube and our respiratory tract, giving rise to and forming the lymphoid pharyngeal ring.
Lymphoid tissue is located at the border of the nasal cavity and mouth, larynx and pharynx. Numerous peripheral lymphoid plaques are present in the walls small intestine, central departments and at the entrance to the large intestine. Single nodes are located in the thickness of the mucous membranes of the urinary tract, digestive organs and respiratory system.
The thymus gland is one of the most important organs of human immunity. The organ got its name from its appearance, which looks like a fork. The thymus is divided into two parts, which can be tightly pressed or fused, but not always symmetrical.
The entire surface of the gland is covered connective tissue and is divided into cortex and medulla. The cortex consists of hematopoietic and epithelial cells. In which hormones and supporting cells, macrophages and T-lymphocytes are produced.
In both parts of the organ there are a large number of T-lymphocytes - cells responsible for recognizing pathogens and foreign organisms.
The peculiarity of the thymus gland is that the organ actively grows in childhood and adolescence, and after 18 years it begins to gradually decrease and soon disappears completely. In place of the thymus gland in adults there is only connective tissue.
Functions of the thymus:
With age, when other organs are formed, part of the tasks performed by the thymus gland will be distributed to them. The organ produces hormones necessary for the full functioning of the body - thymosin, thymalin and thymopoietin.
Disorders of the thymus gland in childhood leads to loss of resistance to viruses and bacteria, sometimes suffers nervous system. Such a child will be constantly sick. Violations in the functioning of the organ can be detected through x-ray diagnostics. In this case, correction with medications is necessary.
The spleen is one of the organs of the immune system. It is located on the path of blood movement from the aorta to the system portal vein, which branches in the liver. Based on this fact, the spleen is considered the filter of the entire circulatory system.
Main functions of the spleen:
The spleen refers to the site of the body's specific immune response to antigens that circulate in the blood. The processes of such an immune response also take place in the lymph nodes that enter there through the lymph.
The spleen, as an organ of the immune system, utilizes “used” and damaged red blood cells, leukocytes or platelets, as well as foreign proteins that have entered the bloodstream.
The spleen does not recover well if damaged. If there was extensive trauma to the organ, it has to be removed. Removing the spleen is a treatment for anemia. Then its functions are partially replaced by other immune organs. People who lack this organ are more sensitive to bacteria and pneumococci.
The combination of all cells and organs of the immune system and the protective antibodies, immunoglobulins, macrophages and cytokines they produce provide protection to our body. Each organ performs its function in the formation of the immune response and is part of complex mechanism, called human immunity.
Human immunity is a state of immunity to various infectious and generally foreign genetic code human organisms and substances. The body's immunity is determined by the state of its immune system, which is represented by organs and cells.
Let's stop here briefly, since this is purely medical information, unnecessary to the common man.
Red bone marrow, spleen and thymus (or thymus) – central organs of the immune system
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Lymph nodes and lymphoid tissue in other organs (for example, tonsils, appendix) are peripheral organs immune system
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Remember: tonsils and appendix are NOT unnecessary organs, but very important organs in the human body.
The main task of the human immune system is the production of various cells.
What types of immune system cells are there?
1) T lymphocytes. They are divided into various cells - T-killers (kill microorganisms), T-helpers (help to recognize and kill microbes) and other types.
2) B lymphocytes. Their main task is the production of antibodies. These are substances that bind to the proteins of microorganisms (antigens, that is, foreign genes), inactivate them and are removed from the human body, thereby “killing” the infection inside the person.
3) Neutrophils. These cells devour the foreign cell, destroy it, and are also destroyed. As a result, purulent discharge appears. A typical example of the work of neutrophils is an inflamed wound on the skin with purulent discharge.
4) Macrophages. These cells also devour microbes, but are not destroyed themselves, but destroy them in themselves, or pass them on to T-helper cells for recognition.
There are several other cells that perform highly specialized functions. But they are of interest to specialist scientists, while the types listed above are sufficient for the common man.
1) And now that we have learned what the immune system is, that it consists of central and peripheral organs, of various cells, now we will learn about the types of immunity:
This gradation is very important for any doctor to understand. Since many medicines act on either one or the other type of immunity.
Cellular is represented by cells: T-killers, T-helpers, macrophages, neutrophils, etc.
Humoral immunity is represented by antibodies and their source – B-lymphocytes.
2) The second classification of species is based on the degree of specificity:
Nonspecific (or congenital) - for example, the work of neutrophils in any inflammatory reaction with the formation of purulent discharge,
Specific (acquired) - for example, the production of antibodies to the human papillomavirus, or to the influenza virus.
3) The third classification is types of immunity associated with medical activities person:
Natural – resulting from a human illness, for example, immunity after chickenpox,
Artificial - resulting from vaccinations, that is, the introduction of a weakened microorganism into the human body, in response to this the body develops immunity.
Now let's look at a practical example of how immunity is developed to human papillomavirus type 3, which causes the appearance of juvenile warts.
The virus penetrates into microtrauma of the skin (scratches, abrasions) and gradually penetrates further into the deeper layers of the surface layer of the skin. It was not present in the human body before, so the human immune system does not yet know how to react to it. The virus integrates into the gene apparatus of skin cells, and they begin to grow incorrectly, taking on ugly forms.
This is how a wart forms on the skin. But this process does not bypass the immune system. The first step is to turn on T-helpers. They begin to recognize the virus, remove information from it, but cannot destroy it themselves, since its size is very small, and the T-killer can only kill larger objects such as microbes.
T-lymphocytes transmit information to B-lymphocytes and they begin to produce antibodies that penetrate through the blood into skin cells, bind to virus particles and thus immobilize them, and then this entire complex (antigen-antibody) is eliminated from the body.
In addition, T lymphocytes transmit information about infected cells to macrophages. They become active and begin to gradually devour the changed skin cells, destroying them. And in place of the destroyed ones, healthy skin cells gradually grow.
The entire process can take from several weeks to months or even years. Everything depends on the activity of both cellular and humoral immunity, from the activity of all its links. After all, if, for example, at some point in time, at least one link - B-lymphocytes - drops out, then the entire chain collapses and the virus multiplies unhindered, penetrating into more and more new cells, contributing to the appearance of more and more warts on the skin.
In fact, the example presented above is only a very weak and very accessible explanation of the functioning of the human immune system. There are hundreds of factors that can turn on one mechanism or another, speeding up or slowing down the immune response.
For example, the body's immune response to the influenza virus occurs much faster. And all because it tries to invade the brain cells, which is much more dangerous for the body than the effect of the papillomavirus.
And one more clear example how the immune system works - watch the video.
The topic of immunity began to develop in the last 50 years, when many cells and mechanisms of the entire system were discovered. But, by the way, not all of its mechanisms have yet been discovered.
For example, science does not yet know how certain autoimmune processes are triggered in the body. This is when the human immune system, for no apparent reason, begins to perceive its own cells as foreign and begins to fight them. It’s like in 1937 – the NKVD began to fight against its own citizens and killed hundreds of thousands of people.
In general, you need to know that good immunity- This is a state of complete immunity to various foreign agents. Outwardly, this is manifested by the absence of infectious diseases and human health. Internally, this is manifested by the full functionality of all parts of the cellular and humoral components.
Weak immunity is a state of receptivity to infectious diseases. It manifests itself as a weak reaction of one or another link, loss of individual links, inoperability of certain cells. There can be quite a few reasons for its decline. Therefore, it must be treated by eliminating all possible reasons. But we’ll talk about this in another article.
Affect human health various factors, but one of the main ones is the immune system. It consists of many organs that perform the functions of protecting all other components from external and internal unfavorable factors, and resists diseases. It is important to maintain your immune system in order to weaken harmful effects from outside.
Medical dictionaries and textbooks say that the immune system is the totality of its constituent organs, tissues, and cells. Together they form a comprehensive defense of the body against diseases, and also destroy foreign elements that have already entered the body. Its properties are to prevent the penetration of infections in the form of bacteria, viruses, fungi.
The functions of the immune system are:
Having emerged as an assistant in the struggle for survival in multicellular organisms, the human immune system and its organs have become an important component of the entire body. They connect organs and tissues, protect the body from cells and substances that are foreign at the genetic level and come from outside. In terms of its functioning parameters, the immune system is similar to the nervous system. The structure is also similar - the immune system includes central and peripheral components that respond to different signals, including a large number of receptors with specific memory.
Lymph nodes, tonsils, appendix belong to the peripheral organs of the immune system healthy person:
Important components for ensuring immunity are leukocytes and lymphocytes:
The complex human immune system and its organs operate at the genetic level. Each cell has its own genetic status, which organs analyze upon entry into the body. In case of a mismatch of status, a protective mechanism is activated for the production of antigens, which are specific antibodies for each type of penetration. Antibodies bind to the pathology, eliminating it, the cells rush to the product, destroy it, and you can see inflammation of the area, then pus is formed from the dead cells, which comes out with the bloodstream.
Allergy is one of the reactions of innate immunity in which healthy body destroys allergens. External allergens are food, chemical, medical supplies. Internal – own fabrics with changed properties. This can be dead tissue, tissue exposed to bees, or pollen. Allergic reaction develops sequentially - during the first exposure to an allergen on the body, antibodies accumulate without loss, and during subsequent exposures they react with symptoms of rashes and tumors.
To stimulate the functioning of the human immune system and its organs, you need to eat right, healthy image life with physical activity. You need to include vegetables, fruits, teas in your diet, do hardening, and go for walks regularly. fresh air. Nonspecific immunomodulators - medications that can be purchased with a doctor's prescription during epidemics - will additionally improve the functioning of humoral immunity.
The structure of the organs of the immune system is quite complex and is only slightly inferior to how the nervous system is built. Its central bodies include:
The immune system also contains peripheral organs. Their total weight (both of them) is about 1 kilogram.
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The immune system has 6 tonsils: 
The following organs also belong to the peripheral part of the immune system:
All of them are located so that they surround the place where the oral and nasal cavities enter the pharynx. If foreign substances (from food or from inhaled air) try to enter the body, then this is where lymphocytes await them.
The interaction of all organs presents a complex picture. Their coordinated work, as well as the structure and functions of the immune system, provide reliable protection for the body.
Long before the baby is born, still in the mother’s womb, the formation of the child’s immune system begins. In order for it to develop further, the child needs mother's milk. For the same purpose, an antigenic load is needed - contact of the child’s body with various microorganisms.
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The functions of the human immune system can be represented as the following algorithm:
Nothing in the body passes without a trace, including the immune response. The immune system, when it first encounters any foreign substance (infection, microbe, etc.), will definitely remember its properties. The next time you meet him, she influences him more effectively.
Bacteria appear in a baby’s life almost immediately after he is born. Many parents believe that the child should be provided with maximum sterility. But this opinion is wrong. Elementary rules Hygiene is necessary, but you shouldn’t go to extremes. Excessive sterility can prevent the baby's immune system from developing its properties. If mother's milk contains a certain amount of bacteria, then you should not refuse it. Children's body must learn to deal with harmful substances. The functions of the immune system include fighting various viruses and bacteria.
In most cases, she deals with them before they have time to show their negative impact on the human body, that is, the person does not even notice that not everything is in order in the body.
But if there are too many pathogenic substances, then not every immune system will be able to cope. There are also pathogens that are beyond your control even in small quantities. good immunity. For example, cholera or chicken pox. Decreased immune system function manifests itself frequent colds, chronic infections, constant temperature of 37-38°C. There are diseases, the peculiarity of which is that a person suffers from them only once in his life. For example, measles. This happens thanks to the immune system, which forms a stable immunity to the disease.
