The lymphatic system differs from the circulatory system in that it is not closed in a circle; lymphatic capillaries begin blindly; there is no basement membrane in the wall of lymphatic capillaries; along the course of the lymphatic vessels there are lymph nodes. Functions of the lymphatic system: participates in hematopoiesis, fat and carbohydrate metabolism, barrier function, provides tissue drainage, metastases (malignant tumors) spread along the lymphatic pathways.

Components of the lymphatic system.

The lymphatic system includes: 1) lymphatic capillaries, which perform the function of absorption of colloidal solutions of proteins from tissues, carry out tissue drainage together with veins - absorption of water and substances dissolved in it, remove foreign particles (destroyed cells, microorganisms) from tissues. 2) lymphatic vessels (they have an inner, middle and outer shell), through which the outflow of lymph from the capillaries to large lymphatic collectors is carried out. 3) lymphatic collectors, through which lymph flows into the veins. 4) lymph nodes located along the lymphatic vessels (perform a barrier-filtration function). 5) lymphoepithelial organs: spleen, tonsils, lymphoid nodules of the digestive tube, appendix.

Major lymphatic collectors.

All efferent lymphatic vessels collect lymph into the right and left (thoracic) lymphatic ducts. The thoracic duct lies on the back wall of the abdominal cavity. It is formed by the confluence of the right and left lumbar lymphatic trunks (collect lymph from the lower extremities) and the intestinal lymphatic trunk (collect lymph from the abdominal organs). In the area of ​​confluence of these trunks there is an extension (cistern). The thoracic duct flows into the left venous angle - the confluence of the left internal jugular and left subclavian veins. The left broncho-mediastinal lymphatic trunk flows into the mouth of the thoracic duct (collects lymph from the organs of the left half of the chest cavity), the left subclavian trunk (collects lymph from the left upper limb) and the left jugular trunk (collects lymph from the left half of the head and neck). The right lymphatic duct flows into the right venous angle (the confluence of the right internal jugular and right subclavian veins).

Organs of the lymphatic system.

The lymphatic system includes the spleen, located in the left hypochondrium. It is covered with peritoneum on all sides (intraperitoneally). The spleen has a fibrous capsule, from which partitions extend into the organ. Between the latter is the red pulp of the spleen, inside which there are accumulations of lymphoid tissue (spleen follicles). The spleen absorbs certain harmful substances from the blood. It destroys red blood cells.

L imphatic nodes are organs of the lymphatic system. They lie along the course of the lymphatic vessels. These are bean-shaped, oval, round and elongated organs. Lymph nodes are usually located in groups. There are the following types of lymph nodes: superficial and deep (located on the limbs), parietal and visceral (collect lymph from the walls and organs of the body cavities)

The lymphatic system also includes lymphoid organs (single lymph nodes, Peyer's patches of the ileum wall) and tonsils.

Organs of the immune system

The organs of the lymphatic and immune systems are closely related to each other by a common origin, structure and function. The immune system combines organs and tissues that protect the body from genetically alien cells or substances that come from outside or are formed in the body. The organs of the immune system produce immunocompetent cells - lymphocytes, include them in the immune process, recognize and destroy cells that have entered the body or formed in it. When foreign substances - antigens - enter the body, protective substances that neutralize them - antibodies (immunoglobulins) are formed in it. The organs of the immune system are represented by central ones - bone marrow, thymus gland (thymus), and peripheral organs - tonsils, lymphoid nodules of the digestive, respiratory and genitourinary systems, lymph nodes, spleen.

Features of the structure of the immune system:

The parenchyma of all organs of the immune system is lymphoid tissue.

Early laying of the immune system organs in embryogenesis.

By the time of birth, the organs of the immune system are morphologically formed and functionally mature.

The organs of the immune system reach their maximum development in childhood and adolescence.

They undergo relatively early age involution.

IMMUNITY

For the first time, the phenomenon of phagocytosis by leukocytes of various microorganisms and their digestion was described by I.I. Mechnikov, initiating the study of the protective properties of blood. For these studies he was awarded the Nobel Prize in 1908. But in addition to the phagocytic function, leukocytes are able to form antibodies in response to the penetration of pathogens into the body. The immunity of the body to various types of diseases is called immunity. Immunity can be natural, if it is developed by the body itself without external intervention, or artificial. If natural immunity manifests itself in a person from birth, i.e. transmitted to the child from the mother by inheritance, it is called innate immunity. And when immunity is developed by a person after any illness, then it is acquired immunity.

Artificial immunity can be active or passive. Active immunity is developed when a vaccine is introduced into the body, i.e. weakened live or killed infectious agents. Such a vaccination causes a disease in a very mild form and a person becomes immune for quite a long time to the disease against which it is made, because. specific antibodies are formed in the body.

Passive immunity is created by introducing into the body during a disease the immune serum of animals or humans, which contains ready-made antibodies against the disease. Passive immunity lasts 4-6 weeks, and then the antibodies are destroyed and the immunity disappears.

So in 1796, Edward Jenner proposed inoculation against smallpox. In 1880, L. Pasteur proposed a scientific method for the manufacture of vaccines for prophylactic vaccinations. In 1883 I.I. Mechnikov discovered the phenomenon of phagocytosis. In 1892 DI. Ivanovsky discovered viruses. At the end of the 9th century, E. Bering discovered antitoxins and the healing properties of antitoxic sera, which he obtained by injecting animals with bacterial cultures and toxins, etc.

The fight against infectious diseases consists in preventive and anti-epidemic measures. These are sanitary and epidemiological supervision and protection of the territory, identification and treatment of patients and carriers of infections, routine vaccination of the population (immunization), against poliomyelitis, diphtheria, whooping cough, smallpox, measles.

AIDS AND THE FIGHT

Acquired immunodeficiency syndrome is a disease that affects the immune system and is characterized by the development of secondary immune deficiency. The causative agent of AIDS was isolated and described in 1983. first in France and then in the USA. It turned out to be a virus that selectively infects blood lymphocytes involved in the development of the body's immunity against pathogens of infectious diseases and the occurrence of malignant tumors. On the recommendation of the World Health Organization (WHO), the AIDS virus received the designation HIV - human immunodeficiency virus.

Due to the fact that the AIDS virus causes the destruction of human lymphocytes, the body's defense against microbes is sharply reduced and this leads to the occurrence of inflammatory diseases of various organs and organ systems, even due to microbes that usually never cause diseases in humans. And also in patients with AIDS, resistance to the occurrence of tumors decreases. The development of inflammation and malignant tumors is the cause of death in AIDS patients.

The disease from a sick person to a healthy person is transmitted primarily through sexual contact, as well as with the help of non-disinfected medical instruments (most often syringes from drug addicts) and through transfusion of infected blood. Early signs of the disease may be a prolonged fever, a long-term persistent enlargement of the lymph nodes. The later ones include chronic inflammatory lesions of the skin, oral mucosa, and genital organs. The manifestation of the disease can also be pneumonia, long-term disorders of the functions of the gastrointestinal tract for no apparent reason, etc. In the presence of such signs, you should consult a doctor.

And since the likelihood of contracting AIDS depends primarily on human behavior, you need to think about whether it is worth dying because of recklessness, frivolity and ignorance.

If we talk about the work of the body and in particular about the fluids that flow in the body, then not many people immediately call lymph.

However, lymph has great importance for the body and has very significant functions that allow the body to function normally.

What is the lymphatic system?

Many people know about the body's need for blood circulation and the work of other systems, but not many people know about the high importance of the lymphatic system. If the lymph does not circulate through the body for only a couple of hours, then such an organism can no longer function.

Thus, every human body experiences continuous need in the functioning of the lymphatic system.

It is easiest to compare the lymphatic system with the circulatory system and isolate the following differences:

1. openness, unlike the circulatory system, the lymphatic system is open, that is, there is no circulation as such.
2. Unidirectional If the circulatory system provides movement in two directions, then the lymph moves in the direction only from the peripheral to the central parts of the system, that is, the fluid first collects in the smallest capillaries and then moves into larger vessels, and the movement goes only in this direction.
3. There is no central pump. In order to ensure the movement of fluid in the right direction, only a system of valves is used.
4. More slow motion fluid compared to the circulatory system.
5. The presence of special anatomical elements- lymph nodes that perform a significant function and are a kind of warehouse for lymphocytes.

The lymphatic system is of the greatest importance for metabolism and for provide immunity. It is in the lymph nodes that the bulk of the foreign elements that enter the body are processed.

If any virus appears in the body, then it is in the lymph nodes that work begins to study and expel this virus from the body.

You yourself can notice this activity when you have, which indicate the body's fight against the virus. In addition, lymph regularly cleanses the body and removes unnecessary elements from the body.

Learn more about the lymphatic system from the video:

Functions

If we talk in more detail about the functions, then it should be noted the connection of the lymphatic system with the cardiovascular system. It is thanks to the lymph that delivery of various items, which cannot be immediately in the cardiovascular system:

• proteins;
• fluid from the tissue and interstitial space;
• fats, which come primarily from the small intestine.

These elements are transported to the venous bed and thus end up in the circulatory system. Further, these components can be removed from the body.

At the same time, many inclusions that are unnecessary for the body are processed at the stage of lymph, in particular, we are talking about viruses and infections that neutralized by lymphocytes and destroyed in the lymph nodes.

It should be noted the special function of the lymphatic capillaries, which are larger in comparison with the capillaries of the circulatory system and have thinner walls. Due to this, from the interstitial space to the lymph proteins and other components can be supplied.

Additionally, the lymphatic system can be used to cleanse the body, since the intensity of the flow of lymph largely depends on the compression of blood vessels and muscle tension.

Thus, massage and physical activity can make the movement of lymph more efficient. Thanks to this, additional cleansing and healing of the body becomes possible.

Peculiarities

Actually the word "lymph" comes from the Latin "lympha", which translates as moisture or clean water. Only from this name it is possible to understand a lot about the structure of the lymph, which washes and cleanses the entire body.

Many could observe lymph, since this liquid exudes on the surface of wounds on the skin. Unlike blood, the liquid is almost completely transparent.

According to the anatomical structure, lymph belongs to connective tissue and contains a large number of lymphocytes in the complete absence of erythrocytes and platelets.

In addition, lymph, as a rule, contains various waste products of the body. In particular, the previously noted large protein molecules that cannot be absorbed into the venous vessels.

Such molecules are often may be viruses therefore, the lymphatic system is used to absorb such proteins.

The lymph may contain various hormones that are produced by the endocrine glands. From the intestines, fats and some other nutrients come here, from the liver - protein.

Direction of lymph flow

The figure below shows a diagram of the movement of lymph in the human lymphatic system. It does not display every lymph vessel and all of the lymph nodes that about five hundred in the human body.

Pay attention to the direction of travel. Lymph moves from the periphery to the center and from the bottom up. Fluid flows from small capillaries, which then join into larger vessels.

The movement goes through the lymph nodes, which contain a huge number of lymphocytes and purify the lymph.

Usually to the lymph nodes more vessels come in than leave, that is, lymph enters through many channels, and leaves one or two. Thus, the movement continues to the so-called lymphatic trunks, which are the largest lymphatic vessels.

The largest is the thoracic duct., which is located near the aorta and passes lymph through itself from:

• all organs that are located below the ribs;
• left side of chest and left side of head;
• left hand.

This duct connects with left subclavian vein, which you can see marked in blue in the picture on the left side. This is where the lymph from the thoracic duct enters.

It should also be noted right duct, which collects fluid from the right upper side of the body, in particular from the chest and head, arms.

From here, lymph enters right subclavian vein, which is located in the figure symmetrically to the left. Additionally, it should be noted such large vessels that belong to the lymphatic system as:

1. right and left jugular trunks;
2. left and right subclavian trunks.

It should be said about the frequent location of the lymphatic vessels along the blood, in particular venous vessels. If you look at the picture, you will see some the similarity of the arrangement of the vessels of the circulatory and lymphatic systems.

The lymphatic system has great importance for the human body.

Many doctors consider lymph analysis to be no less relevant than a blood test, since it is lymph that can indicate some factors that are not found in other tests.

In general, lymph, in combination with blood and intercellular fluid, constitutes the internal liquid medium in the human body.

In our article today:

Introduction.

To maintain life, along with the supply of nutrients, energy resources and oxygen, it is also necessary to remove metabolites and toxic substances from tissues. It has been experimentally established that with complete starvation (only with the intake of water), a person and higher Animals can live for 10-20 days, while if the excretory system is disturbed, death occurs within the very first day.

In addition to the kidneys, the lungs, intestines, and sweat glands also perform an excretory function. In ancient Egypt, friends at a meeting instead of "how are you?" asked each other: "How do you sweat?". It is known that with profuse sweating, the body is freed from many toxins, and this is very important for health. Previously, it was believed that the excretion of metabolites and toxic substances from the body mainly refers to the function of the blood flowing through one or another excretory system.

It has now been established that the excretory and many other functions of the body are closely connected not only with blood, but also with lymph. Removal of toxic substances from the body in various ways is possible with the coordinated work of a single drainage system - the lymphatic venous channel. The scientific study of lymph is at least three hundred years old. However, intensive study of it began to be carried out relatively recently.

To date, it has been established that lymph circulation performs numerous important functions, and its violation leads to the development of severe complications and aggravates the course of many diseases. Today, opportunities have been found to influence the course and development of various pathological processes in the body through the lymphatic system. The impact on the lymphatic system has become widely used in immunology, oncology, cardiology, toxicology, and traumatology. There was even a new term - "lymphotherapy". Endolymphatic administration of various drugs is widely used in medical practice. In various pathological processes, endo- and exotoxins get into the lymph much faster than into the blood. The high efficiency of removing "poisoned lymph" from the body through the catheterized thoracic duct (for various types of intoxication, burns, liver and pancreas lesions, thrombosis, peritonitis, myocardial infarction, extreme and terminal conditions) has been proven both in the experiment and in the clinic.

One of the mysteries of the lymphatic system has been revealed - its role in the body's immune responses. There is an assumption that the lymphatic system is a morphological synonym for the immune system, and lymphocytes are its leading link. The presence of two independent, but jointly creating immunological reactions of T- and B-lymphocytes was discovered. Today, lymphology is developing rapidly. Stimulation of lymphatic drainage of tissues is assessed as one of the principles of pathogenetic therapy for a variety of (especially severe) diseases.

Lymph of a healthy person.

What is lymph?

It is believed that the aquatic environment is the basis of all processes occurring in the body, and maintaining its constancy is the basis of homeostasis. Speaking of a liquid medium, they usually mean blood, which is functionally associated with all tissues and cells of the body. It provides tissues and organs with oxygen, nutritious, plastic material, promotes the removal of toxic and unnecessary metabolic products from the body, performs neurohumoral function and thermoregulation.

The protein fraction of the blood is vital. Its gamma globulin fraction, for example, is necessary for the biosynthesis of antibodies and the enhancement of defense mechanisms. All deviations in the body are immediately reflected in the blood picture. Along with blood in our body, there are no less important liquid media - lymph, interstitial, cerebrospinal fluid and others - closely related to blood. The humoral direction founded by Hippocrates has been continuously changing over the course of twenty centuries of history, acquiring a modern form of the doctrine of humoral environments and humoral transport. It is generally accepted that the system of humoral transport, including the general blood circulation and movement in the "blood - tissue - lymph - blood" chain, is functionally one.

Lymph (in translation - pure water, moisture) is a transparent liquid of slightly yellowish color, sugary smell and salty taste. Some researchers call lymph only the fluid that is in the lumen of the lymphatic pathways (lymphatic capillaries, vessels and sinuses of the lymph nodes). Lymph is an interstitial fluid separated from the interstitium by an easily permeable layer of endothelium. It plays an essential role in maintaining the balance of tissue fluids.

Hence the concept of tissue lymph is born. Potential lymphoforming substrate - interstitial fluid. In the main substance, in the networks of collagen and elastic fibers, there are fixed and mobile elements of the interstitial tissue: pericytes, macrophages, fibrocytes (collagen producers), endotheliocytes, lymphocytes, etc. All of them are involved in certain processes that ensure the normal functioning of the microcirculation system, metabolism substances, the production of vasoactive amines, the mobility of the interstitial substance, the protective reactions of the body. The composition of lymph changes not only depending on the state of the body, but also on the functions of the organ from which it flows.

The amount of lymph in the body is not precisely defined. It is believed that in the lymphatic vessels of a person weighing 60 kg at rest, on an empty stomach contains 1200-1500 ml of lymph. It primarily consists of lymphocytes (there are up to 20,000 of them in the lymph of the thoracic duct in 1 mm3) - the main protective cells of the body. In humans, 35,546 billion lymphocytes enter the bloodstream through the thoracic duct per day.

In terms of chemical composition, lymphoplasm is close to blood plasma, but contains less protein. There are relatively more albumins in the lymph than in the blood plasma, since they, having a smaller molecule, diffuse faster into the lymphatic capillaries. The thoracic duct lymph contains fibrinogen and prothrombin; it coagulates more slowly than blood, forming a loose clot consisting of fibrin filaments and white blood cells. Lymph, like blood, contains all the formed elements, except for platelets and erythrocytes, which enter it under pathological conditions (shock, tumor growth, inflammation, etc.). In terms of mineral composition, lymph also resembles blood plasma. In the first place is sodium chloride (67% of the solid residue), which gives the lymph a salty taste. Sodium carbonate accounts for 25%. Calcium, magnesium, and iron ions are also present in the lymph (in small amounts). The main lymph cations are sodium, potassium, calcium, magnesium, anions - chlorine, phosphorus and protein, which behaves like an anion in the alkaline environment of the lymph. In samples of peripheral lymph, many trace elements were found that are of great importance in the physiology and pathology of the body.

To date, the presence of a special lymphatic system has been established, which includes lymph nodes, follicles, tonsils, spleen, thymus (thymus gland). The main functioning element of the lymphatic system is the lymphocyte. In an adult, lymphocytes circulating in the blood account for about 30% of the total number of leukocytes (in children under 5 years old, about 50%). Mature (small) lymphocytes make up the bulk of lymphoid tissue and over 95% of lymph cells.

Particular attention should be paid to the role of the thymus. It was experimentally established that as a result of the removal of the thymus in a newborn animal, the lymphatic system did not develop. Such animals constantly suffered from intestinal disorders, inflammations, various infections, after a while they inevitably died. It turned out that the removal of the thymus led to the almost complete disappearance of lymphocytes from the blood - cells that play a leading role in the body's defense reactions.

In newborn animals, after a few weeks, this caused a complex of phenomena known as "wasting disease" (sharp aplasia of lymphoid tissue, cachexia, lethargy, diarrhea). If the thymus was transplanted into experimental animals, their immune system was restored.

The main morphological substrate of immunogenesis are lymphoid organs. In cases where the liver, kidneys, and skin show immunological activity, there are serious grounds to attribute this activity not to the specific perichyma of these organs, but to the lymphoid or undifferentiated mesenchymal cells that have penetrated into them. With the weakness of the thymus, inflammation of the lungs develops, the flu and other diseases are severe.

The thymus differs from other organs of the lymphatic system in a number of histological features. Lymphoid elements, of which the thymus mainly consists, are morphologically identical to peripheral blood lymphocytes, but differ from the latter in the nature of the response to physical, chemical, hormonal and immunological effects and to infection. The totality of lymphoid organs in the conditions of the whole organism functions as a single system. The unity of this system is ensured by two main factors: 1) general hormonal and, probably, neuroreflex regulation; 2) special functional connections between individual lymphoid organs.

There is a distinct specialization in the system of lymphoid organs. The first, and sometimes the only object of action of the antigen and, accordingly, the antibody-producing organ is the regional lymph nodes. It has been shown that with the introduction of antigens, the amount of antibodies increases in the regional lymph nodes, and at an earlier time, in a higher titer than in blood serum. Sometimes a similar function can be performed by accumulations of lymphoid tissue or undifferentiated mesenchymal cells directly at the site of invasion of the antigenic factor (in the intestines, lungs, etc.). If a significant dose of the antigen, without being delayed by the regional node, enters the blood, the spleen, distant lymph nodes, lymphoid elements of the bone marrow, etc., are also included in the process of antibody formation.

Cells of the lymphoid type are found in all vertebrates. However, only in higher vertebrates is the lymphoid tissue distinctly separated from the myeloid tissue. One can therefore think that a single lymphomyeloid hematopoiesis, observed in higher vertebrates in the embryonic period, is a kind of recapitulation. A new stage in the development of lymphoid tissue was due to the emergence and improvement of a special drainage system of the body - lymphatic vessels.

The reduced (compared to blood) content of leukocytes and antibodies in the lymph, the initial remoteness of the lymphatic vessels from the main accumulations of lymphoid tissue, the ease of spread of infectious agents throughout the body with the flow of lymph - all this required the appearance of lymph nodes. Their appearance contributed to the protection constancy of the internal environment of the body not only due to the inherent barrier function of the lymph nodes, but also due to the fact that now the body was able to develop means of specific immunological protection (antibodies, sensitized lymphocytes) in response to a local antigenic stimulus before the infectious agent enters the bloodstream.

The place of formation of lymph, the roots of the lymphatic system are the lymphatic capillaries, which, together with postcapillaries, lymphatic vessels, lymph nodes and the main collector trunks, serve as lymphatic pathways. Since the functions of the lymphatic vessels and the main collector lymphatic trunks consist only in conducting lymph, and the lymph nodes perform barrier, protective, exchange and reservoir functions, the structure of these sections of the lymphatic pathways differs significantly from each other.

The lymphatic system proper begins with the lymphatic capillaries, which are closely related to the blood capillaries. Their diameter is several times larger than blood vessels and reaches 35 microns. The body has reserve capillaries that fill up with increased lymph formation. It has been established that there are no lymphatic capillaries and vessels in the brain and spinal cord, meninges, bones, eyeball, cornea, hyaline cartilage, epidermis, placenta. They are relatively few in muscles, dense connective tissue anatomical formations (ligaments, fascia, tendons). They are unevenly distributed in the glands. Lymphatic capillaries form dense networks in the subcutaneous tissue, in the walls of internal organs, serous membranes, joint capsules.

The architecture of networks of lymphatic capillaries and plexuses of lymphatic vessels corresponds to the design of organs and their functions, while the processes of lymph formation are determined primarily by the state of permeability of the walls of blood capillaries and lymphatic terminals, the mobility of the interstitial gel. Unlike blood vessels, movement in lymphatic capillaries is one-way.

Lymphatic capillaries, merging, pass into the lymphatic vessels. The larger the lymphatic vessel, the greater the distance from it are the capillaries and venules. And vice versa, blood capillaries adjoin almost closely to thin lymphatic vessels and postcapillaries. Depending on the structure of the middle membrane, the lymphatic vessels are divided into two groups: amuscular and muscular. Muscleless vessels are formed by a layer of endothelial cells, which is surrounded by a connective tissue sheath containing collagen and elastic fibers. Most human lymphatic vessels, especially in the lower half of the body, on the lower extremities, are muscular.

The structure of the lymphatic vessels, as we see, is not the same. This variability can be observed in the structure of even the same vessel in its various parts. The valve system assumes unidirectional lymph flow. However, in conditions of pathology, in the presence of an obstacle to the flow of lymph (blocking of transport routes, lymph nodes) due to overstretching of blood vessels and insufficiency of valves that are unable to hold the “column” of lymph, as well as due to a decrease in the contractile activity of the muscle layer of the vessel wall (it is impregnated with toxin transudate) the flow of lymph from an intact zone can cause its reverse flow with the opening of lymphovenous anastomoses or the formation of lymphatic collaterals.

Lymph nodes are located on the path of superficial and deep lymphatic vessels and through them they receive lymph from those tissues, organs or parts of the body in which the vessels originate. Such nodes are called regional, or regional. The lymphatic system of mammals is characterized by the presence of a large number of lymph nodes: in a dog, for example, there are an average of 60 nodes, and in humans - 460. Some authors consider the lymph node to be a key area of ​​the lymph flow. They contain smooth muscle elements and can contract under neurohumoral influences. There are afferent lymphatic vessels, through which the lymph enters the lymph nodes, and efferent, through which the lymph flows. The number of bearers exceeds the number of bearers. The lymph nodes and primary nodules lying on the paths of the lymph flow not only determine the nature of the lymphodynamics, but also leave a significant imprint on the cellular composition of the lymph. The circulation of fluid from the blood to the tissues, its movement in the tissues, the flow from the tissues into the blood and lymph are all links in a single system of humoral transport.

Particularly important here belongs to the PAF system (coagulation, anticoagulation, fibrinolysis) in the blood and lymph. By actively influencing the SAF, it is possible to control the movement of fluid from the blood to the tissues and from the tissues to the lymph, which can be important in medical practice.

What keeps lymph moving?

It was found that amphibians and reptiles have so-called lymphatic hearts - special contractile organs, the walls of which contain muscle elements. The frog has two pairs of "lymphatic hearts", and the tailed amphibians have 15 paired lateral "lymphatic hearts" and 8-10 "lymphatic hearts" in the scapular, pelvic and other areas. In birds, "lymphatic hearts" can be observed only at the stage of embryonic development, while in mammals there are no such hearts at all. The movement of lymph in them occurs due to the contraction of skeletal muscles, the suction capacity of the chest, the movement of large nearby arterial pulsating vessels, etc. Some authors argue that the lymph nodes of warm-blooded animals have taken over the function of the disappeared lymphatic hearts. But it is difficult to agree with this. It should be noted that more lymph flows to the node than flows out. Lymph nodes absorb lymph like a sponge, but not all of it is given away, part of the lymph lingers in the node. It is more correct to consider that in warm-blooded animals the lymph nodes are additional organs of lymphopoiesis, which have developed in connection with a more intensive metabolism. It is believed that the function of the disappeared lymphatic hearts was taken over by the wall of the lymphatic vessel, since only in warm-blooded animals do the lymphatic vessels acquire a characteristic clear-shaped shape with well-developed muscle fibers in the walls and a valve apparatus peculiarly arranged to regulate the flow of lymph.

An extremely important discovery in the field of lymphodynamics was the discovery of the rhythmic pulsation of the thoracic duct in humans. As you can see, lymph circulation is an extremely complex process. The information available in the literature indicates the important role of electrolytes and a number of microelements in its work. For the contractile activity of the muscles of the lymphatic vessels, for example, calcium ions are needed. When they are removed, the mechanical activity of the smooth muscle cells of the lymphatic vessels immediately stops. Manganese ions have a depressing effect on the contraction of the lymphatic vessels. Lithium and cobalt salts (in doses higher than biotic) expand the lymphatic capillaries, and salts of rubidium, selenium and partly copper (also in doses higher than biotic), increasing the rhythmic contraction of the neuromuscular apparatus of the wall of the lymphatic vessels, accelerate the lymph flow.

Unlike the circulatory system, as already mentioned, the lymphatic system is characterized by a unidirectional current. This circumstance makes it possible to accurately determine its initial link - the "fixed reference point". Such an initial point should be considered lymphatic capillaries, since only their content fully corresponds to the term "lymph". In humans, the central collector of lymph is the thoracic duct. Numerous lymphatic vessels flow into it, collecting lymph from the lower extremities, pelvis, abdomen, left half of the chest, from the heart and left lung, from the left upper limb, from the left half of the head and neck. This main lymphatic collector is supplemented by the right lymphatic duct, which is formed from the confluent lymphatic vessels of the right half of the head, neck, chest and right upper limb. It flows into the right venous angle. In a biological sense, the lymphatic system is considered closed (closed), but communicating with the circulatory system at the confluence of the thoracic and right lymphatic ducts.

Main functions of the lymphatic system.

The primary task of the lymphatic system, as well as the circulatory system, is to provide all organs and tissues of the body with nutritious, energy and plastic materials and remove metabolites and toxic substances from there. The lymphatic system is not only a transport, but also a physiologically active link, it makes its own independent, far from unambiguous contribution to the composition and condition of the products carried through the vessels.

It plays a particularly important role concentration, barrier, immune functions, which may be affected by the PAF factors. The lymphatic system takes an active part in the metabolism of proteins, fats, vitamins, etc. The participation of lymph nodes in the processes of digestion and metabolism is obviously determined phylogenetically - throughout the evolution of vertebrates, the association of lymphatic tissue with the digestive canal can be traced.

Feeding animals on a diet rich in fat causes hypertrophy of all lymphatic tissues, especially the tonsils, lymph nodes and intestinal follicles. An increase in the number of free macrophages with trapped fat was noted. Fasting leads to a decrease in the number of lymphocytes, the fat content in the nodes decreases.

Lymph nodes are also involved in the metabolism of proteins and in the production of a number of blood proteins (including immunoglobulins). An increase in protein concentration was noted during the passage of lymph through the lymphatic vessels, especially at its low speed. Participation of lymphatic capillaries and postcapillaries in metabolism is predetermined by their orientation and location in vascular microstructures. They are located in the zones of maximum filtration of fluid and substances - in the region of the venular section of the capillary network and post-capillary segments of venules.

Of particular interest is the study of the endothelium of the lymphatic capillaries in a number of diseases, when metabolic processes and the permeability of vascular membranes are disturbed. In such cases, the outgoing protein impregnates the main substance of the connective tissue structures surrounding the capillaries. The main point that causes a number of pathological changes with increased capillary permeability is the blockade of active elements of the connective tissue that have gone beyond the vascular walls. Violation of the permeability of the walls of blood capillaries and other parts of the microvasculature entails disordered transport of fluids, blood cells pass into the tissues, and then into the lumen of the lymphatic capillaries.

Almost all lymphoid organs (with the exception of the thymus) are characterized by a barrier function - the ability to detain and, if possible, neutralize foreign particles and substances entering the organ. Due to the special structure of the lymphoid organs and the phagocytic activity of their cells, most lymphoid organs trap and neutralize bacteria that have entered the lymph. Especially great is the importance of the lymph nodes, which fix microorganisms even before they enter the bloodstream and are therefore a kind of "first line of defense" of the body. The barrier function of lymphoid organs, being a nonspecific factor of immunity, at the same time is a necessary prerequisite for the formation of a specific immunological reaction of this organ and the whole organism.

Other foreign substances are also absorbed in the lymph nodes. Some of them (mascara, thorium, oily products) linger in the lymph nodes forever. Even direct washing of nodes does not help. Numerous facts show that the lymph nodes play the role of not so much a mechanical as a biological filter. However, in cases where the cellular and humoral resources of a given organ and the whole organism as a whole are insufficient to neutralize the pathogenic factor, the barrier function turns into an unfavorable side: the lymphoid organ becomes a reservoir, a focus of real danger. Take for example chronic tonsillitis, foci of infection in the lymph nodes with tuberculosis, brucellosis, metastasis to regional nodes of tumor cells, etc.

The endothelium of the lymphatic capillaries is extremely sensitive to mechanical, chemical, temperature and other influences and reacts to them by a change in permeability. Endothelial cells are able to adsorb protein particles, lipids and other substances. This property of cells is very important, as it is aimed at ensuring the absorption of liquid with toxins dissolved in it, as well as the absorption of foreign particles, bacteria, and viruses.

In the tissue of the nodes, the formation of lymphocytes occurs. They enter the lymph flow, and then through the thoracic and right lymphatic ducts into the blood. The number of lymphocytes in the lymph flowing from the lymph node is greater than in the incoming one.

Lymph and the immune system of the body.

It has long been known that the protective function of the body largely depends on the lymphatic system. For the first time this question was developed by the outstanding Russian scientist I. I. Mechnikov. He explained immunity as a phenomenon of intracellular digestion of microbes and called this process phagocytosis. Subsequently, humoral factors of immunity were identified, which primarily include antibodies. The active participation of lymphoid organs was also established in the implementation of humoral factors of immunity. It has now been established that phagocytosis (the main non-specific factor) and antibodies (the main specific factors of immunity) act together and form the basis of immunological resistance.

The central figure of the immune system is the lymphocyte, and the substrate for the formation of specific immunological reactions is the lymphoid tissue. The totality of human lymphoid organs and tissues is the thymus gland (thymus), spleen, lymph nodes, group lymph follicles and other lymphoid accumulations, bone marrow and peripheral blood lymphocytes. The leading function of the lymphoid organs is maintaining the constancy of the internal environment of the body.

The bulk of lymphocytes is formed in the lymph nodes and lymph follicles of the digestive tract. In addition, they can be produced in the spleen, thymus, and bone marrow.

The nature and degree of participation of various lymphoid organs in immunological processes are not the same. Some lymphoid organs (lymph nodes, spleen) are the direct substrate of the immunogenesis process, others (the goiter, the bag of Fabricius) participate in them indirectly, regulating the immunoreactivity of the lymph nodes and spleen.

Lymphoid cells are able to carry out their immunological function autonomously, sometimes even against other cells of the organism in which they are located. At the same time, the level of their immunoreactivity is regulated by hormonal and, possibly, reflex mechanisms.

A number of studies have shown the ability of large lymphocytes and cells of the germinal centers of lymphoid tissue to produce antibodies, normal gamma globulins, and macroglobulins. The question of the ability of small lymphocytes to produce antibodies remains debatable. It is believed that the main precursors of cells that synthesize antibodies are immature cells of lymphoid tissue: hematocytoblasts and lymphoblasts (large lymphocytes). It is not clear, however, whether these cells are the object of action of the antigen or an intermediate link in the chain of cellular transformations. Large lymphocytes store immunological information (memory) about the previous antigenic stimulus for at least 600 cell generations.

Lymphoid organs after primary immunization acquire specifically increased reactivity to this antigen. The expression of this altered immunoreactivity is, firstly, the ability to respond to smaller doses of antigen and, secondly, a more rapid and vigorous formation of antibodies (revaccination effect). An increase in immunoreactivity as a result of previous exposure to an antigen is a major factor in delayed-type allergic reactions. The immunological memory of lymphoid cells is an essential factor in the body's anti-infective defense.

Recent works have shown a very important role of the thymus gland not only in immunity, but also in the formation of the lymphoid system. This gland is actually the first central lymphoid organ, where mainly T-lymphocytes mature. This type of lymphocytes constantly undergoes training in the thymus gland and learns the ability to separate "own" from "alien". After that, the killers ("killers") and helpers ("assistants"), respectively, perform their functions. In addition, the thymus releases into the blood hormone-like substances that promote the maturation of T-lymphocytes. It supplies lymphocytes to other lymphoid organs, especially in the early postembryonic period.

The thymus and spleen are a kind of peripheral lymph nodes that are actively involved in the neurohumoral regulation of the lymphatic system. Removal of the thymus in newborn animals causes persistent pathological changes, among which the leading factor is systemic hypoplasia of the lymphoid tissue.

The cells of the spleen, as well as the cells of the lymphoid nodes, are characterized by immunological memory - the ability to respond to repeated injection of the antigen with a faster and more intense production of antibodies. In the spleen, in addition to antibodies, lymphocytes or lymphocyte-like cells are also produced, which migrate to other organs, and there they turn into cells that produce antibodies.

The body's resistance to infections and other pathogenic factors depends not only on the ability to develop a highly specialized immune response, but also on numerous so-called non-specific protective reactions of the body. Such reactions include, for example, the impermeability of normal skin and mucous membranes for a variety of microorganisms and the presence of bactericidal substances in skin secretions, gastric juice, blood and other body fluids (saliva, tears, etc.). Specific and non-specific protective factors work together. The significance of the lymphatic system is far from being limited to what has been said. The development of the doctrine of lymph contributes to the identification of its new functions.

Factors affecting the lymph and lymph flow.

Conventionally, they can be divided into internal and external, natural and artificial.

Among the internal factors in the regulation of lymph flow, an important role belongs to the own activity of the lymphatic vessels. Internal factors are inherent in the lymphatic system itself. The concept of own, internal, forces of lymph flow includes lymph formation and contractile activity of lymphatic vessels and nodes. The strength of lymph formation is the initial volume of lymph, without which lymph flow is impossible.

In the transport of lymph, one should also take into account the viscosity of the lymph flowing from the periphery, which can change if lymph formation is disturbed, the tone of the lymphatic valves, the external pressure on the wall of the lymphatic vessel of muscle contractions of the organ and adjacent blood vessels, as well as the values ​​characterizing the mechanical properties of the wall of the lymphatic vessel - thickness and radius of lymphangions, elastic properties of its wall. The intensity of lymph formation correlates with the intensity of blood circulation.

It was previously believed that external factors (respiratory movements of the lungs, rhythmic changes in the volume of the intestines, spleen, pulsation of the walls of blood vessels and contractions of skeletal muscles) are decisive in the promotion of lymph. The proof of this was the almost complete cessation of lymph flow from the immobilized limb. Subsequently, the appearance of edema after prolonged immobilization of the limb (in the experiment) and, along with dilatation of the lymphatic vessels, dystrophic changes in their walls were established. This indicates a violation of the trophism of the lymphatic vessels. The noted changes in the lymphatic vessels did not appear immediately, but after several weeks and even months. It has been noted, however, that during catheterization of the lymphatic vessel of the lower extremity in anesthetized animals, the lymph does not flow out.

Many different mechanisms and factors are involved in the regulation of lymph movement, which is determined by the need to ensure the reliability of the functions performed by the lymphatic system. Lymph nodes have their own contractile activity similar to the lymphatic vessels. It is likely that the motility of smooth muscles contributes (and under certain conditions changes) the transport capacity of the lymph nodes. The movement of lymph through the node may be facilitated by arterial pulsation. The presence of good innervation and smooth muscles suggests the influence of the nervous system on the lymph flow through the lymph nodes.

Among the factors of lymph flow, the most significant after the own contractile activity of the lymphatic vessels are passive and active muscle movements, peristalsis of the gastrointestinal tract, pulsation of arteries and veins. The factors of lymph flow also include the influence of the frequency and strength of heart contractions on the lymph flow.

The lymph flow in the thoracic duct (the main collector of the vasculature of the lymphatic system) is affected by many constant factors (own contractile activity of the lymphatic vessels, respiration, blood pressure, aortic pulsation), the intensity of the influence of which can determine the movement of the lymph or contribute to it. Temporal factors (contractions of the skeletal muscles, the activity of the digestive system) can also largely determine the volume of lymph entering the venous system.

The high sensitivity of lymphatic vessels to thermal factors was noted. It has been proven that hypothermia reduces the tone of the lymphatic vessels by two and a half times. Hypokinesia has a particularly negative effect on the lymph flow. Massage enhances the transport function of the lymph. Dosed stimulation of lymph flow through passive movements of the injured limb with a certain frequency, duration and frequency significantly reduces the toxicity of peripheral lymph.

The human lymphatic system (HLS) is a component of the vascular system, which is important in cleansing the tissues and cells of the body. Lymph nodes are links in the LChS, each of which is responsible for filtering a clear liquid (lymph) from harmful substances.

It is impossible to say unequivocally why the lymphatic system is needed, since it has numerous functions, which will be discussed below.

The structure of the LSC includes:

• lymph;
• lymphatic vessels and capillaries;
• lymph nodes (immune links, formations).

The circulatory and lymphatic systems differ significantly from each other. There are no erythrocytes in a clear liquid, and there are much fewer protein molecules than in blood. LSP is not closed. It lacks the main pump, i.e. the heart. Lymph moves into the LSP smoothly and under minimal pressure.

The structure of the human lymphatic system will tell the scheme. It will also indicate the features of the movement of the lymph. The components of the most important part of the body are described in detail below.

Lymph

The word "lymph" in Latin means "clear water". This is not surprising, because this liquid cleanses the body of harmful substances. In its structure, lymph is a connective tissue and has many lymphocytes, practically does not contain platelets and erythrocytes.

The composition of "pure water" includes the products of the vital activity of the body, including large molecules of proteins. Most often they are viruses that are filtered by the lymphatic system. The clear liquid contains various hormones produced by the endocrine glands.

Lymph moves from the periphery to the center, moving from bottom to top. It passes from small capillaries, which gradually flow into large vessels. The movement goes through formations - lymph nodes that perform the function of filtering. In total, the lymphatic system contains about 500 such anatomical structures.

Lymphatic vessels and capillaries

Click to enlarge

LSP outwardly resembles the roots of a tree. This brings it closer to the nervous and circulatory systems. Lymphatic vessels permeate almost the entire human body, excluding the sclera, the inner part of the ear, and some other segments.

From the tissues, lymph enters the capillaries, which are connected to the lymphatic vessels. The latter surround all organs and often lie in several layers.

The lymph passes through the vessels to the regional links of immunity, localized in the inguinal and elbow areas, armpits, chest, etc. Large trunks emerge from the nodes, which flow into the ducts that open the way to the circulatory system for “clean water”.

Lymph nodes (immune links)

A lymph node (LN) is often a rounded formation that has a gray-pink color and sizes from 0.5 to 50 mm or more. Immune links are localized along the lymphatic and near the blood vessels. Each of the formations serves as a kind of filter. They are responsible for cleansing the body not only from microbes, but also from cancer cells. Thus, it is an essential part of human health.

The node structure includes:

• connective tissue capsule;
• stroma (structural basis) in which macrophages are located;
• cortical substance, consisting of a superficial part and a deep cortex.

The immune links are based on lymphoid tissue, in which there are lymphocytes, reticulocytes and plasma cells. In the formations, the most important components of immunity develop - B-lymphocytes, which participate in its formation.

Functions of the lymphatic system

Lymphocytes actively fight bacteria and viruses that enter the body from outside. This ensures the normal functioning of the body's defenses. Immune links increase if the number of microbes is too large and they can not cope with them. In this case, the help of a specialist is required.

The lymphatic system performs the function of cleansing from microbes and is responsible for the delivery of the most important elements to the venous bed. Later, these components through the blood circulation enter the cardiovascular system and leave the human body.

Most harmful substances are eliminated at the stage of filtration with a clear liquid, i.e., they are destroyed in the links of immunity. The body normally “works” thanks to the lymphatic capillaries, through which proteins and other compounds come from the interstitial space into the clear liquid.

The way "clear water" flows is determined by the degree of muscle tension. Physical activity has a beneficial effect on the movement of lymph, promotes high-quality cleansing of the body and normalization of human health.

Major diseases

The most common problems with the lymphatic system are:

1. Lymphoma:

• Hodgkin - LSP cancer with a high degree of malignancy;
• non-Hodgkin's (B-cell or T-cell).

1. Lymphadenitis - inflammation of the immune links:

• acute, provoked by viruses or bacteria;
• chronic, caused by syphilis, immunodeficiency or tuberculosis, less often - influenza;
• purulent (occurs in advanced cases, characterized by the formation of exudate in the node).

1. Lymphedema (including elephantiasis) is a persistent swelling of an extremity that develops as a result of damage to the LSP, which contributes to impaired lymph circulation or the formation of lymphostasis.

Signs of malfunction of the lymphatic system are:

• swelling of the fingers;
• pain in the chest;
• cold extremities;
• cellulite;
• dry skin.

The lymphatic system and lymph are the most important components of the body, for the normal functioning of which are useful:

• physical activity;
• trampolining;
• yoga classes;
• proper diet;
• breathing exercises;
• rejection of bad habits;
• food according to Ayurveda.

If the cleansing function is violated, health problems arise. A person needs continuous work of LSP. How the structures cope with their task depends on his well-being. To maintain health, lymph is needed periodically.

Which doctor should I contact?

Treatment of LSP pathologies is reduced to the use of drugs or surgery. Having found deviations from the norm, you need to consult with a pediatrician / therapist who will refer you to a specialist.

Below is a table explaining which doctors deal with LSD diseases.

leading symptom	Narrow specialist
Enlarged lymph nodes in the neck	Otorhinolaryngologist
Soreness and proliferation of lymphoid tissue under the jaw	Dentist
Increase in immune links in the groin area	Gynecologist or urologist
Change in the size of formations, accompanied by hemoptysis, a sharp decrease in weight, increased sweating, fever