home Audience 8 Human physiology and anatomy. Lymphatic system. Lymphatic system Lymphatic system briefly

Human physiology and anatomy. Lymphatic system. Lymphatic system Lymphatic system briefly

In the human body, along with the cardiovascular system, there is also a complementary lymphatic system. This structure penetrates all tissues and organs with capillaries, ensuring the movement of biological fluid - lymph and helping to strengthen the body's immune defense.

The lymphatic system helps the body cleanse itself of toxins, waste, microbes and infections, and also removes excess fluid from the intercellular space, pumping it into the vascular bed.

Lymphatic fluid is considered a type of connective tissue and includes lymphocytes - cells of the immune system. They perform vital functions, as they are able to distinguish “their” components from “foreign” ones within the body - red and white blood cells from infections and microbes, and then break down harmful particles with the help of T-lymphocytes.

Lymph also includes:

water;
salt;
minerals;
colloidal solutions of proteins;
fats.

This viscous liquid resembles blood plasma in its properties. The body of an adult contains about one and a half to two liters. Circulation is ensured by contractions of muscle cells in the walls of blood vessels, as well as by the movement of other muscles, the general position of the body and the phases of breathing.

Functions of lymph in the body

Lymph circulation performs several functions at once:

Structure diagram

The anatomical structure of the lymphatic system can be depicted schematically:

The main components of its structure:

capillaries and vessels;
nodes;
ducts;
organs.

Lymphatic capillaries and vessels penetrate almost all organs and tissues of the body. They are not found only in the spinal cord and brain, the internal tissue of the spleen, the lens of the eye, the middle ear and the placenta. The capillaries of the lymphatic system are thicker than those of the circulatory system and have permeable walls that are physiologically more adapted to the absorption of substances. They merge into large ducts - vessels that also have thin walls, but are equipped with valves that prevent reverse or retrograde flow of lymph.

The vessels slowly deliver fluid to groups of lymph nodes consisting of lymphoid tissue, which contains:

lymphocytes;
plasma cells;
reticulocytes are young red blood cells.

Immune cells “mature” in the nodes of the lymphatic system:

B-lymphocytes - produce antibodies and mobilize the immune system in case of a threat;
T-lymphocytes - promote the breakdown of cells damaged by viruses.

The fluid released from the lymph nodes enters the circulatory system through large ducts. As can be seen in the diagram, there are only two lymphatic ducts in the body - right and left, which flow into the corresponding subclavian veins.

The organs of the lymphatic system are:

spleen;
thymus gland or thymus;
tonsils.

The movement of lymph occurs from bottom to top due to the fact that the valves of this system allow fluid to pass in only one direction. Therefore, it is important to massage in the direction of its circulation: from the fingers to the thoracic lymphatic duct, from the toes to the inguinal lymph nodes.

Causes of enlarged lymph nodes

Since the lymphatic system is aimed at cleansing the body and ridding it of harmful microelements, enlarged lymph nodes always indicate the presence of pathology.

The following photo is an example of what an inflamed lymph node looks like. In this case, the neck is affected.

The causes of inflammatory processes can be:

The most common cause of enlarged lymph nodes is infection. They can be either local or generalized, when the inflammatory process first occurs in one lymph node and then spreads to others.

Autoimmune diseases that cause inflammation in the nodes are arthritis and lupus erythematosus.

Oncological diseases of the lymphatic system: Hodgkin's lymphoma, non-Hodgkin's lymphomas. Inflammation can also be caused by other types of cancer, the metastases of which spread to the lymph nodes.

Cleansing the lymphatic system

Since the lymphatic system performs a number of vital functions, removing polluting bacteria, infections and cell breakdown products from the body, it also needs to be cleansed.

A sedentary lifestyle, unhealthy diet, technogenic influence - all this disrupts its functioning and leads to stagnation of lymph in the body. As a result, pathogenic substances are not removed from the body, but remain in it, which reduces the overall level of immunity and increases the risk of autoimmune diseases.

A healthy diet and a special massage will help cleanse the lymphatic system.

The diet should include the following products:

fresh herbs;
seaweed;
linseed oil;
herbal teas.

To improve fluid outflow, you need to drink at least 7-8 glasses of clean water daily.

It will help to “revive” the processes of outflow and lymphatic drainage. However, only a massage therapist trained in a special technique should do it: the lymphatic system is very fragile, incorrect actions can damage the valves and cause fluid to flow back. All movements should be made in the direction of lymph flow - from bottom to top.

Lymphatic drainage:

promotes the penetration of fluid from tissues into the capillaries and vessels of the system;
accelerates lymph circulation;
activates the process of cleansing blood vessels from cell decay products.

Lymphatic system – an integral part of the vascular system that drains tissues by forming lymph and conducting it into the venous bed (additional drainage system).

Up to 2 liters of lymph are produced per day, which corresponds to 10% of the volume of fluid that is not reabsorbed after filtration in the capillaries.

Lymph is the fluid that fills the lymphatic vessels and nodes. It, like blood, belongs to the tissues of the internal environment and performs trophic and protective functions in the body. In its properties, despite the great similarity with blood, lymph differs from it. At the same time, lymph is not identical to the tissue fluid from which it is formed.

Lymph consists of plasma and formed elements. Its plasma contains proteins, salts, sugar, cholesterol and other substances. The protein content in lymph is 8-10 times less than in blood. 80% of the formed elements of the lymph are lymphocytes, and the remaining 20% are the share of other white blood cells. There are normally no red blood cells in lymph.

Functions of the lymphatic system:

Tissue drainage.

Ensuring continuous fluid circulation and metabolism in human organs and tissues. Prevents the accumulation of fluid in the tissue space with increased filtration in the capillaries.

Lymphopoiesis.

Transports fats from the site of absorption in the small intestine.

Removal from the interstitial space of substances and particles that are not reabsorbed in the blood capillaries.

Spread of infection and malignant cells (tumor metastasis)

Factors ensuring lymph movement

Filtration pressure (due to the filtration of fluid from the blood capillaries into the intercellular space).

Constant formation of lymph.

Availability of valves.

Contraction of the surrounding skeletal muscles and muscle elements of the internal organs (they squeeze the lymphatic vessels and the lymph moves in the direction determined by the valves).

The location of large lymphatic vessels and trunks near blood vessels (the pulsation of the artery compresses the walls of the lymphatic vessels and helps the flow of lymph).

Suction action of the chest and negative pressure in the brachiocephalic veins.

Smooth muscle cells in the walls of lymphatic vessels and trunks .

Table 7

Similarities and differences in the structure of the lymphatic and venous systems

Lymphatic capillaries– thin-walled vessels, the diameter of which (10-200 microns) exceeds the diameter of blood capillaries (8-10 microns). Lymphatic capillaries are characterized by tortuosity, the presence of narrowings and expansions, lateral protrusions, the formation of lymphatic “lakes” and “lacunae” at the confluence of several capillaries.

The wall of the lymphatic capillaries is built from a single layer of endothelial cells (in the blood capillaries there is a basement membrane outside the endothelium).

Lymphatic capillaries No in the substance and membranes of the brain, cornea and lens of the eyeball, spleen parenchyma, bone marrow, cartilage, epithelium of the skin and mucous membranes, placenta, pituitary gland.

Lymphatic postcapillaries– an intermediate link between lymphatic capillaries and vessels. The transition of the lymphatic capillary to the lymphatic postcapillary is determined by the first valve in the lumen (the valves of the lymphatic vessels are paired folds of the endothelium and the underlying basement membrane lying opposite each other). Lymphatic postcapillaries have all the functions of capillaries, but lymph flows through them only in one direction.

Lymphatic vessels are formed from networks of lymphatic postcapillaries (capillaries). The transition of a lymphatic capillary into a lymphatic vessel is determined by a change in the structure of the wall: along with the endothelium, it contains smooth muscle cells and adventitia, and in the lumen there are valves. Therefore, lymph can flow through the vessels only in one direction. The area of the lymphatic vessel between the valves is currently designated by the term "lymphangion" (Fig. 58).

Rice. 58. Lymphangion is a morphofunctional unit of a lymphatic vessel:

1 – segment of the lymphatic vessel with valves.

Depending on the location above or below the superficial fascia, lymphatic vessels are divided into superficial and deep. Superficial lymphatic vessels lie in the subcutaneous fat above the superficial fascia. Most of them go to the lymph nodes located near the superficial veins.

There are also intraorgan and extraorgan lymphatic vessels. Due to the existence of numerous anastomoses, intraorgan lymphatic vessels form wide-loop plexuses. The lymphatic vessels emerging from these plexuses accompany the arteries, veins and exit the organ. Extraorgan lymphatic vessels are directed to nearby groups of regional lymph nodes, usually accompanying blood vessels, often veins.

Along the path of the lymphatic vessels there are The lymph nodes. This is what causes foreign particles, tumor cells, etc. are retained in one of the regional lymph nodes. The exceptions are some lymphatic vessels of the esophagus and, in isolated cases, some vessels of the liver, which flow into the thoracic duct, bypassing the lymph nodes.

Regional lymph nodes organs or tissues are lymph nodes that are the first on the path of lymphatic vessels carrying lymph from a given area of the body.

Lymphatic trunks- these are large lymphatic vessels that are no longer interrupted by lymph nodes. They collect lymph from several areas of the body or several organs.

There are four permanent paired lymphatic trunks in the human body.

Jugular trunk(right and left) is represented by one or several vessels of small length. It is formed from the efferent lymphatic vessels of the lower lateral deep cervical lymph nodes, located in a chain along the internal jugular vein. Each of them drains lymph from the organs and tissues of the corresponding sides of the head and neck.

Subclavian trunk(right and left) is formed from the fusion of the efferent lymphatic vessels of the axillary lymph nodes, mainly the apical ones. It collects lymph from the upper limb, from the walls of the chest and mammary gland.

Bronchomediastinal trunk(right and left) is formed mainly from the efferent lymphatic vessels of the anterior mediastinal and superior tracheobronchial lymph nodes. It carries lymph away from the walls and organs of the chest cavity.

The efferent lymphatic vessels of the upper lumbar lymph nodes form the right and left lumbar trunks, which drain lymph from the lower limb, walls and organs of the pelvis and abdomen.

A non-permanent intestinal lymphatic trunk occurs in approximately 25% of cases. It is formed from the efferent lymphatic vessels of the mesenteric lymph nodes and 1-3 vessels flow into the initial (abdominal) part of the thoracic duct.

Rice. 59. Basin of the thoracic lymphatic duct.

1 – superior vena cava;

2 – right brachiocephalic vein;

3 – left brachiocephalic vein;

4 – right internal jugular vein;

5 – right subclavian vein;

6 – left internal jugular vein;

7 – left subclavian vein;

8 – azygos vein;

9 – hemizygos vein;

10 – inferior vena cava;

11 – right lymphatic duct;

12 – cistern of the thoracic duct;

13 – thoracic duct;

14 – intestinal trunk;

15 – lumbar lymphatic trunks

The lymphatic trunks flow into two ducts: the thoracic duct (Fig. 59) and the right lymphatic duct, which flow into the veins of the neck in the area of the so-called venous angle, formed by the connection of the subclavian and internal jugular veins. The thoracic lymphatic duct flows into the left venous angle, through which lymph flows from 3/4 of the human body: from the lower extremities, pelvis, abdomen, left half of the chest, neck and head, left upper extremity. The right lymphatic duct flows into the right venous angle, which brings lymph from 1/4 of the body: from the right half of the chest, neck, head, and from the right upper limb.

Thoracic duct (ductus thoracicus) has a length of 30-45 cm, is formed at the level of the XI thoracic – 1st lumbar vertebrae by the fusion of the right and left lumbar trunks (trunci lumbales dexter et sinister). Sometimes at the beginning the thoracic duct has extension (cisterna chyli). The thoracic duct is formed in the abdominal cavity and passes into the chest cavity through the aortic opening of the diaphragm, where it is located between the aorta and the right medial crus of the diaphragm, the contractions of which help push lymph into the thoracic part of the duct. At the level of the VII cervical vertebra, the thoracic duct forms an arc and, going around the left subclavian artery, flows into the left venous angle or the veins that form it. At the mouth of the duct there is a semilunar valve that prevents blood from entering the duct from the vein. The left bronchomediastinal trunk (truncus bronchomediastinalis sinister), which collects lymph from the left half of the chest, flows into the upper part of the thoracic duct, as well as the left subclavian trunk (truncus subclavius sinister), which collects lymph from the left upper limb and the left jugular trunk (truncus jugularis sinister), which carries lymph from the left half of the head and neck.

Right lymphatic duct (ductus lymphaticus dexter) 1-1.5 cm long, is being formed at the fusion of the right subclavian trunk (truncus subclavius dexter), carrying lymph from the right upper limb, the right jugular trunk (truncus jugularis dexter), collecting lymph from the right half of the head and neck, the right bronchomediastinal trunk (truncus bronchomediastinalis dexter), bringing lymph from the right half of the chest. However, more often the right lymphatic duct is absent, and the trunks that form it flow into the right venous angle independently.

Lymph nodes of individual areas of the body.

Head and neck

In the head area there are many groups of lymph nodes (Fig. 60): occipital, mastoid, facial, parotid, submandibular, submental, etc. Each group of nodes receives lymphatic vessels from the area closest to its location.

Thus, the submandibular nodes lie in the submandibular triangle and collect lymph from the chin, lips, cheeks, teeth, gums, palate, lower eyelid, nose, submandibular and sublingual salivary glands. Lymph flows from the forehead, temple, upper eyelid, auricle, and walls of the external auditory canal into the parotid lymph nodes, located on the surface and in the thickness of the gland of the same name.

Fig.60. Lymphatic system of the head and neck.

1 – anterior ear lymph nodes; 2 – posterior ear lymph nodes; 3 – occipital lymph nodes; 4 – lower ear lymph nodes; 5 – buccal lymph nodes; 6 – mental lymph nodes; 7 – posterior submandibular lymph nodes; 8 – anterior submandibular lymph nodes; 9 – lower submandibular lymph nodes; 10 – superficial cervical lymph nodes

There are two main groups of lymph nodes in the neck: deep and superficial cervical. Deep cervical lymph nodes accompany the internal jugular vein in large numbers, and superficial ones lie near the external jugular vein. In these nodes, mainly in the deep cervical nodes, there is an outflow of lymph from almost all the lymphatic vessels of the head and neck, including the efferent vessels of other lymph nodes in these areas.

Upper limb

There are two main groups of lymph nodes in the upper limb: ulnar and axillary. The ulnar nodes lie in the cubital fossa and receive lymph from some of the vessels of the hand and forearm. Through the efferent vessels of these nodes, lymph flows into the axillary nodes. The axillary lymph nodes are located in the fossa of the same name, one part of them lies superficially in the subcutaneous tissue, the other in the depths near the axillary arteries and veins. Lymph flows into these nodes from the upper limb, as well as from the mammary gland, from the superficial lymphatic vessels of the chest and the upper part of the anterior abdominal wall.

Thoracic cavity

In the chest cavity, the lymph nodes are located in the anterior and posterior mediastinum (anterior and posterior mediastinal), near the trachea (peritracheal), in the bifurcation of the trachea (tracheobronchial), in the hilum of the lung (bronchopulmonary), in the lung itself (pulmonary), and also on the diaphragm. (upper diaphragmatic), near the heads of the ribs (intercostal), near the sternum (peripheral), etc. Lymph flows from the organs and partially from the walls of the chest cavity into these nodes.

Lower limb

On the lower limb, the main groups of lymph nodes are popliteal and inguinal. The popliteal nodes are located in the fossa of the same name near the popliteal arteries and veins. These nodes receive lymph from part of the lymphatic vessels of the foot and leg. The efferent vessels of the popliteal nodes carry lymph mainly to the inguinal nodes.

Inguinal lymph nodes are divided into superficial and deep. Superficial inguinal nodes lie below the inguinal ligament under the skin of the thigh on top of the fascia, and deep inguinal nodes lie in the same area, but under the fascia near the femoral vein. Lymph flows into the inguinal lymph nodes from the lower limb, as well as from the lower half of the anterior abdominal wall, perineum, from the superficial lymphatic vessels of the gluteal region and lower back. From the inguinal lymph nodes, lymph flows to the external iliac nodes, which are related to the nodes of the pelvis.

In the pelvis, the lymph nodes are located, as a rule, along the course of the blood vessels and have a similar name (Fig. 61). So, the external iliac, internal iliac and common iliac nodes lie near the arteries of the same name, and the sacral nodes lie on the pelvic surface of the sacrum, near the median sacral artery. Lymph from the pelvic organs flows mainly to the internal iliac and sacral lymph nodes.

Rice. 61. Lymph nodes of the pelvis and the vessels connecting them.

1 – uterus; 2 – right common iliac artery; 3 – lumbar lymph nodes; 4 – iliac lymph nodes; 5 – inguinal lymph nodes

Abdominal cavity

There are a large number of lymph nodes in the abdominal cavity. They are located along the blood vessels, including the vessels passing through the hilum of the organs. So, along the abdominal aorta and inferior vena cava near the lumbar spine there are up to 50 lymph nodes (lumbar). In the mesentery of the small intestine, along the branches of the superior mesenteric artery, there are up to 200 nodes (superior mesenteric). There are also lymph nodes: celiac (near the celiac trunk), left gastric (along the greater curvature of the stomach), right gastric (along the lesser curvature of the stomach), hepatic (in the area of the hilum of the liver), etc. Lymph from the organs flows into the lymph nodes of the abdominal cavity. located in this cavity, and partly from its walls. The lumbar lymph nodes also receive lymph from the lower extremities and pelvis. It should be noted that the lymphatic vessels of the small intestine are called lacteal, since lymph flows through them, containing fat absorbed in the intestine, which gives the lymph the appearance of a milky emulsion - hilus (hilus - milky juice).

The lymphatic system is an integral part of the vascular system and represents, as it were, an additional channel of the venous system, with which it has common structural features (the presence of valves, the direction of lymph flow from tissues to the heart).

Her main functions– conduction of lymph from tissues into the venous bed (transport, resorption and drainage functions) (Fig. 49), the formation of lymphoid elements (lymphopoiesis) involved in immunological reactions, as well as the neutralization of foreign particles, bacteria, etc. entering the body. (barrier role). Malignant tumor cells also spread through the lymphatic tract.

Rice. 49. Movement of blood, tissue fluid

and lymph in the human body.

Lymphatic system found in all organs of the body. It consists of numerous lymphatic capillaries, lymphatic vessels of various diameters and lymph nodes.

Lymphatic vessels filled with lymph, which moves in one direction - from the organs to the heart and pours into the venous bed. Sports massage promotes the drainage of lymph from organs and tissues. Therefore, they usually massage along the course of the lymphatic vessels, which contributes to the faster movement of the lymph.

Lymph is a clear liquid that contains white formed elements - lymphocytes, a small number of eosinophils and monocytes. In its composition, lymph resembles blood plasma, but the protein content in it is less than in plasma. Cells secrete the products of their metabolism into it. The formation of lymph occurs due to the liquid part of the blood plasma, which is filtered into the lymphatic bed through the main substance of the connective tissue surrounding the blood capillaries. The movement of lymph is much slower than the movement of blood and is due to the pushing effect of newly formed lymph and the physiological activity of organs, in particular muscle contraction.

The lymphatic system is not closed, like the circulatory system (systemic and pulmonary circulation). It begins blindly with a network of lymphatic capillaries in all tissues and ends in the large veins of the neck. Another difference between the lymphatic system and the circulatory system is the presence of lymph nodes along the lymphatic vessels, in which lymphocytes are formed.

Anatomically, the lymphatic system has the following parts: lymphatic capillaries, lymphatic vessels, lymph nodes, lymphatic trunks and ducts.

Lymphatic capillaries blindly begin in organs and tissues and carry out absorption (resorption) from tissues of colloidal solutions of protein substances that are not absorbed into the blood capillaries. They are additional tissue drainage to veins, because... absorb water and substances dissolved in it, remove foreign particles, bacteria, etc. from tissues under pathological conditions. The wall of lymphatic capillaries is built from a single layer of endothelial cells. They are present in all organs, with the exception of the spinal cord and brain, spleen, epithelial skin, cartilage, cornea and lens of the eye, placenta and pituitary gland. Lymphatic capillaries in organs form lymphatic networks from which intraorgan lymphatic vessels, going along with the blood vessels.

Each organ comes out extraorgan lymphatic vessels, which accompany the arteries and veins and go to the lymph nodes.

The lymph nodes located along the course of the lymphatic vessels. They consist of lymphoid and connective tissue and are organs of lymphopoiesis and antibody formation. Particles and pathogens foreign to the body are retained and neutralized in them, and lymph is enriched with lymphocytes. Lymph nodes that are the first on the path of lymphatic vessels carrying lymph from a given area of the body or organ are called regional. The size of the lymph nodes range from 2 to 30 mm.

Each lymph node is covered with a connective tissue capsule, from which septa extend into the node, dividing the node into lobules. Several afferent (discharge) lymphatic vessels approach the lymph node, through which lymph enters it; One or two efferent vessels depart from the node, through which its outflow occurs (Fig. 50).

Rice. 50. The structure of the lymph node.

The lymph node consists of a cortical and medulla located outward. The cortex contains follicles containing immunocompetent cells (B lymphocytes). The medulla is represented by cords, which are an area of accumulation of B-lymphocytes associated with the production of humoral immunity. The lymphatic system also includes lymphoid organs (lymphatic follicles, tonsils), which have only efferent lymphatic vessels.

Lymph nodes can lie isolated or in separate groups. In total, a person has about 460 of them. The largest groups of lymph nodes include: in the head and neck area - submandibular, anterior and posterior cervical; on the upper limb - elbow and axillary; in the chest cavity - anterior and posterior mediastinal; in the abdominal cavity - celiac and superior mesenteric; on the lower limb - popliteal and inguinal. During massage, the movement of the hands should be directed along the flow of lymph to the nearest lymph nodes.

After passing through the last group of lymph nodes, the lymphatic vessels are connected into lymphatic trunks (Fig. 51), corresponding in number and location to large parts of the body - the lumbar trunk (for the lower limb and pelvis), the subclavian trunk (for the upper limb), the jugular trunk (for head and neck), paired bronchomediastinal (for the organs of the chest cavity) and intestinal trunk (for the organs of the abdominal cavity). All these trunks are connected into two terminal ducts - the right lymphatic duct and the thoracic duct (Fig. 51), which flow into large veins, mainly into the internal jugular veins or into the venous angles formed by the confluence of the internal jugular vein and subclavian.

Rice. 51. Trunks and ducts of the lymphatic system.

Thoracic duct collects most of the lymph. Lymph flows into it from both lower extremities, abdominal organs, the left half of the chest, the left half of the head and neck, and the left upper limb. It begins at the level of 1-2 lumbar vertebrae as a result of the fusion of the right and left lumbar trunks, passes through the chest cavity and opens into the left venous angle, formed by the fusion of the left subclavian and internal jugular veins.

Right lymphatic duct collects lymph from the right upper limb, the right half of the head, neck and chest. It drains into the right venous angle or right subclavian vein.

BLOOD FORMING ORGANS AND IMMUNE SYSTEM

Blood and lymphatic vessels are always filled with blood or lymph, respectively, which include the formed elements of blood. Their function and structure are diverse: erythrocytes carry oxygen and carbon dioxide, various leukocytes are involved in the regulatory and protective reactions of the body.

Blood and lymph cells develop in red bone marrow. It is a delicate mass rich in blood vessels, the basis of which is reticular tissue. In its loops, blood and lymph cells are born from special cellular elements - stem cells. Therefore, red bone marrow is both a hematopoietic organ and one of the central organs of the immune system. Red bone marrow is located in the spongy substance of flat bones (sternum), in the spongy substance of the epiphyses of long (tubular) bones.

Immunology– the science of immunity. It arose from the vital need to prevent and treat infectious diseases. The body itself is capable of developing protective properties against infections. Among blood cells - leukocytes - 30% are lymphocytes, which carry out all specific immune reactions - the production of antibodies that fight microorganisms, rejection of transplanted tissues or organs from another person, antiviral protection.

The entire immune system of the body consists of two separately located but working together systems. They are designated by the Latin letters T and B.

T-lymphocyte system represented by the central lymphoid organ – the thymus gland (thymus). Only in it do T-lymphocytes develop from bone marrow stem cells entering this organ.

TO B-lymphocyte system The second central lymphoid organ is the bone marrow. B lymphocytes produce antibodies. The immune process is also ensured phagocytes- white blood cells that can devour microorganisms that enter the human body.

Each group of cells performs a strictly defined function. B lymphocytes primarily carry out the functions of humoral immunity. In it, the main role belongs to fluids (blood, lymph, gland secretions), which contain special substances involved in immune processes. T-lymphocytes of the thymus gland carry out cellular immunity, in which specially sensitive lymphocytes destroy cells that enter the body.

Thus, a whole cellular complex works together in the immune system. Circulating in the body, it interacts with it through receptors and chemical signals of various mediators that can increase or decrease the functional activity of immune blood cells. The main role in it belongs to the thymus gland. The immune system “matures” only after birth, so in newborns the thymus gland is relatively large, since lymphocytes located in peripheral lymphoid organs (lymph nodes, spleen, in the lymphoid tissue of the walls of the digestive, respiratory systems, urinary tract), as well as circulating with blood, without the thymus gland they cannot begin to work - to recognize and destroy foreign cells.

Immunity is the body’s forces that protect it not only from microorganisms and viruses, but also from all genetically foreign cells, tissues and organs. Therefore, the problem of incompatibility during organ transplants from another person is immunological. The main task of modern immunological science is the search for ways to protect the body from living bodies and substances that carry signs of genetically foreign information.

Spleen is a richly vascularized lymphoid organ. In the spleen, the circulatory system comes into close contact with lymphoid tissue, due to which the blood here is enriched with leukocytes developing in the spleen. In addition, the blood passing through the spleen is freed, thanks to the phagocytic activity of spleen macrophages, from obsolete red blood cells (“graveyard” of erythrocytes) and from pathogenic microbes, suspended foreign particles, etc. that have entered the bloodstream.

The spleen is located in the left hypochondrium at the level from 9 to 11 ribs. The peritoneum, fused with the capsule of the spleen, covers it on all sides.

Rice. 52. Structure of the spleen.

The spleen's own capsule continues into the thickness of the organ in the form of crossbars, forming the skeleton of the spleen, dividing it into separate sections. Between the trabeculae is the splenic pulp, which contains lymphatic follicles (Fig. 52). The pulp consists of reticular tissue, various cellular elements, lymphocytes and decaying red blood cells. The lymphoid tissue of the spleen contains lymphocytes involved in immunological reactions. In the pulp, some of the blood cells die. Hemoglobin iron from destroyed red blood cells is sent through the veins to the liver, where it serves as material for the synthesis of bile pigments.

Lymphatic system – an integral part of the vascular system that drains tissues by forming lymph and conducting it into the venous bed (additional drainage system).

Up to 2 liters of lymph are produced per day, which corresponds to 10% of the volume of fluid that is not reabsorbed after filtration in the capillaries.

Functions of the lymphatic system:

Tissue drainage.

Ensuring continuous fluid circulation and metabolism in human organs and tissues. Prevents the accumulation of fluid in the tissue space with increased filtration in the capillaries.

Lymphopoiesis.

Transports fats from the site of absorption in the small intestine.

Removal from the interstitial space of substances and particles that are not reabsorbed in the blood capillaries.

Spread of infection and malignant cells (tumor metastasis)

Factors ensuring lymph movement

Filtration pressure (due to the filtration of fluid from the blood capillaries into the intercellular space).

Constant formation of lymph.

Availability of valves.

Contraction of the surrounding skeletal muscles and muscle elements of the internal organs (they squeeze the lymphatic vessels and the lymph moves in the direction determined by the valves).

The location of large lymphatic vessels and trunks near blood vessels (the pulsation of the artery compresses the walls of the lymphatic vessels and helps the flow of lymph).

Suction action of the chest and negative pressure in the brachiocephalic veins.

Smooth muscle cells in the walls of lymphatic vessels and trunks .

Table 7

Similarities and differences in the structure of the lymphatic and venous systems

The wall of the lymphatic capillaries is built from a single layer of endothelial cells (in the blood capillaries there is a basement membrane outside the endothelium).

Rice. 58. Lymphangion is a morphofunctional unit of a lymphatic vessel:

1 – segment of the lymphatic vessel with valves.

Regional lymph nodes organs or tissues are lymph nodes that are the first on the path of lymphatic vessels carrying lymph from a given area of the body.

Lymphatic trunks- these are large lymphatic vessels that are no longer interrupted by lymph nodes. They collect lymph from several areas of the body or several organs.

There are four permanent paired lymphatic trunks in the human body.

The efferent lymphatic vessels of the upper lumbar lymph nodes form the right and left lumbar trunks, which drain lymph from the lower limb, walls and organs of the pelvis and abdomen.

Rice. 59. Basin of the thoracic lymphatic duct.

1 – superior vena cava;

2 – right brachiocephalic vein;

3 – left brachiocephalic vein;

4 – right internal jugular vein;

5 – right subclavian vein;

6 – left internal jugular vein;

7 – left subclavian vein;

8 – azygos vein;

9 – hemizygos vein;

10 – inferior vena cava;

11 – right lymphatic duct;

12 – cistern of the thoracic duct;

13 – thoracic duct;

14 – intestinal trunk;

15 – lumbar lymphatic trunks

Lymph nodes of individual areas of the body.

Head and neck

Fig.60. Lymphatic system of the head and neck.

Upper limb

Thoracic cavity

Lower limb

Rice. 61. Lymph nodes of the pelvis and the vessels connecting them.

1 – uterus; 2 – right common iliac artery; 3 – lumbar lymph nodes; 4 – iliac lymph nodes; 5 – inguinal lymph nodes

Abdominal cavity

The fluid that enters the tissue is lymph. The lymphatic system is an integral part of the vascular system, ensuring the formation of lymph and lymph circulation.

Lymphatic system - a network of capillaries, vessels and nodes through which lymph moves in the body. Lymphatic capillaries are closed at one end, i.e. end blindly in tissues. Lymphatic vessels of medium and large diameter, like veins, have valves. Along their course there are lymph nodes - “filters” that retain viruses, microorganisms and the largest particles found in the lymph.

The lymphatic system begins in the tissues of organs in the form of an extensive network of closed lymphatic capillaries that do not have valves, and their walls have high permeability and the ability to absorb colloidal solutions and suspensions. Lymphatic capillaries turn into lymphatic vessels equipped with valves. Thanks to these valves, which prevent the reverse flow of lymph, it flows only towards the veins. Lymphatic vessels flow into the lymphatic thoracic duct, through which lymph flows from 3/4 of the body. The thoracic duct drains into the cranial vena cava or jugular vein. Lymph through the lymphatic vessels enters the right lymphatic trunk, which flows into the cranial vena cava.

Rice. Diagram of the lymphatic system

Functions of the lymphatic system

The lymphatic system performs several functions:

The protective function is provided by the lymphoid tissue of the lymph nodes, which produces phagocytic cells, lymphocytes and antibodies. Before entering the lymph node, the lymphatic vessel divides into small branches that pass into the sinuses of the node. Small branches also extend from the node, which unite again into one vessel;
the filtration function is also associated with the lymph nodes, in which various foreign substances and bacteria are mechanically retained;
the transport function of the lymphatic system is that through this system the main amount of fat enters the blood, which is absorbed in the gastrointestinal tract;
the lymphatic system also performs a homeostatic function, maintaining a constant composition and volume of interstitial fluid;
The lymphatic system performs a drainage function and removes excess tissue (interstitial) fluid located in the organs.

The formation and circulation of lymph ensures the removal of excess extracellular fluid, which is created due to the fact that filtration exceeds the reabsorption of fluid into the blood capillaries. Such drainage function The lymphatic system becomes obvious if the outflow of lymph from some area of the body is reduced or stopped (for example, when the limbs are compressed by clothing, the lymphatic vessels are blocked due to injury, they are crossed during surgery). In these cases, local tissue swelling develops distal to the compression site. This type of edema is called lymphatic.

Return to the bloodstream of albumin filtered into the intercellular fluid from the blood, especially in highly permeable organs (liver, gastrointestinal tract). More than 100 g of protein returns to the bloodstream per day with lymph. Without this return, protein losses in the blood would be irreplaceable.

Lymph is part of the system that provides humoral connections between organs and tissues. With its participation, the transport of signal molecules, biologically active substances, and some enzymes (histaminase, lipase) is carried out.

In the lymphatic system, the processes of differentiation of lymphocytes transported by lymph along with immune complexes that perform functions of the body's immune defense.

Protective function The lymphatic system also manifests itself in the fact that foreign particles, bacteria, remnants of destroyed cells, various toxins, and also tumor cells are filtered out, captured and in some cases neutralized in the lymph nodes. With the help of lymph, red blood cells that have left the blood vessels are removed from the tissues (in case of injuries, damage to blood vessels, bleeding). Often, the accumulation of toxins and infectious agents in the lymph node is accompanied by its inflammation.

Lymph is involved in the transport of chylomicrons, lipoproteins and fat-soluble substances absorbed in the intestine into the venous blood.

Lymph and lymph circulation

Lymph is a filtrate of blood formed from tissue fluid. It has an alkaline reaction, it is absent, but contains fibrinogen and, therefore, it is able to coagulate. The chemical composition of lymph is similar to that of blood plasma, tissue fluid and other body fluids.

Lymph flowing from different organs and tissues has a different composition depending on the characteristics of their metabolism and activity. Lymph flowing from the liver contains more proteins, lymph - more. Moving along the lymphatic vessels, the lymph passes through the lymph nodes and is enriched with lymphocytes.

Lymph - a clear, colorless liquid contained in the lymphatic vessels and lymph nodes, in which there are no red blood cells, platelets and many lymphocytes. Its functions are aimed at maintaining homeostasis (return of protein from tissues to the blood, redistribution of fluid in the body, milk formation, participation in digestion, metabolic processes), as well as participation in immunological reactions. Lymph contains protein (about 20 g/l). Lymph production is relatively small (most of all in the liver); about 2 liters are formed per day by reabsorption from the interstitial fluid into the blood of the blood capillaries after filtration.

Lymph formation caused by the passage of water and dissolved substances from blood capillaries into tissues, and from tissues into lymphatic capillaries. At rest, the processes of filtration and absorption in the capillaries are balanced and lymph is completely absorbed back into the blood. In case of increased physical activity, the metabolic process produces a number of products that increase the permeability of capillaries for protein and its filtration increases. Filtration in the arterial part of the capillary occurs when the hydrostatic pressure increases above the oncotic pressure by 20 mmHg. Art. During muscular activity, the volume of lymph increases and its pressure causes the penetration of interstitial fluid into the lumen of the lymphatic vessels. Lymph formation is promoted by an increase in the osmotic pressure of tissue fluid and lymph in the lymphatic vessels.

The movement of lymph through the lymphatic vessels occurs due to the suction force of the chest, contraction, contraction of the smooth muscles of the wall of the lymphatic vessels and due to the lymphatic valves.

Lymphatic vessels have sympathetic and parasympathetic innervation. Excitation of the sympathetic nerves leads to contraction of the lymphatic vessels, and when parasympathetic fibers are activated, the vessels contract and relax, which increases lymph flow.

Adrenaline, histamine, serotonin increase lymph flow. A decrease in the oncotic pressure of plasma proteins and an increase in capillary pressure increases the volume of outflowing lymph.

Lymph formation and quantity

Lymph is a fluid that flows through lymphatic vessels and forms part of the internal environment of the body. The sources of its formation are filtered from the microvasculature into the tissues and contents of the interstitial space. In the section on microcirculation, it was discussed that the volume of blood plasma filtered into tissues exceeds the volume of fluid reabsorbed from them into the blood. Thus, about 2-3 liters of blood filtrate and intercellular fluid that are not reabsorbed into the blood vessels enter per day through the interendothelial cracks into the lymphatic capillaries, the system of lymphatic vessels and return to the blood again (Fig. 1).

Lymphatic vessels are present in all organs and tissues of the body with the exception of the superficial layers of skin and bone tissue. The largest number of them is found in the liver and small intestine, where about 50% of the total daily volume of lymph in the body is formed.

The main component of lymph is water. The mineral composition of lymph is identical to the composition of the intercellular environment of the tissue in which the lymph was formed. Lymph contains organic substances, mainly proteins, glucose, amino acids, free fatty acids. The composition of lymph flowing from different organs is not the same. In organs with a relatively high permeability of blood capillaries, such as the liver, lymph contains up to 60 g/l of protein. The lymph contains proteins involved in the formation of blood clots (prothrombin, fibrinogen), so it can clot. The lymph flowing from the intestines contains not only a lot of protein (30-40 g/l), but also a large amount of chylomicrons and lipoproteins formed from aponrotheins and fats absorbed from the intestines. These particles are in suspension in the lymph, transported by it into the blood and give the lymph a similarity to milk. In the composition of the lymph of other tissues, the protein content is 3-4 times less than in the blood plasma. The main protein component of tissue lymph is the low molecular weight fraction of albumin, which is filtered through the wall of capillaries into extravascular spaces. The entry of proteins and other large molecular particles into the lymph of the lymphatic capillaries is carried out due to their pinocytosis.

Rice. 1. Schematic structure of the lymphatic capillary. Arrows show the direction of lymph flow

Lymph contains lymphocytes and other forms of white blood cells. Their quantity in different lymphatic vessels varies and ranges from 2-25 * 10 9 / l, and in the thoracic duct it is 8 * 10 9 / l. Other types of leukocytes (granulocytes, monocytes and macrophages) are found in lymph in small quantities, but their number increases during inflammatory and other pathological processes. Red blood cells and platelets can appear in the lymph when blood vessels are damaged or tissues are injured.

Absorption and movement of lymph

Lymph is absorbed into lymphatic capillaries, which have a number of unique properties. Unlike blood capillaries, lymphatic capillaries are closed, blind-ending vessels (Fig. 1). Their wall consists of a single layer of endothelial cells, the membrane of which is fixed to extravascular tissue structures using collagen threads. Between endothelial cells there are intercellular slit-like spaces, the dimensions of which can vary widely: from a closed state to a size through which blood cells, fragments of destroyed cells and particles comparable in size to blood cells can penetrate into the capillary.

The lymphatic capillaries themselves can also change their size and reach a diameter of up to 75 microns. These morphological features of the structure of the walls of the lymphatic capillaries give them the ability to change the permeability over a wide range. Thus, during contraction of skeletal muscles or smooth muscles of internal organs, due to the tension of collagen filaments, interendothelial gaps can open, through which the intercellular fluid, the mineral and organic substances contained in it, including proteins and tissue leukocytes, freely move into the lymphatic capillary. The latter can easily migrate into the lymphatic capillaries also due to their ability to amoeboid movement. In addition, lymphocytes formed in the lymph nodes enter the lymph. The flow of lymph into the lymphatic capillaries is carried out not only passively, but also under the influence of negative pressure forces that arise in the capillaries due to the pulsating contraction of the more proximal parts of the lymphatic vessels and the presence of valves in them.

The wall of lymphatic vessels is built of endothelial cells, which on the outside of the vessel are covered in the form of a cuff by smooth muscle cells located radially around the vessel. Inside the lymphatic vessels there are valves, the structure and principle of operation of which are similar to the valves of the venous vessels. When the smooth muscle cells are relaxed and the lymphatic vessel is dilated, the valve leaflets are open. When smooth myocytes contract, causing a narrowing of the vessel, the lymph pressure in this area of the vessel increases, the valve flaps close, the lymph cannot move in the opposite (distal) direction and is pushed proximally through the vessel.

Lymph from the lymphatic capillaries moves into the postcapillary and then into the large intraorgan lymphatic vessels that flow into the lymph nodes. From the lymph nodes, through small extraorgan lymphatic vessels, lymph flows into larger extraorganic vessels that form the largest lymphatic trunks: the right and left thoracic ducts, through which lymph is delivered to the circulatory system. From the left thoracic duct, lymph enters the left subclavian vein at the site near its junction with the jugular veins. Most of the lymph moves into the blood through this duct. The right lymphatic duct delivers lymph to the right subclavian vein from the right side of the chest, neck and right arm.

Lymph flow can be characterized by volumetric and linear velocities. The volumetric flow rate of lymph from the thoracic ducts into the veins is 1-2 ml/min, i.e. only 2-3 l/day. The linear speed of lymph movement is very low - less than 1 mm/min.

The driving force of lymph flow is formed by a number of factors.

The difference between the hydrostatic pressure of lymph (2-5 mm Hg) in the lymphatic capillaries and its pressure (about 0 mm Hg) at the mouth of the common lymphatic duct.
Contraction of smooth muscle cells in the walls of lymphatic vessels that move lymph towards the thoracic duct. This mechanism is sometimes called the lymphatic pump.
Periodic increase in external pressure on the lymphatic vessels, created by contraction of skeletal or smooth muscles of internal organs. For example, contraction of the respiratory muscles creates rhythmic changes in pressure in the chest and abdominal cavities. The decrease in pressure in the chest cavity during inhalation creates a suction force that promotes the movement of lymph into the thoracic duct.

The amount of lymph formed per day in a state of physiological rest is about 2-5% of body weight. The rate of its formation, movement and composition depend on the functional state of the organ and a number of other factors. Thus, the volumetric flow of lymph from the muscles during muscle work increases 10-15 times. 5-6 hours after eating, the volume of lymph flowing from the intestines increases and its composition changes. This occurs mainly due to the entry of chylomicrons and lipoproteins into the lymph.

Compressing the leg veins or standing for long periods of time makes it difficult for venous blood to return from the legs to the heart. At the same time, the hydrostatic blood pressure in the capillaries of the extremities increases, filtration increases and an excess of tissue fluid is created. Under such conditions, the lymphatic system cannot sufficiently provide its drainage function, which is accompanied by the development of edema.