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Lymphocapillary vessels constitute one of the links in the microvasculature. The lymphocapillary vessel passes into the initial, or collecting, lymphatic vessel, which then passes into the efferent lymphatic vessel.
The transition of lymphocapillary vessels into lymphatic vessels is determined by a change in the structure of the wall, and not by the appearance of valves, which are also found in capillaries. Intraorgan lymphatic vessels form wide-loop plexuses and go together with blood vessels, located in the connective tissue layers of the organ. From each organ or part of the body, drainage lymphatic vessels emerge and go to various lymph nodes.
The main lymphatic vessels, resulting from the fusion of secondary and accompanying arteries or veins, are called collectors. After passing through the last group of lymph nodes, the lymphatic collectors are connected into lymphatic trunks, corresponding in number and location to large parts of the body. Thus, the main lymphatic trunk for the lower limb and pelvis is truncus lumbalis, formed from the efferent vessels of the lymph nodes lying near the aorta and inferior vena cava, for the upper limb - truncus subclavius, running along v. subclavia, for the head and neck - truncus jugularis, running along v. jugularis interna. In the chest cavity, in addition, there is a paired truncus bronchomediastinalis, and in the abdominal cavity an unpaired truncus intestinalis is sometimes found. All these trunks eventually connect into two terminal ducts - ductus lymphaticus dexter and ductus thoracicus, which flow into large veins, mainly into the internal jugular.
Lymphatic vessels (lat. vasa lymphatica) are an important element of the human lymphatic system, which ensures the transport of lymph throughout the body. They closely interact with the circulatory system, removing purified lymph into the venous system. With pathologies of these vessels, the outflow of lymph is disrupted, which negatively affects the functioning of the lymphatic system.
Lymphatic vessels penetrate almost the entire human body. They provide transport of lymph, which cleanses the body of toxic compounds and promotes their removal through the venous system. Lymphatic vessels that flow into the circulatory system constantly transport tissue fluid, thereby ensuring the normal functioning of the entire body.
Every day these vessels “receive” 2 liters of lymph - this is exactly the amount of tissue fluid produced in the human body per day.
The functioning of the entire lymphatic system depends on the functioning of the vessels. Damage and pathology of these important structures lead to disruption of lymph transport in a certain area, which can lead to the development of edema and disruption of tissue trophism.
Structural features
The structure of lymphatic vessels
The formation of lymph vessels begins in the early embryonic period. It is interesting that the lymphatic system in newborns is well developed, since otherwise the immune system is greatly weakened.
Fluid flows from the intercellular space into the lymphatic capillaries. They have a small diameter (about 100 microns). Capillaries consist of large cells, between them there are gaps into which lymph penetrates. Capillaries pass into lymphatic vessels. A special feature of the structure of lymphatic vessels is a wall consisting of smooth muscle cells and connective tissue. Lymphatic vessels have special valves, thanks to which the movement of lymph is possible only in one direction.
It is interesting that in large vessels the valves are often located, literally every half centimeter.
From small vessels, tissue fluid is transported to larger ones, which enter the lymph nodes. At the exit from the nodes, they form even larger structures (collectors), the connection of which forms the ducts of the lymphatic system. Lymph is transported through these ducts into the venous bed in the area of the subclavian veins.
Lymphovascular function
The movement of lymph through lymphatic vessels is the main function of these structures. As already mentioned, this fluid comes from the tissues into the capillaries of the lymphatic system, then penetrates the lymph vessels, which carry it to the lymph nodes. As it travels, the lymph is freed from toxins and infectious agents, and in the lymph nodes it is enriched with immune cells and antibodies. Further, its movement continues to the junction of the lymphatic ducts with the venous bed, from where the purified tissue fluid penetrates into the blood.
It is worth noting that lymph does not circulate in the body constantly. Each time it is formed from tissue fluid, which enters the lymph nodes through capillaries and vessels.
Where are the vessels located?
Lymphatic vessels are found almost throughout the human body
Having understood what lymphatic vessels are and why they are needed, you should know where lymph flows and how lymph drainage occurs. The structure and structure of lymphatic vessels resembles the structure of blood vessels, while the lymphatic system is as developed as the circulatory system. The difference lies in the absence of a “pump” that ensures constant circulation of lymph, as in the circulatory system.
The vessels of the lymphatic system are located in all organs and systems with rare exceptions. Moreover, their location runs parallel to all large veins and vessels of the circulatory system.
Thus, the location of the lymphatic vessels of the face repeats the localization of large blood vessels in this area. The lymphatic vessels of the head and neck are connected to the cervical, submandibular, parotid and other lymph nodes of the head. The function of the lymphatic vessels and nodes of the head and neck is to provide lymphatic drainage to this area. Each lymph node of the head and neck is connected to lymphatic vessels, through which intercellular fluid is removed and purified.
A peculiarity of the location of lymphatic vessels and nodes in the chest cavity is their presence near all vital organs, which ensures the fulfillment of the barrier function of the lymphatic system, preventing the penetration of infections into the most important systems of the body.
Lymphatic vessels are absent only in the placenta, eyes (lens and membrane of the eyeball), in the epithelium, cartilage tissue and epidermis.
Lymph movement
Lymph flow occurs only in one direction - from bottom to top. Intercellular fluid from all tissues and organs penetrates the walls of lymphatic capillaries. At this stage it turns into lymph. Then the lymph passes through a branched system of lymph vessels, is purified in them, is saturated with immune cells in the “intermediate bases”, which are the lymph nodes, and then enters the circulatory system. In this way, the necessary substances are transferred into the blood.
You should know that lymphatic vessels are susceptible to disease. There are two vascular pathologies – lymphedema (lymphostasis) and lymphangioma.
Lymphedema, or lymphostasis, is a pathological condition characterized by impaired lymph outflow. The disease is associated with dysfunction of the lymphatic vessels, which can be caused by both congenital structural anomalies and acquired pathologies, for example, due to damage to blood vessels during trauma or as a result of surgery.
Pathology of the lymphatic system is often congenital
Lymphostasis is a widespread disease. According to some reports, about 10% of the population experience lymphatic stagnation. Most often, the pathology affects the lower extremities. Damage to the lymph vessels of the arms is observed as a complication after mastectomy - surgery to remove the mammary gland due to oncology.
Typical symptoms:
- severe swelling of the limb;
- fast fatiguability;
- pain on exertion;
- general weakness.
The disease requires timely treatment. Progressive lymphostasis leads to elephantiasis (multiple increase in the volume of the limb). This makes it difficult to move the affected arm or leg, and over time the person loses the ability to self-care, which leads to disability.
Lymphostasis requires complex treatment. At the initial stage of lymph stagnation, non-drug methods are used. A good effect is achieved when wearing compression garments. In case of severe edema, drug therapy is prescribed, which includes taking angioprotectors and diuretics.
Lymphangioma is a benign neoplasm that develops from the tissues of the vessels of the lymphatic system. The pathology is most often congenital. This disease is characterized by the proliferation of blood vessels in the lymphatic system, or the formation of cavities in the walls of blood vessels. Lymph accumulates in the cavities and stagnation develops. A characteristic symptom of this pathology is a noticeable enlargement of any part of the body - face, neck, limb, etc. If the disease has affected the lymphatic vessels of the face, people with this pathology are offered surgical intervention.
lymphatic vessels
Lymphatic vessels (vasa lymphatica) are vessels that conduct lymph from tissues into the venous bed. Lymphatic vessels are found in almost all organs and tissues. The exceptions are the epithelial layer of the skin and mucous membranes, cartilage, sclera, vitreous body and lens of the eye, brain, placenta and spleen parenchyma.
The beginning of the formation of the lymphatic system in the human embryo dates back to the 6th week of development, when paired jugular lymph sacs can already be distinguished. By the beginning of the 7th week, these sacs are connected to the anterior cardinal veins. All other lymph sacs appear somewhat later. The growth of lymphatic vessels from the primary sacs occurs through the proliferation of endothelial outgrowths. Valves HP are formed in the 2-5th month of uterine life in the form of flat annular thickenings of the endothelium.
Among L. s. distinguish: lymphatic capillaries; small intraorgan HP; extraorgan (so-called abducent) HP; L. s., connecting the lymph nodes; large trunks - lumbar (trunci lumbales dext. et sin.), intestinal (tr. intestinalis), subclavian (trr. subclavii dext. et sin.), bronchomediastinal (trr. bronchomediastinales dext. et sin.), jugular (trr . jugulares dext. et sin.), formed from the lymphatic vessels of the corresponding areas, and two lymphatic ducts - the thoracic (ductus thoracicus) and the right (ductus lymphaticus dext.). Both of these ducts flow respectively from the left and right into the confluence of the internal jugular and subclavian veins.
The totality of lymphatic capillaries is, as it were, the source of the lymphatic system. Metabolic products from tissues enter the lymphatic capillaries. The capillary wall consists of endothelial cells with a poorly defined basement membrane. The diameter of the lymphatic capillary exceeds the diameter of the blood capillary. The organ has superficial and deep networks of lymphatic capillaries connected to each other. Transition of lymphatic capillaries into subsequent L. s. determined by the presence of valves. Along with significant fluctuations in caliber for HP. characterized by the presence of narrowings at the locations of the valves. Small intraorgan L. s. caliber 30-40 microns do not have a muscular shell. In lymphatic vessels with a caliber of 0.2 mm and above, the wall consists of three layers: internal (tunica intima), middle muscular (tunica media) and external connective tissue (tunica adventitia). Valves HP represent folds of the inner shell. Number of valves in HP. and the distance between them varies. Distance between valves in small HP. equal to 2-3 mm, and in large ones - 12-15 mm. The valves ensure lymph flow in one direction. In pathologically expanded L. s. Valve insufficiency appears, in which retrograde lymph flow is possible.
The number of lymphatic capillaries flowing into individual small collecting lymphatic vessels ranges from 2 to 9. Intraorgan HP. They form broadly looped plexuses with different shapes of loops in organs. They often accompany blood vessels, forming transverse and oblique anastomoses with each other. Several groups of efferent lymph nodes emerge from an organ or part of the body, which, merging, are directed to the regional lymph nodes. Abductor L. s. of the small intestine, passing in its mesentery, are called milky (vasa chylifera), since they carry milky juice (chylus).
Lymph flow in HP. determined by the contractility of their walls, the mechanical influence of passive and active movements and the energy of lymph formation. Pressure in the outlet HP. changes due to the different functional state of the organ.
L.S. regenerate well. After 3-20 weeks, the cut vessels are completely restored. L. c., like blood vessels, have their own vessels feeding their wall (vasa vasorum). Innervation of HP carried out by nerve plexuses present in the wall of the vessel; Free nerve endings were found in the adventitia and the middle layer of the wall.
Pathology of lymphatic vessels - see Thoracic duct,
The human body has a complex structure and includes several systems, the work of which ensures the proper functioning of the internal organs. One of the important systems is the lymphatic system, which includes lymphatic vessels. Thanks to the work of this system, the immune and hematopoietic function of the body is ensured, as a result of the drainage of lymph from organs and tissues.
The functioning of lymphatic vessels is in close contact with blood vessels, largely in the direction of microcirculation, where tissue fluid is formed and penetrates into the general channel. Due to this, lymphocytes are released from the general circulation, and they are absorbed from the lymph nodes into the blood.
These vessels include:
- Capillaries are the initial section in the structure of the system, performing the function of drainage. From the tissues of organs, part of the plasma is absorbed into them together with metabolic products; in case of diseases, foreign bodies and microorganisms are absorbed. It is also possible for malignant tumor cells to spread.
- Outflow vessels. The circulatory and lymphatic systems are similar in structure, but the main difference is that the lymphatic vessels include a significant number of valves and their membrane is well developed. They ensure the outflow of formed fluid from the organs (abdominal cavity, intestines and others) to the heart. Based on size, they are divided into: small, medium and large. Large lymphatic vessels empty into veins.
- Thoracic lymphatic duct. The structure of the wall is different relative to their location. It is most strongly developed in the area of the diaphragm (the unpaired muscle that separates the chest cavity from the abdominal cavity).
- Valves. In the area of the thoracic duct there are up to nine semilunar valves. At the beginning of the valve in the wall of the duct there is an expansion created as a result of the accumulation of connective and muscle tissue.
The peculiarity of the position of the lymphatic vessels is that, when leaving the muscles and organs (lungs, abdominal cavity), they most often exit with the blood vessels. Superficial vessels are located next to the saphenous veins. Their structure has the peculiarity of branching before the joint and then reconnecting.
Lymphatic vessels of body parts and organs
Lymphatic vessels are found in almost all organs, with only a small number. Thus, the lymphatic vessels of the heart begin in the subepicardial cardiac plexus and are located in the longitudinal and coronary grooves. There are no lymphatic capillaries in the heart muscle valves and tendon threads. The lymphatic vessels of the heart are located along the movement of the coronary arteries and are included in the mediastinal nodes anteriorly and posteriorly.
The lymphatic vessels and nodes of the head and neck unite into the jugular trunks (in Latin, trunci jugulares dexter et sinister). Before lymph from the head and neck enters the venous flow, it must pass through the regional lymph nodes. The vessels of the upper part of the abdominal cavity are directed upward, and the lower part, vice versa. The abdominal cavity contains: pariental and visceral lymph nodes. The number of parietal lymph nodes in the abdominal cavity is 30-50. The visceral lymph nodes of the abdominal cavity are divided into 2 groups: along the branches of the celiac trunk and along the mesenteric artery.
Lymphatic vessels and nodes of the upper limb are of two types; movement along them is directed to the lymph nodes located in the elbow and armpit. Superficial lymphatic vessels are located near the saphenous veins. With the help of deep ones, lymph moves from tendons, muscle tissue, joints, ligaments, nerve endings, and accompany large arteries and veins of the hands.
The lymphatic vessels of the small and large intestines (in Latin, vasa lymphatica intestinalia) create a network of capillaries in the intestinal lining.
The vessels of the membrane originate in the villi from the central lacteal sinuses, which are channels formed at the top of the villi. Intestinal villi is a growth of the lamina propria of the intestinal mucosa. They are located in the central part of the villi parallel to their long axis and enter the capillary system of the intestinal mucosa.
Possible diseases
When the correct functioning of any of the body systems is disrupted, various pathologies develop. Lymphatic is no exception. If the functioning of blood vessels is disrupted, the following pathologies may occur:
- Inflammation of the lymphatic vessels (Lymphostasis). The pathology is secondary. Its development occurs as a result of purulent-inflammatory processes of the skin. The disease can occur in acute and chronic forms. Characteristic symptoms are: weakness, increased fatigue, general malaise, increased body temperature. A distinctive symptom is pain in the area of the lymph nodes. The causative agent of the disease can be a pyogenic type bacterium (Escherichia coli, enterococcus, staphylococcus), benign and malignant tumors.
- Hodgkin's disease (lymphogranulomatosis). The development of the disease is typical mainly for young patients. At the beginning of development, there are no symptoms, enlarged lymph nodes do not bother the patient. Subsequently, metastases spread, the tumor spreads to other lymph nodes and organs. Symptoms such as fever, weakness, increased sweating, itching of the skin, and weight loss occur.
- Lymphadenopathy is a condition accompanied by inflammation of the lymph nodes and is a benign tumor. The disease has two forms: reactive and tumor. Tumor lymphadenopathy can be inflammatory or non-inflammatory. Inflammatory diseases are classified into: infectious and non-infectious diseases. They are often accompanied by an allergic reaction, rheumatoid arthritis. An increase (tumor) occurs as a result of toxic damage to the body or infection, a progressive inflammatory process.
- Ductal sarcoma is a malignant tumor. The manifestation of pathology is possible at any age. The onset of the course is characterized by enlargement (tumor) of the lymph nodes on one side. The progression of the disease is rapid, the process of metastasis is very fast. In a short period of time, the patient’s well-being deteriorates greatly. A person suffering from lymphosarcoma develops a fever, a sharp decrease in body weight, and severe sweating at night.
Vascular diseases, like any other disease, require mandatory consultation with a doctor. After the examination, the specialist will prescribe appropriate examination and treatment. The circulatory and lymphatic systems are the object of examination of angiologists. They have more in-depth knowledge in this area of medicine.
Lymphatic vessels play an important role in the life of the human body. Violation of their functioning in any of the organs entails serious disorders. Thanks to the lymphatic vessels, many substances beneficial to the body are absorbed and subsequently released into the blood.