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Structure of the lymphatic system
Last reviewed: 06.07.2025
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The lymphatic system (systema lymphaticum) includes capillaries branched in organs and tissues, lymphatic vessels, lymph nodes, which are biological filters for tissue fluid, as well as lymphatic trunks and ducts. Through the lymphatic vessels, lymph (tissue fluid) flows from the place of its formation to the confluence of the internal jugular and subclavian veins, which form the venous angle on the right and left in the lower parts of the neck.
The lymphatic system performs the most important protective functions in the body - it filters tissue fluid (through the lymph nodes) and returns it (purified) to the blood, and then again to the organs and tissues. With the help of the lymphatic system, particles of dead cells and other tissue elements, large-dispersed proteins that are unable to pass through the walls of blood capillaries, as well as foreign particles and microorganisms that have ended up in the human body are removed from the organs and tissues.
According to the structure and functions in the lymphatic system, lymphatic capillaries (lymphocapillary vessels) are distinguished. They absorb tissue fluid, which together with crystalloids dissolved in it, products of metabolism in the lymphatic capillaries, is called lymph (from Latin lympha - clean water). In its composition, lymph is practically no different from tissue fluid. It is colorless, it contains a certain number of lymphocytes, and macrophages are also found.
Through the lymphatic vessels, the lymph from the capillaries, together with the substances contained in it, flows to the regional lymph nodes corresponding to a given organ or part of the body, and from them to the large lymphatic vessels - trunks and ducts. Lymphatic vessels can serve as pathways for the spread of infection and tumor cells.
Lymphatic trunks and lymphatic ducts are large collector lymphatic vessels through which lymph flows from body regions to the lower parts of the neck - to the terminal parts of the subclavian or internal jugular vein or to the venous angle - the place where these veins merge. As a result of this merger, the right (left) brachiocephalic vein is formed.
Lymph flowing through the lymphatic vessels to the lymphatic trunks and ducts passes through the lymph nodes, which perform barrier-filtration and immune functions. In the sinuses of the lymph nodes, the lymph is filtered through loops of reticular tissue.
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