The lymphatic system is a complex branched network of special vessels and structural elements in tissues and organs, without which the body cannot function. The system is considered part of the immune system. Lymphatic vessels pass on their way through the lymph nodes, which are physiological filters. Lymph itself (translated from Latin means “moisture” or “pure water”) is a kind of interstitial fluid. It is transparent and colorless, washes and cleanses the entire body.
The task of the lymphatic system
She plays the most important role:
- barrier function and utilization of malicious agents;
- helps circulate tissue fluid, flushing out toxins and metabolites from tissues;
- is engaged in the delivery of nutrients from the small intestine in the form of fats, fatty acids (proteins are absorbed into the blood immediately by themselves);
- produces lymphocytes - the main elements of immunity.
It is known that the lymphatic system in women has a largebranching, but men have more lymph nodes.
In total, there are more than 500 knots in the body! At the same time, elements hostile to the body are filtered and processed at the stage of lymph and destroyed in the lymph nodes. These are the remains of dead cells, other tissue elements, mutant cells, microbes and their metabolites. Lymph, in fact, acts as a filter, that is, it cleanses of toxins, pathogenic agents and tissue decay products.
Anatomy of the lymphatic system
Anatomically, the lymphatic system consists of:
- lymphatic capillaries;
- lymphatic vessels with enlarged caliber - they merge into ducts or trunks;
- lymph nodes;
- lymphatic organs (these include the thymus, tonsils and spleen).
Lymph movement
Lymph flow is always directed from the periphery to the center, and at a constant speed. A large number of vessels approach the nodes, and 1-2 come out. The walls of blood vessels are constantly contracting due to their muscle fibers and the work of the valves.
And the movement of lymph also occurs with their help. There are noticeably more valves in the lymph vessels than in the blood vessels. Lymph is synthesized in the lymphatic capillaries. After the nodes, the purified and filtered lymph flows into large veins. On the way from each organ, the lymph passes through several lymph nodes.
Meaning of lymph
If the lymph does not circulate through the body for at least 2 hours, it will not be able to continue its vital activity. Thus the bodyconstantly needs the work of the lymphatic system.
Differences between the lymphatic system and the circulatory system
The differences between the two systems are as follows.
- There is no fluid circulation in the lymphatic system due to its openness.
- If the blood in the blood vessels moves in 2 opposite directions - veins and arteries, then in the lymphatic - in one direction.
- There is no central pump in the form of a heart muscle in the lymph system. Only a valve system is used to move the lymph.
- Blood moves faster than lymph.
- Important! There are no special formations in the form of nodes in the circulatory system; lymph nodes are a kind of warehouse for lymphocytes, which are synthesized and trained here. These blood elements are the first helpers of immunity in the fight against infection.
Structure of lymphatic capillaries
Capillaries are the initial link of the lymph system. The structure of the lymphatic capillaries differs markedly from the blood capillaries: they are closed only at one end. The blind ends of the capillaries are pin-shaped and slightly dilated.
Together, lymphatic capillaries, despite their very small caliber, form a rather powerful network in organs and tissues. Merging, they pass smoothly into the lymphatic vessels of a larger diameter, just as in the blood capillaries they pass into arterioles.
The walls of the capillaries are super thin, thanks to just one layer of endothelial cells. Protein compounds pass through them without difficulty. From here they are already delivered to the veins. Lymph capillariesfunction almost everywhere, in any tissue of the body. They are absent only in the brain tissue, its membranes, cartilage and in the immune system itself. They don't exist in the placenta either.
Lymphatic capillaries are larger in diameter (up to 0.2 mm) compared to blood capillaries, due to their extensions (lacunae) at the points of confluence into the network. Their contours are uneven. The walls of capillaries are formed by a single layer of endotheliocytes, which are several times larger than blood cells. The size of the diameter predetermines the participation in the composition of the capillary wall.
Functional features of lymphocapillaries
The meaning and functions of the lymphatic capillaries are lymph production, protective barrier function and lymphopoiesis.
Lymphatic vessels were first described and identified in the Middle Ages (1651) by Jean Pequet, an anatomist from France. As a rule, the lymphatic vessels in the tissues run parallel to the blood vessels. According to their location, they are deep (in the internal organs) and superficial (next to the saphenous veins). These vessels communicate with each other by anastomoses.
Structure of lymphatic vessels
Lymphatic capillaries and lymphatic vessels of a larger caliber differ not only in size, but also in the structure of the walls. The walls of small vessels are composed of a layer of endothelial cells and connective tissue.
The structure of medium and large lymphatic vessels resembles veins - their walls are also three-layered. This is:
- outer connective tissue layer;
- mediumsmooth muscle layer;
- endothelial inner layer.
Due to the extensions, they look like a rosary. Vascular valves are formed by folds of the endothelium. The thickness of the valves contains fibrous fibers.
Large lymphatic vessels have their blood capillaries in their walls, from which they receive food for themselves, and their nerve endings. Lymphatic vessels are found in almost all tissues and organs. The exceptions are cartilage, parenchyma of the spleen, sclera and lens.
