The lymphatic system is a complex of a network of special vessels and structural elements, branched 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. The lymph itself (translated from Latin. Means "moisture" or "pure water") is a type of interstitial fluid. It is transparent and colorless, washes and cleanses the entire body.
The challenge of the lymphatic system
She plays a crucial role:
- barrier function and disposal of malicious agents;
- It helps the circulation of tissue fluid by washing toxins and metabolites from tissues;
- engaged in the delivery of nutrients from the small intestine in the form of fats, fatty acids (proteins are absorbed into the blood immediately themselves);
- produces lymphocytes - the main elements of immunity.
It is known that the lymphatic system in women has a large branching, but in men a larger number of lymph nodes.
In general, the body has more than 500 nodes! At the same time, elements hostile to the body are filtered and processed even at the lymph stage and are destroyed in the lymph nodes. These are the remains of dead cells, other tissue elements, mutant cells, microbes and their metabolites. Lymph, in fact, serves as a filter, that is, it cleanses of toxins, pathogenic agents and tissue breakdown products.
Lymphatic anatomy
Anatomically, the lymphatic system consists of:
- lymphatic capillaries;
- lymph vessels with enlarged caliber - they merge into the ducts or trunks;
- lymph nodes;
- lymphatic organs (these include the thymus, tonsils and spleen).
Lymph movement
Lymphatic flow is always directed from the periphery to the center, and at a constant speed. A large number of vessels approaches the nodes, but 1-2 come out. The walls of blood vessels are constantly contracting due to their muscle fibers and valve function.
And the movement of lymph also occurs with their help. Valves in lymph vessels are noticeably larger than in blood vessels. Synthesized lymph in the lymphatic capillaries. After the nodes, the cleaned and filtered lymph flows into the large veins. On the way from each organ, the lymph passes through several lymph nodes.
The 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 activity. Thus, the body continuously needs the lymphatic system.
Differences between the lymphatic system and the circulatory
The differences between the two systems are as follows.
- In the lymphatic system there is no fluid circulation in a circle due to its openness.
- If the blood in the blood vessels moves in 2 opposite directions - the veins and arteries, then in the lymphatic - in one.
- There is no central pump in the form of cardiac muscle in the lymph system. Only the valve system is used to promote lymph.
- Blood moves faster than lymph.
- Important! In the circulatory system there are no special formations in the form of nodes; lymph nodes are a kind of warehouse for lymphocytes, which are synthesized and trained here. These blood elements are the first helpers of the immune system in the fight against infection.
The structure of the lymphatic capillaries
Capillaries - the initial link of the lymph system. The structure of the lymphatic capillaries is markedly different from the blood capillaries: they are closed only from one end. The blind ends of the capillaries are pin-shaped and slightly widened.
Together, the 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 larger diameter, just as they pass into the arterioles in the blood capillaries.
The walls of the capillaries are ultra-thin, thanks to just one layer of endothelial cells. Through them, protein compounds pass without difficulty. From here they are already delivered to veins. Lymphatic capillaries function almost everywhere in any body tissue. They are absent only in the brain tissue, its membranes, cartilage and in the immune system itself. In the placenta, they also do not exist.
Lymphatic capillaries are larger in diameter (up to 0.2 mm) compared to blood capillaries, due to their extensions (gaps) at the points of confluence into the network. Their contours are uneven. The walls of the capillaries are formed by a single layer of endotheliocytes, which are several times larger than blood cells. The diameter determines the participation in the composition of the capillary wall.
Functional features of lymphocapillaries
The significance and functions of the lymphatic capillaries are in the production of lymph, protective and barrier function and lymphopoiesis.
Lymphatic vessels were the first to be described and identified in the Middle Ages (1651) by Jean Pécs - an anatomist from France. As a rule, the lymph vessels in the tissues run parallel to the blood vessels. By their location, they are deep (in the internal organs) and superficial (near the saphenous veins). These vessels communicate with each other by anastomoses.
The structure of the lymphatic vessels
Lymphatic capillaries and lymph 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. It:
- outer connective tissue layer;
- middle smooth muscle layer;
- endothelial inner layer.
Due to the extensions they have the appearance of a rosary. Vascular valves are formed by folds of the endothelium. In the thickness of the valves contains fibrous fibers.
Large lymphatic vessels have their own blood capillaries in the walls, from which they receive nutrition, 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.