Lymph

As lymph ( v. Latin lymphatic, mostly lymphae in the plural, clear water ', gräzisierende modification of lumpae or limpae, originally Italic water deities ) is called the aqueous pale yellow liquid contained in the lymphatic vessels, which the link between the tissue fluid ( intercellular fluid ) and the blood plasma forms. The lymphatic system to the lymph vessels as pathways in addition to the blood circulation is the most important transport system in the human body. It specializes in the transport of nutrients and wastes and disposed of in the lymph nodes and pathogens such as bacteria and foreign bodies.

Properties and composition

Lymph consists of formed elements (cells) and Lymphplasma. Your pH is 7.41, its density 1.14 g / cm ³.

The lymph is initially similar to the tissue fluid composed from which they formed. It contains urea, creatinine, glucose, sodium, potassium, phosphate and calcium ions. There are also numerous enzymes such as diastase, catalase, dipeptidases and lipases, as well as fibrinogen and fibrin precursors. Fibrinogen and fibrin are responsible for the coagulation in long standing lymph. The lymphocytes are included, the supernatant is referred to Lymphserum.

The concentration of proteins ( proteins ) in the tissue fluid is about two grams per liter. In the lymphatic vessels of the intestinal tract, this concentration up to four, in which increase of the liver up to six grams per liter. By mixing the average protein content of lymph is three to five grams per liter. After a high-fat meal, the concentration of lipids in the lymph may be one to two percent. Fat-rich lymph looks milky and is ( chýlos Greek χυλός, juice ', in allusion to the chyme, the chyme ) as chyle called.

Bacteria can be dragged with the lymph of disorders of the lymph nodes, where they are recognized and destroyed by lymphocytes.

Education

From the capillaries, microscopic blood vessels which reached a portion of the blood plasma due to the difference between the osmotic pressure and perfusion pressure in the surrounding tissue, which is completely impregnated with it. This process is the nutrition of the surrounding cells as well as the removal of metabolic waste products. Since the cellular elements of the blood do not penetrate the vessel wall, this is now called lymph fluid only of water and solutes.

With the dissolved and given to the removal metabolites about 90 percent of the lymph taken back into the blood vessels. The remaining liquid accumulates as lymph in the lymphatic vessels in humans is about 1.5 to 2 ml / min or two to three liters a day.

As lymphagogues lymphtreibende agents are referred to. These include egg white, bile, peptone, salts, urea and sugar.

Function

The lymphatic system transports substances whose large molar mass or hydrophobicity their direct transport does not allow out of the tissue through the blood vessel walls into the bloodstream. These include proteins and lipids from the digestive tract, the latter in the form of chylomicrons. The lymph undertakes the important task of supplying a large part of the absorbed after digestion by intestinal lipids via the thoracic duct to the liver where they are metabolized.

Furthermore, it plays a central role in the immune system, as they transported debris and pathogens to the lymph nodes. Here, the immune response is initiated by the multiply -specific foreign body in question lymphocytes. The proliferation of specific T cells and B cells in the lymph node will be referred to as the germinal center reaction. The lymphocytes are taken and fed to the circulation. This ensures that foreign bodies can be controlled anywhere in the body.

Lymphatics

The object of the lymphatic vessels is recorded in the lymph tissue again supplied to the bloodstream. You begin as blind lymphatic capillaries that are embedded with Ankerfilamenten between the cells of the tissue. There, the conversion of tissue fluid takes place in lymph. Lymphatic capillaries consist of a single layer of endothelial cells connected to each other by cell junctions, but has gaps regarding the influence of the tissue fluid. Your lumen ( vessel diameter ) is slightly greater than that of blood capillaries to carry away and clotted blood in injuries protein molecules.

Several lymph capillaries unite to form larger lymphatic vessels. They have a similar blood vessels of tunica intima (innermost layer ), tunica media ( middle layer ) and tunica adventitia (outermost layer) existing vessel wall. The lymph vessels lead to lymph nodes, which serve as a collection point and filters for the lymph. By laxative vessels ( vasa efferentia ) lymph again leaves the lymph nodes. These tubes combine to Lymphsammelstämmen that eventually in under the so-called venous angle between the internal jugular vein (internal jugular ) and the subclavian vein ( subclavian vein ) and thus open into the bloodstream. Important among these tribes in particular the collection, breast duct 'whose lymph ( after digestion of fat-containing food) by the secreted by intestinal chylomicrons is appear milky. Some lymphatic vessels pass through more than one lymph node. The initially very cell-poor fluid absorbs up to 700,000 newly formed lymphocytes per microliter as it flows through the lymph nodes.

Lymph node

Lymph nodes belong to the lymphoid organs and can be found everywhere in the body except in the central nervous system. Heaped they are found in the neck, armpit and groin, where they serve as collection points for the lymphatic vessels of the limbs and the head and neck area. They are 5 to 20 mm in size and oval to bean- shaped. Your bindegewebshaltige capsule encloses an outer cortex ( cortex) and an inner cord (medulla ). Inside you can find dense accumulations of lymphocytes and macrophages.

The afferent ( afferent vessels) direct the lymph in the marginal sinus (sinus submarginales ). From there it flows over Intermediärsinus (sine capsulares ) to the marrow sinus (sinus medullares ) that they collect and drain into the efferent vessels ( vasa efferentia ).

In the lymph nodes, the lymph is analyzed and filtered to harmful substances. If an infection occurs in the catchment area of a lymph node can take the lymph antigens in the lymph nodes. Here they meet at these antigens specific lymphocytes and stimulate their proliferation, which can lead to a swelling of the lymph node. The lymphocytes formed are distributed to fight the infection throughout the body.

Discomfort

If a malfunction of the lymphatic drainage due to blockage of the lymphatic vessels leads to lymphedema, fluid accumulation in the interstitium ( interstitial space ). This can also occur when part of a tumor resection, the adjacent lymph were removed. Another cause is the predominantly occurring in tropical regions elephantiasis, in which insect-borne parasitic worms ( filaria ) impede the flow of lymph. Affected are usually the legs and external genitals.

A caused by bacteria inflammation of the lymphatic vessels is called lymphangitis, the inflammation of the lymph nodes as lymphadenitis. Cancer cells can spread from the primary tumor through the lymph vessels in the body. One then speaks of lymphatic metastasis. Metastases that form in the lymph nodes, lymph node metastasis hot.