noun, plural: lymphatic vessels
The lymphatic system is a biological system that is responsible mainly for the collection and returning of the fluid and proteins into the blood. It is comprised of lymph nodes, lymph vessels, lymphoid tissues, and lymph. The lymph is the clear, slightly alkaline fluid circulating through the lymphatic system. The vessel that is responsible for carrying lymph is the lymphatic vessel. It carries lymph and eventually empties it into the [[[bloodstream]]. Its function is essential in maintaining the balance of body fluids.
The lymphatic vessels are vessels made up of a layer of (simple squamous) epithelial cells, as in lymph capillaries. In larger lymphatics such as the thoracic duct and the right lymphatic duct, though, additional layers are present, such as an outer layer of adventitia (fiber tissues) and a layer of smooth muscles surrounding the innermost epithelial layer. The adventitial layer binds the lymph vessels to the surrounding tissue.
The lymphatic vessels are the counterpart of the blood vessels in the cardiovascular system and instead of blood the lymphatic vessels carry lymph. The lymph capillaries collect lymph from the interstitial fluid. They drain lymph into the collecting lymphatics that propel lymph towards lymph nodes or towards a lymph duct. The vessel that carries lymph from the tissues towards a lymph node is referred to as an afferent lymph vessel. In contrast, the vessel that carries lymph from the lymph node is called an efferent lymph vessel. The efferent lymph vessel, though, may carry lymph towards another lymph node, or to other routes such as to a larger lymph duct or to a vein. There are two large lymph ducts: the right lymphatic duct and the thoracic duct. Both ducts drain into the circulatory system by emptying into the right and the left subclavian veins.
- lymph vessel