There are several functions of the lymphatic system. One is to act as a drainage system to transport needed proteins and fluids that have leaked out of the blood capillaries (and into the interstitial fluid) back to the bloodstream via the veins. In addition, the lymphatic vessels in the intestines absorb lipids (fats) from the small intestine and transport them to the bloodstream.

Another function fo the lymphatic system is related to the immune system: The defense of the body against foreign organisms such as bacteria and viruses. Lymphocytes and monocytes, originating in lymph nodes and organs such as the spleen and thymus gland, protect the body by producing antibodies or by phagocytosis (engulfing and destroying foreign matter).

LYMPHATIC SYSTEM - ANATOMY

Lymph capillaries begin in the spaces around cells throughout the body. Like blood capillaries, they are thin-walled tubes. Lymph capillaries carry lymph from the tissue spaces to large lymph vessels. Lymph vessels have thicker walls than those of lymph capillaries and, like veins, contain valves so that lymph flows only in one direction, toward the thoracic cavity. Collections of stationary lymph tissue, called lymph nodes, are located along the path of the lymph vessels. Special cells, called macrophages, are located in lymph nodes, and they can phagocytose (engulf and destroy) foreign substances. When bacteria are present in lymph nodes that drain a particular area of the body, the nodes became swollen with collections of cells and their engulfed debris and become tender.

Lymph vessels all lead toward the thoracic cavity and empty into two large ducts in the upper chest. These are the right lymphatic duct and the thoracic duct. The thoracic duct drains the lower body and left chest, whereas the right lymphatic duct drains the right chest. Both ducts carry the lymph into large veins the neck where lymph then merges with the blood system.