The function of the lymphatic system is manifold and interconnected with several other body systems, including the immune system and the circulatory system. It performs several vital functions but primarily maintains the proper balance of bodily fluids between the circulatory system and the interstitial fluid. It also filters and transports wastes and fatty acids and is the basis for the immune system.
Maintenance of the immune system is one primary function of the lymphatic system, and it is responsible for transporting white blood cells to and from the bones and lymph nodes, which filter waste and toxins from the lymphatic fluid. Lymphatic fluid is a clear fluid that fills the spaces between the cells of body tissues and makes up the portion of our blood known as plasma. The lymph system helps to fight infections, including cancer, and to prevent their spread. White blood cells, which fight infections, are transported from the bone marrow to the lymph nodes where they destroy hostile microbes and cancer cells.
The transport of interstitial fluid, which fills the spaces between cells, and maintaining its balance with circulatory fluids is another function of the lymphatic system.Tiny amounts of plasma migrate through the tiny blood vessels known as capillaries and into the spaces between cells. The fluid carries some waste and toxins from cells and body tissues.
This process prevents the passage of certain elements of blood plasma, and the fluid is not properly plasma once it has passed into the interstitial spaces, where it is called interstitial fluid or lymph. The lymphatic system returns this fluid to the blood stream, where the wastes and toxins can be filtered by the kidneys. Without a properly functioning lymphatic system to remove these fluids from the tissues, tissue damage and swelling would occur and eventually could even be fatal.
The circulation of the lymph fluids from the bloodstream and back also facilitates another function of the lymphatic system, which is to transport certain hormones, nutrients, and proteins to and from cells and tissues. The lymph system does not circulate within itself, originating instead as microscopic lymph capillaries in the tissues, which drain the interstitial fluid and flow in only one direction, eventually combining and emptying into the bloodstream. The lymphatic system also helps maintain levels of fatty acids in the blood by absorbing and transporting them from the digestive system to the bloodstream, supplying individual cells with this important resource.
The thymus gland, the spleen, and the tonsils are part of and support the lymphatic system. The thymus gland helps white blood cells in fighting infections, and the spleen filters red blood cells as well as acting as storage for white blood cells. The role of the tonsils is not well understood, but it is thought that they help to fight infection, operating in a similar fashion to the lymph nodes.