What Is the Purpose of the Lymphatic System?

The lymphatic system maintains immune function and fluid pressure throughout the body, as well as draining off waste and aiding in the digestion of fat. The multi-faceted functions of the lymphatic system make it almost as vital to health as the cardiovascular system it parallels and supports.

The lymphatic system is a network of vessels and bodily organs that run parallel to the cardiovascular system. Its main purpose is re-absorbing fluid that has exited the blood vessels. As blood travels throughout the body, some of the liquid is leached off and becomes interstitial fluid. Interstitial fluid carries oxygen, nutrients and hormones directly into cells.

The lymphatic system reabsorbs interstitial fluid so that the body does not lose liquid with every pump of the heart. Once it enters the lymphatic system, interstitial fluid is called lymph. Lymph contains fat from circulating through the small intestine as well as numerous waste products from bodily cells. The waste is slowly filtered out by a series of small bean-shaped organs called lymph nodes. The fat stays in the lymph and is eventually re-circulated as a nutrient.

Lymph nodes, in addition to filtering, add copious amounts of immune-boosting white blood cells to the lymph. These white blood cells originate in the bone marrow. Some of them enter the lymphatic system directly, while others undergo maturation in the thymus or are stored in the tonsils. The biggest organ in the lymphatic system is the spleen, which serves as its major filter of waste.

After the lymph is thoroughly filtered and infused with white blood cells, it is returned to the cardio-vascular system via the left subclavian artery. This is where fat from the small intestine enters the blood to feed the rest of the body.