Functions of the Lymphatic System


The lymphatic system has several functions that work together with other systems of the body to maintain health and prevent disease. One such function is its role in cardiovascular health. Every day an average of 20 liters of fluid, called plasma, seeps out of blood vessels into the space between our blood vessels and cells, called the interstitial space. Our blood vessels reclaim roughly 17 liters of that fluid, and the lymph vessels of the lymphatic system absorb the remaining 3 liters. The vessels take that fluid and return it to the veins, maintaining a healthy blood volume. Without this function, our blood volume and blood pressure would drop, which could have potentially fatal effects.

 l The word “lymph” comes from the Latin lympha, which means “water.” Like water, lymph fluid is clear and colorless. It contains a mixture of proteins, nutrients, glucose, salt, white blood cells and even bacteria, which excluding bacteria, return to the bloodstream for essential bodily functions.

 Besides maintaining healthy blood volumes, the lymphatic system contributes to fighting infection. The offending agents, such as bacteria or even cancer cells, enter lymph vessels and pass through various “checkpoints,” called lymph nodes. The nodes filter the lymph fluid, and white blood cells called lymphocytes, become active if they find threats.

 l When lymph nodes become active, they can swell. Termed lymphadenopathy, this swelling is a sign of infection or disease. The tonsils, a lymph node organ, can swell leading to sore throat, or lymph nodes in the chest may swell because of cancer. A lymph node biopsy (tissue sample) of a swollen node is often helpful in determining the source of an unknown disease.

Beyond nodes and vessels, organs are an important part of the lymphatic system. The main lymphatic organs are the tonsils, adenoids, spleen, and thymus. These organs contain lymphoid tissue and serve various functions. Tonsils in the back of the throat filter bacteria coming in through the mouth, and adenoids in the nose protect the digestive system and lungs from foreign invaders. The spleen and thymus, above the left kidney and chest, respectively, help in blood filtration, fighting infection, and maintaining a proper immune system.