The Lymphatic System
The lymphatic system consists of lymphatic organs like the thymus gland, spleen, lymph nodes, tonsils, appendix and Peyers patches found in the small intestine.
The lymphatic system’s primary function is to be the body’s defense against bacteria, virus, fungi, parasites and abnormal cells like cancer. The lymphatic system and organs make WBCs called lymphocytes, which stop these invaders from taking over our bodies. Lymphocytes are circulated and stored in lymph nodes around the body, migrating through tissues and seeking to destroy any foreigner. Meanwhile, many WBCs circulate through the blood, constantly seeking to destroy foreigners as well.
The lymphatic system’s second function is returning tissue fluid into blood vessels. Tissue fluid seeps out when blood goes into capillaries before returning to the veins and the heart. This fluid, known as lymph fluid, collects in lymph channels, which empty into larger and larger lymph vessels until they reach the thoracic duct. The lymph fluid then returns to the circulating blood via the jugular and subclavian vein junction in the neck (which the thoracic duct drains into.)
The third function of the lymphatic system is the filtration of bacteria, virus, fungi and parasites in the lymph nodes, which help prevent the spread of infection. The lymph nodes are growth-and-storage areas for WBCs, which consume bacteria or viruses in the lymph fluid, preventing the spread of infections. This explains why when you have a sore throat, your lymph nodes and your neck become enlarged: They are actively killing viruses and bacteria and preventing the spread of infection to other areas of the body. The lymphatic system is also critical in fighting and destroying cancer cells. So, swollen lymph nodes can indicate not only infection in the body, but perhaps even cancer.
The fourth function of the lymphatic system is to absorb fats from digestion via the lymph capillaries of the intestinal villa—microscopic finger-shaped absorption tissue.