The Lymphatic System and Immunity

The lymphatic system consists of a fluid, lymph, a network of lymphatic vessels, specialized cells called lymphocytes, and an array of lymphoid tissues and lymphoid organs scattered throughout the body. This system has three major functions: (1) to protect the body through the immune response; (2) to transport fluid from the interstitial fluid to the bloodstream; and (3) to help distribute hormones and nutrients, and transport waste. The immune response produced by activated lymphocytes is responsible for the detection and destruction of foreign or toxic substances that may disrupt homeostasis. For example, viruses, bacteria, and tumor cells are usually recognized and eliminated by cells of the lymphatic system. Immunity is the specific resistance to disease, and all of the cells and tissues involved with the production of immunity are sometimes considered to be part of an immune system. Whereas the lymphatic system is an anatomically distinct system, the immune system is a physiological system that includes the lymphatic system as well as components of the integumentary, cardiovascular, respiratory, digestive, and other systems.