25.2 : Functions of the Lymphatic and Immune System

The lymphatic system plays a crucial role in bolstering our immune system. It consists of a network of lymphoid organs, lymph, and lymphatic vessels that provide structural and functional support in safeguarding the body against pathogens such as viruses and bacteria.

The primary lymphoid organs, including the bone marrow and the thymus, serve as the maturation sites for lymphocytes. Secondary lymphoid organs, like the mucosa-associated lymphoid tissue, activate these lymphocytes and serve as the first line of defense against pathogens at mucosal surfaces.

The lymphatic system also facilitates the circulation of immune cells throughout the body via the lymph flowing through the lymphatic vessels. These immune cells, specifically B and T lymphocytes, drive the adaptive immune response. B lymphocytes produce antibodies to neutralize pathogens, while T lymphocytes directly engage and eliminate pathogens through cell-mediated cytotoxicity. This process is a key part of the body's defense against harmful invaders.

Additionally, dendritic cells, which present antigens to lymphocytes, and macrophages, phagocytes that engulf and digest pathogens, facilitate the adaptive immune response. The lymphatic system also performs accessory functions, such as transporting lipid-soluble vitamins and dietary lipids. Furthermore, it recovers excess fluid that leaks from capillaries, returning it to the bloodstream, thereby helping maintain blood volume.