What are the functions of the spleen?

• A. Filtration of lymph only
• B. Hormone production
• C. Oxygen transport
• D. Defense, tissue repair, hematopoiesis, RBC and platelet destruction, blood reservoir

Answer: (D)

The spleen serves as both a blood-filtering organ and a key player in immune defense. Its white pulp is rich in lymphocytes that respond to blood-borne pathogens, supporting defense against infection, while the red pulp contains macrophages that remove old or damaged red blood cells and platelets, helping maintain healthy circulating cells and contributing to tissue cleanup that aids healing. In fetal development the spleen produces blood cells, and in adults it can resume hematopoiesis under certain disease conditions. It also acts as a blood reservoir, holding a substantial volume that can be released quickly when needed, such as during hemorrhage or increased demand. Putting these roles together, the function that lists defense, tissue repair, hematopoiesis, RBC and platelet destruction, and blood reservoir best captures what the spleen does. The other options describe functions (lymph filtration only, hormone production, or oxygen transport) that are carried out by other organs or systems.