How the Body Works: The Spleen

The spleen is a small organ located behind the stomach in the left, upper part of the abdomen. A mass of lymphoid tissue, it contains two distinct areas, the white pulp and the red pulp. The white pulp is distributed, as tiny nodules of lymphatic tissue, among the red pulp, which fills all the remaining space. The white pulp is responsible for the production of lymphocytes. Some lymphocytes enter the blood, while others remain in the spleen, where they ingest and destroy foreign or damaged cells. The red pulp contains many blood channels, expanded capillary lakes, which act as filters when blood is forced through them, removing damaged or abnormal red cells and allowing normal ones to pass through. The lymphocytes then engulf and destroy these damaged red cells. The spleen also acts as a store for red blood cells.