Spleen
. Spleen, flattened, oblong organ that removes disease-producing organisms and worn-out red blood cells from the bloodstream. The spleen is situated in the upper left abdominal cavity, in contact with the pancreas, the diaphragm, and the left kidney. It is supported by bands of fibers that are attached to the peritoneum (the membrane lining the abdominal cavity). The spleen varies in size but, in adult humans, it is about 13 cm (about 5 in) long, up to 10 cm (4 in) wide and 3.8 cm (1.5 in) thick, and weighs about 200 g (about 7 oz). The spleen is fed by the splenic artery, and venous blood from the spleen enters the liver. The spleen removes iron from the hemoglobin of red blood cells for use in the body. It also removes such waste materials as bile pigments for excretion as bile by the liver. The spleen produces antibodies against various disease organisms and manufactures a variety of blood cells. In some mammals (but not in humans) it stores red blood cells and feeds them into the