Cross-sectional illustration of a human spleen. It's normal size is ca. 4x8x12cm. The typical layers of the spleen (capsule, cortex, medulla) are shown, as well as the vessels (artery, vein) in the splenic hilus (in the middle of the spleen). The enhanced image shows a section of the splenic pulp. The spleen takes part in the defense against infections and cleaning of the blood.