A picture of a spleen is located at home.comcast.net/~wnor/spleen.htm. The spleen is a secondary lymphoid organ located in the upper left part of the abdomen under the ribcage. It works as part of the lymphatic system to protect the body, clearing worn-out red blood cells and other foreign bodies from the bloodstream to help fight off infection. Its three main constituents are reticuloendothelial tissue, which cleanses the blood stream, venous sinusoids to expel the blood, and white pump to provide antibodies to increase immune defence systems. At the pump, the spleen processes foreign antigen and produces specific immunoglobulin M. Blood departs via the splenic vein- the inferior mesenteric vein- the superior mesenteric vein and finally the portal vein. The spleen is also a blood reservoir. It supplies the body with blood in emergencies such as a bad cut. The spleen is also the location where white blood cells trap organisms. The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections. One of the lymphatic system's major jobs is to collect extra lymph fluid from body tissues and return it to the blood. This process is important because water, proteins, and other substances are continuously leaking out of tiny blood capillaries into the surrounding body tissues. If the lymphatic system didn't drain the excess fluid from the tissues, the lymph fluid would build up in the body's tissues and they would swell. To this end, the spleen contains lymphocytes and another kind of white blood cell called macrophages, which engulf and destroy bacteria, dead tissue and foreign matter and remove them from the blood passing through the spleen. Splenomegaly, or an enlarged spleen, can be caused by viruses or mononucleosis. If you have an enlarged spleen, your doctor will probably tell you to avoid contact sports like football for a while. If you're hit, the swollen spleen is vulnerable to rupturing (bursting) which can cause heavy blood loss.
