The spleen is an internal organ located behind the stomach on the left side of the abdomen. The spleen aids in clearing the blood of harmful substances and produces lymphocytes. It can be damaged by a number of diseases such as sickle cell anemia and malaria. Some patients with diseases of the spleen undergo a splenectomy, or removal of the spleen, to prevent severe complications. Patients with an understanding of the basic characteristics of the spleen will better comprehend their disease and any treatments they are given.
Location and Size
The spleen is located between the stomach and the diaphragm on the left side of the abdomen. With a weight of 150 g, or approximately 5.3 ounces, the spleen is the largest lymphoid organ, according to PathologyOutlines.com. Lymphoid organs produce a specific type of white blood cell called a lymphocyte.The spleen is covered by a thin layer of connective tissue called a capsule. The capsule helps hold the organ in place and provides protection against traumatic injury.
Immune Function
The spleen is part of the body's immune system. In addition to producing lymphocytes, the spleen also contains another type of white blood cell called macrophages, reports KidHealth.org. Both of these cells help combat bacterial and viral infections. They can be released from the organ and proceed to the site of the infection. Furthermore, invading organisms can be brought to the spleen, where they are then destroyed by the lymphocytes and macrophages within the organ.
Platelet Storage
The spleen functions as a storage area for platelets, according to the "Journal of the American Medical Association." Platelets are special blood cells that are responsible for clotting the blood when bleeding occurs. Without platelets patients would suffer from excessive bleeding. The spleen stores these cells and allows them to enter the blood when they are needed.
Red Blood Cell Destruction
The spleen filters out old red blood cells from the blood, states PathologyOutlines.com. Red blood cells have an average life cycle of 120 days. After this period, the cells start to become more fragile and lose their shape. Once these cells become abnormal they are no longer able to pass through the spleen properly. Once they have been sequestered in the spleen, the old red blood cells are broken down. The remnants of the old cell are reabsorbed and used in the production of new red blood cells.
Microscopic Anatomy
Under a light microscope, the spleen is composed of a red pulp and white pulp divided by a marginal zone, according to PathologyOutlines.com. The red pulp is composed of splenic sinusoids connected by specialized structures called the cords of Billroth. These microscopic formations help the spleen filter out damaged or old red blood cells. The sinusoids are small spaces within the blood vessels of the spleen. Once the blood enters the spleen, it must pass through these tiny holes. Old red blood cells and cells that are infected with bacteria or viruses become misshapen. Any material that is not shaped properly or is very fragile gets caught in the sinusoids and destroyed by the cells within the spleen.
The white pulp is responsible for forming lymphocytes and sending them into the blood stream. The marginal zone is filled with immature lymphocytes that are being prepared for secretion into the blood.
