The spleen is a small organ located in the left upper quadrant of the abdomen, behind the stomach. Since the body can survive without the spleen, it is an often overlooked organ. The spleen does, however, play a very important role with blood cells and the immune system. Those who have their spleens removed are subject to becoming sick more often.
Filter and Save
All of the body's red blood cells have to be shunted through the spleen. Every single cell is checked for proper size, shape and function. Healthy cells move through the spleen with no problem. If there is anything wrong with any of those markers, however, the spleen destroys the cell and removes it from the system.
The body is an efficient recycler. When the spleen destroys old red blood cells, it saves any usable parts, specifically iron. The iron is either stored in the spleen or sent to the bone marrow, where more red blood cell components are made. The destroyed red blood cells are eaten up by macrophages, and the waste is sent to the lymphatic system, where the body disposes of those materials further.
Immune System
The spleen plays an important part in the immune system. Since all of the blood cells have to filter through the spleen, the spleen is one of the first-line defenders in recognizing foreign substances, such as bacteria or viruses in the blood. Once the spleen has recognized a foreign substance, it releases B and T lymphocytes. These lymphocytes are white blood cells and have antibodies that coat the virus or bacterium to prevent the infection from spreading and to signal the body that this item needs to be destroyed.
The spleen has been found to contain monocytes, according to an August 2009 article in "The New York Times." The article went on to say that the spleen has 10 times more monocytes than the circulating blood. Monocytes are important after a trauma or heart attack because these cells stimulate scar tissue and repair.
Storage
The spleen is a very venous, spongy material. It is surrounded by blood vessels. In a healthy system, the veins around the spleen change in size and swell to store extra blood when the body is not in need. The spleen can hold up to 1 cup of blood, according to the Children's Hospital of Pittsburgh. If there is trauma or any type of blood loss, the spleen can send the reserve blood out into the body once again. It is similar to a bank, in that deposits and withdrawals are made on a regular basis.
Blood Cell Production
In adults, red blood cells are made in the bone marrow, which is located within the long bones of the body. The spleen is a secondary source of red blood cells. The only time it plays a primary role in making red blood cells is in a developing fetus. Once the baby is born and the long bones develop, the spleen moves to a secondary role.
