The lymphatic system has the responsibility of keeping you alive and healthy. The spleen, which is in the upper left abdominal area, is one of the organs in this system. The spleen of an adult holds the largest amount of lymphoid tissue. An adult spleen is about 5 inches long and weighs approximately 4 oz.
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Removal of Red Blood Cells
One of the functions of the spleen is to remove any old red blood cells, according to Kim Barrett, professor of medicine at the University of California at San Diego, writing in “Ganong’s Review of Medical Physiology.” The normal lifespan of a red blood cell is 120 days. After that time period, when the blood cell passes through the spleen, it will be broken down and some parts recycled. But the spleen also removes all abnormal red blood cells. A normal red blood cell is very flexible. An abnormal one is not. It will not be able to pass through some of the sections of the spleen. David Darling explains this in “The Internet Encyclopedia of Science.”
Part of Immune Response
The immune response describes the fight against foreign substances. As blood passes through the spleen, not only are old and abnormal red blood cells removed, but microorganisms are, as well. According to Elizabeth Corwin, a registered nurse with a doctorate in physiology, macrophages will take pieces of a microorganism to the B and T lymphocytes while inside the spleen. Macrophages, B and T lymphocytes are all types of white blood cells. The B lymphocytes make antibodies. T lymphocytes trigger the B lymphocytes to act, release toxic chemicals to destroy foreign substances and circulate through the bloodstream because they remember what foreign substances they already have encountered, Corwin wrote in the “Handbook of Pathophysiology.”
Reservoir for Blood
The spleen holds a reserve supply of blood. Dr. Thomas Kipps, a professor of hematology and oncology at the University of California, writes in “Williams Hematology” that the average adult spleen weighs 4 oz., but can weigh up to 8 oz. When all of the blood is drained, it only weighs approximately 2.8 oz. Whenever the blood pressure drops, the spleen can send blood into circulation to bring the blood pressure back up. But it is also the most injured organ in trauma. Sometimes, it can rupture from minor trauma because it is enlarged, as when it enlarges during leukemia, AIDS or infectious mononucleosis. If it ruptures for any reason, the body loses so much blood that this can lead to hypotension, or low blood pressure, and shock.
Erythropoiesis means the formation of red blood cells. The spleen makes red blood cells during the time that the fetus is 9 to 28 weeks old, according to Dr. George Segel, a professor of pediatrics, medicine and oncology at the University of Rochester Medical Center writing in "Williams Hematology." The bone marrow is then the main site for making blood cells once the fetus is 28 weeks. The bone marrow continues to make the blood cells once the child is born. The spleen is able to make red blood cells for a child only if the bone marrow stops functioning. It can also do this for adults who have certain disorders, like thalassemia.