By Dr Ananya Mandal, MD
The spleen is an organ found in almost all vertebrate animals. It mainly acts as a filter for old red blood cells. It is also an important organ in the immune system.
The spleen is important for many functions in the body from filtering out old red blood cells to creating antibodies but it is not vital for life. Without the spleen the human body tends to adapt itself.
Anatomy and location of the spleen
The spleen is located in the left upper quarter of the abdomen. The spleen commonly lies under the ninth to the twelfth rib. In healthy adults it is around 10 to 12 centimetres in length and weighs around 150 to 200 grams. The pulp within the spleen is covered by a capsule.
The spleen has only efferent or outgoing lymphatic vessels. The spleen is part of the lymphatic system of the body and thus plays an important role in maintaining immune functions.
The spleen is supplied with blood via the splenic artery. The red pulp contains blood vessels that are called splenic sinusoids. These contain woven connective tissues called splenic cords.
Within the spleen are small arteries or arterioles that are called penicilliary radicles. The red pulp helps in filtering blood of the old and defective cells. The white pulp lies within the red pulp and contains lymphoid tissues. The antibodies are made in this white pulp.
Immune cells like the B lymphocytes and the T lymphocytes are made and matured within the spleen.
One of the major functions of the spleen is to filter the blood of old and dying red blood cells.
Although the spleen acts as a reservoir of special type of white blood cells called monocytes in humans, in animals this is not so. The monocytes stored in the spleen migrate to the injury sites and transform into dendritic cells and macrophages that may help in healing wounds and injuries.
In humans the spleen also stores platelets that normally help in blood coagulation and clotting. In animals the spleen as acts as a reservoir of blood cells.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)