The spleen and its role in immune function
The spleen is not part of the digestive system however is connected to the blood vessels of both the stomach and the pancreas.The spleen is situated on the left side of our body; under the ribs and above the stomach. It is a part of the lymphatic system and can weigh between 150 – 200 grams in a healthy adult and is approximately 10-12 cm in its longest dimension.
The function of the spleen is largely unknown but has to do with both the immune function of the body and filtering of the blood stream.
Different cell types with different function
The spleen is composed of two primary regions namely, red pulp and white pulp. The red pulp makes up for little more than three-fourth of the spleen. A region designated marginal zone is a transition area that separates it from the white pulp.
Red pulp
The red pulp is made up of connective tissue and splenic sinuses. The splenic sinuses are filled with blood and give the red pulp its characteristic color. The red pulp is made up of blood cells such as platelets, granulocytes, and red blood corpuscles. It acts as a filter and cleans up the blood by removing antigens and damaged red blood cells.
White pulp
The white pulp acts as a source of antibodies and lymphocytes for the immune defense system. The spleen stores platelets, red blood cells, and also blood which can be released into the blood stream in case of hemorrhagic shock.
Evolution has deemed this ability to serve as a reservoir of blood products in times of extreme stress as more important in animals than currently in humans.
Enlarged spleen known as splenomegaly
If the spleen gets enlarged beyond its natural size the condition is termed splenomegaly. The spleen can become enlarged when a person is suffering from malaria, systemic lupus, leukemia and other conditions.
In rare cases there is a danger of the spleen rupturing if it grows too big. Blunt force trauma in an accident can also cause an already enlarged spleen to rupture.
Spleen removal also called splenectomy
Spleen removal or splenectomy is necessitated under certain conditions such as tumors and spleen rupture. If the spleen needs to be removed it can often be removed with small incisions in a manner known as laparoscopic splenectomy. It is interesting to note that the body can function without this organ and with little side effect. A person without a spleen is at increased risk from pneumonia and other adverse conditions caused from encapsulated bacteria.
The spleen usually works with the liver to fight infection and remove bacteria from the blood stream. The body becomes more susceptible to certain bacteria and responsiveness to vaccines is reduced if the spleen is removed.
