Lymphoid organs/Spleen

Spleen is a large and secondary lymphoid organ(organ associated with immunity).It is located in the upper part of the abdominal cavity behind the stomach and close to diaphragm. spleen in embryo is hemopoietic and thus gives rise to RBCs in the process of hemopoiesis. In adults, spleen acts hemopoietic only when the person is sick and is in demand for RBCs. Humoral and cellular immunity occurs in spleen in response to antigens when it traps the blood borne antigens in it.

Functions of spleen

 * Spleen acts as a filter by trapping foreign particles that pass through circulating blood. It is the major immunological function of spleen.
 * Plays major role in keeping the body fluids balanced.It controls the level of WBCs,RBCs and platelets.
 * It is the graveyard of worn out blood cells.
 * A reserve tank in the formation of RBCs.

Individuals who do not possess spleen are prone to blood borne bacterial infections.If spleen fails to work properly, it might start removing healthy blood cells leading to anaemia.