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Spleen Function, Location, Size and Disorders

Spleen is the largest lymphatic organ in the human body. Lymphatic or lymphoid organs are the major parts of the immune system of our body. Function of the immune system is to protect the host (i.e. human body) from the invasion of foreign organisms. Immune system helps the body to distinguish its own tissues from external substances such as bacteria, viruses and toxins. Thus dysfunction or deficiency of components of the immune system can lead to various diseases ranging from arthritis, HIV and cancer.

Spleen

Location of the spleen

Location Of Spleen

Spleen weighs about 150 gm in adults and lies under the diaphragm in the left upper part of the abdomen at the level between 9th and 11th ribs. Anterior to the spleen lies stomach and medially lies the superior part of the left kidney. Spleen resembles the size and shape of a clenched fist.

Functions of the spleen

  • Spleen participates in the primary immune response to invading bacteria, viruses, parasites or foreign particles. Spleen is a strong defense against blood-borne pathogens. Removal of spleen increases the risk of infection.
  • Spleen acts like a filter for the blood; it removes cellular residues, particulate matter, senescent RBCs and other abnormal cells from the bloodstream.
  • Spleen synthesizes antibodies, macrophages and activated lymphocytes in its white pulp. About 25% of the body's T lymphocytes and 15% of B lymphocytes are present in the spleen.
  • RBCs have an average life span of 120 days after which they are destroyed mainly in the spleen. When the spleen is removed surgically due to any irreversible damage, increased numbers of abnormal RBCs are seen in blood smears. Spleen also removes old defective platelets from the circulation.
  • The spleen can act like a blood reservoir. Due to its spongy structure the spleen can enlarge and store up to 1000 ml of blood and when needed it can also help to stabilize the blood volume by transferring excess plasma from the bloodstream into the lymphatic system.
  • In certain diseases such as leukemia or extreme anemia the spleen can resume its role of producing blood cells; this function is usually present during fetal life.

Disorders of the spleen

Splenomegaly

It is the abnormal enlargement of spleen. When the spleen is diseased it can be 10 times larger than its normal size. Causes include:

  • parasitic infection such as malaria, kala azar
  • chronic tuberculosis
  • typhoid, septic shock, infective endocarditis
  • rheumatoid arthritis, systemic lupus erythematosus
  • portal hypertension, liver diseases
  • lymphomas, anemia, leukemia

Splenectomy

It is the surgical removal of spleen and is usually performed due to severe trauma or rupture of the spleen. In the long run there is an increased risk of overwhelming infections after the removal of the spleen. Numbers of platelets in the blood are also increased immediately.