What are the functions of the spleen?

The spleen It is an organ located under the diaphragm on the left side of the abdominal cavity. It is part of the lymphatic system and its structure is similar to a large node or lymph node.

The spleen functions they can be divided into two broad categories: hematic functions and immune functions.

The blood functions take place in the red pulp. These include the destruction of erythrocytes and the metabolism of hemoglobin with the recycling of iron and the formation of bilirubin.

The immune functions take place in the white pulp. These include the production of antibodies, the production of opsonins and the destruction of bacteria and cells covered by antibodies.

Next we will see in more detail the functions of the spleen in each category.

hematic functions of the spleen

structure of the spleen
Structure of the red pulp and white pulp of the spleen, each related to specific functions

The main blood function of the spleen is destruction of red blood cells or old, damaged, or otherwise abnormal red blood cells. The spleen also destroys platelets old or damaged.

This function is carried out in the red pulpa part of the spleen in which abound sinusoids blood capillaries.

Among the capillaries are those known as billroth laces., also called splenic cords Billroth's cords consist of connective tissue with a large population of monocytes and macrophages.

The discontinuities of the sinusoidal capillaries make mechanical blood filter that reaches the spleen. The erythrocytes are forced to deform to pass through Billroth's cords. Old or damaged red blood cells have less flexibility, so they cannot pass through and are destroyed.

The spleen also metabolizes hemoglobin of the erythrocytes. The heme group is converted into bilirubina substance that is excreted through the bile, and the iron it is recycled.

Other blood functions

The hematopoiesis takes place in the spleen during fetal development, with all blood cells forming here until about the fifth month of gestation.

After birth, hematopoiesis takes place in the bone marrow, although many types of lymphocytes continue to mature and differentiate in the spleen, which is why it is still considered a hematopoietic organ.

The spleen retains a large number of erythrocytes, platelets and lymphocytes that are released when necessary, so it also acts as a reservoir for these cells.

immune functions

The spleen is a central organ in the immune system activityboth in humoral immunity and in cellular immunity.

The immune functions of the spleen occur in the white pulpformed by lymph nodes known as Malpighian bodieswhich consist of lymphoid tissue around a central arteriole.

In Malpighian bodies three zones are differentiated:

  • Periarteriolar lymphoid sheath: contains mainly T lymphocytes.
  • lymphoid follicles: They are located after the periarteriolar sheaths and act as germinal centers of B lymphocytes.
  • fringe area: is located between the lymphoid follicles and the red pulp. It contains antigen-presenting cells, mainly dendritic cells and specialized macrophages.

The organization of the spleen facilitates the filtration of antigens, pathogens and abnormal cells present in the blood circulation and facilitates the interaction between antigen-presenting cells and T and B lymphocytes, acting as a regulator of the immune response.

The spleen also synthesizes opsonins tuftsin and properdin, which together with IgM and IgG2 are very important for the opsonization and phagocytosis of certain types of pathogens, especially encapsulated bacteria.

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