File:Spleen anatomy.jpg

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Spleen Anatomy

  • The spleen is located in the upper left abdominal cavity, just beneath the diaphragm, and posterior to the stomach.
  • It is similar to a lymph node in shape and structure but it is much larger.
  • The spleen is the largest lymphatic organ in the body.
  • Surrounded by a connective tissue capsule, which extends inward to divide the organ into lobules, the spleen consists of two types of tissue called white pulp and red pulp.

White pulp - is lymphatic tissue consisting mainly of lymphocytes around arteries.

Red pulp - consists of venous sinuses filled with blood and cords of lymphatic cells, such as lymphocytes and macrophages.

  • Blood enters the spleen through the splenic artery, moves through the sinuses where it is filtered, then leaves through the splenic vein.

Function

Immune

  • filters blood in much the way that the lymph nodes filter lymph.
  • Lymphocytes in the spleen react to pathogens in the blood and attempt to destroy them.
  • Macrophages then engulf the resulting debris, the damaged cells, and the other large particles.

Red Blood Cell Removal

  • The spleen (and liver) removes old and damaged erythrocytes from the circulating blood.
  • Like other lymphatic tissue, it produces lymphocytes, especially in response to invading pathogens.

Blood Reservoir

  • The sinuses in the spleen also act as a reservoir for blood.
    • In emergencies, such as hemorrhage, smooth muscle in the vessel walls and in the capsule of the spleen contracts.
    • This squeezes the blood out of the spleen into the general circulation.


Image and Modified text source: National Cancer Institute - SEER Training Modules

http://training.seer.cancer.gov/anatomy/lymphatic/components/spleen.html

http://training.seer.cancer.gov/anatomy/lymphatic/components/

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