The Spleen

Spleen Structure and Composition

• The spleen is divided into two main structures: the white pulp and the red pulp.
• The red pulp consists of splenic cords and venous sinuses.
• The spleen is surrounded by a fibroelastic capsule, which contains collagenous fibers, elastic fibers, and smooth muscle cells.
• The trabeculae, which are extensions of the capsule, branch into the spleen and contain smooth muscle cells, collagenous fibers, and elastic fibers.
• The trabecular network is a three-dimensional structure that provides support to the spleen.

Spleen Location and Blood Supply

• The spleen is situated in the upper left region of the abdominal cavity, just below the diaphragm.
• The spleen receives its blood supply from the splenic artery, which arises from the celiac trunk.

Accessory Spleens

• Approximately 10-30% of people have one or more accessory spleens, which are small, functional spleens located outside the main spleen.
• Accessory spleens are typically found in the following locations: near the hilum of the spleen, in the gastrosplenic ligament, in the lienorenal ligament, or in the greater omentum.

Functions of the Spleen

• The main functions of the spleen include filtering the blood, storing red blood cells, and producing immune cells called macrophages and dendritic cells.
• The spleen plays a significant role in the immune system by removing pathogens and old or damaged red blood cells from the circulation.
• The red pulp of the spleen is responsible for filtering the blood, storing red blood cells, and recycling iron from old red blood cells.
• The venous sinus in the red pulp acts as a filter, allowing blood cells to pass through while trapping old or damaged cells.
• The trabecular network provides support to the spleen and allows it to expand and contract during blood filtration.

Spleen and Circulatory System

• The spleen is connected to the circulatory system through the splenic artery and vein.
• The spleen is the largest lymphoid organ in the body, playing a crucial role in the immune system.

Miscellaneous

• The outer serous coat of the spleen is composed of a thin layer of mesothelial cells and a layer of loose connective tissue.
• The spleen contributes to the immune system by producing immune cells and removing pathogens from the circulation.

Test your knowledge on the structure of the spleen, the largest lymphoid organ in the body. Learn about its location, vascular nature, and the presence of accessory spleens.