Red pulp

The red pulp is the part of the spleen that is responsible for filtering the blood. It plays a crucial role in the breakdown and recycling of old or damaged red blood cells. The red pulp also acts as a reservoir for platelets and blood cells and participates in the immune response.

Structures:

• Sinuses and Cords: the red pulp consists of a network of sinuses (blood-filled spaces) and splenic cords (also known as the cords of Billroth). The sinuses are lined by endothelial cells and are surrounded by the splenic cords, which contain a meshwork of reticular fibers and various immune cell

• Cellular composition: the splenic cords are rich in macrophages, which phagocytose (engulf and digest) old or damaged red blood cells, pathogens, and cellular debris. The red pulp also contains lymphocytes, plasma cells, and other blood cells.

Blood flow:

The blood supply to the red pulp comes from the splenic artery, which branches into smaller arterioles within the spleen:

• Trabecular arteries: the splenic artery divides into trabecular arteries, which run along the trabeculae (connective tissue structures) of the spleen.

• Central arteries: the trabecular arteries give rise to central arteries, which are surrounded by the white pulp.

• Penicillar Arterioles: the central arteries branch into smaller penicillar arterioles, which eventually enter the red pulp.

Functions:

• Blood Filtration: the red pulp filters the blood by trapping and removing old or damaged red blood cells and recycling their components, including iron.

• Immune Response: macrophages and other immune cells in the red pulp help to identify and destroy pathogens and present antigens to lymphocytes, initiating an immune response.

• Storage: the red pulp acts as a reservoir for platelets and various blood cells, which can be released into the circulation when needed.

In summary, the red pulp is a critical part of the spleen's structure and function, responsible for filtering blood, recycling iron, and contributing to the immune response. Its complex network of sinuses and cords, along with the blood flow from the splenic artery, enables it to carry out these vital functions effectively.