What is the function of the spleen in the lymphatic system?

The spleen plays a critical role in the lymphatic system by filtering blood and helping to fight infections. It acts as a blood reservoir, filtering out old or damaged red blood cells and recycling their components, particularly iron. This process is vital for maintaining healthy blood composition.

Additionally, the spleen is involved in the immune response. It contains lymphocytes and other immune cells that respond to pathogens in the blood, enhancing the body’s ability to fight infections. When an infection occurs, the spleen can produce antibodies and activate immune cells, making it a key player in the body’s defense mechanism.

While the production of red blood cells occurs primarily in the bone marrow, the spleen does have a role during fetal development. However, in adults, its primary focus remains on blood filtration and immune functions, rather than the production of red blood cells.

The other options highlight functions that are less relevant to the spleen’s primary roles. For example, storing excess iron and nutrients is primarily a function of the liver, and regulating fluid balance in tissues is largely managed by the lymphatic system and kidneys, making them less applicable in the context of the spleen's main functions.