What is the primary function of the spleen?

The primary function of the spleen is to filter blood and help fight infections. The spleen plays a crucial role in the immune system by filtering out old and damaged red blood cells and pathogens. It contains white blood cells, particularly lymphocytes and macrophages, which help identify and destroy bacteria and other foreign substances in the blood. This filtering process is vital for maintaining healthy blood composition and aiding the body’s defense mechanisms against infections.

Other options represent functions associated with different organs. Hormone production is primarily done by endocrine glands, bile storage occurs in the gallbladder, and blood sugar regulation is mainly managed by the pancreas. Understanding these distinctions highlights the unique role of the spleen within the body's complex systems.