What is the primary function of the spleen?

The primary function of the spleen is to filter blood and recycle iron. This organ plays a vital role in the body's immune response and in the management of blood components. The spleen filters out old and damaged red blood cells, breaking them down and recycling their components, particularly iron, which is then reused in the production of new red blood cells. Additionally, the spleen helps to mount an immune response against pathogens found in the blood, making it critical for maintaining overall health and proper immune function.

In contrast, the production of hormones is primarily the role of glands such as the pituitary, thyroid, and adrenal glands, rather than the spleen. The storage of bile is a function of the gallbladder, which is responsible for concentrating and storing bile produced by the liver, not the spleen. Regulation of body temperature is managed through various mechanisms involving the hypothalamus and other systems, but it is not a function associated with the spleen. Thus, the function of filtering blood and recycling iron distinctly sets the spleen apart from these other options.