Which of the following is NOT a function of the spleen?

The function identified as not belonging to the spleen is excretion of waste products. The spleen is primarily involved in filtration of blood, particularly in the destruction of old or damaged red blood cells, storage of platelets, and production of certain types of white blood cells.

Specifically, it plays a crucial role in the immune response by producing lymphocytes and filtering pathogens, as well as contributing to the recycling of iron from hemoglobin. Additionally, it acts as a reservoir for platelets which can be released into the bloodstream during times of need.

While some organs, like the kidneys and liver, are responsible for the excretion of waste products from the body, the spleen does not have this function. Instead, it focuses on blood maintenance and immune functions, distinguishing it from organs involved in waste elimination.