Final answer:
The spleen is a part of the reticuloendothelial system and removes pathogens from the blood. It contains red pulp that stores blood and removes damaged red blood cells, and white pulp that helps remove bacteria from the blood.
Step-by-step explanation:
The spleen is part of the reticuloendothelial system and it removes pathogens from the blood. It consists of two types of tissue: red pulp and white pulp. The red pulp stores blood and removes damaged red blood cells, while the white pulp is rich in lymphocytes that remove antigen-coated bacteria from the blood.