Final answer:
The spleen is the lymphatic organ that stores excess blood and releases it when needed. It filters pathogens and worn out red blood cells from the blood, and its lymphocytes destroy them. The spleen also acts as a location for immune responses to blood-borne pathogens.
Step-by-step explanation:
The lymphatic organ that stores excess blood and releases it when needed by the body is the spleen. The spleen is the largest secondary lymphoid organ and is located in the upper abdomen. It filters pathogens and worn out red blood cells from the blood, and its lymphocytes destroy them. The spleen also acts as a location for immune responses to blood-borne pathogens.