What is the functional difference between red pulp and white pulp in the spleen?

• A. Red pulp filters blood and removes old or defective red blood cells.
• B. White pulp filters blood and removes old or defective red blood cells.
• C. Red pulp produces lymphocytes.
• D. White pulp stores bile.

Answer: (A)

The spleen has two distinct zones with different tasks: red pulp handles filtering and breakdown of blood cells, while white pulp manages immune responses to blood-borne antigens. In the red pulp, blood passes through splenic sinusoids where aging or defective red blood cells are recognized and removed by macrophages. This is where clearance and recycling of red cell components (like iron) primarily occur, and the red pulp also serves as a reservoir for platelets. The white pulp, on the other hand, is lymphoid tissue organized around arteries and is the site where immune cells—especially T cells in the periarterial lymphatic sheath and B cell–rich follicles—encounter antigens and mount adaptive immune responses.

So the statement that the red pulp filters blood and removes old or defective red blood cells aligns with its primary role. The white pulp does not mainly remove old RBCs; its function is immune surveillance and activation against blood-borne pathogens. Storing bile is not a function of the spleen at all.