The correct option is Both A and R are true but R is NOT the correct explanation of A
Explanation
The spleen is a large, bean-shaped secondary lymphoid organ located in the upper left quadrant of the abdomen. It performs two primary physiological functions: acting as a blood filter to remove old cells (Red Pulp) and serving as an immune center to trap pathogens (White Pulp).
Statement-wise Analysis
- Assertion (A) is Correct: Erythrocytes (Red Blood Cells or RBCs) have a finite lifespan of approximately 120 days. Upon becoming senescent (old) or damaged, they lose membrane flexibility and are trapped in the splenic cords. Macrophages within the spleen engulf and destroy these worn-out cells. Due to this specific role in the destruction and recycling of RBCs, the spleen is designated as the "graveyard of RBCs."
- Reason (R) is Correct: The spleen functions as a filter for the blood, distinct from lymph nodes which filter lymph. It effectively traps blood-borne microorganisms and particulate matter. The presence of lymphocytes and phagocytes allows the spleen to mount an immune response against these trapped pathogens.
- Relationship Analysis: Although both statements are individually true, the Reason (R) describes the immune/filtration function regarding microorganisms. This does not explain the specific designation of the spleen as the "graveyard of RBCs," which is derived from its role in destroying old erythrocytes. Therefore, R is not the correct explanation of A.
Key Takeaway: The spleen is called the "graveyard of RBCs" because it destroys senescent red blood cells in the Red Pulp, whereas its ability to trap microorganisms is a separate function related to immune defense.