Aged erythrocytes are destroyed in the?

Step 1: Analyze the question Erythrocytes are red blood cells (RBCs). The question asks where old, worn-out RBCs are broken down.

Step 2: Explain the concept Red blood cells live for about 120 days. They have no nucleus, so they cannot repair themselves. As they age, their membranes become fragile. They are then removed from circulation by macrophages, mainly in:

• the spleen (the "graveyard of red blood cells")
• the liver
• the bone marrow

In the liver, haemoglobin is broken down. The iron is stored or recycled, and the heme part is converted into bile pigments (bilirubin and biliverdin), which are excreted in bile.

Step 3: Check each option

• A. Pancreas: It produces digestive enzymes and insulin/glucagon. It does not destroy RBCs.
• B. Liver: Its Kupffer cells (macrophages) destroy aged RBCs and process haemoglobin into bile pigments. This fits.
• C. Lymph nodes: They filter lymph and fight infection, not old RBCs.
• D. Kidney: It filters blood and forms urine. It also produces erythropoietin, which stimulates RBC production, but it does not destroy them.

Step 4: Answer The spleen is the classic answer in many textbooks, but it is not among the options.

Tip: Remember "Spleen and Liver = RBC graveyard." If the spleen isn't offered, pick the liver. Also remember that RBCs are made in the bone marrow and destroyed in the spleen and liver.