what happens to worn out cells when they die?
The hemoglobin is the part of the erythrocyte that actually carries the oxygen and carbon dioxide. Red blood cells are made in the red marrow of bones, and live about 120 days. Because they wear out so quickly, an entire supply of red blood cells is renewed every four months. As red blood cells wear out in the bloodstream, they are taken in by the spleen, an organ on the left side of the abdomen below the stomach, and destroyed. Parts of the old cells are salvaged to make new red blood cells. The picture below shows what a blood smear looks like under a microscope.