system
Given the following post, respond as if you're commenting on Reddit:
human
When your body creates new blood what happens to the blood that it's replacing it with?

The question says it all I hope.
gpt
The Kupffer cells in your liver go to work. The iron gets taken out of the hemoglobin to be used in the new cells (that's why humans do not need much iron in their diet). The rest of the hemoglobin gets converted to bilirubin (a building block for bile in the digestive tract). The cell itself doesn't have a nucleus so it usually just gets pooped out.