Well, the heme group is ultimately broken down and form and broken down and transformed into something called bilirubin. And bilirubin eventually exits and enters the blood plasma, where it travels into the liver. And the liver either transfers that bilirubin into our kidneys or it combines it with the bile that is excreted into the intestines, where the bile combines with our remnants of whatever we ingest and eventually is excreted by the large intestine of our body. So this is the process by which we produce our red blood cells. And we also destroy those red blood cells and recycle those red blood cells so that we can reuse some of the components to form more red blood cells in our bone marrow. So, to summarize, red blood cells are formed in our bone marrow and they are recycled, they are broken down by macrophages and either the liver, the spleen, or our lymph nodes.