Now, amino acids can actually travel in the blood plasma by themselves, but this iron has to be carried by special protein carrier known as a transferring. So transferring carries the fe atom to the bone marrow, or if the fe remains in that cell, it can be used by that cell for some type of process. Now, what about the heme group? 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.