What Is Hemoglobin Breakdown?

Red blood cells, which form one of the major constituents of blood, are characterized by the absence of nuclei, hence they are unable to undergo cellular division or generate new erythrocytes from old ones. This eventually leads to cell disintegration, which typically occurs 4 months after the fully developed red blood cells have been in circulation within the bloodstream. During the degeneration of the red blood cells, some components of the hemoglobin are excreted from the body while other parts are conserved.

Hemoglobin comprises two major parts: a protein-complex called globin and four heme groups. Each heme group contains one atom of iron, which is the binding site for oxygen molecules, notes Infoplease. When old or damaged red blood cells rupture, the hemoglobin is engulfed by macrophages, which are large phagocytic white blood cells. The globin chain of hemoglobin is broken down into amino acids that are either metabolized by the macrophages or absorbed by the bloodstream.

The heme groups undergo chemical decomposition and they are converted to biliverdin and then into biliburin. The biliburin, which is carried to the liver by blood albumin, forms a conjugate with glucuronic acid. The conjugated biliburin is then eliminated from the body through the large intestine in the form of fecal matter or via the kidneys in the form of urine. The iron atoms that are released from the heme groups are conserved and then transported by transferin to the bone marrow, where they are utilized in the production of new hemoglobin. Excess iron can also be stored in the liver.