Final answer:
The breakdown of heme from erythrocytes primarily occurs in the spleen, where heme is converted into biliverdin and then into bilirubin, which is transported to the liver and used in bile production.
Step-by-step explanation:
The breakdown of erythrocytes, particularly focusing on heme, involves several steps. First, the globin portion of hemoglobin is broken down into amino acids, returned to the bone marrow to be reused. Heme, the iron-containing component of hemoglobin, undergoes a complex degradation process. The iron is either stored in the liver or spleen as ferritin or hemosiderin, or carried by transferrin in the bloodstream back to the bone marrow to be incorporated into new erythrocytes.
As for the non-iron part of heme, it is initially converted into biliverdin, a green pigment, and then rapidly reduced to bilirubin, a yellow pigment. This bilirubin binds to albumin and is transported to the liver where it is used to produce bile. The conversion of heme into biliverdin and subsequently into bilirubin predominantly occurs in the spleen and then processed by the liver, not the liver, bone marrow, or kidneys as suggested in the question's options.
Finally, in the intestines, bilirubin is further metabolized by bacteria into urobilinogen and then into stercobilin, which ultimately contributes to the brown color of feces. If bilirubin enters the urinary system, it can lead to a yellow coloration of the urine due to related metabolic byproducts.