<unk>  often forms after bleeding (haemorrhage). When blood leaves a ruptured blood vessel, the red blood cell dies, and the hemoglobin of the cell is released into the extracellular space. Phagocytic cells (of the mononuclear phagocyte system) called macrophages engulf (phagocytose) the hemoglobin to degrade it, producing<unk>  and biliverdin. Excessive systemic accumulations of<unk>  may occur in macrophages in the liver, lungs, spleen, kidneys, lymph nodes, and bone marrow. These accumulations may be caused by excessive red blood cell destruction (haemolysis), excessive iron uptake/hyperferraemia, or decreased iron utilization (e.g., anaemia of copper toxicity) uptake hypoferraemia (which often leads to iron deficiency anemia). Cellular iron is found as either ferritin or<unk> . It is identified in cells by the Perls or Prussian blue reaction, in which ionic iron reacts with acid ferrocyanide to impart a blue color.
Hemosiderin
Hematoporphyrin
Respiratory pigment
Iron metallic discoloration
Iron lung
Melanin
Fomite
Hemosiderosis