WHY does a bruise appear and changes its color? When a bump or bruise occurs, the
capillaries are damaged. Blood flows from them into the surrounding soft tissues under the skin. Blood contains plenty of
hemoglobin, giving it that bright red color.
White blood cells arrive at the site of the injury. They surround the site of the hemorrhage and begin to
destroy the blood cells.
Destruction of hemoglobin produces decomposition products —
biliverdin (green bile pigment) and
bilirubin (yellow-red bile pigment).
