Mapping Color Changes of Bruises
Why are bruises "black and blue"? Watch what is exactly happening in your body as bruises change from blue to green to yellow to brown, and why bruises move downwards.
from Scientific American
Key Facts In This Video
Bruises change colors because of hemoglobin, the compound in red blood cells that brings oxygen to your body. (0:19)
Broken capillaries under the surface of where you were injured make the outside of your skin appear bluish-black. (0:30)
Bilirubin is what turns bruises yellow. Bilirubin is waste we excrete, and is what gives urine its yellow color. (1:00)
Sometimes, bruises move downward because gravity is pulling the debris in that direction. (1:24)