Why is it that a person's blood is blue and when it hits oxygen it turns red?

Question

I wonder why your blood isn't blue when it comes out. It doesn't stay the same color.

Answer 1

Your blood is not blue; blood is always red, whether it is in your body or out of it. The variation in color from bluish red (in the veins) to bright red (in the arteries) is a reflection of the amount of oxygen the blood is carrying; higher oxygen levels will produce a brighter red (a scarlet color), and lower oxygen levels will produce a darker bluish red (almost maroon). Your veins may appear blue on the surface of the skin because of the reflection of light through the skin and the thin walls of the veins, not because the blood itself is blue.

Answer 2

Blood gets its color from different things in it. The primary color change portion is a substance called heme and is part of hemoglobin. This is an iron rich substance and when it is exposed to oxygen, it binds it and changes color to the red. As soon as blood is exposed to air, it begins binding oxygen and so appears to be red. Oxygen poor blood isn't actually blue but it looks blue in comparison to the bright red of oxygen rich blood.

Answer 3

Your blood never really is blue, it is a dark red and looks blue through your skin when it is not carrying oxygen. It turns bright red as soon as it is exposed to oxygen, though.

Answer 4

The blood turns blue when it's low in oxygen and runs in the veins, so naturally when you cut yourself open the blood are exposed to oxygen it turns red.

Answer 5

Iron oxide, oxidation

Answer 6

iron oxide is red