Is human blood blue?

Question

big argument at work. I say all blood is red.

Answer 1

The human blood is red!

Answer 2

SCRATCH WHAT I SAID, EARLIER! I RESEARCHED IT.

When the red blood cells go to the lungs, the iron in them picks up oxygen.

Blood then goes to the heart and then to the rest of the body through vessels called arteries.  The arteries appear reddish as do many other organs, because the iron in the blood gives up its oxygen to the cells that need it as the red blood cells travel throughout the body.  By the time the

blood is back on its way to the heart and then to the lungs it has less than half as much oxygen as it did before.  The veins, therefore, do not

get as much oxygen as the other tissues and they appear bluish.

The bottom line is: blood is red.

Answer 3

I don't know , I heard that blood is actually blue preserved in the body. Once it is  exposed to oxygen it turns to red. Good Question, if you find an accurate answer let me know.

Answer 4

Blood that is not exposed to outside air and is in your body is blue once it hits the outside air it turns red.  

Answer 5

oxygenated blood is "firetruck red"

deoxygenated blood is "purple-ish"

if you really want to get fancy you can say: deoxygenated blood looks purple because the oxygen-carrier is iron that when oxidize is red but when reduced is 'indigo' (uh-oh...that means blue). however, blood returning to the heart is not truly blue but is purple-ish (you know, what you get when you mix red and blue...) and only appears blue (visible in veins just below the skin surface) because of light diffraction through tissue.

Answer 6

You're right.  All human blood is red, regardless of whether or not it comes in contact with oxygen.  When it is oxygenated, it is a bright red, when it is deoxygenated, it is a darker maroon color.  The blue color of veins is from the veins themselves and the fact that they are a little ways under the skin (only blue light has enough energy to penetrate that far).

If they don't believe you, then ask them if they've ever had blood drawn from their arm.  When a nurse takes a sample, he or she uses an evacuated tube attached to a needle and draws from a vein.  The tube has no air in it, in order to pull blood inside.  If you look at the blood that is drawn, it is a dark red, but it is still deoxygenated because it came from a vein and there was no air inside the sample tube.

Answer 7

Humans' blood is never blue. Deoxygenated blood is a deeper red but still red nonetheless. It only appears blue in the veins because blue light penetrated better into the skin and then reflected out.