Is blood really blue?

Answer 1

No, it is not. It is red.
Your vein may look blue, but that is because you see them through the skin.
That said, there are animals with blue blood. The horseshoe crab has blood with copper based oxygen carrier, as opposed to iron based. And copper salts are greenish or blueish, hence the blue blood of this marine creature.

Answer 2

Human blood is red, ranging from bright red when oxygenated to dark red when not. It owes its colour to hemoglobin, a metalloprotein compound containing iron in the form of heme, to which oxygen binds. There exists a popular misconception that deoxygenated blood is blue and that blood only becomes red when it comes into contact with oxygen. Blood is never blue, but veins appear blue because light is diffused by skin. Moreover, the blood inside is dark red and exhibits poor light reflection. From a physiological perspective, veins and arteries appear similar when skin is removed and are seen directly.

Answer 3

No, blood is not blue. That is just a common misconception.

Blood is always red, just various shades. Deoxygenated blood is dark red and oxygenated blood is very red. The blue you see under your skin are your VEINS which carry the blood. They are blue but the blood is not.

Answer 4

Yes.. That is why your veins are blue.. When blood makes contact with air it instantly turns red. I had some questions about that because technically there is oxygen in your blood so i was suspicious.. But it is true blood really is blue.

Answer 5

This is a great question one with a great deal of informaiton.

It turns out that the presence or relative absence of oxygen is what determines the 'color' of blood. Hemoglobin is an important
constituent of red blood cells. Hemoglobin contains iron atoms (you might remember seeing rock formations with a high content of iron and remember that they often have a reddish color) and has the ability to loosely associate with oxygen molecules. Hemoglobin can also associate with carbon dioxide. What gas (oxygen or carbon dioxide) associates with hemoglobin is
based almost solely on how much of each is available. In the lungs, there is alot of oxygen available and so it associates with hemoglobin in the blood. The blood then travels in arteries out to your tissues(muscle, skin etc). Oxygen delivered to tissues is rapidly used by the cells to perform all the chemical reactions that keep them healthy and the by-product is carbon dioxide. So when the blood gets to the tissues there is very little oxygen and plenty of carbon dioxide, which means that the oxygen leaves hemoglobin for the tissues and carbon dioxide leaves the tissues for the hemoglobin in the blood. The blood then travels in veins back to the lungs where we start all over.


Finally, to your question. It turns out that hemoglobin has a red color to it and that oxygenated hemoglobin is bright red. So in arteries blood appears to be bright red. This is true inside and outside. Outside of the body the color actually fades a bit (becomes darker), because there is less pressure to keep oxygen associated with the hemoglobin. But if you cut an
artery the blood squirting out will appear bright red. Blood that is in veins, however, has very little oxygen associated with it and this yields a color that is much darker. As you noted, because of having to look through the skin at veins they actually take on a blue tint, but really the blood inside (and if you cut a vein) is just a deep shade of red. You can also see this in persons that have stopped breathing or have blood flow blocked to a specific area; they appear blue. (A condition referred to as cyanosis.)

So, a long answer to a short question. Blood is never actually blue, although it appears to be blue when we look at veins through skin. Blood is always red: bright red when it is oxygenated on the arteriolar side of our circulation, and deep red when it is not oxygenated on the venous side.

Answer 6

No, blood carries oxygen so it's always in contact with O(2). It's red because of hemoglobin -an iron-containing molecule.

Answer 7

I thought veins are blue, blood is red.

Answer 8

blood that lacks oxygen is blue... The reason that the blood that comes out when you are bleeding isnt blue, is because it becomes red as soon as it is exposed to oxygen..

Answer 9

yup. It's red when it comes in contact with oxygen. If you look at your hand and inner wrist, can you see faint blue lines (especially when you're cold)? That's your blood.

Answer 10

Ok its red and blue making it purple.