That's a good observation. When you see blood outside the body it is usually a dark red. This blood is from the veins. Sometimes you may cut an artery. This blood is bright red. It also spurts out in pulses instead of oozing like the blood from veins. So even outside the body, blood can be different colors. (What's the difference between veins and arteries and why would that affect the color? Why does arterial blood spurt?) The blood vessels you see at the surface of your skin are veins. Everyone's skin is slightly different in color, so the veins can look different in different people, but blood is exactly the same color in everyone. It still doesn't look red. That's because we're seeing the *walls* of the veins too. When you see lemon-lime flavored soft drinks in plastic bottles they usually look green, but when you pour them out, they're often clear or yellow. It's not the blood that's bluish, it's the whole vein, including the walls, just like the soft drinks look green because they're in colored bottles.

Have you ever seen a totally white rabbit or mouse? They're called "albinos" because they can't make pigments (the substances that color our eyes, skin, and hair). Their veins look red, even though their blood is the same color as ours. Why is that?

Your blood gets its red color from oxygen.Your blood has this molecule in it called hemoglobin. Hemoglobin is like a little transporter for oxygen. It is used by your body to get oxygen to your muscles. This starts when hemoglobin attaches onto oxygen it gets from your lungs. After that, your heart pumps your blood to your muscles so they can use the oxygen. Then, your blood returns to your lungs so that the hemoglobin can pick up more oxygen.

When oxygen attaches to a hemoglobin, the hemoglobin changes "shape" and it looks "red". After that oxygen is removed by your muscles, the hemoglobin changes "shape" again, and this time it looks "blue". So...when you're looking at your veins and arteries, the ones that look "blue" have blood without oxygen in them. The ones that look "red" have blood with oxygen in them.

The current mythology is that arterial blood and that exposed to the air (bleeding) is red because oxygen binds with the hemoglobin resulting is a red color. Venous blood is "bluish" because it is oxygen depleted which results in a "blue" color. The veins that carry the venous blood are just under the skin hence this is the "blue" blood you see. The arterial blood is carried in the arteries which are deep in the body and not seen through the skin. Also people who are suffocating (oxygen depleted) turn "blue" because the blood at the surface in the skin becomes oxygen depleted and gives the body a bluish cast.

Hope this helps. If I learn more I will pass it on.

You have a good question. The "color" of blood depends on how much oxygen is in the blood; when here is plenty of oxygen, the blood is more "reddish in color. The reason that this is so is because of a protein called HEMOGLOBIN, which carries the oxygen in your blood. When hemoglobin has a full oxygen load, it gives the blood a reddish color. Here are a few questions for you to think about:

1. Why is blood very bright red when you get a cut? (Think about what is in the air).

2. Do you think that blood coming FROM the lungs will be more "red" or more "blue" compared to blood that is coming BACK INTO the lungs?

To simply answer your question, it is because of the science of light. The colors we are able to see is due to the wavelengths of light that go back into our eyes. We look at the veins which are red, but the light that hits our skin that goes back into our eyes for our brain to understand it, is blue to our brain.

Your veins are not actually blue. They are a dark reddish-brown, but appear blue because the fat under our skin only allows blue light to travel all the way down to our veins. Since it is the only color of light that makes it to our veins, it is the only color that is reflected, and thus our veins appear blue! I hope this helps.

Your blood is actually always red! Blood in your veins has very little oxygen and is a dark red color that looks almost blue when covered by your skin. Your arteries have bright red blood because it has a lot of oxygen in it that is being carried throughout your body to be used by tissues. So it is your skin that is tricking you into thinking your blood looks blue when in fact it is always red.

A common answer to this question is that deoxygenated blood in the body is blue and when it comes to the surface (like when you get a cut) it turns red so your veins look blue because your body contains deoxygenated blood. Although it is true that you have deoxygenated blood in your body, it is not the reason why your veins appear blue - your blood is NEVER really actually blue. Deoxygenated blood is dark red and when it comes to the surface it's red.

So back to your question about why your veins don't appear reddish when looking at them from your skin. It depends on a variety of things. One is that the skin usually absorbs blue light; subcutaneous fat, or fat beneath the skin, only allows for blue light to be absorbed all the way to your veins so your veins reflect back that way. Also, since the blood in your body is a lot darker, the veins appear darker. You may also notice that different sized blood vessels appear to be different colors. Another thing it can depend on is how you see color and how your brain perceives certain color against the color of your skin.

If you're ever eaten meat or dissected an animal you can see that veins aren't really blue, they are in fact reddish in color.

A scientist suggested the following link in order for you to learn more about blood vessels and color