Why are veins blue?

Question

Thanks Jennifer you are getting best answer.

Rach I like your answer too.

Answer 1

In humans and other hemoglobin-using creatures, oxygenated blood is a bright red in its color. Deoxygenated blood is a darker shade of red, which can be seen during blood donation and when venous blood samples are taken. However, due to an optical effect caused by the way in which light penetrates through the skin, veins typically appear blue in color in light-skinned people. This has led to a common misconception that before venous blood is exposed to air it is blue. The appearance of blood as dark blue is a wavelength phenomenon of light, having to do with the reflection of blue light away from the outside of venous tissue if the vein is @ 0.02in deep or more. This is due to the difference in color between deoxyhemoglobin and oxyhemoglobin; the red color ultimately originates from the iron atom in heme. When red blood cells die, the hemoglobin within them is released and broken up: the iron in hemoglobin is salvaged, transported to the bone marrow by a protein called transferrin and used again in the production of new red blood cells; the remainder of the hemoglobin becomes a chemical called bilirubin that is excreted into the bile which is secreted into the intestine, where it gives the feces their characteristic yellow-brown color.

Veins are closer to the surface of the skin and so you are able to see them if you have light skin. Arteries can sometimes be seen in a light-skinned baby.

"Blue blood" in the sense of "aristocracy" is actually a direct translation of the Spanish phrase "sangre azul." The oldest families of Castile in Spain prided themselves on the "purity" of their lineage, believing it never to have been "contaminated" by Moorish, Jewish or other "foreign blood," and as evidence offered the blueness of their veins against their fair complexions. In truth, their blood was the same color as everyone else's, and it was simply the lightness of their skins that made their veins appear blue, but "sangre azul" was taken into English around 1834 as "blue blood" and has been a synonym for "nobility" or "aristocracy" ever since.

Answer 2

Still wrong. Now ... my lifestyle has change I have notice they have become Very Very Blue... I at really badly sugar filled **** before I eat barely any meat and eat lentils and such... I ran I felt so alive it was like being in a constant bliss feeling like whatever I wanted and it did came to me! Now That I am not things in my life are rotten they are decayed and diseased. It has to do with your Mind set and what you do eat that is important you can't go eating junk and think ok I will be this awesome ball of fruitful light and life... Naaa nooo. Doesn't work that way. I know for fact and I have proof that your veins are not meant to be blue... that is a sign of slow blood flow.. I can't say here but once not you're in tune and many things in your life will change but I can't say a whole lot here. Just that don't eat so much red meat... maybe once a week wean off of it get up and out exercises every single day do not stop and you too will see how wrong these doctors and heh hem others are so wrong. I will once again regain this status because it is a state one can never forget.

Answer 3

Because the blood in them only turns red when it has oxidised.
The veins comming from your lungs would be redder than the ones leading back to your lungs.
When you've been cut the blood then has free access to oxygen so then turns bright red.

I had a blood check a while back and when they took the blood into a vacuum syringe it was very dark blue.

Answer 4

Veins are blue because these ones run the oxygenated blood all around the body.

Artries are red becasuse they carry unoxygenated blood around.

Answer 5

Because oxygen is what makes your blood red. Veins carry the blood that is draining away from the heart and lungs. The oxygen in this blood has already been passed into the tissues and organs.

Answer 6

The veins themselves are a kind of unimpressive purpley-greyish colour when drained of blood. The blue colour you see is because of the deoxygenated haemoglobin in them, faded a bit through the layers of skin you usually look at to see them.
Deoxygenated blood itself is more of a dark-purpley colour.

Basically, blood goes through the lung, picks up oxygen.
Oxygen binds to the haemoglobin protein in red cells, causing it to change shape slightly, just enough to change the degree to which it refracts light. Hence, oxygenated blood appears red.
This is what you see in the arteries, then as it goes through the tissues of the body, oxygen is withdrawn from blood as it is used by the tissues becoming blue-purple again.
Veins then drain blood from the body tissues back to the heart via veins hence the veins you see in the skin look blue.

In fact, in strict anatomical terms, a vein is a vessel which drains blood back to the heart whilst and artery is a vessel which drains blood away from the heart.

By this definition, you can argue that venous blood is NOT always blue since the pulmonary ARTERY drains blood from the heart to take it into the lung (so it is deoxygenated blood in this vessel). Then the pulmonary VEIN drains blood back from the lungs to the heart (whilst it is red and oxygenated) and thence it is pumped to the body.

Of course you cannot SEE the pulmonary vein or artery normally so one could are the blood does not "appear" in these parts at all unless you are performing open chest surgery.

Also, you tend not to see arteries from the surface as they are thick walled and often deeply burried beneath skin so you do not see their corresponding red colour. You do however see blood in the capillary bed (which is why skin looks pinkish and someone who has lost a large amount of blood looks white).

Does that answer your question?

Answer 7

Veins appear blue because they carry deoxygenated blood ( back to the heart) which is darker than the bright red oxygen rich blood carried by arteries.

Answer 8

They're not. The veins which appear blue are carrying the de-oxygenated blood, the others are carrying the oxygen rich stuff. Hence the apparent colour difference.

Answer 9

Because those are the veins that don't have oxygen to them. The minute the veins are exposed to the air, the blood from them will come out red. Simple as!

Answer 10

Oxygen, or the lack thereof! The only reason the blood circulates within the blood stream is to gather the oxygen from the lungs and get rid of the carbon dioxide. Ups, I should have said "one" of the only reasons! So, there ya' have it - the veinus blood hasn't made the trip to the lungs as yet and, therefore, the blood hasn't been oxygenated! Blood is always (a type of) "red" in coloration, it's just "redder" after it's trip via the lungs.

Answer 11

Because your blood is blue, Blood turns Red once it comes into contact with Oxygen this is why we only see red blood