Why do veins look blue under the skin look blue?

even though unoxygenated blood is in fact a dark red color?
Why do veins look blue under the skin look blue?
The blood in your veins is called venous blood.





What colour is venous blood?





When the haemoglobin in your blood combines with oxygen it turns bright red. When it loses oxygen it turns dark red. It may be described as dark crimson which reflects some blue but not enough to make it look blue or purple.





I have taken blood samples from veins many times and have donated blood many times and it always comes out of the vein as a very dark red colour. I have seen many blood agar plates kept in conditions where there is no oxygen--and the plates are dark red. I have taken blood with a vacuum syringe which contains no air at all. I have never seen the blood inside the syringe look blue.





Some people think that blood comes out of the vein and immediately turns red because it comes into contact with oxygen. When you watch blood coming out of your arm into a transparent tube, you realise that it is not contacting oxygen and it is a very dark red. In low light it almost looks black. When I first saw a bag of blood at the Red Cross I didn't recognise it at first because it was so dark red.





So why does the dark red blood look blue when it is in the veins? Veins are white, so the colour of the veins is not the reason.





It's because the light from the sun and light globes, etc is made up of many different colours and these are absorbed at different rates the deeper you go through the skin.





It's like what happens underwater...





I have been scuba diving and the deeper you go the less red you see unless you take a light with you. Everything looks blue, green or black. The water is absorbing the red end of the spectrum so that only blue light remains to be reflected. When you look into a deep swiming pool with a white bottom, it appears blue. Apparently skin does the same thing to the light. The deeper under the skin you go the bluer things look.





Then why does the skin of pale-skinned people turn red when they blush or become flushed? The tiny capillaries which carry the blood are so close to the surface of the skin that none of the red colour is filtered out.





But the blood in the veins which are a little further in under the skin look blue. Although it is really dark red!
Why do veins look blue under the skin look blue?
pigment from / light absorption of the skin and lack of oxygen in vein.
Reply:viens are typically all different colors, some red, some grey, others green. I believe it is the mixture of the blood showing under the green vein creating the bluish green color
Reply:Actually, unoxengenated blood is blue and once it reached air it turns red. So through your skin the bloods pumping and the veins are blue....
Reply:veins carry blood w/out oxygen back to the heart. arteries carried oxygenated blood to the body. blood w/out oxygen is blue; it become dark red when oxygen is introduced like from a cut or blood draw.
Reply:Arteries pump oxygenated blood, and veins pump unoxygenated blood. Blood with no 02 is blue, blood with 02 is red.
Reply:I am assuming you are light skinned. Your skin plus the burgundy color of the skin makes the blue-green tint that you see. Take away the skin and the blood is normal color so the only choice is the skin.
Reply:It's because the deep red color of the blood plus the color of the blood vessel and the color of your fat and skin tissue all mixed together, forming the nice bluish purplish color. Arteries appear almost the same way. Even the blood vessels in umbilical cords look the same. BTW, there is a bit of color difference in the blood in veins vs. arteries. Arterial blood is much deeper red because it is oxygenated.