If the blood is red, why the veins appear blue?

@alinka (184)
Greece
March 6, 2010 12:10pm CST
I was having a conversation with a friend about this topic and my friend definitely belived that the color of blood when is not in contact with oxygen ,is blue.That made me very curious and I made some searches on google,looking for an answer. I found out that the human blood is red,more exact,dark red in its deoxygenated form and a bright red in its oxygenated form.The veins appear blue because the light,that penetrates the skin,is absorbed and reflected back to the eye.This is the affirmation of a phlebotomist(person who draws blood). A medical doctor says that when the blood is oxygenated in the lungs it is red,but when blood gives up oxygen to different parts of the body it becomes blue(the veins that take blood back to the lungs and heart,which are near the surface of the skin).What i belive is that we see color due to the reflection and absorption of light(which at different wavelengths appear as different colors)When light hits your skin ,certain wavelengths(colors) are absorbed and others are reflected back to your eyes.For the bloods color,most wavelengths dont have enough energy,after hitting your skin,to be reflected back...besides the blue wavelength.That's what makes the human blood look blue. What do you thing?What's your opinion ?
11 responses
• United States
6 Mar 10
I always thought that our blood was indeed blue and when oxygen hits blood it turns red. After reading what you had to say now I am not sure. I would have to research this a little before knowing the real answer. I was always told the above of what I just stated so know I am not for sure. Nice topic and happy mylotting to you.
@alinka (184)
• Greece
6 Mar 10
Thank you,momtrying2makeit.
@primeaque86 (8112)
• Philippines
6 Mar 10
Hi my friend... I think I am afraid to give my opinion but I want to give you a link: http://www.imt.liu.se//edu/courses/TBMT36/pdf/blue.pdf
• Philippines
6 Mar 10
I hope it could add to the searches you made...
@alinka (184)
• Greece
6 Mar 10
THX,primeaque86.Have a great day!
@savypat (20246)
• United States
6 Mar 10
I thought I knew, but now am totally confused. It seems like it should be an easy question but I guess not. The only time I see my blood is due to injury so oxygen has come in contact with it or when they take a blood draw and even then oxygen has come in contact. My veins appear blue or green. Bottome line I just don't know
@alinka (184)
• Greece
6 Mar 10
It's amazing how a simple question like this can have a confusing answer.Due to my knowledge from high school the blood is red...because...is blood...lol.But it seams that is not that simple.If any of you find out a different theory about the bloods color i would be glad to hear it.THX,savypat,for posting.
@cupkitties (7175)
• United States
7 Mar 10
Blood is never ever blue ya'll. I'm just saying..That whole thing with the oxygen and what not is a myth. Do some research or ask a doctor.They'll tell you.
• China
7 Mar 10
The blood is dark red in the vein with less oxygen. The medical doctor is right. When the blood is oxygenated in the lungs it is bright red. Coz the blood is dark red so it looks like it's blue or green in the light. And the color turn from dark red into blue or green is something about the wavelength. hope you healthy!
@sknsknskn (393)
• India
7 Mar 10
When blood is oxygenated in the lungs, it is red. This red, oxygenated blood is pumped by the heart through arteries to different parts of the body. You can't see these arteries, because they are deeper inside the body. When blood gives up oxygen to the different parts of the body, it becomes blue. The veins take blood back to the heart and lungs. They are near the surface of the skin, so you can see them.
• India
7 Mar 10
Well you have given quite a technical overview of the situation. What i know is that the color of the blood is always red no matter what the case might be ... (i have never seen someone with blue blood). I would like to believe that the color of the blood does vary in the intensity of the color it or the darkness of the red color.. so when the blood gets de oxygenated then the blood is very close to the Dark red color. and maybe the veins are blue blue in color so we get to see the blue color from outside. so i guess that wold be you first theory of light reflection and absorption of wavelengths by the human skin..
@kaylachan (4776)
• Daytona Beach, Florida
7 Mar 10
Red blood cells are responsible for giving blood its red color. This is done usually after the oxygenation process. And, due to its dark contrasting nature can appear black. As for the vaines I can see they almost looked a bit greenish to me, but the vain against the skin is mearly a shell for the blood flowing through it. But, light in various forms is the source of all vision. so that can be inturpted how you like.
@cupkitties (7175)
• United States
7 Mar 10
Veins are not blue during surgery when they are exposed. I think maybe the blue color you see them as underneath the skin has something to do with how the light reflects from the blood.
@redhotpogo (4398)
• United States
6 Mar 10
wavelengths, and zeptune rays wtf. I'm not a doctor, but i think that your veins are blue. Not sure that you can actually see the blood running through them. That would be creepy. or maybe a little cool.
• India
6 Mar 10
The reason why only veins appear blue is that veins are the only vessels we actually observe through the skin. This is due to the fact that veins are larger, have thinner walls, and are more superficial than arteries . All of these aspects of veins have clear biological rationales. Beyond just carrying blood back to the heart, the primary function of the venous system is as a blood reservoir. In fact, about two-thirds of your blood volume is held in your veins at any given time, hence their larger size. Because the heart has to push blood directly through arteries, their walls are subject to higher pressures than the walls of veins, so they need to be thicker. Finally, veins are located closer to the surface of the skin, because they also play an important role in heat exchange with the outside environment (to help cool the body). Arteries could perform this function just as well, but it's much more advantageous to keep those higher pressure blood conduits deeper in the body and protected from injury. The take-home message here is that the bluish appearance of veins in the skin has everything to do with where they are located, and nothing to do with the concentration of oxygen within them. In fact, if we could see them through the skin as well, even arteries would look blue.