Colors of blood vessels

[hurly]

Lack of oxygen causes bluecolored skin.
Capillary vessels are see-through because they don't have muscles.

Why are the big vessels on your hand blue-colored? Same reason as above? Lack of oxygen? Wouldn't our hand be pretty much dead?
Also, are blood vessels mainly red or is it the red blood cells that makes up the red color?

[zenith_beth]

Mmmm interesting... I'm not sure about this but perhaps the blue-coloured vessels are veins, which carry blood which has lost much of its oxygen and which is a dull, brownish-red. In such a case you would be right because they would be blue-coloured because of the lack of oxygen.

[Morris]

I don't know if blood vessel with a lack of oxigen have less red blood cells; I know that pepple with genetic defects in which emoglobin's eme is oxidated have less oxigen bound to eme e for it they are bluecolored. The color I think depends by emoglobin.
Hands heve veins and arteries: veins usually have blood without oxigenand they're blue; hands have arteries to that have red blood cells with oxigen and for it they're red.
Blood vessels I think aren0t coloured by the numeber of cells, but by the density of oxigen they have.

[Dr.Stein]

Vessels are colorless, it is blood (corpuscles and plasma) that gives their color

[hurly]

Nobody has yet answered me why we have blue colored vessels in our hands...

All bloodvessels carries oxygen, don't they?

[biostudent84]

All bloodvessels carries oxygen, don't they?

Yes. Oxygenated blood carries between 100 and 95 mmHg of oxygen. Deoxygenated blood carries about 40 mmHg of oxygen.

[Dr.Stein]

Nobody has yet answered me why we have blue colored vessels in our hands...

If veins carry dark red blood, and the vessels themselves are transparent, why is it that in the arms, hands, and legs of fair-skinned people they nonetheless look blue? After carefully studying how light travels through skin, some Canadian researchers have come up with a surprisingly simple answer to this commonly asked question.

Lothar Lilge, a physicist at the Photonics Research Ontario in Toronto, and his colleagues approached the problem by setting up a simulated version of blood vessels near the skin's surface. They filled glass tubes of varying sizes with blood and immersed them in a milk-like fatty fluid that was chemically very similar to light-colored skin in the way it transmits and reflects light. As they lowered the tubes into the fluid, the tubes gradually changed color. "Right at the surface, they look red," says Lilge. "But when you start lowering them down, the tubes look really nicely blue."

Why the color change? Lilge's group used a camera and various light filters to measure how the milky liquid and the glass-enclosed blood absorbed light of different wavelengths. When not immersed in the fluid, the blood in the glass tubes absorbed almost all light, although it did reflect some red light, which, of course, is why blood outside our bodies appears red.

But when surrounded by fluid--or, presumably, skin tissue--it becomes blood of a different color. Fair skin normally reflects most of the light that hits it. Longer, redder wavelengths, though, can penetrate more deeply into the skin than shorter, bluer wavelengths before reflecting out. A vein looks blue because red light travels far enough into the skin to be absorbed by the blood in the vein. If the blood vessel is far enough below the skin, however, blue light--which would normally also be absorbed by the vein--reflects out of the skin before reaching the vein. So the light reflecting from tissue over the vein contains less red light than blue, giving the vein a bluish cast.

Lilge found that for a vein to look blue, it has to be at least .02 inch below the surface, which explains why fair-skinned people look pink and not blue when they blush. The small surface capillaries that become engorged during blushing lie just a thousandth of an inch below the skin's surface. Past about .08 inch, light can't penetrate, and blood courses unseen.

[hurly]

Thanks Dr. Stein

[123Herpatology]

This makes a lot of sense because when someone is very cold (like if you went swimming in a cold pool) you're lips turn bluish/purple...