Why is blood red?

[poeima]

Why is blood red?

[ykkp]

I believe it's because of the iron in blood and oxygen.

[j2buttonsw]

it is the haem in haemoglobin

[shaun_04]

It is the colour that the Iron in the Haemoglobin turns when it rusts (oxidises). Producing Iron Oxide (common rust).

[alvin100]

blood is actually blue in the body, which is why you can see blue veins under your skin, It turns red on contact with air.

[Ausf-A]

alvin100, either you were smoking crack during Biology lessons, or you're a member of the royal family.

[oldhamfan]

hahahahaaa

[remesses]

the metal that our blood uses is iron, iron has a tendancy to to form redish looking compounds when oxidised,
no to through a spanner in the works, octopi have a copper based molecule that carries oxygen as opposed to our iron bassed hemeglobin...so infact an octopus's blood is pale blue...
so to finally answer your question it's the metal in our blood which determines it's colour
if our blood utelised potassium we would have purple blood just hypothetically :-)

[pleasehelpme]

http://en.wikipedia.org/wiki/Blood#Color

click the link for utter clarity.

[shaun_04]

I assure you J2, I am not full of ****.

[matt66]

Blood is coloured red because the ingredients in blood absorb all the other wavelengths in the colour spectrum except red. hence you can see red. This applies to all colours that you see. the sky is blue because the atmosphere absorbs all colours of the spectrum except blue.

[mycats]

oooh alvin100 !! I was sooo hoping that nobody was gonna give that reply! I swear that is the third time I have seen someone on AB say that! It makes me groan everytime, how can people really think that?

[crete]

red strange , mine is blue

[stevie21]

Can you imagine getting embarrassed or flushed and your face goes blue!???

[jaffacake]

Red corpuscles contain haemaglobin which gives bllod its red colour.Arteries have dark red blood and veins bright red.

[Pebbilita]

i know i'm a bit late.... but does it have something to do with porphyrin in the haemoglobin that gives it the red pigment?