There has been some question around the office lately as to the true color of human blood. Some maintain, as I do, that blood is crimson and becomes redder as it oxygenates. Some are convinced of what I believe is an old wives tale, that blood is blue in the body until it mixes with air. We’ve been able to find support for both theories via the wealth of (mis)knowledge called the internet. Can any of you help us shine some light on this subject?
-adam s
sethadam1@hotmail.com
Oxygenated blood, such as when exposed to air and on the way from the lungs) is red. It becomes blueish when the oxygen is removed from it.
That’s what I’ve always been taught as far as I can remember.
I’m not too sure about whether blood gets more crimson as it gets oxygenated (although all the blood I’ve seen in teaching labs has been roughly the same colour…it wasn’t human though)
However I really can’t think of how blood could possibly be blue…the red colour comes from the iron ion in haemoglobin, but there’s no ion in the blood which is blue in colour, AFAIK.
I do remember reading that lobsters / other crustaceans have blue blood, but I think that’s 'cos they have different transport molecule (i.e. not haemoglobin). Anyone else know about this?
One final point; when you refer to the colour of blood, I assume you mean whole blood, like it is in the body. If you separate blood in a centrifuge, you get a red layer (red blood cells), a white layer (white blood cells) and a big straw-coloured layer (plasma).
(I know this is kind of simplified)
This will probably answer your question: