[beem (OP)]

Both the nosebleed and the blood test vial are fresh blood.

So why is a nosebleed a bright red colour and the vial looks dark purple, like it contains prune juice?

[Chemistry4me]

Hmmm...prune juice [][][]

[Chemistry4me]

On a more serious note:
You mean (the colour of the blood) like the one on the right?

[beem (OP)]

The prune juice merely references my age []

Re the blood colours, it obviously has something to do with oxygen.
A recent nosebleed was a lot lighter in colour than the contents of my blood test vial today.

If oxygen is indeed involved, wouldn't the nosebleed blood be darker than the fresh blood in the vacuumvial?

...it's very good of you to provide...a...er...graphics  [:0]

[Chemistry4me]

Oxygenated blood is scarlet red in colour, deoxygenated blood is dark red.

[Chemistry4me]

What happened at your blood test? I mean, what did they do with your blood?

[Chemistry4me]

...it's very good of you to provide...a...er...graphics  [:0]

But was I correct? Was your blood sample like the one on the right?

[beem (OP)]

Oxygenated blood is scarlet red in colour, deoxygenated blood is dark red

I thought it would've been the reverse.
Yes, the blood sample more closely resembled the colour at right.
Maybe even darker.

Or maybe I'm thinking of rust.   []

What they did with it?
Gee, maybe they're punctuating THEIR forum sentences with it  [] []
Part of annual probe/poke.

[Chemistry4me]

A bust nose will be from an artery(s) so that'll have oxygenated blood (scarlet red), when they took your blood sample it would have been from a vein so it would be darker red in colour.

[beem (OP)]

I still think the noseblood would give them more information, i.e. pollution levels, or whether I have a cat or dog, and so on.

Just a little difficult to give noseblood on command at 8 a.m. in the lab.  [xx(]

[Chemistry4me]

Hmmm... do you get nose bleeds often? Because if you do, you might like to contribute to this thread.

[beem (OP)]

Fortunately, no, I don't.

I'm congratuling myself  []for resisting the urge to ask how you were able to come up with your...er....a...graphics

Cheers!

[chris]

You've pretty much got to the answer.

The nose receives a very rich blood supply and when the nasal mucosa (lining) is traumatised the superficial capillaries supplying the tissue are damaged. The blood that escapes is highly oxygenated, making it look redder.

Venous blood, by comparison, is more deoxygenated because it has already flowed through a capillary bed and released its oxygen to the tissue and picked up carbon dioxide. The reduction in oxygen makes the haemoglobin molecule change shape, affecting the wavelengths of light it reflects causing it to look darker.

Chris

[beem (OP)]

Thanks ever so much!