[neilep (OP)]

Now I find this hard to believe but I heard on the radio that the veins you see in your arms, wrists etc are blue cos the blood is, and that it's only when the blood is oxygenised , ie: in contact with the air that it turns red !!!...it's a load of bull yes ?...or not ?

Your bloody answers will be most helpful.[]

'Men are the same as women...just inside out !'  

[MooseHole]

Yes, definately.  When you're bleeding, the blood comes in contact with a lot of oxygen, so it turns red.  Blood is mainly used for distribution of oxygen throughout the body.

[neilep (OP)]

seriously ?...really ?...I do believe you but never knew that....then why when I shine a torch through my fingerprints does it appear red ?.........I'm truly stunned though....thanks for the answer Moosehole and the stunning that it caused !

'Men are the same as women...just inside out !'  

[Ylide]

Arterial blood is oxygenized, therefore red.  In your fingertips, there are capillaries that get all the blood to your tissues, much of this blood is oxygenated (all your cells need oxygen) and that's what you see when your shine a light through them.



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[neilep (OP)]

quote:Originally posted by cannabinoid

Arterial blood is oxygenized, therefore red.  In your fingertips, there are capillaries that get all the blood to your tissues, much of this blood is oxygenated (all your cells need oxygen) and that's what you see when your shine a light through them.



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Thanks for clearing that up

'Men are the same as women...just inside out !'  

[Rokitansky]

I would say it is more dark-red when it is not oxigenated, or blue-red.

By the way, Neil, where do you find all this crazy smily-pictures, that explode, fart and puke... I started to collect them (those you left) and I already have about 25 !

[bezoar]

I'm just going to apply a little common sense here.  When I draw blood on my patients, I draw into a vacutainter, which is a test tube with a vacuum.  Assuming that the vacuum has little air in it, the blood is still dark red, so I guess it's really dark red in your body too, but looks blue because of skin pigment colors that combined with the dark red appear blue.

[chris]

There is more to this story than merely the colour of the blood when it is deoxygenated.

Blood is a beautiful rich red colour because it contains haemoglobin, the protein which carries oxygen from the lungs to the tissues. Haemoglobin is actually 4 proteins stuck together, known as a tetramer, comprising 2 alpha-haemoglobin and 2 beta-haemoglobin molecules, each with an iron ion (Fe 2+) at the centre. It is this iron which gives haemoglobin its colour.

Each molecule of haemoglobin can bind 4 molecules of oxygen and when the oxygen unites with the haemoglobin it changes its shape and its light absorbency so that it reflects more red light. Thus arterial blood, as outlined above, looks much redder than venous blood. In hospital we occasionally perform arterial blood collections in order to see how much oxygen is in the blood from which we can infer how effectively the lungs are working. In a well-oxygenated person the blood is a bright brick red. If the person is very short of oxygen, or if you miss the artery and instead collect the sample from an adjacent vein, the blood appears much darker and is a red-black maroon colour...but not blue.

So whilst it seems reasonable to assume that the colour of veins is partly down to the colour of blood that they contain, that's not the whole story, because superficial veins (those just below the skin surface) don't look blue at all. Anyone with 'thread veins' on their legs or face knows only too well that they are red. So what's going on there ?

The answer is that the apparent blue colour of veins is actually down to the skin. Blue light penetrates more deeply into the skin than red lights - that's why shining a torch into your finger produces a red glow - because all of the red light is being bounced about and absorbed by the superficial layers. The light that reaches the veins and is reflected back for you to see is blue. Hence larger, deep veins look blue. Superficial veins look red because they are closer to the skin surface and hence are illuminated by light containing more red wavelengths.

As an aside, some animals, including lobsters, crabs, shrimps, and other crustacea, genuinely do have blue blood and that's because they use copper, instead of iron, in their equivalent of haemoglobin, a protein called haemocyanin. In these animals the blood is blue when it is oxygenated and gradually loses its colour as the oxygen is removed.

The hippies of the haemoglobin world are definitely the brachiopods, sipunculids, priapulids and Magelona (a type of worm). These animals have a blood pigment called hemerythrin which is a bright violet pink when it is charged with oxygen !

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[neilep (OP)]

WOW !!...well I just wish we could choose the colour of our blood at will to suit our mood...that would make for cool effects when bleeding !!

'Men are the same as women...just inside out !'  

[qazibasit]

actually blood becomes blue when the oxygen is combined with heamoglobin which is an iron compound and as iron is a transition element and when transition element goes oxidized coloured compound is formed and thus when oxygen combines with haemoglobin it forms a red coloured compound oxy-haemoglobin and thats why the blood is red and the deoxygenated blood which have small amount of carbondioxide is not reb and is blue because of the change in oxidation number.

[chris]

Gazibasit - have you actually read the answer I have given above ? If what you are saying were true than superficial (thread) veins would look blue, not red !

The oxidation status of the iron ion does not change when haemoglobin binds oxygen. Why should it ?

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[qazibasit]

it should coz it forms a dative bond with oxygen chris.

[Exodus]

quote:Originally posted by chris
 superficial (thread) veins would look blue, not red !

Cool, imagine what Brian Clough's face would look like!!!

[Exodus]

quote:Originally posted by qazibasit

it should coz it forms a dative bond with oxygen chris.

I'm sorry Gazi, but i have never come across an oxidation state of iron that is blue! You need to start looking at complex ions for that! What Christopher has written is correct.

[qazibasit]

i think i have to read the BLOOD chapter again and this time from Gyton or Ganong.

[qazibasit]

well blood is not blue it is due to cyanosis that we get blueness skin in different places which is due to the increase in de-oxy Hb level.

[chris]

Yes, I think that the stated figure is 15g of deoxygenated haemoglobin per decilitre to produce cyanosis.

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx