From: sbharris@ix.netcom.com(Steven B. Harris)
Subject: Re: Colour Of Human Blood....
Date: Tue, 25 Nov 1997
Newsgroups: misc.health.alternative

In <880388410.3480@dejanews.com> sunil@youngindia.com writes:
>
>Dear Netizen,
>
>My name is Sunil and I am an young Business man from India.
>
>My query below may please be answered to -
>
>`The colour of blood flowing through the arteries is red and those
>through the veins blue.

No, actually the "color" of venous blood is rather dark.  There is no
blue tint at all, but just a sort of blackish-muddy look with red, not
blue, undertones (looking at venous blood in the clear plastic return
line of a heart-lung machine, for example).  That venous blood is
"blue" is one of the great myths of our time.


>Why is the colour of the blood which flows
>through the veins bluish ?


   It isn't.  Some veins are quite blue (almost sky blue) when seen in
surgery, but this is not due to the blood, and is seen even in veins
filled with saltwater.  It's a color of the distended vessel wall
itself, and has something to do with collagen or some other protein.



> Also if any vein gets cut the blood which
>comes out is again coloured only red. Why ?'

   In slow bleeds the blood gets exposed to oxygen in the air fast
enough, and is in thin enough layers, to turn red.  Rapid bleeding from
veins really is dark as it runs down the body <g>.  Trust me.   Even
after it pools, rapidly spilled venous blood can still remain quite
dark, right up until it congeals, in the right circumstances.  Much
depends on how thin it gets smeared.

                                     Steve Harris, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med
Subject: Re: blood question
Date: 27 Mar 1999 13:26:27 GMT

In
<5E3B349761A11685.390F2E060574596B.14DCCB871435360A@library-proxy.airne
s.net> jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox) writes:

>Unoxygenated hemoglobin actually is a dark maroon/blue color.

Nah, it's dark maroon.  Look really hard at the tube the next time you
draw blood.  No blue there.   People who think they see blue are the
same people who think that front of US currency is "green."  You have
to make them take it out of their pockets and actually look at it
before they realize that it's not.  There are a few green threads in
there, but green is not the general color of the front of greenbacks
(hence the name).  In deoxygenated blood, the situation is even worse.
There isn't even a hint of blue, but people seem to hallucinate it, due
to what they've been told, and due to looking at vein walls.  I'm
reminded of my childhood, a time when my imagination was so strong I
was sure I could see the color of superman's cape and suit on the
George Reeves TV show.



>  Just
>deprive a neonate of oxygen for a few seconds and watch his lips.


    You're looking at veins.  There's a lot of vein wall blue that gets
hidden by tissues rich in red blood.


>Actually, carboxyhemoglobin refers to hemoglobin bound to carbon
>monoxide, not carbon dioxide.  Carboxyhemoglobin is actually a
>brighter red than oxyhemoglobin.

Yep.  Dead people poisoned with a lot of CO are sometimes quite pink--
far more than you'd expect in somebody unembalmed (embalming fluids are
naturally mostly colored red).  Rubor is a very unreliable sign for CO
poisoning in living people, however, and is almost never seen.
Remember, the unnatural thing about CO color is what DEAD people look
like, not live ones.

From: jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox)
Newsgroups: sci.med
Subject: Re: blood question
Date: Sun, 28 Mar 1999 15:59:13 GMT

On 27 Mar 1999 13:26:27 GMT, sbharris@ix.netcom.com(Steven B. Harris)
wrote:

>In
><5E3B349761A11685.390F2E060574596B.14DCCB871435360A@library-proxy.airne
>s.net> jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox) writes:
>
>>Unoxygenated hemoglobin actually is a dark maroon/blue color.
>
>Nah, it's dark maroon.  Look really hard at the tube the next time you
>draw blood.  No blue there.   People who think they see blue are the
>same people who think that front of US currency is "green."  You have
>to make them take it out of their pockets and actually look at it
>before they realize that it's not.  There are a few green threads in
>there, but green is not the general color of the front of greenbacks
>(hence the name).  In deoxygenated blood, the situation is even worse.
>There isn't even a hint of blue, but people seem to hallucinate it, due
>to what they've been told, and due to looking at vein walls.  I'm
>reminded of my childhood, a time when my imagination was so strong I
>was sure I could see the color of superman's cape and suit on the
>George Reeves TV show.

I did leave it at that ambiguous dark maroon/blue description because
it depends on the oxygen saturation.  When you draw venous blood, and
it's only dark maroon, that is because there is a mixture of
deoxygenated hemoglobin and oxygenated hemoglobin, giving a mixture of
blue and red.  After all, the oxygen saturation of venous blood is no
where near 0%, so there is going to be a red-blue mix, no?

>>Just
>>deprive a neonate of oxygen for a few seconds and watch his lips.
>
>    You're looking at veins.  There's a lot of vein wall blue that gets
>hidden by tissues rich in red blood.

As explained above, I still believe totally deoxygenated blood is
blue.  Empty veins are white.  Extravasated venous blood (bruises) is
blue too, not being seen through vein walls.  And when you compress
vein-less lips and fingernails so that the blood leaves them, they are
white.  So when you aggravate a neonate and he turns blue in the lips
and fingernails, I believe you are seeing blue blood.

But then again, I have some red-green color blindness, so maybe it all
is just dark maroon (which to me is a mixture of red and blue) and I'm
just not seeing the red portion.

--
Jonathan R. Fox, M.D.

From: Steve Harris <sbharris@ix.netcom.com>
Newsgroups: sci.med
Subject: Re: silly question about blood colour
Date: 15 Mar 2005 13:35:56 -0800
Message-ID: <1110922556.944794.210990@z14g2000cwz.googlegroups.com>

Not just by skin. I can tell you from much direct surgical experience
that many isolated veins, not covered witih skin or even vessel sheath,
are quite blue when filled, white when not (so it's not quite true the
veins are blue-- only filled veins are blue). But the blood within them
is indeed dark muddy-red, not blue.

Some of this may have to do with the thinness and structure of veins
and skin, vs the relatively much thicker and more muscular arteries.

Here's something interesting: it's possible for venous blood to be
quite red in a well-oxygenated animal, and yet the veins STILL blue.
For example, I just saw a few drops of blood drawn from an external
vein (probably an external branch of the femoral vein) in the rear leg
of an anesthetized cat breathing 100% oxygen as part of anesthesia. The
small blood sample (0.2 mL) was taken for antibody/virus testing. Such
blood samples from this area are generally dark when taken from cats
breathing normal 21% oxygen air, but in a very-well-oxygenated resting
cat, such venous blood may be quite red-- nearly as bright red as
arterial blood. Yet the vein it comes from, remains blue anyway!  In
this case, albeit seen through skin.

The cognoscenti may wonder how it is that venous pO2 at all when 100%
O2 is breathed, since oxygen content of arterial blood doesn't go up
that much. But there's some normal A-V shunting in the drainage of the
heart and lungs which affects venous pO2, and also there's a lot of
shunting in resting muscle, such as in a limb. Anesthetics affect
shunting also. So not all venous blood has been though a capillary bed.

SBH

From: Steve Harris <sbharris@ix.netcom.com>
Newsgroups: sci.med
Subject: Re: silly question about blood colour
Date: 15 Mar 2005 19:26:02 -0800
Message-ID: <1110943562.411481.38020@f14g2000cwb.googlegroups.com>

Thank you.

This is a bit like the people who believe that the printing on the
front side of an American $1 bill, is green. They'll insist on this,
right up the act of taking it out and looking at it. It's not green.
The green is mostly on the backside. There are a few green letters on
the front, and a very muted greenish background for the paper.
Basically, however, most of the print on the front, is simply
black.That's kind of the way it is with blood. People see what they
expect to.

The bark of most trees in a temperate climate isn't brown, either. Go
out and look.

SBH