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LostAngeles
9th July 2007, 07:02 PM
I know, it sounds like a no-brainer and I told the kid that yes, I was pretty sure that it can, but he seemed to want to know more of how cold it would have to be and what would happen. I'm rather sure it's not exactly the same as frostbite, but I'm only rather sure. Frostbite, as I understand it, is when the water in your extremities starts to freeze and ice crystals form which, as Alton Brown loves to say, is pretty destructive. But the more I consider that, the more I'm thinking that the water in the blood and not just the water in the cells might also be freezing.

Now I'm not even sure I understand frostbite, but then, I've never been very good when dealing with cells and the finer points of cellular operation.

I figure I should get the student an answer, so tell me, can your blood freeze and how cold would it have to be? What would happen and can you fix it?

As to why I'm discussing frostbite and freezing blood in the midst of July in Los Angeles...

Jeff Corey
9th July 2007, 07:10 PM
Yes. Prick a finger and you can freeze a drop in a freezer, not as fast as tap water,but more like salt water.
If the student meant. "Can it freeze in the body?'
Sure, you can freeze a whole corpsicle. Viz, Howard Hughes.

LostAngeles
9th July 2007, 07:38 PM
Yes. Prick a finger and you can freeze a drop in a freezer, not as fast as tap water,but more like salt water.
If the student meant. "Can it freeze in the body?'
Sure, you can freeze a whole corpsicle. Viz, Howard Hughes.

But what about in an individual part of a still-living body? I think that's what he was really looking for.

Dr. Imago
9th July 2007, 08:11 PM
Well, actually you should be thankful that blood can freeze otherwise modern transfusion practices would grind to a screeching halt.

I don't know if this directly answers your question, but if you froze a finger solid (ie., fourth degree frostbite), amputated it, and then thawed it out, it most certainly would have blood in it. Most of it probably would have been shunted away in the earlier vasoconstriction phases, but certainly some would still be there. Likewise, if someone completely froze to death - and were solid like a popsicle - then their blood would be frozen too. Ask Walt Disney. :D

-Dr. Imago

LostAngeles
9th July 2007, 08:30 PM
Well, actually you should be thankful that blood can freeze otherwise modern transfusion practices would grind to a screeching halt.

I don't know if this directly answers your question, but if you froze a finger solid (ie., fourth degree frostbite), amputated it, and then thawed it out, it most certainly would have blood in it. Most of it probably would have been shunted away in the earlier vasoconstriction phases, but certainly some would still be there. Likewise, if someone completely froze to death - and were solid like a popsicle - then their blood would be frozen too. Ask Walt Disney. :D

-Dr. Imago

Ah! I think I understand!

So is part of the problem with frostbite that blood is being shunted away from the tissue and that the ice crystals are tearing up the tissue? Because I had been under the impression that the problem was the latter.

DRBUZZ0
9th July 2007, 08:55 PM
Ah! I think I understand!

So is part of the problem with frostbite that blood is being shunted away from the tissue and that the ice crystals are tearing up the tissue? Because I had been under the impression that the problem was the latter.

It's both. And actually in theory, if you could freeze something cold enough, but without forming the damaging ice crystals, you could keep the finger and reattach it later. This is something that would be great for organ transplants and there have been experiments with vitrication of tissues. (http://en.wikipedia.org/wiki/Vitrification)

Unfortionately right now there's no way of doing so that doesn't involve using a time consuming process of adding chemicals. As such, it would kill the tissue anyway.

When something freezes, it's not just the blood that freezes, the molecular structure of cells is torn apart. Lymphatic fluid and the fluid inside cells freeze. Redblood cells and platelets are pretty simple, so they could probably get through it okay. I'm not sure if white blood cells can be frozen and not destroyed, but I wouldn't be surprised if they could not.

I'm not sure what the freezing point of blood is, but it is probably less than water, since it has salt and lipids in it.

Cuddles
10th July 2007, 04:24 AM
If blood couldn't freeze, the whole field of cryogenics would look a little silly.

Big Les
10th July 2007, 05:27 AM
If blood couldn't freeze, the whole field of cryogenics would look a little silly.

Only if blood couldn't freeze??!

Rolfe
10th July 2007, 05:43 AM
Red blood cells don't "get through it OK". They rupture, and all the haemoglobin is released free into the plasma. A little of this probably won't have much effect when the circulation gets going again, but a lot would be serious.

If you freeze blood without any preparation, the red cells just disintegrate completely.

Rolfe. Who has tried it. On purpose. Because totally destroyed blood was required for a trick question in an exam.

Ziggurat
10th July 2007, 06:25 AM
If you freeze blood without any preparation, the red cells just disintegrate completely.

I seem to remember something from highschool biology where destroying the red blood cells turns blood from an opaque red to a transparent red. Although I think in the picture, they did it by adding blood to salt water (which didn't do anything - opaque red) and adding it to deionized water (which made the cells swell up and burst - transparent red). But that was a long time ago, so my memory of it could be faulty.

Deetee
10th July 2007, 06:32 AM
Blood freezes, sure enough.
Perhaps your questioner was asking about the figurative origin of the saying: "It made my blood freeze!"

Nancarrow
10th July 2007, 09:22 AM
Rolfe. Who has tried it. On purpose. Because totally destroyed blood was required for a trick question in an exam.

Okay, let's play 'guess what exam'.

I'll start with 'cordon bleu chef'.

joobz
10th July 2007, 09:23 AM
I seem to remember something from highschool biology where destroying the red blood cells turns blood from an opaque red to a transparent red. Although I think in the picture, they did it by adding blood to salt water (which didn't do anything - opaque red) and adding it to deionized water (which made the cells swell up and burst - transparent red). But that was a long time ago, so my memory of it could be faulty.
nope, you're right. It's called hemolysis. And is a first test to determine if a material will be biocompatible (well, if it will be hemocompatible).

Stitch
10th July 2007, 01:22 PM
Stick your arm in liquid nitrogen for a couple of minutes and let me know what you discover :D

Metullus
10th July 2007, 01:39 PM
Stick your arm in liquid nitrogen for a couple of minutes and let me know what you discover :DOkay. Now what do I do?

666
10th July 2007, 02:13 PM
Stick your arm in liquid nitrogen for a couple of minutes and let me know what you discover :D

Okay. Now what do I do?
You continue typing with one hand.

skeptifem
10th July 2007, 02:17 PM
it doesnt seem to take much longer than regular water. ive only had to freeze a few whole blood samples though, most of the stuff that got frozen was serum or plasma.

Metullus
10th July 2007, 02:23 PM
You continue typing with one hand.'kay.

Ben Tilly
10th July 2007, 03:54 PM
Stick your arm in liquid nitrogen for a couple of minutes and let me know what you discover :D

I've actually seen that!

OK, not for a couple of minutes, but still I was watching a demo of cold, and after the usual tricks with showing how fragile frozen flowers, balls, etc are, the demonstrator really quickly dove his hand and arm in then whipped it out and smacked it on the table. It gave a dull "thump". He was obviously uninjured, but it sure didn't sound like I expected.

I think that he did it so fast that all that froze was the outer skin which is dead anyways. I also think that he was crazy to do it at all.

Metullus
10th July 2007, 04:04 PM
Stitch did not say how long so I left my arm in the liquid nitrogen for 42 minutes. It broke off rather neatly just below the shoulder. The doctor says he does not often see this kind of thing. I'm special.

LostAngeles
10th July 2007, 05:27 PM
If blood couldn't freeze, the whole field of cryogenics would look a little silly.

Blood freezes, sure enough.
Perhaps your questioner was asking about the figurative origin of the saying: "It made my blood freeze!"

I guess I wasn't clear. We were discussing cold weather and he asked if it could get so cold, your blood would freeze, as in, say, frostbite, which is what it does turn out to do.

Red blood cells don't "get through it OK". They rupture, and all the haemoglobin is released free into the plasma. A little of this probably won't have much effect when the circulation gets going again, but a lot would be serious.

If you freeze blood without any preparation, the red cells just disintegrate completely.

Rolfe. Who has tried it. On purpose. Because totally destroyed blood was required for a trick question in an exam.

That's really interesting.

Of course, I would have done it just to see what happened (after I did my work properly of course.) :D

L.A. Who possesses the soul of someone who needs to be restrained from finding out what would happen if I did this???...

Cuddles
11th July 2007, 03:58 AM
I've actually seen that!

OK, not for a couple of minutes, but still I was watching a demo of cold, and after the usual tricks with showing how fragile frozen flowers, balls, etc are, the demonstrator really quickly dove his hand and arm in then whipped it out and smacked it on the table. It gave a dull "thump". He was obviously uninjured, but it sure didn't sound like I expected.

I think that he did it so fast that all that froze was the outer skin which is dead anyways. I also think that he was crazy to do it at all.

Nope, nothing froze at all. Heat takes time to transfer, so if you stick your arm in quickly, absolutely nothing will happen. In addition, since the difference in temperature is so great, any nitrogen in contact with your body vapourises instantly and forms an insulating layer between you and the liquid. This effect can be observed by pouring a small amount of water onto a hot hob - the water will form little droplets that skate around for much longer than would be expected because a layer of steam forms that insulates the liquid water from the hot surface.

Liquid nitrogen is only really dangerous if you are in contact with it for several seconds, which can happen if you get it in your clothes which will act as a wick. As long as you ensure the nitrogen only comes into contact with your skin it is actually quite hard to hurt yourself. This makes it especially fun as a demonstration to prospective physics students who don't know what to expect. One of my lecturers used to do an even more impressive one where he would take a sip of liquid nitrogen and then blow smoke out of his nose. This is generally regarded as a bad idea, even by those who play with the stuff, but it does look very cool. Unfortunately, if you swallow it your stomach will explode.

Edit: Incidentally, if you spit in liquid nitrogen it will form a perfect sphere, which can then be thrown at people.

bjornart
11th July 2007, 04:53 AM
If you crash on your bike in cold weather and blood drips from your chin onto the crossbar, it makes light pink frozen splashes.

Rolfe
11th July 2007, 05:24 AM
I seem to remember something from highschool biology where destroying the red blood cells turns blood from an opaque red to a transparent red. Although I think in the picture, they did it by adding blood to salt water (which didn't do anything - opaque red) and adding it to deionized water (which made the cells swell up and burst - transparent red). But that was a long time ago, so my memory of it could be faulty.
Sounds about right.

The effect would be obvious only because you were diluting the blood as well as lysing it, though. Haemolysed whole blood is to all intents and purposes opaque because the concentration of haemoglobin is so high. However there is a very perceptible change in colour and texture.

Rolfe.

skeptifem
11th July 2007, 01:42 PM
I have never heard of the appearance of whole blood being changed by hemolysis. Maybe through a microscope or something, but in general it looks like regular blood until you spin it(the serum or plasma looks pink or red depending on how bad it is). thats been my experience anyway!