2 replies to this topic

[katfagan]

I am working on a medical product involving a balloon inflated in a blood vessel. This balloon is made of latex so there is significant permeability through the latex. We have performed bench testing in the past that substituted water for the blood. Of course, this has caused a discrepancy between the in body data and bench data. Could someone tell me the difference in the solubilityof CO2 in blood versus distilled water?

thanks

[MrShorty]

It's been a long time, but I majored in biology as an undergraduate. I recall that a significant portion of one section of my physiology class was dedicated to how blood transports CO2. I can't remember specifics, but I recall that there was a significant amount of bicarbonate in the blood, not only to transport CO2, but the body also uses bicarbonate as a buffer to regulate blood pH. I don't remember details, but I'm certain the chemistry of the blood is a lot more complicated than the chemistry of CO2 dissolving into distilled water.

As common as undergraduate physiology classes are, I would bet that a Google (or whatever your favorite search engine is) search should be able to find some professor's class notes or study guides on-line where you could learn a little bit about the chemistry of the blood. If you have access to a good library, you could probably also find that kind of information in a physiology textbook.

[Adriaan]

The hemoglobin in the red bloodcells binds gasses to its surface; the CO2 binding is stronger than the oxygen binding (CO is a MUCH stronger binding). I would not call this process DISSOLVING of carbon dioxide really...

Another issue is blood temperature; blood does indeed have a pH buffering capacity but this only works under normal conditions (it is the reason why a high fever can kill you; the blood goes acidic at temperatures over 41 'C or so because the buffering mechanism fails). I rather expect that a sufficient increase in CO2 causes acidity (buffering) problems too, though suffocation is a much more immediate problem in that case.