Can someone explain this

[anondukie]

“How would our respiratory systems adjust if we moved to higher altitudes where less oxygen is available? First, we would breathe more rapidly to try to avoid hypoxia; second, the binding dynamics of hemoglobin to oxygen would be altered to facilitate the unloading of oxygen at the tissues. As we will discuss in Chapter 7, the natural response of hemoglobin to the decreased carbon dioxide concentration in the environment would actually be to decrease the unloading of oxygen to tissues, so other mechanisms can counteract and override this phenomenon to allow adequate delivery of oxygen.”

^ The bolded portion is a little confusing. Why did they suddenly begin talking about CO2 concentrations in the environment? Is this a typo?

Thanks!

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[cardzkp]

I'm over a year out of biochem and just under a year out of MCAT prep, but I'll give it a shot. CO2, 2-3BPG, H+ and O2 concentrations all make a difference, but CO2 binds allosterically in a way that when bound will destabilize the oxygenated form. A place with higher CO2 concentrations (like respirating tissues) will unload oxygen much easier.

So, I think you're right—I believe it means to ask about oxygen, since higher altitudes = lower [O2]. The partial pressure perhaps is not enough to completely saturate hemoglobin in the lungs, thus other mechanisms must be at play in order to saturate the protein in it's deoxy form.