Does venous blood in the tissues contain more or less carbon dioxide than arterial blood?

Answer 1

It depends on how you look at it.

Hemoglobin doesn't JUST carry oxygen. If it hasn't got any oxygen, then it can carry a proton and carbonate instead. Dissolved carbon dioxide can react with water and turn into these things... hemoglobin picking up those products tends to deplete the end products and draw more carbon dioxide into that kind of reaction. (In the lungs, an oxygen sticks to the molecule, the carbonate is released, and the reverse reaction happens in spades... handy!)

So on the one hand, there's a lot less. It's being sucked up into alternate molecules by hemoglobin. On the other hand, there's probably more overall if you include those alternate forms.

Depends on whether you're referring to the presence of that molecule specfically or the overall carried amount.

Answer 2

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