In a person breathing room air (and with all else being normal), if the alveolar PCO₂ rises from 40 to 70 mm Hg, what would you expect?

Question

Quizplus · Accepted Answer

When the partial pressure of carbon dioxide (PCO2) in the alveoli increases, it displaces oxygen, leading to a decrease in the partial pressure of oxygen (PAO2) in the alveoli. The change in PAO2 is roughly equivalent to the change in PCO2, hence an increase in PCO2 from 40 to 70 mm Hg would cause PAO2 to fall by about 30 mm Hg.

In a Person Breathing Room Air (And with All Else