Breathing rate and O2

[super112]

Would a high blood O2 partial pressure decrease breathing rate? I was thinking not b/c only CO2 and H levels can determine breathing rate. I suppose having a higher O2 concentration means a lower CO2 concentration, but even then they're saying that higher O2 concentration DECREASES breathing rate and to me that implies that the O2 caused a difference in breathing rate.

Any thoughts on this?

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[DAT Destroyer]

There are chemoreceptors in the aorta, the carotid body of carotid arteries, and in the medulla oblongata of the brainstem that are sensitive to pH. As carbon dioxide levels increase there is a buildup of carbonic acid, which releases hydrogen ions and lowers pH. Thus, the chemoreceptors do not respond to changes in oxygen levels (which actually change much more slowly), but to pH, which is dependent upon plasma carbon dioxide levels. In other words, CO2 is the driving force for breathing. The receptors in the aorta and the carotid sinus initiate a reflex that immediately stimulates breathing rate and the receptors in the medulla stimulate a sustained increase in breathing until blood pH returns to normal. As CO2 levels decrease......as in the case of increasing O2......think about running and then catching your breathe,,,,,...breathing rate would decrease ...in the sense of responding to CO2 levels.

Hope this helps

Dr. Romano