[dillydogg]

In my thoracic surgery rotations in med school I was taught that the strongest stimulus for increasing the respiratory drive was the acidification of cerebrospinal fluid. Which, of course, correlates with the blood pH. This information comes from some studies in the 60s with goats, and the old guard are happy to hang their hat on it.

There are also chemoreceptors for oxygen concentration in the circulatory system as well.

I think everything you have said is correct, I just wanted to add a few more details for anyone who is interested.