Which three factors determine the difference in bronchial responsiveness between healthy subjects and patients with asthma?
Surely in general both the sensitivity and the reactivity differ between healthy subjects and patients with asthma. However, you have not grasped that the slope of the dose-response curve is the reactivity! Go back to 'Expressing responsiveness' and pay special attention to the animation that appears by clicking on 'Show me' in the right upper illustration.