What are the pathophysiologic changes in asthma?

Bronchial hyperresponsiveness (BHR): exaggerated bronchoconstriction due to stimuli, can be determined by PFT, tested also by delivering nebulized methacholine in doubling concentrations till FEV1>20% falls, we see the degree by PC20 (dose to get this fall, if no asthma doesn't reach 16 mg/ml, mild asthma 4-16, modetare 1-4, severe <1) Airway limitation (bronchoconstriction, mucus plugging, wall edema, inflammatory infiltrates, fibrosis, smooth-muscle hypertrophy, elastic recoil uncoupling.