Figure 3: Diagram showing the airway responsiveness component on the left, the inflammatory/remodeling component on the right, and various ways by which they contribute and interconnect to affect asthma symptoms following exposure to asthma trigger(s). As seen in the diagram, a direct challenge with a spasmogen intervenes upstream, which means that airway responsiveness is affected by many downstream factors. The inflammatory/remodeling component can modify airway responsiveness (positively or negatively) either directly or indirectly by acting at different levels (enumerate 1 to 3 in the diagram) and by affecting both the size and the contractile capacity of ASM tissue. Reprinted and minimally adapted from Pulmonary, Pharmacology & Therapeutics, 26/1, West AR, Syyong HT, Siddiqui S, Pascoe CD, Murphy TM, et al. (2013) Airway contractility and remodeling: Links to asthma symptoms, pages 3-12, Copyright, with permission from Elsevier.