During an asthma attack smooth muscles located in the bronchioles of the lung constrict and decrease the flow of air in the airways. The amount of air flow can further be decreased by inflammation or excess mucus secretion.
Review Date 5/20/2018
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.