Pathophysiology of Asthma
Airway inflammation. In those with asthma, cells and tissues within the airway are prone to inflammatory reactions against normally harmless substances. This inflammation can cause swelling, mucous production and lead to airway narrowing (Lemanske 2010). Airway narrowing. Airway narrowing gives rise to asthma symptoms. When the airways are exposed to substances that trigger a reaction, immunoglobulin E (IgE) antibodies produced by B-cells help facilitate the release of inflammatory mediators including histamine and leukotrienes from mast cells. These mediators cause the airway smooth muscles to contract or spasm, triggering airway narrowing (i.e., bronchoconstriction). Sensory nerves in the muscles become more sensitized, contributing to more bronchospasms (Miller 2001).
Airway remodeling. Structural changes in bronchial tubes can occur with chronic and uncontrolled asthma attacks. For instance, epithelial cells (the layer of cells that line the airways and function as a barrier) can shed, allowing irritants or allergens to further penetrate into the inner muscle cells (James 2005; Davies 2009; Campbell 1997). Sensory nerves can also become exposed leading to reflex neural effects on the airways (Kaufman 2011).