Asthma is a chronic lung disease that mainly affects the bronchial tubes by blocking airflow through them. During an asthma attack, the tubes become inflamed and obstructed, and the air sacs become enlarged. (See Diagram 1)
Bronchial tube obstruction may occur because of one or more of the following changes: (See Diagram 2) Inflammation: Lining of the tubes becomes inflamed (irritated) and swollen Bronchospasm: Smooth muscles surrounding the bronchial tubes constrict (narrow) Mucus production: Mucus builds up in the tubes, and it may plug them completely
