3 Antiasthmatic drugs Why asthma makes it hard to breathe Air enters the respiratory system from the nose and mouth and travels through the bronchial tubes In a non-asthmatic person, In an asthmatic person, the the muscles around th muscles of the bronchial tubes bronchial tubes are relaxed tighten and thicken, and the and the tissue thin air passages become allowing for easy inflamed and mucus. airflow difficult for air to move Inflamed bronchial tube of an asthmatic Normal bronchial tube3. Antiasthmatic drugs