Asthma is a common illness caused by inflammation (redness and swelling) of the bronchi (airways). It may progress and manifest itself in a number of different ways.
The airways are tubes that carry air to the lungs. In asthma, the airways become sore (inflamed) and swollen and produce more secretions than normal.
This inflammation makes muscles surrounding the airways more sensitive (hyper-reactive). As a result, these muscles tend to contract (get smaller) and cause further constriction (narrowing) of the airways (bronchospasm).
Bronchial inflammation and bronchospasm constrict airways, blocking the normal flow of air. This variable narrowing of the airways can cause shortness of breath, coughing, wheezing, tightness of the chest and bronchial secretions.
Not all asthmatics experience the same symptoms, nor are symptoms as intense for each person. Asthma that is well controlled is virtually symptom-free. If a person has serious asthma or is not receiving adequate treatment, symptoms may persist.