Asthma is a chronic disease that affects the air passages (bronchi) of the lungs. The characteristic feature of asthma is acute broncho-constriction which causes airflow limitation and the symptoms of asthma such as wheezing, coughing and chest tightness. The airways in asthmatics are inflamed and this makes the airways extra-sensitive to a number of different trigger factors that can cause broncho-constriction and introduce asthma symptoms.
When you breathe in, the air passes through the nose where it is warmed, filtered, and humidified. It then passes through the windpipe (or the trachea) to the two large tubes called the right bronchus and the left bronchus (these are formed by division of the trachea). The bronchus divide into several much smaller tubes in the lungs called bronchi and bronchioles. The small and large bronchi are generally affected in asthma.
In a person with asthma the small airways in the lung become constricted and more inflamed when exposed to an irritant or trigger factor. The narrowing and swelling of the airways makes it very difficult for the person to breathe. Asthma is a chronic disorder and the inflammation in the lungs persists even when an asthmatic person does not have symptoms for a long time. Asthma can flare up at any time in a person who has inflamed airways or when he is exposed to a trigger factor.
Asthma can be categorised as Allergic asthma and Non-allergic asthma