Asthma is a chronic respiratory condition that affects the air passages (bronchi) of the lungs. Its hallmark feature is acute bronchoconstriction, which leads to airflow limitation and typical symptoms such as wheezing, coughing, and chest tightness. Individuals with asthma have inflamed airways, making them extra sensitive to various triggers that can induce bronchoconstriction and provoke asthma symptoms.
When air is inhaled, it passes through the nose for warming, filtering, and humidification before traveling down the windpipe (trachea) into the two main tubes known as the right and left bronchi, formed by the tracheal division. These bronchi further branch into smaller tubes within the lungs called bronchioles. Both the large and small bronchi are commonly affected in asthma.
In asthma, exposure to irritants or trigger factors causes constriction and inflammation of the small airways in the lungs. This narrowing and swelling make breathing difficult for affected individuals. Importantly, asthma is a chronic condition, and lung inflammation persists even during symptom-free periods. Asthma can flare up unpredictably in individuals with inflamed airways or when exposed to triggers.
Asthma can be categorized into two main types:
- Allergic asthma: This type is more prevalent in children and adolescents but can develop in adults as well. Acute asthma attacks in allergic asthma are triggered by exposure to allergens to which the person is sensitized.
- Non-allergic asthma: More common in middle-aged adults, non-allergic asthma is triggered by factors such as exercise, cold air, and respiratory infections, rather than allergens.