Bronchial asthma is a clinical syndrome characterized by increased responsiveness of the tracheobronchial tree to various stimuli. The primary physiological manifestation is variable airway obstruction. Pathologically, asthma is defined as a disorder of the airways characterized by chronic inflammation with infiltration of lymphocytes, eosinophils and mast cells. Asthma has many potential triggers including allergens, infections, pollutants, exercise and emotions.