What is asthma?In asthma, exposure to particular triggers cause the airways to narrow too much and too easily, making it difficult to breathe.

Airways don’t narrow

Nonasthmatic

Airways narrow

Asthmatic Common triggers are: allergens pollens, pets & moulds

respiratory infections colds & flu

exercise certain medicines aspirin

irritants smoke

extreme emotions

Importantly, these triggers do not cause airway narrowing in people that don’t have asthma.

AsthmaticNonasthmatic

Airway narrowing in asthmaAirway narrowing ( internal diameter of airway) is usually caused by variable combinations of:

contraction of the airway smooth muscle that surrounds the airways (bronchoconstriction)

inflammation of the airways (e.g. thickened airway wall, hypersecretion of mucous into the airway

lumen).

Narrowed airway

Normal airway

Airway narrowing induces asthma symptoms

In asthma, exposure to triggers causes airway narrowing.

Excessive airway narrowing produces symptoms of

shortness of breath (dyspnea),Listen carefully to the audio clips below. “Is it more

difficult for the person with asthma to breathe in or breathe out?”

wheezing ‘whistling sound made as air passes through a

narrowed airway’

cough

chest tightness