What is the etiology & pathology of asthma in layman terms?

Bronchospasm: The small airways in your lung are lined with muscles which help your body direct air to the right areas of the lung. In asthma these muscles all contract which makes it hard to get air out of the lung. The wheezing is the sound of air rushing thru the narrow passages. There can be many triggers to this event including stress or allergies.

Inflammation: Inflammatory cells enter the lining of the airways in response to a variety of stimuli including allergies, dust, exercise, perfumes, etc. These cells cause the airways to become very sensitive and narrow (bronchoconstriction). As air passes through the narrowed airways you become short of breath or wheeze.

Chronic inflammation: Asthma pathology is ongoing inflammation (swelling, mucus) in the small airways of the lungs, twitchy airways that constrict leading to cough and wheezing. Asthma is more common in people with allergies, children exposed to cigarette smoke, children who had RSV virus, low birth weight preemie infants, certain occupations with chemical/allergen exposure. Exact etiology is still being investigated.