When Does Bronchoconstriction Occur?

This muscle contraction causes the bronchus to narrow and restrict the amount of air passing into and out of your lungs. Bronchoconstriction usually occurs in asthma, emphysema, and other lung diseases. However, bronchoconstriction can also happen to those without any lung disease during intense exercise.

What triggers bronchoconstriction?

Causes. The process of bronchoconstriction starts when something triggers the muscles along the airways to tighten. This squeezes the bronchi and bronchioles, which narrows your airway. In susceptible people, a variety of stimuli in the airway can cause tightening.

When does bronchodilation occur?

Smooth muscle contraction leads to bronchoconstriction (decrease in the diameter of the bronchioles) while smooth muscle relaxation leads to bronchodilation (increase in the diameter of the bronchioles). Parasympathetic stimulation causes bronchoconstriction while sympathetic stimulation causes bronchodilation.