The bronchus is the pathway that moves air to and from your lungs. 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.

What causes bronchioles to constrict?

Parasympathetic stimulation causes bronchoconstriction while sympathetic stimulation causes bronchodilation. During an asthma attack, the muscles that encircle the airway tighten or constrict, limiting the flow of air to and from the lungs.

What is bronchoconstriction and bronchodilation?

Physiology. Bronchoconstriction is defined as the narrowing of the airways in the lungs (bronchi and bronchioles). Air flow in air passages can get restricted in three ways: a spasmodic state of the smooth muscles in bronchi and bronchioles. an inflammation in the middle layers of the bronchi and bronchioles.