Bronchiole

Overview
The bronchioles are the first airway branches that no longer contain cartilage. They are branches of the bronchi, and are smaller than one millimeter in diameter.

There are no glands or cartilage in any of the bronchioles, and the epithelial cells become more cuboidal in shape.

The bronchioles terminate by entering the circular sacs called alveoli.

Control of airflow resistance and air distrubution in the lungs is controlled by the bronchioles.

Pathology
Bronchospasm, a life-threatening situation, occurs when the smooth muscular tissue of the bronchioles constricts, severely narrowing their diameter. Bronchospasm is commonly treated by oxygen therapy and bronchodilators.

The medical condition of inflammation of the bronchioles is termed bronchiolitis. Diseases of the bronchioles include asthma, bronchiolitis obliterans, respiratory syncytial virus infection, and influenza.