Bronchioles are small air passages in the respiratory system that branch off from the bronchi, which in turn stem from the trachea. Their main function is to carry air deep into the lungs, facilitating gas exchange.
As bronchioles become narrower, their walls contain smooth muscle that can contract or relax to control airflow.
This dynamic allows regulation of air distribution and control over the amount of air reaching different parts of the lungs. The bronchioles ultimately lead to tiny air sacs called alveoli, where oxygen is taken up by the bloodstream and carbon dioxide is expelled during exhalation, supporting proper respiratory function.