Bronchioles are small, tube-like structures in the lungs that branch off from the larger airways called bronchi. They play a crucial role in the respiratory system by directing air to the alveoli, where gas exchange occurs. Bronchioles are lined with smooth muscle and are much narrower than bronchi, allowing for fine control of airflow. These tiny air passages are essential for proper lung function. They can constrict or dilate to regulate airflow based on the body's needs. In conditions like asthma, the bronchioles can become inflamed and narrow, making it difficult to breathe.