The bronchioles are small tubes in the lungs that branch off from the bronchi and are responsible for delivering air to a network of around 300 million alveoli in the lungs. The bronchioles are one of the smallest airways in the respiratory tract and lead directly to the alveolar ducts, which house the alveoli responsible for exchanging gases with the blood. The bronchioles are lined with smooth muscle and elastic fibers to maintain their wall integrity and control airflow through contraction and dilation of the airway. The bronchioles also contain cilia, which help move mucus and particles out of the lungs. The function of the bronchioles is to carry oxygen-rich air into the lungs and carry carbon dioxide-rich air out of the lungs, thereby aiding in the respiratory process. The bronchioles work with the respiratory system to help us breathe, and they are an essential part of the respiratory system.