Which bronchi divide into 2-10 alveolar ducts?

The correct answer is that the respiratory bronchioles divide into 2-10 alveolar ducts. Respiratory bronchioles represent the transition between the conducting and respiratory zones of the respiratory system. While primary or tertiary bronchi are part of the conducting zone and serve to direct airflow, they do not directly give rise to alveolar ducts where gas exchange occurs.

Respiratory bronchioles are characterized by the presence of alveoli, allowing for gas exchange to begin. As they branch out, they give rise to alveolar ducts, which lead to clusters of alveoli. This structure is crucial for efficient gas exchange due to the high surface area provided by the numerous alveoli.

Thus, understanding the structural hierarchy within the respiratory system helps clarify the function and organization of the airways as they transition from conducting functions to respiratory ones, making respiratory bronchioles essential in connecting the air passages to the site of gas exchange in the alveoli.