Smallest branches of the bronchi are called which of the following?

• A. Trachea
• B. Bronchi
• C. Alveoli
• D. Bronchioles

Answer: (D)

The branching of the airways progresses from the trachea to the main bronchi, then to smaller bronchi, and finally to the bronchioles. The smallest subdivisions of this bronchi system are the bronchioles. They are smaller than the bronchi, lack cartilage in their walls, and lead further to the alveolar sacs where gas exchange occurs. Bronchioles play a key role in regulating airflow through smooth muscle constriction and dilation. Alveoli are air sacs for gas exchange at the end of the airway tree, not branches themselves, and the trachea is the main windpipe before the bronchi.