The bronchioles carry air from the bronchial tubes to the ____________.

The bronchioles carry air from the bronchial tubes to the ____________.

• A. Alveoli
• B. Larynx
• C. Pharynx
• D. Trachea

Answer: (A)

Air travels from the larger airways into progressively smaller passages until it reaches the alveoli, tiny sacs where gas exchange occurs. The walls of the alveoli are extremely thin and surrounded by a dense network of capillaries, which lets oxygen diffuse into the blood and carbon dioxide diffuse out to be exhaled. The bronchioles are the last airways before this exchange surface, so their job is to deliver air right to the alveoli. The other structures are parts of the airway system that don’t participate directly in gas exchange: the larynx is at the top and houses the vocal cords, the pharynx is the throat region, and the trachea is the main windpipe leading to the bronchi. Therefore, the correct completion is alveoli.

Air travels from the larger airways into progressively smaller passages until it reaches the alveoli, tiny sacs where gas exchange occurs. The walls of the alveoli are extremely thin and surrounded by a dense network of capillaries, which lets oxygen diffuse into the blood and carbon dioxide diffuse out to be exhaled. The bronchioles are the last airways before this exchange surface, so their job is to deliver air right to the alveoli. The other structures are parts of the airway system that don’t participate directly in gas exchange: the larynx is at the top and houses the vocal cords, the pharynx is the throat region, and the trachea is the main windpipe leading to the bronchi. Therefore, the correct completion is alveoli.