In the airway pathway, which structure directly precedes the alveoli?

In the airway pathway, which structure directly precedes the alveoli?

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

Answer: (B)

Tracing the airway down to the gas-exchange surface shows that air travels from the trachea into the bronchi, then into progressively smaller passages called bronchioles, which lead directly to the areas where gas exchange occurs—the alveolar sacs. The bronchioles are the last purely conducting airways before air reaches the alveoli, so they are the structure immediately before the alveoli. The other structures are higher up in the pathway: the trachea is the main airway that branches into the bronchi, while the larynx sits above the trachea.

Tracing the airway down to the gas-exchange surface shows that air travels from the trachea into the bronchi, then into progressively smaller passages called bronchioles, which lead directly to the areas where gas exchange occurs—the alveolar sacs. The bronchioles are the last purely conducting airways before air reaches the alveoli, so they are the structure immediately before the alveoli. The other structures are higher up in the pathway: the trachea is the main airway that branches into the bronchi, while the larynx sits above the trachea.