How do cartilage and glands change from bronchi to bronchioles?

• A. Bronchi have cartilage and submucosal glands; bronchioles lack cartilage and glands.
• B. Bronchioles have cartilage and glands; bronchioles lack cartilage and glands.
• C. Bronchioles have more cartilage than bronchi.
• D. Bronchi are without glands.

Answer: (A)

The main idea is that structural support and mucus production decrease as the airways branch from bronchi to bronchioles. In the larger airways, cartilage in the wall keeps the passage open, and submucosal glands secrete mucus to trap particles and humidify the air. As you get to the bronchioles, that cartilage disappears and the glands in the submucosa are absent, leaving a more flexible, narrow passage whose lining is geared toward regulating flow with smooth muscle and special epithelial cells. This combination—cartilage and glands present in bronchi, absent in bronchioles—best fits how these regions are built to function. The other statements would imply that bronchioles retain cartilage or glands or that bronchi lack glands, which doesn’t align with the actual histology of the conducting airways.