What components make up the lower respiratory tract?

• A. Nose, nasal cavity, and pharynx
• B. Trachea, bronchi, bronchioles, and alveoli
• C. Sinuses and larynx
• D. Lungs and diaphragm

Answer: (B)

The lower respiratory tract includes the airways and gas‑exchange units below the larynx, responsible for moving air into the lungs and exchanging gases. The trachea serves as the main passage from the larynx to the lungs, then divides into the bronchi, which branch into bronchioles. The bronchioles lead to the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses out. Structures such as the nose, nasal cavity, and pharynx are considered part of the upper airway, serving to filter and condition air before it reaches the lower tract. The diaphragm is a breathing muscle, not part of the airway itself. So the components that make up the lower respiratory tract are the trachea, bronchi, bronchioles, and alveoli.