Which structures comprise the upper airway?

• A. Trachea, Bronchi, Lungs
• B. Alveoli
• C. Nose, Mouth, Pharynx, Larynx
• D. Diaphragm

Answer: (C)

The upper airway consists of the nose, mouth, pharynx, and larynx. These structures form the entry pathway for air and perform initial conditioning of the air we breathe. The nose filters, warms, and humidifies inspired air; the mouth provides an alternative entry route; the pharynx serves as a shared passage for air and food, connecting the nasal/more anterior structures to the larynx; and the larynx acts as a gatekeeper to the lower airway, protecting it with the epiglottis during swallowing and housing the vocal cords for sound production. The trachea, bronchi, and lungs are part of the lower airway and gas-exchange system, the alveoli being the sites of oxygen and carbon dioxide exchange, and the diaphragm being a primary breathing muscle rather than part of the airway.