Which structure of the respiratory system assists in moistening and humidifying inhaled air?

• A. Nasal cavity
• B. Larynx
• C. Pharynx
• D. Trachea

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the function of the respiratory system structures listed in the problem. The respiratory system is responsible for gas exchange, and certain structures play a role in conditioning the air (moistening, warming, and filtering).
2. Step 2: Focus on the nasal cavity. The nasal cavity is lined with mucous membranes and cilia, which help trap particles and humidify the air. It also contains blood vessels that warm the air as it passes through.
3. Step 3: Compare the nasal cavity to the other structures listed. The larynx is primarily involved in sound production and protecting the lower respiratory tract during swallowing. The pharynx serves as a passageway for air and food but does not specialize in humidifying air. The trachea is a conduit for air to the lungs and contains cilia for filtering, but it does not primarily humidify air.
4. Step 4: Recognize that the nasal cavity is the structure most specialized for moistening and humidifying inhaled air due to its mucous membranes and vascularization.
5. Step 5: Conclude that the nasal cavity is the correct answer based on its specific role in conditioning inhaled air, compared to the other structures listed.