Which structure delivers air directly to each lung in the human respiratory system?

• A. Alveolus
• B. Larynx
• C. Primary bronchus
• D. Trachea

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the anatomy of the human respiratory system. The respiratory system is responsible for gas exchange, and air travels through a series of structures before reaching the lungs.
2. Step 2: Identify the role of each structure listed in the problem: - Alveolus: These are tiny air sacs in the lungs where gas exchange occurs, but they do not deliver air directly to the lungs. - Larynx: Known as the voice box, it is involved in sound production and serves as a passageway for air but does not directly deliver air to the lungs. - Trachea: This is the windpipe that carries air from the throat to the bronchi but does not directly deliver air to each lung. - Primary bronchus: These are the two main branches of the trachea that directly deliver air to each lung.
3. Step 3: Focus on the primary bronchus. The trachea divides into the left and right primary bronchi, which are responsible for delivering air directly to the left and right lungs, respectively.
4. Step 4: Understand the hierarchical structure of the respiratory system: Air flows from the nasal cavity → pharynx → larynx → trachea → primary bronchi → lungs → bronchioles → alveoli.
5. Step 5: Conclude that the primary bronchus is the correct structure that delivers air directly to each lung, based on its anatomical function and position in the respiratory pathway.