Where does gas exchange occur in the lungs?

Where does gas exchange occur in the lungs?

• A. Bronchioles
• B. Trachea
• C. Alveoli
• D. Bronchi

Answer: (C)

Gas exchange happens in the alveoli. These tiny air sacs are at the ends of the airways and are surrounded by a dense network of capillaries. Their walls are extremely thin, forming the respiratory membrane, which lets oxygen diffuse from the air into the blood and carbon dioxide diffuse from the blood into the air to be exhaled. The large surface area of countless alveoli and their close proximity to blood vessels make diffusion efficient. The trachea, bronchi, and bronchioles mainly serve to conduct air to the lungs and condition it (warm, humidify, filter) rather than exchange gases.

Gas exchange happens in the alveoli. These tiny air sacs are at the ends of the airways and are surrounded by a dense network of capillaries. Their walls are extremely thin, forming the respiratory membrane, which lets oxygen diffuse from the air into the blood and carbon dioxide diffuse from the blood into the air to be exhaled. The large surface area of countless alveoli and their close proximity to blood vessels make diffusion efficient. The trachea, bronchi, and bronchioles mainly serve to conduct air to the lungs and condition it (warm, humidify, filter) rather than exchange gases.