The exchange of gases in the alveoli of the lungs takes place by:
Correct answer: D. diffusion.
- A. passive transport
- B. active transport
- C. osmosis
- D. diffusion.
Explanation
(d) : Diffusion is the net flow of a substance from a region of higher concentration to a region of lower concentration. The exchange of gases between the alveoli and blood in the lung is the result of difference in partial pressure of respiratory gases. The partial pressure of oxygen (pO 2 ) of the alveolar air is higher than the pO 2 of blood in alveolar capillaries, thus O 2 diffuses rapidly from the alveolar air into the blood of alveolar capillaries. The pCO 2 of blood reaching the alveolar capillaries is higher than the pCO 2 of alveolar air. Therefore, CO 2 into the alveolar air.
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About Respiration
The human respiratory system includes the air passages, lungs, alveoli and breathing muscles, while gaseous exchange explains how oxygen enters blood and carbon dioxide leaves it by diffusion. The effects of smoking include damage to cilia and alveoli, reduced gas exchange, chronic bronchitis, emphysema and increased risk of lung cancer.
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