Final answer:
The partial pressure of oxygen (alveolar Po₂) in the alveoli at sea level is approximately 160 mm Hg, while the partial pressure of carbon dioxide (alveolar Pco₂) is about 40 mm Hg.
Step-by-step explanation:
The partial pressures of O₂ (oxygen) and CO₂ (carbon dioxide) in the alveoli under resting conditions at sea level can be calculated using the provided information. The atmosphere at sea level is at a pressure of 760 mm Hg, and dry air contains 20.9% oxygen, which equates to a partial pressure of oxygen (alveolar Po₂) of approximately 160 mm Hg (760 mm Hg × 0.209).
For carbon dioxide, the partial pressure in the alveoli (alveolar Pco₂) is about 40 mm Hg. Despite the lesser difference in partial pressures between the alveoli and the capillary blood for CO₂ (approximately 5 mm Hg), the relatively higher solubility of CO₂ compared to O₂ ensures a comparable diffusion rate across the respiratory membrane.