At a height of 3000 m above sea level atmospheric pressure is 30 kPa less than at sea level. A consequence of this lower pressure is that less oxygen will dis- solve in the alveolar fl uid. The reason for this is that: A. the solubility coeffi cient of oxygen is lower. B. the partial pressure of oxygen in the atmosphere is lower. C. water vapour evaporating from the lung will exert a greater partial pressure. D. there will be more carbon dioxide leaving the blood and entering the alveoli.
Option B. At 3000 m, atmospheric pressure is 70 kPa, the oxygen partial pressure is 20 % of this (approximately 14 kPa). 14 kPa is much less than 20 kPa (oxygen’s partial pressure at sea level), so much less oxygen will dissolve withinside the alveolar fl uid at 3000 m than at sea level.
