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The factors that determine the values for alveolar pO2 and pCO2 are: *The pressure of outside air *The partial pressures of inspired oxygen and carbon dioxide *The rates of total body oxygen consumption and carbon dioxide production *The rates of alveolar ventilation and perfusion Following is a list of average partial pressures (in torr) for a human at rest: ==Partial pressure of oxygen== The alveolar oxygen partial pressure is lower than the atmospheric O2 partial pressure for two reasons. * Firstly, as the air enters the lungs, it is humidified by the upper airway and thus the partial pressure of water vapour (47 mmHg) reduces the oxygen partial pressure to about 150 mmHg. * The rest of the difference is due to the continual uptake of oxygen by the pulmonary capillaries, and the continual diffusion of CO2 out of the capillaries into the alveoli. The alveolar pO2 is not routinely measured but is calculated from blood gas measurements by the Alveolar gas equation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pulmonary gas pressures」の詳細全文を読む スポンサード リンク
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