BIOA02H3 Lecture Notes - Lecture 6: Vapor Pressure, Hyperoxia, Partial Pressure
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BIOA02H3 Full Course Notes
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Respiratory systems and breathing: partial pressures of gases. The partial pressure of a gas is the pressure that a particular gas exerts when it is in a gas mixture. Excluding trace gases, the gaseous composition of air on earth is below. The air pressure (atmospheric pressure) is the sum of the partial pressures of all of the gases within the air plus the partial pressure of water vapour (in the case that relative humidity is anything other than 0%). Pair = pn2 + po2 + pco2 + ph20. At sea level, the atmospheric pressure (with a relative humidity of 0%) is 760 mmhg (millimeters of mercury). Therefore, in order to calculate the partial pressure of any given gas, you multiply the atmospheric pressure by the fractional concentration of a particular gas. For example, air is 79% nitrogen so the fractional concentration of n2 is 0. 79. Pn2 = 0. 7904 (760 mmhg) = 601 mmhg.