BPK 407 Lecture Notes - Lecture 3: Pulmonary Function Testing, Pressure Sensor, Spirometer
26 Aug 2016
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Dry air contains several gases: oxygen 20. 93%, carbon dioxide 0. 03%, nitrogen 78. 04%, trace gases 1. 00%, these percentages add to 100, and add to 1. 00 when expressed as gas fractions (e. g. oxygen 0. 2093). Oxygen and carbon dioxide are the two physiologically active gases. Proper si units of gas pressure if pascals (1 pa = 1 nm^-2) or kilopascals (kpa), gas pressures are often measured in mmhg. Pressure at sfu 730mmhg, pressure at sea level 60mmhg. Although barometric pressure varies with altitude, percentage composition of the atmosphere stays relatively constant. Earth"s gravitational field produces a force that gas molecules are attracted to the center of the. Earth, causing the density of the atmosphere to increase with proximity to the earth"s center. This causes atmospheric/barometric pressure to increase with proximity to the earth"s center. Each gas in the atmosphere exerts an individual pressure, the barometric pressure is the sum of the individual pressures (daltons law).
