Dalton's law states that the total pressure exerted by a mixture is the sum of the pressures exerted
independently by each gas in the mixture and that each gasses pressure, or partial pressure, is
directly proportional to its percentage in the mixture. For example:
Gas
Nitrogen
Oxygen
Carbon dioxide
Water
Atmosphere
Alveoli
Percentage; PP (mmHg) Percentage; PP (mmHg)
78.6; 597
74.9;
569
20.9; 159
13.7; 104
0.04; 0.3
5.2; 40
0.46; 3.5
6.2; 47
100% 760 mmHg
100% 760 mmHg
a) What would the partial pressure of each of these gases be at high elevations, where the external pressure is
500 mmHg? If we increased the pressure to 1000mmHg, what are the new partial pressures (PP)? What would
happen to the partial pressure if a person was given 70% oxygen (at sea level)? How would each of these
scenarios affect external respiration (i. e. breathing)?