Atmospheric Pressure

• Atmospheric Pressure:

  • Respiratory pressures are ALWAYS described relative to atmospheric pressure
  • Atmospheric pressure is 760 mmHg
  • It is the pressure exerted by the air (gases) surrounding the body
• Atmospheric Pressure:

  • It is the pressure exerted by the air (gases) surrounding the body
• Atmospheric Pressure:

  • (760 mmHg) is the sum of all the partial pressures of the different gases within air
  • Partial pressure of oxygen is 159 mmHg
  • So the % of oxygen in the air is 21%
  • Rest of air made up mostly of nitrogen - 78%
• Atmospheric Pressure:

  • Negative respiratory pressures means less than atmospheric pressure
  • Positive respiratory pressure means more than atmospheric pressure
  • Zero respiratory pressure is equal to atmospheric pressure