Alveolar Ventilation definition

• Alveolar ventilation:

  • is the amount of minute ventilation reaching respiratory zone used in gas exchange
• • tidal volume – anatomical dead space = alveolar ventilation
  • 500 ml – 150 ml = 350 mls / breath
  • 350 ml x 12 bpm = 4.2 L min-1 / minute
• 2 ways to increase alveolar ventilation:

  • take bigger breath
  • breathe more times per minute
• During exercise:

  • we take a bigger breath (used more with healthy people)
  • we take more breaths per minute
• Why is adequate alveolar ventilation important?

  • if we breathe too little, co2 in the blood increases
  • if we breathe too much, co2 in the blood decreases
• Alveolar ventilation

  • Determines O2 and CO2 levels in alveolar gas
  • Other factors are
  • rate of O2 consumption (VO2 )
  • rate of CO2 production (VCO2 )
• Factors affecting arterial O2 content:

  • Ventilatory pattern
  • V/Q matching
  • Haemoglobin content of blood
  • Haemoglobin affinity for O2
  • Atmospheric pressure O2
  • Specific characteristics of alveolar membrane