Surface area of alveolar membrane

• Surface area of membrane:

  • Adult lung contains around 300 million alveoli
  • Gives gas exchange surface area 70 - 80 m2
  • Huge capacity which can be utilised to maintain acid-base balance
  • e.g. during exercise
• Clinical relevance surface area:

  • If surface area is decreased, despite adequate diffusion sufficient gas exchange may not be possible
  • decrease in O2 and increase in CO2 and decrease in pH
  • Temporary loss of surface area:
  • Bronchial obstruction (tumour, mucus plug)
  • Atelectasis
  • Consolidation
  • Permanent loss surface area
  • Emphysematous bullae