Exchanging substances: Alveoli

• Lungs contain air sacs (alveoli) where gas exchange takes place
• 2. the lungs transfer oxygen to the blood and to remove waster CO2 from it
• 3. the alveoli are specialised to maximise the diffusion of oxygen and CO2. They have:

  • large surface area
  • moist lining for dissolving gases
  • very thin
  • good blood supply