ALVEOLAR EPITHELIUM

• WHERE ARE GASES EXCHANGED IN THE ALVEOLAR EPITHELIUM?

  between epithelium and blood
• WHAT ARE ALVEOLI?

  tiny air sacs
• HOW MANY ALVEOLI ARE THERE IN A HUMAN LUNG?

  300 million creating a very large SA for gas exchange
• ADAPTION OF EPITHELIUM CELLS?

  very thin to minimise diffusion distance
• ADAPTION OF EACH ALVEOLUS?

  surrounded by a capillary network to remove exchanged gases, maintaining a concentration gradient