B4.5 Gas Exchange

• Trachea

  Where air passes from the mouth to the lungs
• Bronchi

  Where the trachea splits to each lung
• Bronchioles


  Where bronchi subdivide into smaller tubes
• Alveoli

  • Air sacs at the end of bronchioles
  • Where gases diffuse in and out of the blood stream
• How do millions of alveoli help diffusion of gases?

  Gives lungs a larger surface area
• How do thin walls of alveoli help exchange of gases?

  Shorten the path of diffusion
• What do alveoli need to have?

  Good blood supply
• When oxygen is diffused...

  It is rapidly removed to ensure a steep concentration gradient