11-Gas Exchange in the Lungs

• Trachea


  • Contains rings of cartilage to prevent it from collapsing when we inhale
• Air passage into the lungs

  1. Trachea

  2. Bronchi

  3. Bronchioles

  4. Alveoli
• Alveoli


  • Microscopic air sacs where gas exchange occurs
• Alveoli adaptations for gas exchange


  • Huge surface area
  • Very thin walls (short diffusion path)
  • Good blood supply
• Oxygen diffuses into the bloodstream


  Carbon dioxide diffuses out of the bloodstream
• Breathing


  Brings fresh oxygen into the alveoli and takes away carbon dioxide, increasing the concentration gradients for these gases
• The adaptations of the lungs for gas exchange are very important and you will find plenty of questions on them in the revision workbook