The Lungs

• • Gaseous exchange happens in the alveoli
• • The role of the lungs is to transfer oxygen to the blood and remove carbon dioxide
• To increase the rate of diffusion, the alveoli have:

  • Large surface area
  • A moist lining for dissolving gases
  • Very thin walls
  • A good blood supply
• • Villi are found in the small intestine
  • Villi increase the surface area so increased rate of digestion into the blood
  • Villi have a single layer of surface cells
  • Villi have a good blood supply - quick absorption