Fish

• Explain how the gills of a fish are adapted for gas exchange

  1)Gills made of many filaments covered with many lamellae

  • Increases SA for diffusion

  2)Thin lamellae wall/epithelium

  • Short diffusion pathway between water/blood

  3)Lamellae have a large number of capillaries

  • Remove O2 and bring CO2 quickly so maintains a concentration gradient
• Explain the Counter Current Flow

  1. Blood and water flow in opposite directions through/over lamellae
  2. So oxygen concentration always higher in water
  3. So maintains a concentration gradient of O2 between water and blood
  4. For diffusion along whole length of lamellae