Across gills of fish

• Counter current exchange principle

  • Diffusion of oxygen from water to blood takes place in opposite direction
  • maintains maximum concentration gradient for diffusion across lamallae and capillary
  • Diffusion takes place across the length of the lamallae
  • Equilibrium is never reached
• Adaptation of gills

  • lots of gill filaments to provide large surface area
  • thin surface to reduce diffusion distance

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

  ● Gills made of many filaments covered with many lamellae

  ○ Increase surface area for diffusion
• Explain how the gills of fish are adapted for gas exchange

  ● Thin lamellae wall / epithelium

  ○ So short diffusion distance between water / blood
• Explain how the gills of fish are adapted for gas exchange

  ● Lamellae have a large number of capillaries

  ○ Remove O2 and bring CO2 quickly so maintains

  concentration gradient
• If parallel flow, equilibrium would be reached so oxygen wouldn’t diffuse into blood along the whole gill plate.