Adaptations of the lungs

• What is the significance of the alveolus having a thin membrane?

  It allows substances to pass over it easily
• How thick is the membrane of the alveolus?

  One cell thick
• Why is the capillary membrane also one cell thick?

  To facilitate easy transfer of substances
• What role does the concentration gradient play in gas exchange in the alveoli?

  It allows air to constantly move in and out
• How does carbon dioxide move from the blood to the alveolus?

  By diffusion from high concentration in blood to low concentration in air
• How is oxygen transported from the alveolus to the blood?

  By diffusion from high concentration in air to low concentration in blood
• What happens to the concentration of oxygen and carbon dioxide during gas exchange in the lungs?

  Oxygen concentration increases in the blood, while carbon dioxide concentration decreases
• What happens to the air that is exhaled from the lungs?

  It contains slightly less oxygen and more carbon dioxide than the air that was inhaled
• What are the main adaptations of the lungs for gas exchange?

  • Thin membranes (one cell thick)
  • Large surface area (equivalent to 15 table tennis tables)
  • Constant concentration gradient (air and blood movement)
• What is the function of red blood cells in gas exchange?

  They carry oxygen and carbon dioxide
• How does the heart contribute to the gas exchange process in the lungs?

  It pumps blood, ensuring a constant flow to and from the lungs
• What happens to carbon dioxide in the blood during gas exchange?

  It moves from the blood into the alveolus
• How does the structure of the alveolus facilitate its function in gas exchange?

  The spherical shape and thin walls maximize surface area and diffusion efficiency
• 6 marks

  • Contains lots of alveoli which increases the surface area
  • Has thin capillaries to make a small diffusion distance (makes it quicker)
  • Good blood supply which allows carbon dioxide in the lungs.
  • Breathing constantly, this allows carbon dioxide to be transported out the lungs and keeps a concentration gradient.