Diffusion

• Diffusion

  • the movement of molecules
  • from an area of higher concentration
  • to an area of lower concentration
  • a spreading out and mixing process
• Net


  overall
• • cells need glucose and oxygen for respiration, which move into them by diffusion
  • respiration produces carbon dioxide and water which leaves cells by diffusion
• In a leaf

  • oxygen moves out of cells by diffusion
  • carbon dioxide moves into cells by diffusion
• In the lungs

  • blood from the body high in carbon dioxide and low in oxygen
  • carbon dioxide diffuses from high concentration in blood to low concentration in alveolus
  • oxygen diffuses from high concentration in alveolus to low concentration in blood
  • blood to the body high in oxygen and low in carbon dioxide
• Liver cells

  • high concentration of urea in liver cells
  • low concentration of urea in blood vessel in liver
  • urea is filtered from the blood by the kidneys