Diffusion

• Diffusion


  The overall movement of any substance from an area of higher concentration to an area of lower concentration
• Diffusion only happens in liquids and gases because their particles move randomly from place to place
• Diffusion happens naturally and so does not require energy
• Diffusion of oxygen in the body

  1. Oxygen moves by diffusion from an area of higher concentration inside the lungs to an area of lower concentration in the blood

  2. Oxygen is then carried away by red blood cells

  3. Oxygen moves by diffusion from an area of higher concentration in the blood to an area of lower concentration in the cells

  4. Cells use oxygen in respiration, lowering the concentration in the blood

  5. Blood returns to the lungs to pick up more oxygen by diffusion
• Diffusion of glucose in the body

  1. Glucose moves by diffusion from an area of higher concentration in the small intestine to an area of lower concentration in the blood

  2. Glucose moves by diffusion from an area of higher concentration in the blood to an area of lower concentration in the cells

  3. Cells use glucose in respiration, lowering the concentration in the blood

  4. Blood returns to the small intestines to pick up more glucose by diffusion
• Osmosis


  The diffusion of water from an area of higher to lower concentration across a membrane
• Substances that diffuse


  • Oxygen
  • Carbon dioxide
  • Glucose