Diffusion and the Alveoli pack 2

• What is the primary function of the alveoli in mammals?

  To facilitate gas exchange between oxygen and carbon dioxide
• How does diffusion occur in the lungs?

  Gases are exchanged in the lungs by diffusion
• What are the three main factors that affect the rate of diffusion?

  Distance, concentration gradient, and surface area
• Why do substances diffuse more quickly when they have a shorter distance to move?

  Because the time taken for diffusion decreases with shorter distances
• What happens to the rate of diffusion if there is a higher concentration difference?

  The rate of diffusion increases
• How does surface area affect the rate of diffusion?

  The larger the surface area, the faster the diffusion occurs
• What is the role of the lungs in gas exchange?

  To transfer oxygen to the blood and remove carbon dioxide
• What are the alveoli?


  Millions of tiny air sacs in the lungs where gas exchange occurs
• What is the concentration of carbon dioxide in blood returning to the alveoli?

  It contains lots of carbon dioxide and not much oxygen
• How does oxygen diffuse in the alveoli?

  Oxygen diffuses from the alveoli (high concentration) into the blood (low concentration)
• What adaptations do alveoli have to maximize gas exchange?

  Moist lining, good blood supply, thin walls, and large surface area
• What is the approximate surface area of alveoli in humans?

  About 75 m²
• What does Fick's Law describe?

  The relationship between the rate of diffusion and the factors affecting it
• According to Fick's Law, what happens to the rate of diffusion if the surface area doubles?

  The rate of diffusion will double
• What does 'x' mean in the context of Fick's Law?

  'x' means 'is proportional to'
• What happens to the rate of diffusion if the thickness of the membrane halves?

  The rate of diffusion will double
• What are the adaptations of alveoli for efficient gas exchange?

  • Moist lining for dissolving gases
  • Good blood supply to maintain concentration gradients
  • Very thin walls to minimize distance for gas movement
  • Enormous surface area (about 75 m² in humans)
• What is the process of gas exchange in mammals?

  1. Oxygen is transferred from the alveoli to the blood.
  2. Carbon dioxide is removed from the blood to the alveoli.
  3. This process maximizes the concentration gradient for both gases.
• How does Fick's Law relate to the efficiency of gas exchange?

  • Rate of diffusion is proportional to:
  • Surface area
  • Concentration difference
  • Rate of diffusion is inversely proportional to:
  • Thickness of the membrane