Gas exchange extra

• Movement of air in the lungs:

  • Mechanics of breathing produce inspiration and air flow
  • During inspiration air initially moves into lungs via convection
  • Air passes through the conducting zone to respiratory zone of the bronchial tree
  • Air in smallest airways move into the alveoli sacs by diffusion
  • The actual exchange of gases occurs across the capillaries in the alveoli sacs
• Convection:

  • in the most general terms refers to the movement of currents within fluids (i.e. liquids, gases)
• Diffusion:

  • Diffusion refers to the process by which molecules intermingle as a result of their kinetic energy of random motion
  • Extremely rapid process
  • Can only occur over very small distances