lungs

• Features of gas exchange

  • very large surface area - 500-700million alveoli (70-100m2)
  • very thin gas exchange surface - alveoli and capillary walls only one cell thick and are made up of squamous epithelium - flat cells
  • good blood supply - oxygen is continually taken away from the alveoli by red blood cells and carbon dioxide is constantly being brought to the alveoli. this maintains a high concentration gradient of both gases.
• tidal volume = normal breathing volume
• inspiratory/ Expiratory reserve volume = maximum amount you can breath in and out
• residual volume = the air that is in your lungs after you fully breathe out
• vital capacity = total volume from fully breathed in to fully breathed out
• Total lung capacity = vital capacity plus the residual volume