Breathing System

• Breathing system


  The taking in of oxygen for respiration and the removal of the waste gas carbon dioxide
• Alveoli


  • Only one cell layer thick
  • Moist to allow gases to dissolve
  • Occur in large numbers to increase surface area for gas exchange
  • Surrounded by lots of capillaries for gas exchange
• CO2 carried dissolved in plasma
• H2O carried in plasma
• Difference between air breathed in and out

  • Nitrogen: 78% in, 78% out
  • Oxygen: 21% in, 14% out
  • Carbon Dioxide: 0.04% in, 5% out
  • Water vapour: Variable in, Much higher than inhaled out