The lungs

• Lungs

  Organ that gets the oxygen we need from the air into our bloodstream
• Gas exchange in the lungs

  1. Air passes through mouth/nose

  2. Trachea

  3. Bronchi

  4. Bronchioles

  5. Alveoli
• Alveoli


  • Small sacs arranged like bunches of grapes
  • Site of gas exchange
• Alveolus

  • Made up of one layer of thin cells
  • Have a very large surface area
  • Alveolar walls are moist
• Oxygen in alveoli

  Diffuses into blood in capillaries
• Carbon dioxide in blood

  Diffuses into alveoli and is breathed out
• Carbon dioxide is dissolved in blood plasma, not carried by red blood cells
• Gas exchange in the lungs is a continuous process
• Breathing rate

  Number of breaths taken per minute
• Calculating breathing rate

  Divide number of breaths by time in minutes