lungs and gas exchange

• Lungs


  Function: Get the oxygen that we need from the air all around us into our bloodstream where it can be transported to the rest of the body
• Air flow through the lungs

  1. Mouth/nose

  2. Trachea

  3. Bronchi

  4. Bronchioles

  5. Alveoli
• Alveoli


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


  Single alveoli
• Alveolus


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

  Higher than in blood capillaries
• Carbon dioxide concentration in blood

  Higher than in alveoli
• 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 per minute
• Calculating breathing rate


  Number of breaths / Time in minutes