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 like oxygen
• Gas exchange in the lungs is a continuous process
• Breathing rate

  Number of breaths taken per minute
• Calculating breathing rate

  Number of breaths / Time in minutes