Gas exchange in lungs

• 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
  • Made up of one layer of very 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 not carried by red blood cells like oxygen is, it is just dissolved in the blood plasma
• The blood keeps moving throughout the entire process with a constant supply of deoxygenated blood entering the capillaries and oxygenated blood leaving
• Breathing rate


  Number of breaths taken per minute
• Calculating breathing rate


  Divide number of breaths by time in minutes