The Lungs - Breathing and gas exchange

  • Created by: hxhh
  • Created on: 18-04-22 15:44
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  • Breathing : The Lungs
    • Function of the lungs - to enable gas exchange to take place
    • Oxygen diffuses into the blood and carbon dioxide diffuses out
    • Ventilation - air is constantly moving in and out of the lungs (breathing)
    • Inspiration - (inhalation) occurs when air pressure in the atmosphere is greater than of the lungs, forcing the air into the alveoli
    • Expiration - (exhalation) occurs when air pressure in the lungs is greater than that in the atmosphere, forcing air out of the alveoli
    • When you inhale: the air travels down the trachea, the bronchi and alveoli, where gas exchange takes place. Oxygen diffuses from the alveoli into the blood in the capillaries and carbon dioxide diffuses the other way, into the alveoli where it can be exhaled.
    • Lungs consist of the trachea, the bronchi and the alveoli surrounded by a network of capillaries
    • Adaptations of the lungs
      • Walls are 1 cell thick which lets oxygen and carbon dioxide pass easily between alveoli and capillaries (SHORT DIFFUSION DISTANCE)
      • Millions of alveoli create a large surface area = higher rate of diffusion
      • Surface fluid maintains shape of the air sac and helps keep it open so that oxygen and carbon dioxide can pass
      • High concentration gradient due to many capillaries with a supply of oxygenated blood
    • Pulmonary ventilation  = tidal volume x ventilation rate
      • We use a spirometer to measure tidal volume


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