(AQA GCSE B3.1.2) Gaseous Exchange in the Lungs

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  • Created by: Em
  • Created on: 17-04-13 17:39
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  • Gaseous Exchange in the Lungs
    • The THORAX is the upper part of the body (chest, etc.), the ABDOMEN is the lower part (stomach, etc.) Between these is a muscle called the DIAPHRAGM.
      • The diaphragm lies below the lungs.
    • When breathing in, the INTERCOSTAL MUSCLES between the ribs contract, causing the ribs to move upwards and outwards.
      • As well as this, the diaphragm contracts. It becomes a more horizontal shape below the lungs.
        • These cause the lungs to expand, they have a higher volume and low pressure. This low pressure is unbalanced with the higher pressure outside the lungs, and therefore air is drawn in
    • When breathing out, the intercostal muscles relax. The ribs move back down.
      • The diaphragm also relaxes, it becomes more of a curve.
  • This causes the opposite effect to breathing in. The volume decreases and the pressure increases, causing air to be pushed out
    • The diaphragm also relaxes, it becomes more of a curve.


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