Biology 0610 · IGCSE · Gas exchange in humans

Gas exchange in humans — practice question

Which changes result in expiration?

  • Aexternal intercostal muscles contract; diaphragm relaxes and moves down
  • Bexternal intercostal muscles contract; diaphragm relaxes and moves up
  • Cexternal intercostal muscles relax; diaphragm relaxes and moves down
  • Dexternal intercostal muscles relax; diaphragm relaxes and moves up

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