Biology 5090 · O Level · Human gas exchange

Human gas exchange — practice question

The table illustrates the changes that happen in the thorax during breathing. Which changes happen during inspiration?

  • Adiaphragm contracts; external intercostal muscles contract; internal intercostal muscles relax; pressure in thorax falls and then rises
  • Bdiaphragm relaxes; external intercostal muscles relax; internal intercostal muscles contract; pressure in thorax rises and then falls
  • Cdiaphragm relaxes; external intercostal muscles contract; internal intercostal muscles relax; pressure in thorax rises and then falls
  • Ddiaphragm contracts; external intercostal muscles relax; internal intercostal muscles contract; pressure in thorax falls and then rises

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