ventilation (breathing)

INSPIRATION

  • air is taken in by the lungs

  • diaphragm pulls down

  • external intercostal muscles contract

  • internal intercostal muscles are not used

  • rib cage is pulled up & out

  • volume of the thoracic cavity increases = decrease in pressure

  • allows air to rush in


EXPIRATION (  QUIET BREATHING)

  • air is exhaled through the lungs

  • diaphragm moves up

  • external & internal intercostal muscles relax

  • rib cage moves down & in

  • volume of the thoracic cavity decreases = increase in pressure

  • allows air to be forced out of the lungs


FORCED EXPIRATION

  • air is forcefully pushed out of the lungs, typically during aerobic activities where a high amount of oxygen is needed?

  • diaphragm moves up

  • external intercostal muscles relax

  • internal intercostal muscles contract

  • rib cage move down & in forcefully

  • abdominal muscles also contract & push up

  • volume of thoracic cavity decreases = increase in pressure

  • air is forcefully pushed out of lungs