• Created by: Saarah17
  • Created on: 29-10-22 19:46


—> ventilation is the movement of air in and out of the lungs

—> involves the intercostal muscles

—> and diaphragm contracting and relaxes

—> to change the size of the thorax

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Inspiration : breathing in -> energy - using process because muscles contract.

  • the diaphragm contracts, flattening and lowering
  • the external intercostal muscles contract moving the ribs upwards & outwards
  • increase the volume of the thorax which decreases the pressure in the thorax
  • pressure falls between atmospheric pressure
  • air is drawn in through the nasal passages, trachea, bronchi and bronchioles into the lungs down a pressure gradient
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Expiration : breathing out -> passive process because muscle relax

  • the diaphragm relaxes so move into it’s domed shape
  • the external intercostal muscles relax moving the ribs downwards and inwards
  • decreases the volume of the thorax, so the pressure is increased
  • higher than the atmospheric pressure
  • air moves out through the nasal passages, trachea, bronchi and bronchioles out of the longs down a pressure gradient
  • elastic fibres in alveoli return to normal length forcing air out
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Ventilation 2

—> when someone has a fever lung infection or respiratory muscle weakness, they struggle to ventilate themselves

—> a ventilator is used in hospitals to help those that can’t ventilate properly themselves

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