inspiration

• • The external intercostal and diaphragm muscles contract.
  • This causes the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax (the space where the lungs are).
  • As the volume of the thorax increases the lung pressure decreases (to below atmospheric pressure).
  • This causes air to flow into the lungs
• inspiration is an active process- requires energy