Expiration

• give the process of expiration?

  1. the external intercostal and diaphragm muscles RELAX
  2. the ribcage moves downwards and inwards and the diaphragm becomes CURVED again
  3. volume of thoracic cavity DECREASES, causing the air pressure to increase (to above atmospheric pressure)
• what process is NORMAL EXPIRATION?

  a passive process - it does not require energy

  HOWEVER expiration can be forced
• give an example of forced expirarion?

  if you want to blow out the candles on your birthday cake
• what happens during FORCED EXPIRATION?

  • The external intercostal muscles relax and internal intercostal muscles contract
  • This pulls the ribcage further down and in
  • During this time, the movement of the two sets of intercostal muscles is said to be ANTAGONISTIC (opposing)