Mechanics of Breathing

• Mechanics of Breathing:

  • air always moves from an area of high pressure to an area of low pressure
  • to inhale pressure in lungs must be less than pressure in atmosphere
  • to exhale pressure in lungs must be greater than pressure in atmosphere
• Muscles used in Expiration:

  • AT REST: passive -> diaphragm relaxes, external intercostal muscles relax
  • EXERCISE: internal intercostal muscles, abdominal muscles
• Muscles used in Inspiration:

  • AT REST: diaphragm contracts, external intercostal muscles
  • EXERCISE:diaphragm, external intercostal muscles, scalenes, pectoral major, sternocleidomastoid