Mechanics of Breathing

• inspiration


  • diaphragm contracts and flattens, intercostals raise the sternum and thorax out
  • chest cavity is bigger, lowering the pressure less than the environment
  • air drawn into the lungs
• expiration


  • diaphragm relaxes and forms a dome shape, intercostals relax the sternum and thorax down
  • chest cavity is smaller, increasing pressure higher than the environment
  • air drawn out of the lungs