ch4.2 mechanics of breathing

• ventilation = the process by which air is moved into and out of the lungs
• inspiration = the process of taking air into the lungs
• inspiration

  1. diaphragm contracts and moves downward, intercostal muscles contract and move rib cage up and out
  2. volume increases inside the lungs - air pressure inside is lower than outside
  3. air moves from high pressure to low pressure so air flows into the lungs
• expiration = the process of exhaling air out of the lungs
• expiration

  1. diaphragm relaxes and moves upward, intercostal muscles relax moving rib cage down and in
  2. volume decreases inside the lungs - air pressure inside is greater than outside
  3. air moves from high pressure to low pressure so air flows out of the lungs