mechanics of breathing

• inspiration

  intake of air into the lungs which happens by increasing the volume of the chest cavity
• expiration

  expulsion of air from the lungs by reducing the volume of the chest cavity
• inspiration

  • diaphragm flattens
  • intercostals contract
  • ribs move up and out
  • chest cavity volume and size increases
  • air pressure in chest cavity deacreases
• expiration

  • diaphragm relaxes
  • intercostals relax
  • ribs move down and in
  • chest cavity volume and size decrease
  • air pressure in chest cavity increases
  • air is forced out
• lung volume

  amount of air in the lungs at rest at any given time
• tidal volume

  amount of air that enters the lungs during normal inspiration at rest
• inspiratory reserve volume

  amount of extra air inspired after maximal inspiration
• expiratory reserve volume

  amount of extra air expired after maximal expiration
• residual volume

  amount of air left in the lungs after forceful expiration
• vasoconstriction

  the narrowing of the internal diameter of a blood vessel to restrict the volume of blood travelling through
• vasodilation

  widening of the internal diameter of a blood vessel to increase the volume of blood flow through it
• stroke volume

  volume of blood pumped out of the heart during one contraction
• cardiac output

  volume of blood ejected from the heart in one minute
• heart rate

  number of times the heart beats per minute