spirometers

• tidal volume 


  the volume of air in each breath.
• vital capacity 


  the maximum volume of air that can be breathed in or out
• breathing rate 


  how many breaths are taken per unit time
• oxygen uptake

  that rate at which a person uses up oxygen
• Spirometer


  An instrument that measures the volume of air inhaled and exhaled by the lungs
• How a spirometer works

  1. Oxygen-filled chamber with movable lid

  2. Person breathes through tube connected to chamber

  3. Lid moves up and down as person breathes in and out

  4. Movements recorded by pen on rotating drum or motion sensor

  5. Soda lime in tube absorbs carbon dioxide
• The total volume of gas in the chamber decreases over time
• To get a valid reading from a spirometer

  • Person must wear a nose clip to ensure they only breathe through mouth
  • Machine must be airtight
• diagram

  A) vital capacity

  B) tidal volume

  C) oxygen uptake in one minute