Lung Volume and Spirometers

• Spirometer

  • Measure lung function
  • Chamber of medical-grade oxygen/air floats on water tank
  • Spirometer trace has peaks and troughs, peak to peak is one breath
  • Used to measure inhalation/exhalation volume and speed
  • Useful to test for asthma, pulmonary fibrosis, cystic fibrosis, emphysema, and COPD
  • Precautions when using a spirometer (experiment):
  • Maintain constant temperature (affects gas volume)
  • Ensure apparatus is airtight (no leaks, lips sealed around mouthpiece)
  • Be cautious about subject’s health
• Measure Lung Volume

  • Attach person to spirometer by disposable mouthpiece, connected to oxygen chamber
  • Use nose clip to ensure only air from chamber is breathed in and air breathed out only goes into the chamber
  • Inhalation: oxygen from chamber leaves and chamber sinks down
  • Exhalation: air is breathed into oxygen chamber which then rises again
  • CO_2 in air breathed out is removed as it passes through soda lime
  • Important or its would become dangerous and inhaled
  • Spirometer trace slants down with successive cycles
• Ventilation

  • Breathing: “Pulmonary Ventilation”
  • Pulmonary - related to lungs
  • For air to enter thorax, its pressure has to be lower than atmospheric
  • At rest lungs need to be ventilated with about 6.0dm^3 of air a minute
  • Concentration of new air entering alveoli with each breath is small compared to total alveolar air volume (~6.0dm^3)
  • Forced breathing out:
  • Contraction of abdominal wall muscles forces diaphragm up even further
  • Depressing ribcage decreases chest volume
  • Some help from internal intercostals, latissimus dorsi, and abdominal muscles
• Definitions

  • Tidal Volume: Volume inhaled or exhaled per breath
  • ~0.5dm^3 at rest
  • Vital Capacity: Max volume forced out after deepest possible inhalation
  • Residual Volume: Air volume always in lungs, even after max exhalation
  • Max: ~1.5dm^3
  • Normal exhalation: ~2.5dm^3
  • Dead Space: Part of residual volume unavailable for gas exchange
  • Permanently in trachea, bronchi and bronchioles
  • Ventilation Rate: Breath number per minute, at rest ~16-17
  • Pulmonary Ventilation: Total air volume moved into lungs per minute (dm^3 min^-1)
  • Tital Volume x Ventilation Rate
• Muscles in Ventilation

  Fill in Table

  A) contract

  B) relax

  C) up and out

  D) contract

  E) flattens

  F) down

  G) increases

  H) decreases

  I) below

  J) into

  K) Relax

  L) contract

  M) gravity

  N) lower

  O) Down and in

  P) relax

  Q) Domes

  R) Decreases

  S) Increases

  T) above

  U) out