3. Measuring the process

• MEASURING CAPACITY OF LUNGS

  1. Peak flow meter: measures rate at which air can be expelled from lungs, those with asthma use this to monitor how well lungs are working
  2. Vitalographs: patient breathes out as fast as they can through a mouthpiece = instrument produces a graph of amount of air they breathe out + how quickly its breathed out

  This vol of air is called = forced expiratory volume in 1 second
• SPIROMETER

  Spirometer: used to measure different aspects of lung volume/to investigate breathing patterns diff types of spirometers = all have same principle

  • Co2 is absorbed from exhaled air by soda lime to stop conc of co2 in re-breathed air from getting too high as this can cause respiratory distress
• COMPONENTS OF LUNG VOLUME:

  • Tidal volume: vol of air that moves in + out lungs with each resting breath. Around 500cm3 in most adults at rest = uses 15% of vital capacity of lungs
  • Volume of air breathed in/out during normal breathing at rest
  • Vital capacity: vol of air that can be breathed in when strongest possible exhalation is followed by deepest possible intake of breath
  • the maximum volume of air that can be breathed in /out in one breath
• COMPONENTS OF LUNG VOLUME 2:

  • Inspiratory reserve volume: maximum vol of air you can breathe in over and above a normal inhalation
  • Expiratory reserve volume: extra amount of air you can force out of your lungs over and above normal tidal vol of air you breathe out
  • Residual volume: vol of air left in your lungs when you have exhaled as hard as possible = cannot be measured directly
  • Total lung capacity: sum of vital capacity + residual volume
• BREATHING RATE:

  • Breathing rate: no. of breaths taken per minute
  • Ventilation rate is the total vol of air inhaled in 1 min
  • Ventilation rate = tidal vol x breathing rate [per min]
  • When o2 demands increase = TV of air moved in and out lungs with each breath can increase from 15% to as much as 50% of VC
  • Ventilation of lungs + o2 uptake during gas exchange can be increased to meet demands [exercise]