1. The Respiratory System Lung Volumes

2. Lung volumes The volume of air breathed in and out varies a lot between quiet breathing and forced breathing (as when exercising) No matter how hard we try we can never totally empty our lungs of air; if we did they would collapse and stick together. We have air reserves, which make up part of our total lung volume. Lung volumes are an important aspect of pulmonary function testing because they can provide information about the physical condition of the lungs.

3. The machine used to measure lung volumes is the spirometer This works by measuring the amount of air that we breathe in and out over a period of time. The results of this are displayed in a graph

4. What does it measure? Tidal volume (TV) Vital capacity (VC) Inspiratory reserve volume (IRV) Expiratory reserve volume (REV) Residual volume (RV) Total lung capacity (TLC) Functional residual capacity (FRC) Inspiratory capacity (IC)

5. Tidal volume (TV) Tidal volume is the amount of air involved in one normal inspiration and expiration, approx 0.5 litres or 6-7 litres per minute. 500ml Vital capacity (VC) This is the maximum amount of air that can be exhaled after maximal inhalation. 5000ml Inspiratory reserve volume (IRV) Maximal volume of air inspired above resting inspiration 3000ml Expiratory reserve volume (ERV) Maximal volume of air expired above resting expiration 1000-1200ml

6. Residual volume (RV) Volume of air remaining in the lungs after maximal expiration 1200ml Total lung capacity (TLC) Volume of air in the lungs following maximal inspiration (VC + RV) 6000ml Functional residual capacity (FRC) Volume of air remaining in the lungs following resting expiration (ERV + RV) 2500ml Inspiratory capacity (IC) Maximal inspiratory volume (TV + IRV) 3500ml

7. Tidal Volume Inspiratory Reserve Volume Inspiratory Capacity Vital Capacity Total Lung Capacity Expiratory Reserve Volume Residual Volume Functional Residual Capacity