1. TOTAL PULMONARY VENTILATION
Total pulmonary ventilation or Minute respiratory volume = Ventilation rate x Total volume =12 breaths/ mt x 500 ml/ breath =6000 ml / mt

2. Dead Spaces
Anatomic dead Space + Physiological dead space Alveolar dead space }

3. Rate of Alveolar Ventilation
=Ventilation rate x ( Tidal volume – dead space volume) = 12 x 500 – 150 = 12 x 350 = 4200 ml / mt

4. Respiratory Unit

5. Respiratory membrane

6. Physics of Diffusion
D  P x A x S
d x MW

7. Gas Exchange at alveoli & Cell

8. Partial pressure of gases in air at various respiratory levels
Atmosphere
Inspired air
Air entering the lungs
Alveolar air Expired air
PN2 (including traces of other gases
600.6
596
563.4
PO2
PCO2
159.1
0.3
158
149.3
PH2O
Total
Nil
760
5.7
47.0

9. Partial pressure of O2 (Po2) at various sites.
Po2 (mm Hg)
Atmospheric air (dry)
159
Inspired air ( partially wet)
158
Air entering lungs
149.3
Alveolar air
100
Arterialized blood in pulmonary veins entering left atrium 97
Arterial blood ( in aorta, arteries, arterioles ) 95
Tissue cells
40 or less
Mixed venous blood 40

10. Partial pressure of CO2 (PCo2) at various sites.
PCo2 (mm Hg)
Tissue cells
50 – 70
Venous Blood 46
Alveolar Air 40
Arterial Blood
Expired air 32