1. Comparative Vertebrate Physiology
Physiology of air breathing The lungs

2. Respiration Oxygen utilization varies with activity Rest: 200 ml/min.
Exercise: 6,000 ml/min.
O2 utilization depends on metabolic demands
pH regulation of ECF

3. Organization
Conducting zone
Respiratory zone

4. Functions of pathway Conducting zone Warm, cleanse and humidify air
Phonation (vocal cords)
Regulation of air flow

5. Functions of pathway
Respiratory zone
Gas exchange

6. Functions of pathway Cell type I (gas exchange)
Cell type II (surfactant)

7. Gas Exchange
Gases must penetrate 3 areas 1 2 3

8. Diffusion distances Shorter is better (µm) Animal
Diffusion distance (ｵm)
Toad
Birds
pigeon
swallow
shrike
Mammals
rat
human
shrew
0.09
0.17
0.27
(µm)

9. Lung ventilation Closed compartment Pleura
Head, diaphragm, sternum, ribs and intercostal muscles
Pleura
Parietal (chest)
Visceral (lungs)
Pleural fluid

10. Ventilation steps Exchange of air between atm. and alveoli
Ventilation, bulk flow
Exchange of O2 and CO2 between alveoli and lung capillaries
Diffusion
Transport of gases by blood
Bulk flow
Exchange of gases between blood and tissues

11. Ventilation

12. Ventilation What pressure changes? Ans: alveolar Bulk flow: F = K (∆P)
How does pressure change?
Intrapleural vs. intrapulmonary pressure

13. Ventilation Intrapleural pressure Tendency of lung recoil
Surface tension of alveolar fluid
Opposed by chest wall elasticity
Intrapleural pressure
Intrapulmonary pressure

14. Ventilation
Balloon within a balloon

15. Ventilation

16. Air flow
Flow (F) = ∆P/R
∆P: change in pressure between atmosphere and alveoli
R: resistance of airways

17. Air flow
∆P: altered by contraction of inspiratory and expiratory muscles
Resistance
Inversely proportional to 4th power of radius A B

18. Measuring lung volumes
Respirometer

19. Respirometry data

20. Dead space