1. Comparative Vertebrate Physiology
Vertebrate Respiration Systems

2. Respiration systems Gill Lung External invagination High surface area
Internal invagination
Ventilation

3. Patterns of air flow
Fishes
Amphibians
Countercurrent flow

4. Patterns of air flow
Birds
Mammals
Crosscurrent flow
Tidal flow

5. Cutaneous respiration
Increase skin surface area
Ineffective above 1,000g
When PO2 low use reduced lungs
Lake Titicaca in Peru

6. Lamella gills
Anatomy
Gill arches, filaments, secondary lamellae

7. Gill ventilation
Mouth
Buccal cavity (positive pressure)
Operculum

8. Countercurrent flow
Is it more efficient?

9. Ram ventilation Fast swimmers (i.e., tuna, some sharks)
Forcing water across gill surface

10. Aquatic respiration Physiological consequences Variable Density (Kg/l)
Viscosity (cPi)
O2 diffusion
coefficient
O2 content
Water
Air
1.0
0.001
1.14
0.02
0.2
1 - 6
210
(ml/L)

11. Aquatic respiraton Aquatic: 1L water for 1 ml O2
Terrestrial: 25 ml of air for 1 ml O2
It’s harder to breathe under water

12. Amphibians Varied respiratory systems Positive pressure buccal pump
Cutaneous, gills, lungs
Positive pressure buccal pump
IV phases

13. Reptiles Negative intrapulmonary pressure
All have ribs and intercostal muscles (except chelonians)
Crocodiles
Muscle contraction

14. Reptiles Chelonians Rigid carapace (ribs?) and diaphragm
Breathe by movement of girdles and muscle contraction

15. Birds Air sac system Connected to trachea, lungs and long bones
One way system

16. Birds
Two breaths to remove air from pathway

17. Extremes of respiration
1. Increase in altitude
PO2 at 5,800 m is 80 mmHg compared with 155 mmHg at sea level
Birds migrate at 6,000 m
Humans
Short-term response: Increase in depth of respiration (not rate), regulated by pH of CSF
Long-term response: Increase in erythropoietin and RBC count

18. Extremes of respiration
2. Diving in air-breathing animals
e.g.reptiles, mammals

19. Extremes of respiration
2. Diving
Cope with hypoxia by using all available oxygen
High levels of Hb, myoglobin
Blood shunt to brain and heart

20. Extremes of respiration
Preventing “the bends”
Nitrogen narcosis caused by an increase in pressure

21. Extremes of respiration
Solution: evacuate lungs of air