1. Vertebrate Respiration
Bi 150/150.1

2. Functions
Intake and distribution of oxygen, elimination of carbon dioxide
Passive diffusion: simplest form
Dependent on surface area and difference in partial pressures
Ventilation – passage of air or water over respiratory surface
Perfusion – driving of blood through capillaries
Differ with regard to habitat
Unidirectional vs. bidirectional

3. Basic: Origins of the Organs
Gills: from pharyngeal slits
Lungs: endodermal outpocketings from the gut
Gas bladders: may be homologous to lungs

4. Ventilatory Mechanisms
Ciliatory mechanisms
Muscular mechanisms
Dual Pump (water ventilation) – in most fishes
Buccal Pump (air ventilation)
Two-stroke – in air-breathing fishes and most amphibians
Four-stroke – in some salamanders
Aspiration Pump (air ventilation) – in amniotes

5. http://ars. els-cdn. com/content/image/1-s2. 0-S1095643310000838-gr2

6. http://upload. wikimedia

7. http://www. cvphysiology

8. Phylogeny of the System
Elasmobranchii
Countercurrent flow across gills
Ram ventilation (obligate in some)
First gill slit reduced to spiracle

9. Osteichthyes Operculum covers the gills
Some use gas bladders (sometimes connected to the buccal cavity via the pneumatic duct)

10. Amphibia Gill ventilation as juveniles
Cutaneous respiration and lung ventilation as adults

11. Reptilia
Single central air chamber with faveoli (compartments that increase surface area and are sites of gas exchange)
Aspiration (exhalation sometimes passive)
Snake lungs singular and divided into respiratory and saccular portions
Crocodile livers act as pistons.
Limb movement important in turtles

12. Journal Article*
Farmer CG, Sanders K Unidirectional airflow in the lungs of alligators. Science 327:

13. Birds Passageways branch off into parabronchi (unidirectional)
With 6-12 (usually nine) avascular air sacs, which extend into the cores of large bones
Crosscurrent flow

14. Mammals Extensive use of diaphragm and intercostals
With alveoli (bidirectional)
Viscera also assist in respiration.

15. Functional considerations
Types of flow
Ventilation and perfusion rates should be balanced (ratios depend on ecology)
Metabolic costs of living in water vs. air
Regulation of blood pH levels