Sherwood: Chapter 11

Objective:  Most air breathing vertebrate respiratory sytems are ventilated by a tidal flow of air with the exception of birds whose air can flow unidirectionally through the lung during inspiration and expiration.

1.  Amphibians
        a.  positive pressure buccal pump
        b.  cutaneous gas exchange
2.  Reptiles
        a.  negative intrapulmonary pressure
3.  Birds
        a.  air sacs and air spaces
        b.  cross-current gas exchange system