Meeting Abstract
Bird lungs have conventionally been thought to be unique in having air flow through most of the conducting airways in the same direction during both inspiration and expiration. Aerodynamic valves cause unidirectional flow through a circular system of tubes, which are organized in an analogous manner to the arteries, capillaries and veins of the blood circulatory system. In contrast, the conducting airways of mammalian lungs arborize, with the branches ending in dead-end, gas-exchange units (the alveoli) and gases travel tidally in the bronchial tree. Although conventionally crocodilians have been thought to have tidal flow and dead-end gas exchange structures, it is becoming clear that their lungs have both avian-like anatomy and patterns of flow. These data raise new questions about the functional underpinnings of unidirectional flow, the selective drivers for this trait, and the evolutionary history this system. This research was funded by NSF (IOS – 0818973 and IOS 1055080).
