Lung architecture volume and static mechanics in five species of lizards.

Compared with mammals, lizards have large, highly compliant lungs and a compliant body wall. High lung compliance is not necessarily associated with high body wall compliance but rather with the degree of development of the caudal and ventral dilatations of the lung. Comparison of the midinflation distance between inflation and deflation curves on standard volume--pressure diagrams indicates hysteresis may have an intrapulmonary component related to the degree of lung partitioning and an extrapulmonary component, attributable to forces hindering the free movement of the lung in the body cavity. Simultaneous consideration of lung structure, mechanical properties and certain nonrespiratory functions such as buoyancy and display indicate that the function of the lung in gas exchange may be only one of several factors important in determining lung structure in lizards.