Jones J H, Effmann E L, Schmidt-Nielsen K
Respir Physiol. 1985 Jan;59(1):15-25. doi: 10.1016/0034-5687(85)90014-3.
The avian lung has been considered to be rigid and to remain isovolumetric during the respiratory cycle. We tested this hypothesis by implanting radiopaque markers of tantalum on the dorsal pulmonary surfaces and ventral pulmonary aponeuroses of Pekin ducks (Anas platyrhynchos) and measuring changes in lung thickness during the respiratory cycle using high speed cineradiography. We found small but regular changes in lung thickness that were synchronous with respiratory phase. Lung thickness was greatest at mid-inspiration (0.6% greater than mean) and least at mid-expiration (0.8% less than mean). Measurements made on ostrich (Struthio camelus) respiratory structures suggest that the maximal force that could be generated by the muscles (Mm. costopulmonales) at the margins of the ventral pulmonary aponeurosis is more than two orders of magnitude greater than would be required to resist pressure-induced changes in lung volume during respiration at rest. The action of these muscles could account for the very small magnitude of the volume changes measured during the respiratory cycle.
禽类的肺被认为是僵硬的，并且在呼吸周期中保持等容状态。我们通过在 Pekin 鸭（Anas platyrhynchos）的肺背表面和腹侧肺腱膜上植入钽的不透射线标记物，并使用高速电影放射摄影术测量呼吸周期中肺厚度的变化，来检验这一假设。我们发现肺厚度有微小但规律的变化，这些变化与呼吸阶段同步。肺厚度在吸气中期最大（比平均值大 0.6%），在呼气中期最小（比平均值小 0.8%）。对鸵鸟（Struthio camelus）呼吸结构的测量表明，腹侧肺腱膜边缘的肌肉（肋肺肌）产生的最大力量比在静息呼吸时抵抗压力引起的肺容积变化所需的力量大两个数量级以上。这些肌肉的作用可以解释在呼吸周期中测量到的非常小的容积变化量。
