High rates of pulmonary gas exchange require three things: 1) that gases at the contact surface of the lung's capillaries are replenished rapidly from the environment; 2) that this surface is large and thin; 3) that the capillaries are effectively perfused with blood. In spite of this uniform requirement, lungs have evolved complex and highly diverse architectures, but we have a poor understanding of the drivers of this diversity. Here, I briefly discuss some of the diversity in gross anatomical features directing airflow in avian and non-avian reptiles. I also review new insights into the cellular anatomy of the blood-gas barrier, which in mammals is composed of specialized endothelial as well as epithelial cells.

高速率的肺气体交换需要三件事：1）肺毛细血管接触面的气体从环境中迅速补充；2）这个表面又大又薄；3) 毛细血管被血液有效灌注。尽管有这种统一的要求，肺已经进化出复杂且高度多样化的结构，但我们对这种多样性的驱动因素知之甚少。在这里，我简要讨论了鸟类和非鸟类爬行动物在引导气流的大体解剖特征方面的一些多样性。我还回顾了对血气屏障细胞解剖学的新见解，在哺乳动物中，血气屏障由特化的内皮细胞和上皮细胞组成。