On the other side of the pneumocytes are endothelial cells that line the capillary walls, which is what holds the blood.

而肺泡细胞的另一边就是毛细血管壁的内皮细胞，毛细血管携带的便是我们亲爱的血液。

So the alveolar wall, the basement membrane, and the capillary wall is really all that separates the air from the blood, and this is called the blood-gas barrier.

所以，肺泡壁、基底膜和毛细血管壁将空气和血液分离，这个结构叫气血屏障。

Water-soluble substances, like ions, cross the capillary wall through either water-filled spaces, called clefts, between the endothelial cells, or through large pores in the walls of fenestrated capillaries.

水溶性物质，如离子，通过内皮细胞间的充水空间（裂缝），穿过毛细血管壁或由有孔毛细血管壁的小孔穿过。

Capillaries have walls that are only one epithelial cell thick. The capillary walls are transparent and are made of smooth plate like cells that continue from the lining of the arteries.

毛细血管壁极薄，故氧及营养物质能从血流离开，进入（胞外）组织液。

Capillary walls are made of just a single layer of epithelial tissue, which form only the tunic intima, so they're able to deliver the oxygen and other nutrients in your blood to their cellular destinations through diffusion.

毛细血管壁仅由单层上皮组织组成，仅形成被膜内膜，因此它们能够通过扩散将血液中的氧气和其他营养物质输送到细胞目的地。