Pulmonary surfactant is produced by cells within the lungs and decreases surface tension by breaking bonds between water molecules.

肺表面活性剂由肺内的细胞产生，并通过破坏水分子之间的键来降低表面张力。

Therefore, pulmonary surfactant allows the lungs to expand so we can breathe.

因此，肺表面活性剂可使肺扩张，从而使我们可以呼吸。

Therefore, pulmonary surfactant allows the lungs to expand so air can enter and gas exchange can occur.

因此，肺表面活性物质使肺扩张，这样空气就可以进入，气体交换就可以发生。

Fortunately, specialized cells within the lungs produce pulmonary surfactant, which decreases the surface tension by breaking the bond between water molecules.

所幸，肺内的特殊细胞产生肺表面活性物质，通过破坏水分子之间的键降低表面张力。

But in healthy people, alveoli stay properly inflated because they're full of chemicals called pulmonary surfactants that make the small alveoli more stretchy and less squeezy, balancing the pressure between air sacs.

但在健康的人体内，肺泡会适当的保持充气状态，因为肺泡中充满了一种叫做肺表面活性剂的化学物质，这种物质能使小肺泡更有弹性，挤压力度更小，从而平衡气囊之间的压力。

Human lungs have essentially the same setup, but in healthy people, alveoli stay properly inflated because they're full of chemicals called pulmonary surfactants that make the small alveoli more stretchy and less squeezy, balancing the pressure between air sacs.

人类的肺基本上具有相同的设置， 但在健康人中，肺泡保持适当的膨胀， 因为它们充满了称为肺表面活性剂的化学物质， 使小肺泡更有弹性， 更少挤压，平衡气囊之间的压力。