呼吸部肺泡数多，每支呼吸性细支气管分出68支肺泡管，肺泡较小，处于半充容状态。
Respiratory region has a great number of alveolar ducts . There are 6 to 8 alveolar ducts in each of pneumatic bronchiole . Alveolus is rather small and semi-full .
充容