air sac
air sac
air sac
n.（名词）
1.An air-filled space in the body of a bird that forms a connection between the lungs and bone cavities and aids in breathing and temperature regulation.
气囊：鸟体内连结肺和骨穴的气囊，帮助呼吸和温度调节
2.See alveolus
参见 alveolus
3.A saclike, thin-walled enlargement in the trachea of an insect.
气囊：昆虫气管中囊状薄壁的扩张
