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Fav十万个为什么
为什么打呵欠会有眼泪？
打哈欠时流泪是因为面部肌肉收缩导致鼻腔压力升高，泪液无法通过鼻泪管排出，从而积聚在眼眶中。
1、面部肌肉收缩：打哈欠时，面部肌肉（包括面颊、舌和咽喉部）会紧张收缩，压迫泪囊，使泪液回流至眼眶。
2、鼻腔压力升高：打哈欠时，鼻腔内压力增高，导致鼻泪管暂时无法正常排泄泪液，泪液积聚在眼眶中，形成流泪现象。
3、泪液循环受阻：正常情况下，泪液通过鼻泪管流向鼻腔，但在打哈欠时，鼻腔压力和肌肉收缩共同作用，使泪液无法顺畅排出，从而引发流泪。
总结：打哈欠时流泪是因为面部肌肉收缩导致鼻腔压力升高，泪液无法通过鼻泪管排出，从而积聚在眼眶中。
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