夏日难题!为什么太阳光能把人的皮肤晒黑?

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公开课模版测试文章(编辑别推)

李承新

中国人民解放军总医院皮肤科主任医师

太阳光为什么会把人的皮肤晒黑?

紫外线包括UVA、UVB和UVC。UVC由于波长比较短,到达不了地球的表面,对我们的皮肤没有任何的伤害。UVA和UVB可以通过云层到达地球的表面,对我们的皮肤产生各种各样的生物学效应。UVA和UVB都能对我们的皮肤造成损伤,通常来讲,UVA会使皮肤晒黑,UVB是晒红。

夏日难题!为什么太阳光能把人的皮肤晒黑?

晒黑的最主要原因,是紫外线照射皮肤以后,会激活黑色素细胞合成黑色素,使得黑素小体的生成、转移、代谢功能变强。此时皮肤表皮中就会有很多的黑色素颗粒,皮肤的透光性减弱,使人看起来变黑了。当然,紫外线还可以影响表皮中的角质形成细胞和真皮中的成纤维细胞,产生很多细胞因子,反过来作用于黑色素细胞。

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