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每个人都有头发,同学们了解自己的头发吗?1、“怒发冲冠”的理由:每一根头发可分为毛干和毛根两部分。露在皮肤外面的是毛干,埋在皮肤里的是毛根。毛根是毛发的生长点,使毛发不断生长。毛根的外面包着筒状的毛囊,毛囊外面附着一小束肌肉,叫作竖毛肌。当人激动时,竖毛肌有时也会收缩,使短发直立。不过,人的竖毛肌没有动物的发达,因此,经常可见猫等动物的毛直立起来。
Everyone has hair. Do classmates know their hair? 1. Reasons for “bashing”: Each hair can be divided into hair shaft and hair root. It is hair shaft that is exposed on the skin, and hair roots are buried in the skin. Hair roots are the growing point of the hair and keep the hair growing. Hairy roots are covered with tubular hair follicles. A small bundle of muscles is attached to the outside of the hair follicles. It is called erector muscles. When the person is excited, the piloereus sometimes shrinks, causing the hair to stand upright. However, human erector muscles have no developed animals. Therefore, animals such as cats can often stand erect.