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Lips are a visible body part at the mouth of humans and many animals. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be erogenous when used in kissing and other acts of intimacy. == Structure == The upper and lower lips are referred to as the "Labium superius oris" and "Labium inferius oris", respectively.〔(【引用サイトリンク】title=Labium Superius Oris -- Medical Definition )〕〔(【引用サイトリンク】title=Labium Inferius Oris -- Medical Definition )〕 The juncture where the lips meet the surrounding skin of the mouth area is the vermilion border,〔(【引用サイトリンク】title=Vermilion Border -- Medical Definition )〕 and the typically reddish area within the borders is called the vermilion zone.〔(【引用サイトリンク】title=Vermilion Zone -- Medical Definition )〕 The vermilion border of the upper lip is known as the cupid's bow.〔(【引用サイトリンク】title=Cupid's Bow -- Medical Definition )〕 The fleshy protuberance located in the center of the upper lip is a tubercle known by various terms including the procheilon (also spelled ''prochilon''), the "tuberculum labii superioris", and the "labial tubercle".〔(【引用サイトリンク】title=Tubercle Of Upper Lip -- Medical Definition )〕 The vertical groove extending from the procheilon to the nasal septum is called the philtrum.〔(【引用サイトリンク】title=Philtrum -- Medical Definition )〕 The skin of the lip, with three to five cellular layers, is very thin compared to typical face skin, which has up to 16 layers. With light skin color, the lip skin contains fewer melanocytes (cells which produce melanin pigment, which give skin its color). Because of this, the blood vessels appear through the skin of the lips, which leads to their notable red coloring. With darker skin color this effect is less prominent, as in this case the skin of the lips contains more melanin and thus is visually darker. The skin of the lip forms the border between the exterior skin of the face, and the interior mucous membrane of the inside of the mouth. The lip skin is not hairy and does not have sweat glands. Therefore it does not have the usual protection layer of sweat and body oils which keep the skin smooth, inhibit pathogens, and regulate warmth. For these reasons, the lips dry out faster and become chapped more easily. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「lip」の詳細全文を読む スポンサード リンク
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