* 保護： Skin is a barrier against bacteria, viruses, and other harmful substances.
* Regulation of temperature: Skin helps to regulate body temperature through sweating and blood flow.
* 感覚： Skin contains sensory receptors that allow us to feel touch, pressure, pain, heat, and cold.
* 排泄： Skin helps to excrete waste products through sweat glands.
* ビタミンD合成： Skin produces vitamin D when exposed to sunlight.
Let's consider some options that are NOT functions of human skin:
* 消化
* 呼吸
* Blood filtration
Let me know if you need more clarification!
