Skin can not only regulate body temperature through sweat excretion and volatilization, but also reduce sweat gland activity and blood circulation on the body surface, thus preventing heat loss and protecting body temperature? The skin has highly developed receptors? Rich sensory nerves and huge vascular system, so human skin is not only a place for information exchange inside and outside the human body, but also an important storage organ for human essence and blood? Then, the skin is the biggest mirror to see through the diseases in the human body, and it is the information officer and contact map to communicate human health.
Skin color varies according to race? Age? The degree and position of sun exposure are different. Is it related to the distribution of capillaries? How full is the blood? What is the amount of pigment? The thickness of subcutaneous fat and other factors? Observing the change of skin color is very helpful for judging the condition?