If the oxygen carrying capacity is sufficient, the skin looks rosy, whereas if anemia, malnutrition, lack of sleep and long-term heavy smoking, the skin looks gray and pale.
③ Endocrine factors:
Both physiological and pathological changes affect the changes of pigment synthesis, such as the changes of estrogen during pregnancy, and the increase of melanocyte secretion during thyroid diseases, which can lead to the increase of melanin synthesis and the deepening of skin color. Second, smoothness: healthy skin has fine texture and high smoothness. On the contrary, the skin is rough and dull. Three textures: the surface texture of healthy skin is delicate, shallow, soft and smooth. Skin aging, including natural aging and light-induced aging, or some skin diseases, will lead to the increase, thickening or deepening of the texture in the corresponding area and wrinkles. Elasticity: When the moisture content of skin and the thickness of subcutaneous fat are moderate, the texture of skin is flexible and elastic. After skin aging, subcutaneous fat shrinks, water content is low, and skin elasticity is correspondingly weakened. Humidity: When skin metabolism and secretion and excretion function are normal, a moderate sebum film can be formed on the skin surface, making the skin moist, stretched and shiny. When sebum secretion is too much, the skin looks greasy, while when sebum secretion is too little, the skin is dry, peeling and wrinkled.
Six skin functions:
Normal skin function can not only make the skin have a healthy appearance, but also effectively maintain the balance between the internal and external environment of the skin and delay skin aging.