Why do people get tanned? To what extent is it irreversible? Is tanning hereditary?

Tanning is a protective reaction of the human body, melanin can absorb ultraviolet rays, some people are very white but not suitable for tanning, just like Europeans, such people are more likely to suffer from cancer than ordinary people in the same sunlight, so such people should be the most in need of sun protection.

So is ultraviolet rays not beneficial at all, no, I saw a book in the library that said that ultraviolet rays have a good impact on various systems of the human body, and basking in the sun will also increase their sun resistance, compared with white, in fact, health is more important; But on the other hand, due to the destruction of the ozone layer, UV rays are indeed becoming more and more dangerous, and the incidence of melanoma has skyrocketed, so it is necessary for people who are exposed to strong sunlight or long-term outdoor activities to take sun protection measures.

Can tanning be inherited, this question is okay for middle school students, as long as it does not cause mutations in germ cells, it will not be inherited; While it is true that UV light significantly increases the chance of mutation, this possibility is still negligible.

This is not inherited, but it can be whitened.

Because there are ultraviolet rays hitting the ** on the ** will burn **. **It secretes melanin to fight ultraviolet rays. That's it, my beautician told me.

There are strong ultraviolet rays in sunlight, which can cause the formation of melanin, which leads to easy blackness.

People's exposure to sunlight for a long time without sunscreen protection can lead to the body secreting a large amount of melanin, and excessive melanin deposition in it may cause Pibifeng skin to tan.

The ultraviolet rays in the sunlight can be divided into long-wave, medium-wave and short-wave, the ozone layer of the atmosphere will absorb the short-wave ultraviolet rays in the sun, because the penetration of long-wave ultraviolet rays and medium-wave ultraviolet rays is very strong, so Ling Huihong can reach the dermis layer of the human body through the clouds, resulting in melanocyte proliferation and differentiation, so after the sun, it is easy to completely absorb ultraviolet rays, which will easily lead to blackening.

People will tan because the exposure to ultraviolet rays has led to the improvement of pigment and the increase of pigment synthesis, so as to darken. Ultraviolet rays are mainly divided into three wavelengths: UVA, UVB and UVC, of which UVC is absorbed by the atmosphere and will not be directly irradiated to the ground, while UVB wavelength is more harmful to us, mainly causing sunburn, redness, swelling, blisters, cancer and other problems. At the same time, although the UVA wavelength does not cause reactions such as redness and blisters, it is a longer wavelength of ultraviolet light, which is stronger in the depth of penetration, so it will also be directly irradiated to the deep layer, which will lead to aging.