Sunburn as a protective reaction to UV - stress. Skin color and melanin, tan and melanoma

TYPES OF SKIN BY FITSPATRYKU. The Fitzpatrick classification of skin types is the most well-known and, perhaps, the most successful in the entire history of humanity's interest in the issue of skin color and tan. Thomas B. Fitzpatrick, a professor at Harvard Medical School, developed this classification in 1975. In accordance with it, all of humanity is divided into six phototypes, which are determined by the direct relationship between the skin color or the content of a constant amount of melanin in the epidermis and the effectiveness of tanning - an additional temporary amount of melanin.

The decisive factor in the description of each phototype is skin color. The boundaries of the phototype are relative. The main conclusion: people with darker skin get tanned faster and burn less.

Type I - Celtic. The skin is very white, often with freckles, bright red or very blond hair; eyes are light blue or green. The highest risk of sunburn, almost no tan.

Type II - Germanic or Nordic. The skin is white, freckles little or not at all. Hair is light, different shades. The eyes are blue, gray, greenish. Sunburn weak, high risk of sunburn.

Type III - Central European. The skin is light, without freckles. Hair from medium blonde to dark blonde, from medium brown to dark chestnut. Eyes from light brown to dark brown, gray-green, dark green. There is a risk of sunburn, but the tan is formed well and the skin is able to acquire a rather dark complexion.

Type IV - Mediterranean or South European. The skin is dark, olive. The hair is dark, different shades. Brown eyes. The skin quickly acquires a smooth, bronze tan, sunburns rarely occur.

Type V - Indonesian or Middle East. The skin is usually dark with a yellowish tinge. The hair is very dark, often black. Eyes deep brown, closer to black. The skin quickly darkens in the sun, the probability of getting a sunburn is almost absent.

Type VI - African American. The skin is very dark, brown or black. Hair and eyes are black. This type has the highest level of melanin in the skin (the indigenous population of the African continent). Sunburn does not happen. Tan on black skin is almost invisible.

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TANNING IS A PROTECTIVE RESPONSE TO UV - STRESS. Tanning occurs as an additional pigmentation of the skin as a result of increased melanin synthesis in response to the dangerous exposure to ultraviolet rays. The trouble is that it does not appear as a preventive protection against UV rays, but in response to the “SOS” signals of skin cells about their direct damage either by the UV rays themselves or by free radicals, the number of which increases when they are in the open sun in the skin.

Excessive exposure to solar radiation leads the skin to severe oxidative stress and severe damage to cellular and intercellular vital structures, and only then tan, as the desire of the skin cell of the skin to prevent the further destructive effects of solar radiation on our body and protect us from the penetration of harmful UVA and UVB rays. UVB spectrum.

So tanning is not at all a sign of beauty and health, on the contrary, it is evidence that our body has suffered serious damage, unfortunately, often irreparable.

WANT TO KNOW ABOUT THE NEGATIVE CONSEQUENCES OF THE ACTION OF UV - RAY ON SKIN IN DOSE CAUSING A TANNING? Here is a rough list:

1. Reduced immunity;

2. Burn, dermatitis, allergies

3. Thickening of the stratum corneum with the inevitable coarsening of the surface relief;

4. Dehydration, feeling of dryness;

5. Loss of elasticity and elasticity;

6. Premature aging;

7. Cancer.

UV - SKIN PROTECTION. The skin has different protective mechanisms from the damaging effects of UV - rays. It is known that with increased skin insolation, the stratum corneum thickens. The thickness of the material in the path of the UV rays is extremely important for the efficiency of their absorption. Thus, completely transparent glass with a thickness of 0.1 mm freely lets in the sun rays of the entire UV - spectrum, and glass with a thickness of 3 mm is transparent only for the rays of the UVA - spectrum and completely absorbs the rays of the UVB.

The fact that the skin thickens under the influence of UV rays, protecting our body, is wonderful! But do not forget about the aesthetic effect of such protection: the skin becomes coarser, stiffer, less elastic, the relief of its surface is heterogeneous, all its flaws appear - wrinkles, pores, irregularities.

In the hydrolipid layer on the surface of the epidermis is urocanic acid, which gets there with sweat. It is much less known as a UV filter, although, like melanin, it perfectly absorbs UV rays. But the only really effective protection against their destructive penetration into the living tissues of the epidermis and dermis is provided only by melanin, which not only can filter up to 90% of UV rays, but is also a powerful antioxidant.

Melanin Melanin Razn. Man has two types of melanin: eumelanin and pheomelanin. “Correct” melanin - with the prefix “eu”. That he is one of the most effective natural UV - filters and antioxidants. It has a black and brown color. The one with the prefix “feo” is ineffective. His color is yellow-red.

In accordance with the evolutionary theory, eumelanin appeared in humans after the loss of hair on the body, pheomelanin is much older. As the cradle of humankind is Africa, people who have acquired brown or black skin have survived evolutionarily on this hot and sunny continent due to the natural selection for high eumelanin content. People with white skin often died early from melanoma, an extremely malignant skin cancer, as is the case today with albinos Africans. Those who gradually migrated to the north, mastering new spaces for living, found themselves in a colder climate, which led to the need for most of the year to wear clothes that protected them from UV rays. And from the point of view of UV insolation, the atmosphere in temperate latitudes is much more benign. White people in northern latitudes had no particular need for eumelanin.

DIFFICULT TO ACHIEVE PERFECT IN A FEW DAYS. The ratio of eu- and pheo-melanin is individual for each of us. Most of all are pheomelanin and there is practically no eumelanin in red or blond white-eyed, blue-eyed people (phototype I). Therefore, stay in the open sun of all the people living on our planet, the most dangerous for them. Additionally, pheomelanin produced by the cells of their skin is not effective for filtering UV rays. Quality eumelanin prevails in the skin of black Africans. From the point of view of protection from UV radiation, they are evolutionarily more advanced than members of the white race. In our desire to change the color of the skin to a darker one in a few days, sunbathing and sometimes burning on the beach, not reaching the evolutionary perfection that nature has been creating for millions of years, we only harm our health in the illusory pursuit of questionable values ​​imposed by society.

TERRIBLE LEADERSHIP OF THE SOLAR CONTINENT. Direct evidence of the danger of sunburn is the statistics of melanoma - skin cancer, the most malignant among all known - in Australia. After Europeans, poorly protected from UV rays, mastered Australia and successfully developed the beach industry in the 20th century, which continues to flourish to this day, this sunny continent has taken a dreadful 1st place on the planet in terms of the number of melanoma per capita.

So is it worth it to burn? It is clear that black Africans do not tend to turn a little more black. But for some time white-skinned Europeans, namely from the middle of the last century, are terribly preoccupied with acquiring tan - for some reason they are not satisfied with their skin color. I would like us to think and realize that the tan is not a sign of health and beauty, but a protective reaction to the damaging and sometimes irreversible effect of UV rays on our body. Perhaps, then we will stop tanning under the pressure of public opinion, that is, to acquire a darker skin that is not inherent to us. And in response to a question from those around you after the vacation that was spent at sea, “Why did you not get a tan at all?�� We will answer with a smile: Why? Light skin is so beautiful! No less than dark.

Marina Kryuchkova