Why does the sun tan a person s skin

The principle of tanning, which is how melanin is formed.

When irradiated by heat or sunlight**, melanocytes located within the basal lamina are excited and activated, and they are present in a 10:1 ratio within the basal cells, which have a dendritic shape and shuttle through the epidermal cells. Melanocytes contain pigment granules, which synthesize melanosomes in the crude endoplasmic reticulum, which catalyzes a series of tyrosine reactions and generates melanin proteins, while tyrosinase will be inactive and act as a transporter to transfer them to keratinocytes.

The more melanin is transferred to keratinocytes, the darker the skin tone. After people of the same skin color are also exposed to the same amount of sunlight, why are some people tanned and some people's ** has not changed much? This has to do with a number of factors.

It mainly depends on how much melanin is produced and how much melanin is transferred to keratinocytes, that is, the more melanin is produced and the more it is transferred to keratinocytes, the darker the skin tone, and vice versa.

Because of the melanin of the human body. When the sun's ultraviolet rays have been exposed to ** for a long time.

Melanin will protect the health of the **, and it will appear to the appearance, and it will naturally be black.

In order to prevent ultraviolet rays from harming the human body, tissues produce melanin to block ultraviolet rays.

Because Grandpa Sun is in a bad mood and is too jealous of us, he makes us not beautiful.

Basking in the sun is only one of the factors that affect whiteness, and other factors that affect whiteness are:

1. The influence of eating habits:

**The internal supplement accounts for 70%, and the external care only accounts for 30%. Internal supplement is to do a good job of eating on the table, and nutrition should be balanced, because the highest level of nutrition is balance, to ensure the sufficient amount of collagen and elastic fiber. Some people often say that the beauty of water means to have good drinking habits.

Water absorption by human cells is an osmosis method, which can only be absorbed little by little. So drink the water slowly.

Drink frequently, drink when you are not thirsty, and ensure that you can drink 2500 ml of water every day to provide the body with enough body fluids for the delivery of nutrients and the excretion of waste. In addition, excessive intake of smoking, drinking, coffee, drugs and the top ten junk foods will accelerate the aging of **.

2. The influence of living habits:

Especially to have a good work and rest time, as the saying goes, sleep beauty, to have enough sleep time, adults must ensure seven hours of sleep every day, 10 o'clock at night - 3 o'clock is beauty sleep, during this time of good sleep, your skin will get twice the result with half the effort.

3. The impact of mental stress:

If the pressure from life, work and study is too great, it will lead to the production of free radicals in the body, which will also accelerate the formation of melanin, and will also affect the aging of the body. People who are stressed take two approaches: one is to exercise properly to help relieve stress, promote blood circulation and cell metabolism; The other is to choose skin care products with anti-free radical ingredients to effectively reduce the signs of facial aging.

4. The influence of time:

It is a natural phenomenon that the metabolism gradually slips from its peak with the passage of time. This requires the choice of skin care products for prevention or repair according to the relationship between ** and age to delay the aging process.

5. Influence of natural phenomena:

Including sunshine, temperature and sandstorm, all affect the ** condition. Choose sunscreen and moisturizers that can help protect your skin from these factors.

6. The impact of environmental pollution:

The chemical floats in the air increase, and it is easy to clog pores and even cause allergies when attached to **. In this case, choose a gentle cleanser to help cleanse the surface without damaging the sebum film and keeping the pores open. At the same time, acne, acne and other ** problems can naturally reduce the chance of occurring.

It will tan people. The reason why people get tanned is because of the melanin in the human body. When the ultraviolet rays in the sunlight irradiate the human body, in order to protect themselves, melanocytes will produce a large amount of melanin to absorb the sun's ultraviolet rays, thus turning black.

Although the sun is not very strong in the morning, it does not mean that ultraviolet rays are not present. All the sun's ultraviolet rays can penetrate the clouds and cause damage, but they are not easy to feel because the infrared rays are absorbed by the clouds when it is cloudy or cloudy.

The UV index varies from 0 to 15, and in general, the UV index is 0 at night and 15 in tropical, highland, and sunny days. When the ultraviolet index is higher, it means that the degree of erythema damage caused by ultraviolet radiation to the human body is more aggravated, and similarly, the higher the ultraviolet index, the greater the damage to ** in a shorter time.

So no matter what time the sun is, you should be prepared for sun protection.