The beauty of ultraviolet rays in sunbathing

180 1 year, Little discovered that there is an invisible light besides violet light in visible light, which we call ultraviolet light. Its wavelength is the shortest, but its biological function is the most active. Almost all ultraviolet rays irradiated to human body are absorbed by epidermal tissue, which can cause a series of physiological changes.

1. dyeing

After several days of repeated ultraviolet irradiation or a large amount of skin irradiation at one time, the skin gradually appears pigmentation and is dark brown. This is because there is a layer of basal cells in the epidermis, which contains "melanogen". Under the action of ultraviolet rays, "melanogen" turns into a black cord and deposits on the surface of sunburned skin. The precipitated pigment can absorb more light and quickly convert it into heat energy, thus stimulating sweat gland secretion.

2. Calcium and phosphorus metabolism

Normal calcium and phosphorus metabolism is of great significance to prevent osteoporosis, osteomalacia, infantile rickets, tuberculosis, fracture and hypertension in the elderly. The normal metabolism of calcium and phosphorus in human body depends on the participation of vitamin D. If vitamin D is deficient, even if there is enough calcium and phosphorus in the body, it cannot be fully absorbed and utilized. Usually vitamin D is not only supplemented by food, but also synthesized by related substances in the skin. 7- dehydrocholesterol in the human body will be converted into vitamin D after being irradiated by ultraviolet rays in the sun.

Step 3 disinfect

Ultraviolet rays with a certain intensity have bactericidal effect. Scattered ultraviolet rays can weaken the vitality of bacteria and viruses and inhibit their reproduction; Direct ultraviolet rays can directly kill bacteria and viruses. For example, mycobacterium tuberculosis can survive in dark and humid places for several months, but it will die after being exposed to the sun for several hours: typhoid bacilli can be killed in two hours under direct sunlight. Therefore, basking in the sun indoors and drying bedding frequently can reduce the occurrence of diseases and be beneficial to health and longevity. The germicidal ability of ultraviolet rays is related to wavelength, and the fastest absorption of bacteria is 253.7 nm. So we often use this wavelength as an ultraviolet tube for disinfection.

The principle of ultraviolet sterilization is very complicated. First, it will cause protein degeneration of bacteria, leading to death. Ultraviolet radiation will also reduce the role of some enzymes, make the oxidation ability of bacteria disappear, and hinder growth and reproduction. In addition, it is also related to the growth stage, growth environment and ultraviolet radiation intensity of bacteria.

4. Health care function

After the human body is irradiated by ultraviolet rays, the activity function of the central nervous system is strengthened, which can promote the body's metabolism and improve the body's immunity and disease resistance. Pigmentation caused by ultraviolet radiation can thicken the stratum corneum, enhance the skin's defense ability, and play a certain role in preventing and reducing the occurrence of skin diseases such as miliaria, furuncle and folliculitis.

5. Erythema

After receiving a certain amount of ultraviolet radiation, the human body can decompose the protein of skin cells and turn histidine into histamine and special substances similar to histamine. It can dilate and congest the blood vessels of the skin and form erythema in the incubation period of several hours. This ultraviolet erythema has many functions, such as anti-inflammatory, anti-neuralgia, anti-allergic, accelerating blood flow, enhancing metabolism, increasing gastric acid secretion, stimulating appetite, improving skin disease resistance and so on. It can promote the regeneration of connective tissue and accelerate the healing of wound ulcer surface.

Note: The two kinds of ultraviolet rays in sunlight are the most harmful to human body.

Sunlight is made up of different light waves. The latest research shows that two kinds of light in the sun can cause serious skin damage and even skin cancer.

The University of California Institute of Health participated in the study. According to the college, the most dangerous thing in sunlight is ultraviolet B(UVB). The wavelength of ultraviolet B is relatively short, which is the main cause of skin tanning. If exposed to ultraviolet B for a long time, ultraviolet B will affect people's immune system and eventually lead to melanoma, basal cell carcinoma and squamous cell carcinoma.

Ultraviolet b mainly affects the surface layer of skin. The closer to the equator or the higher the altitude, the greater the intensity of ultraviolet UVB. In addition, in summer, the intensity of ultraviolet B is relatively high.

Compared with ultraviolet B, ultraviolet A(UVA) does less harm to people. The wavelength of ultraviolet A is relatively long. It mainly damages the connective tissue of the skin. Ultraviolet rays can lead to premature skin aging and skin cancer.

Researchers say that ultraviolet A is often used in beauty salons, mainly to make the skin darker. However, researchers say that ultraviolet A can cause cataracts and damage the retina. Although researchers still believe that ultraviolet B is more likely to make the skin tan, ultraviolet A is also one of the important factors that cause harm to people, and it can also lead to the malignant development of skin cancer.

Many sunscreen oils can block ultraviolet B, but for ultraviolet A, the effect is not very good. Moreover, ultraviolet A can also cause skin cancer, which is really worrying.

Researchers say that 65% of melanoma, 90% of basal cell carcinoma and squamous cell carcinoma are caused by ultraviolet (UV) radiation. Scientists are studying a new generation of sunscreen that can block all ultraviolet rays.

Precautions for sunbathing

Sunshine is good for our health, and we should fully enjoy its gift. The simplest way is sunbathing, commonly known as sunbathing. The human body is not only influenced by infrared rays, visible rays and ultraviolet rays contained in sunlight, but also by meteorological factors such as temperature and humidity in the air. Therefore, it can be said that sunbathing has many effects on health. In winter, the sun is located in the south, and the sun can only tilt. Ultraviolet rays are reflected a lot by the thick atmosphere. Only about 1/6 of ultraviolet rays reach the ground in summer, and even less at sunrise and sunset. Therefore, the sunshine in winter is especially valuable.

1. Sunbathing is best done outdoors. The windless weather in winter should be clean, flat and dry, with good surrounding greening, good air circulation and sunny weather, and the best soil fertility can avoid strong winds. Sunbathing is also suitable in mountainous areas and places close to natural water sources.

However, it should be noted that sunbathing should not be carried out on the asphalt floor, and it should also be avoided near the stone wall. For example, the asphalt floor will emit toxic substances when heated, which will pollute the skin and is not conducive to breathing. If the temperature is very low in winter, it can also be done indoors, but be sure to open the doors and windows to avoid the glass blocking the passage of ultraviolet rays.

2. Sunbathing time is usually 1 1 to 12 in winter and 9- 1 1 or 4-6 pm in summer. The length of time can be gradually increased from the initial 10 minutes to L-2 hours.

Sunlight is valuable, but exposure must be moderate. Especially when sunbathing, don't sleep on an empty stomach. You can expose your body properly. You should always change your body. You'd better wear a straw hat and sunglasses to protect your head and eyes. Also pay attention to prevent colds (heatstroke prevention in summer) and skin burns caused by excessive exposure.

4. Anyone suffering from hemorrhagic diseases, severe heart disease, uremia, active tuberculosis and other diseases should not spend more time in the sun. In addition, too strong solar radiation is easy to cause cataracts, actinic dermatitis, conjunctivitis and thermal regulation disorders, and special prevention should be strengthened.

5. Pay attention to self-reaction. When sunbathing shows symptoms such as rising body temperature, nausea, vomiting, headache, dizziness, loss of appetite or sleep disorder, the irradiation time should be stopped or shortened immediately.