Other people are predisposed to make melanin at a slower rate, which results in a lighter skin color. A person’s rate of melanin production can be influenced by exposure to UV radiation. Exposure to UV radiation will increase melanin production and produce a tanned appearance in lighter-skinned individuals.
Why is UV radiation harmful to fair-skinned people?
Fair-skinned individuals are exposed to higher “realized” doses of UV radiation in the skin and UV-induced mutations, which directly contribute to melanoma and other forms of skin cancer, accumulate over time. Much UV-induced pathology, including skin cancer, can be avoided by minimizing UV exposure (Table 2). Table 2 UV Safety Tips. Sun exposure
How does UV exposure affect skin cancer risk?
Fair-skinned individuals are exposed to higher “realized” doses of UV radiation in the skin and UV-induced mutations, which directly contribute to melanoma and other forms of skin cancer, accumulate over time. Much UV-induced pathology, including skin cancer, can be avoided by minimizing UV exposure (Table 2).
Why is UV radiation classified as a carcinogen?
Abstract UV radiation (UV) is classified as a “complete carcinogen” because it is both a mutagen and a non-specific damaging agent and has properties of both a tumor initiator and a tumor promoter. In environmental abundance, UV is the most important modifiable risk factor for skin cancer and many other environmentally-influenced skin disorders.
How does solar UV radiation penetrate the skin?
Solar UV radiation can be subdivided into UVA, UVB and UVC components, however because of atmospheric ozone that absorbs UVC, ambient sunlight is predominantly UVA (90%–95%) and UVB (5%–10%). UV penetrates the skin in a wavelengthdependent manner. Longer wavelength UVA penetrates deeply into the dermis reaching well into the dermis.
What is the relationship between UV radiation and melanin?
In most people, UV rays activate a chemical in the skin called melanin. This is the skin's first defense against the sun. Melanin absorbs the dangerous UV rays that can do serious skin damage. This is the process that gives you a tan.
What does UV radiation do to the skin?
UV rays, either from the sun or from artificial sources like tanning beds, can cause sunburn. Exposure to UV rays can cause premature aging of the skin and signs of sun damage such as wrinkles, leathery skin, liver spots, actinic keratosis, and solar elastosis.
What is the connection between natural selection UV radiation and skin pigmentation?
Human skin pigmentation is the product of two clines produced by natural selection to adjust levels of constitutive pigmentation to levels of UV radiation (UVR). One cline was generated by high UVR near the equator and led to the evolution of dark, photoprotective, eumelanin-rich pigmentation.
Why is dark skin selected for in areas of high UV radiation?
Generally, it can be stated that in geographical areas of high UV-exposure there is selection for dark skin to prevent sunburn, skin cancer and photolysis of folic acid (48, 49) and to protect the sweat glands to prevent abnormal thermoregulation (50).
Does melanin protect against UV?
Melanin helps block out damaging UV rays up to a point, which is why people with naturally darker skin are less likely to get sunburned, while people with lighter skin are more likely to burn. Sunburns can increase your risk of skin cancer, including melanoma.
Does melanin absorb UV light?
The large system of freely-moving (delocalized) electrons that gives melanin its color is also what allows it to absorb UV light.
What determines skin color?
pigment melaninMany factors influence the color of people's skin, but the pigment melanin is by far the most important. Melanin is produced by cells called melanocytes in the skin and is the primary determinant of skin color in people with darker skin.
How is skin Colour biologically determined?
Skin colour is primarily determined by genetic inheritance but exposure to sunlight also alters skin colour. There are six skin types, fair skin that always burn, dark skin that never burns and everything in between. Melanin is the pigment that determines skin colour as well as hair and eye colour.
Why did humans develop dark skin?
Evolution. Due to natural selection, people who lived in areas of intense sunlight developed dark skin colouration to protect against ultraviolet (UV) light, mainly to protect their body from folate depletion. Evolutionary pigmentation of the skin was caused by ultraviolet radiation of the sun.
Does your skin get lighter if you avoid the sun?
Keeping out of the sun will keep skin from producing extra melanin, which may help the pigment return to a paler state. If your skin is naturally dark, however, staying out of the sun won't do much. Keep out of the sun as much as possible, especially in the late morning and afternoon.
Does the sun make your skin darker permanently?
A tan is never permanent because skin naturally exfoliates itself over time. This causes the tanned skin to flake off. New cells are formed and older skin sloughs off.
Which Colour of the skin will give greater protection from the sun rays?
Which colour of the skin will give greater protection from the sun's rays ? Solution : The darker skin would offer greater protection from the sun. s rays. As darker in contains more amount of melanin, therefore such skin will have better protective value against the ultraviolet rays of the sun.
What are 5 harmful effects of UV rays on humans?
Depending on the amount and form of the radiation, as well as on the skin type of the individual exposed, ultraviolet radiation causes erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity.
How deep does UV light penetrate skin?
between 20 and 150 μmWithin the solar radiation spectrum [11], UV is an electromagnetic wave with a wavelength between 10 and 400 nm, corresponding to a penetration depth between 20 and 150 μm in the human skin [12] .
How long does it take for the sun to damage your skin?
It only takes 15 minutes in the sun to damage your skin.
How can we protect our skin from UV rays?
How to protect your skin from the sunUse sunscreen every day, even if it's cloudy.Apply at least one ounce of sunscreen (enough to fill a shot glass) at least 15 to 30 minutes before going outside. ... Choose a broad spectrum sunscreen that protects against both UVA and UVB radiation. ... Reapply sunscreen every two hours.More items...•
What is the main factor that determines skin complexion and UV sensitivity?
Melanin . The amount and type of epidermal melanin is the main factor that determines skin complexion and UV sensitivity. Melanin is a large bio-aggregate composed of subunits of different pigment species formed by oxidation and cyclization of the amino acid tyrosine [10,25,26] (Figure 2).
How does UV affect the body?
Abundant in the environment, UV contributes to a variety of skin maladies including inflammation, degenerative aging and cancer [1]. Historically, humans have been exposed to UV radiation mainly through occupational exposure to sunlight. Recreational UV exposure, however, has increased dramatically in recent years because of outdoor leisure activities and to purposely tan for cosmetic purposes [42,43]. Being a component of the electromagnetic spectrum, UV photons fall between the wavelengths of visible light and gamma radiation. UV energy can be subdivided into UV-A, -B and -C components based on electro physical properties, with UV-C photons having the shortest wavelengths (100–280 nm) and highest energy, UV-A having the longest (315–400 nm) but least energetic photons and UV-B falling in between (Figure 3). Each component of UV can exert a variety of effects on cells, tissues and molecules.
Where are melanocytes found?
Melanocytes are also found in hair follicles to impart pigment to nascent hair [12]. Dermal melanocytes can be found in nevi (moles). Because melanocytes are the only source of pigment in the skin, inherited pigmentary defects such as albinism tend to be caused by melanocytic genetic defects [10,13].
What is the biosynthesis of melanin?
Melanin Biosynthesis. Melanin, a large bioaggregate composed of pigmented chemical species, is found in two major forms: the brown/black highly UV-protective “eumelanin” pigment and the red/blonde UV-permeable “pheomelanin”. Both eumelanin and pheomelanin are derived from the amino acid tyrosine.
What is the epidermis?
The epidermis, of ectodermal origin, is the outermost layer and serves as the body’s point of contact with the environment . As such, epidermal biological and physical characteristics play an enormous role in resistance to environmental stressors such as infectious pathogens, chemical agents and UV [1–6].
What are the three most common types of skin cancer?
UV is epidemiologically and molecularly linked to the three most common types of skin cancer, basal cell carcinoma, squamous cell carcinoma and malignant melanoma, which together affect more than a million Americans annually. Genetic factors also influence risk of UV-mediated skin disease.
Is tanning harmful to UV?
Tanning can be addictive, leading to frequent and significant UV exposure over time [50–52], and since tanning often appeals to adolescents and young adults, tanning patrons’ UV history can be significant for many years [53]. Indoor tanning clearly increases incidence of skin cancers [54,55].
What are the signs of skin cancer?
The most common warning sign of skin cancer is a change in the appearance of the skin, such as a new growth or a sore that will not heal.
Where is skin cancer most common?
The incidence of skin cancer is relatively very high in Australia and New Zealand and among fair skinned people. But, no matter where you live, and what color you are, you need to take the following steps to protect yourself from the sun:
Should children be encouraged to use sunscreen?
Hence, children should be encouraged to use sunscreen, wear appropriate clothing and avoid both the strongest midday sun levels and indoor tanning.
Is skin visible to the naked eye?
Skin is a very important part of our body, perhaps the largest organ and it is impossible to imagine a person without any skin. Ultraviolet radiation (UVR) is the part of the electromagnetic spectrum with wavelengths between 100 and 400 nanometers (shorter than visible light) which makes it invisible to the naked eye.