General Knowledge - Basic General Knowledge - Discussion

UVB :

(a) UVB has a wavelength range from 290 nm to 320 nm.
(b) Because its wavelength is shorter than UVA it cannot pass through window glass.
(c) it causes tanning and is roughly 1000 times more likely than UVA to cause sunburn.
(d) However, it does helps the body with normal vitamin D production.
(e) the ozone layer is very effective at screening out UVB. For radiation with a wavelength of 290 nm, the intensity at Earth's surface is 350 million times weaker than at the top of the atmosphere.
(f) unlike UVA the intensity of UVB reaching the Earth's surface varies with the season. It is more intense in the summer than in the winter.
(g) its intensity varies with weather conditions and the time of day. It is more intense at midday than in the morning or late afternoon.
(h) it is also more intense at high altitudes and near the equator.
(i) it is known to be an important factor in the development of cataracts and the growth of 90% of skin cancers.
(j) you can protect yourself against the effects of UVB by using sunscreens containing a sun protection factor.

Sun light includes many type of radiations such that gamma rays, x-rays, ultra Violet rays, light rays, infrared rays, micro waves, radio waves, here gamma rays, x-rays, UV rays are much more harmful of certain wavelength, but these gamma and x-rays are filtered ozone layer, by a some chemical reaction called ozone filtration action, but UV rays of certain wavelength (which are harmful) are gets filtered, then remaining UV rays of less harmful wavelength rays are reaches the Earth, also up to morning 10:40 AM the harmful effect is zero (proved) on living things, so before that time those rays are touches the skin of animals, so the water content and Melanin oil content which is secreted by Mitochondria (called the power house of cell) in cells on skin under goes chemical reaction in the skin cells using UV rays boost the rate of reaction so that it gives energy, Vitamin-D, and water along with some urea (nitrogen content) and that water along with urea come out from the body as a waste, in this way UV rays helps our body in converting into Vit-D.

According to me, the correct answer is "C".

Ultraviolet (UV) rays from the sun do not convert skin oil into Vitamin D. The process of Vitamin D synthesis in the body involves UVB radiation from the sun interacting with a form of cholesterol present in the skin called 7-dehydrocholesterol.

When UVB rays penetrate the skin, they convert 7-dehydrocholesterol into pre-vitamin D3. Previtamin D3 is then converted into active Vitamin D3 (cholecalciferol) through a process that occurs within the body. This conversion is not related to skin oil.

It's important to note that while limited exposure to sunlight is necessary for the synthesis of Vitamin D, excessive exposure to UV rays can be harmful and increase the risk of skin damage, including sunburn and skin cancer. It's recommended to maintain a balance between sun exposure and protection by using sunscreen and taking other precautions as advised by healthcare professionals. Additionally, obtaining Vitamin D from dietary sources or supplements is also an option to ensure adequate levels.

Your body is able to produce its own vitamin D3 when your skin is exposed to the sun's ultraviolet rays, specifically ultraviolet (UVB) radiation. When UVB rays hit your skin, a chemical reaction happens: Your body begins the process of converting a prohormone in the skin into vitamin D. In this process, a form of cholesterol called 7-dehydrocholesterol (7-DHC), naturally found in your skin, absorbs the UVB radiation and gets converted into cholecalciferol. Cholecalciferol is the previtamin form of D3. Next, the previtamin travels through your bloodstream to your liver, where the body begins to metabolize it, turning it into hydroxyvitamin D, which is also known as 25-hydroxyvitamin D or 25(OH)D. The kidneys then convert the 25(OH)D into dihydroxyvitamin D, also called 1,25-dihydroxyvitamin D or 25(OH)2D -- this is the hormone form of vitamin D your body can use.

@Vanitha.

Actually there are three types of u.v. rays depending upon it's wavelength.. (u.v.A 320-400 NM) & (u.v.B 280-320 NM) & (u.v.C 200-280 NM) actually u.v..c is cut off by ozone layer while we get maximum exposure to u.v.A & u.v.B because it is closer to visible wavelength which we can see with our eyes. rainbow color.

Vitamin D3 is made in the skin with ultraviolet light of UVB type at wavelengths between 270 and 300 nm, with peak synthesis occurring between 295 and 297 nm, which is then converted into active form of Vitamin D which is necessary for body defense mechanism.

The body basically need daily sunlight to produce vitamin d since vitamin cannot be stored in body like fat & proteins.. so daily exposure is necessary in morning.

Vitamin D is a group of fat-soluble secosteroids. In humans Vitamin D is unique both because it functions as a prohormone and because when sun exposure is adequate the body can synthesize it (as Vitamin D3). Measures of the serum levels reflect endogenous synthesis from sun exposure as well as intake from the diet and it is believed that synthesis may contribute generally to the maintenance of adequate serum concentrations. The evidence indicates that the synthesis of vitamin D from sun exposure works in a feedback loop that prevents toxicity but, because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine for the amount of sun exposure required to meet vitamin D requirements.

Vitamin D is a fat-soluble vitamin which can provide for the body's needs in one of two ways. Through the action of sunlight on the skin, or through the major food sources of cod liver oil, cold-water fish, butter, and egg yolks. When the sun shines on the skin, the ultraviolet rays activate a form of cholesterol which is present in the skin, converting it to Vitamin D (1). Because the body can provide sufficient Vitamin D to meet its needs simply through exposure to sunlight, some feel it is not really a vitamin, but instead is a hormone.

Vit.D is fat soluble vitamin its chemical name is ergocalciferol (in plant source )& colicalciferol ( Animal source) its also called sunsine vitamin. sun light is most important source of vitamin D, its basically two form vit.D2 & vit.D3. vitamin D consumed with the help of Folic acid & calcium. vitamin D3 help bone &cartilage. if laking of vit D3 caused Rickets disease in baby.

Morning exposure of sunlight is good for our skin which activates vitamin D present in our body and there will be less exposure of UV rays so it doesn't harm to our skin. During day time it means from 11 to 3 excess of UV rays are exposed and they are harmful to our body. And its compulsion to have every vitamin that human need, and yes its the process of one of those vitamins to gain so.

Ozone layer either pass uv rays or stop them. Whats the meaning of filtered uv rays. Sunlight is filtered no doudt through ozone. Moreover uv rays are of short wavelength, if it penetrate in skin, it would cause skin cancer or may cause mutation in cells. Sunlight stimulate the formation of melanin pigment in the skin layers. Which is helpful in maintaining homeostasis of body.