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  • I sunburn super easily.

  • It just takes a few minutes sitting in my garden or on a beach, and then a couple days later my skin starts peeling off.

  • It’s seriously pretty grossnot exactly the effect most people go for when they sunbathe.

  • But, what really happens when you get a sunburn?

  • I’m Anna Rothschild, and this is Gross Science.

  • Most burns occur if you come in contact with something hot, like when you scald the roof of your mouth on a slice of pizza.

  • But sunburns are actually not caused by heat.

  • Sunlight is made up of a bunch of different types of radiation.

  • One of them is infrared radiation, which is primarily what makes sunlight feel hot.

  • But there’s also visible light, which allows us to see sunlight, and then there’s ultraviolet radiation.

  • Ultraviolet, or UV, radiation is what causes a sunburn.

  • It can wreak havoc on skin cells by disrupting important molecules, like DNA.

  • So, your body does its best to protect you from it.

  • When UV radiation hits your skin, pigments called melanin absorb it, and shield your DNA from harm.

  • Now, melanin is present in our skin cells all the timeit’s what gives your skin its particular color.

  • It’s created by special cells called melanocytes, which then distribute the melanin to other cells called keratinocytes.

  • Those are the most common cells in your outermost layer of skin.

  • When your skin is exposed to UV, the melanocytes ramp up their melanin production, and also transfer more melanin to the keratinocytes.

  • This happens to varying degrees based on your genetic makeup, but that’s why your skin might turn darker, or tan, if youre out in the sun for a while.

  • But, the melanin defense is far from foolproofregardless of how dark your skin is, or how much you tan, some UV rays can sneak past.

  • And when they do, they can damage your DNA.

  • This can actually happen in a few different ways.

  • Sometimes the radiation will directly zap your DNA, damaging it in just a trillionth of a second.

  • Alternatively, UV rays can do something more sinisterthey can actually turn your melanin against you.

  • The radiation can make your cells produce these harmful molecules called free radicals.

  • Now, this is a little bit complicated, but essentially the free radicals excite an electron in your melanin. I'm excited!

  • The melanin then bumps into your DNA and excites an electron there. I'm excited too!

  • which can cause the DNA to kink.

  • Regardless of how it happens, once your cells are damaged they start producing warning molecules, signalling that something bad is going on.

  • If enough cells produce the signal, your body will mount an inflammatory response, sending lots of different types of blood cells to the area to stop and repair the damage.

  • And it’s this influx of blood that causes the redness you typically see with a sunburn, depending on how light your skin is.

  • So, what about the peeling?

  • Well, your skin cells are shedding all the time without you noticing it.

  • You actually have stem cells in your skin that live for decades.

  • The stem cells produce layers of keratinocytes, which fall off and are replaced over time.

  • But those keratinocytes don’t mature properly when theyre damaged by UV.

  • So instead of flaking off inconspicuously, they all clump up and peel off together.

  • Now, your body actually has enzymes that repair a lot of the DNA damage caused by UV rays.

  • But, it can’t always repair all of it.

  • And if the damage isn’t fixed in one of your stem cells, you might have a real problem.

  • When those cells replicate, they might create a mutation at the site of the damage.

  • And depending on where the mutation occurs, this could lead the cell to become cancerous sometime down the road.

  • Remember, even if you don’t tend to burn, UV radiation can damage your DNA.

  • So if you know youre going to be out in the sun for a while, make sure youre covered up or wearing sunscreen.

  • For me, being outside and exploring the world is super important for my happiness, and excites my curiosity.

  • But it’s way more fun to go on an outdoor adventure without coming home to disgusting peeling skin.

  • Got a question about sunburns? Let me know in the comments.

  • And for more gross science, hit subscribe.

I sunburn super easily.

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B2 US melanin skin radiation dna sunburn damage

What Really Causes Sunburns?

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    羅紹桀 posted on 2016/09/11
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