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Speaker 1: Welcome to brain Stuff, a production of I Heart Radio.

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Speaker 1: Hey brain Stuff. I'm Lauren Volga Bam and this this

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Speaker 1: is another classic episode from our archives. I'm pretty sure

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Speaker 1: this one was originally written for our earstwhile YouTube series.

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Speaker 1: It's about how our skin protects us from the sun,

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Speaker 1: or tries to by making us tan and freckle. Hey

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Speaker 1: brain Stuff, Lauren vog O Bam. Here when the weather

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Speaker 1: is nice, I've been made to understand that some people

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Speaker 1: enjoy spending time outdoors where they're exposed to, among other things, sunlight.

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Speaker 1: Stuff in sunlight can make stuff in your skin produce

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Speaker 1: more pigment, which shows up as freckles or a tan.

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Speaker 1: But how why? Scientifically speaking, the skin freckling tan both

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Speaker 1: happen in your epidermis, which is the tough, resilient frosting

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Speaker 1: on our body's cake. Under normal circumstances, it protects and

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Speaker 1: helps hold in our precious, squishy insides. Your epidermis contains

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Speaker 1: a few kinds of cells, but the ones were primarily

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Speaker 1: concerned with here are the carrotino sites and the melano sytes.

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Speaker 1: Carrotino sites make up most of your epidermis. Their skin

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Speaker 1: cells that are maturing and getting pushed upward towards your

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Speaker 1: skin surface by new cell growth. Melano Sytes are specialized

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Speaker 1: cells that create pigmented proteins called melanin. And by the way,

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Speaker 1: they're not only found in our skin. Melano Sytes are

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Speaker 1: also at work in your eyes and hair, giving them

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Speaker 1: their color, and in your heart, inner ear, and brain

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Speaker 1: doing No one is really sure what conspiring to make

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Speaker 1: you enjoy reality television maybe, but in your skin, melanocytes

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Speaker 1: produce the pigments that help give your skin its tone.

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Speaker 1: Whatever color your skin is, it contains an average of

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Speaker 1: one thousand, two hundred melanosytes per square millimeter. Your genes

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Speaker 1: and various factors in your environment tell your melanocytes how

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Speaker 1: much melanin to produce and what types. One of those

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Speaker 1: environmental factors is ultraviolet radiation, probably from sunlight or maybe

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Speaker 1: from black lights at raves, and cellular biology is really complicated.

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Speaker 1: To paraphrase in Ego Montoya, I'm just going to sum up.

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Speaker 1: When certain types of ultraviolet photons pass into your skin,

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Speaker 1: as specifically into your carrotino sites there and smack into

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Speaker 1: molecules of your DNA, those photons cause minor damage that

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Speaker 1: sets off a chain reaction. The end result, your melano

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Speaker 1: sytes go into overdrive producing melanin particles. Your melano sytes

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Speaker 1: carefully pack those melanine particles into special organelles called melanosomes,

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Speaker 1: sort of like little intercellular shipping boxes. These melanan packages

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Speaker 1: moved to the very edges of the melano site, and

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Speaker 1: neighboring carrotino sites bite the melanosomes right out of the

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Speaker 1: cell and absorb them. It doesn't hurt the melanosyte. It

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Speaker 1: just sounds creepy because it is okay, so you catch

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Speaker 1: some sun. If your melano sytes and therefore your melanin

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Speaker 1: packed melanosomes are spread evenly around among your carrotino sites,

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Speaker 1: you can, But if your melanosytes are clustered together freckle.

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Speaker 1: Either way, the melanin particles absorb incoming UV radiation and

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Speaker 1: transform it into infrared radiation, which is just low level heat. Thus,

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Speaker 1: your delicate squidgy insides and your cells DNA are protected

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Speaker 1: from further UV damage Without frequency and exposure, Tans and

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Speaker 1: freckles fade over time because your caroteno sites don't last forever.

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Speaker 1: As new skin cells grow and mature, your old caroteno

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Speaker 1: sites are eventually pushed to the very surface of your skin,

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Speaker 1: where they become dehydrated and die. And that's right. These

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Speaker 1: cells on the surface of our skin, the ones that

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Speaker 1: we can see and touch, are actually dead, but it's

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Speaker 1: for a good cause. During the process of drying out

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Speaker 1: and dyeing, your caroteno sites become the strong, durable layer

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Speaker 1: that makes our skin so effective at keeping blood in

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Speaker 1: and germs out. And when your caroteno sites move on

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Speaker 1: to that big skin layer on the surface, they bring

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Speaker 1: any melanin that they've collected along with them. And when

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Speaker 1: those cells slough off through normal wear and tear, the

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Speaker 1: melanin goes to and your skin returns to its usual pigment,

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Speaker 1: which in my case is translucent like a deep sea shrimp.

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Speaker 1: Today's episode isn't based on an article, but was written

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Speaker 1: by me Lauren Vogelbaum when I was writing for house

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Speaker 1: Stuff works dot com. Brain Stuff is now a production

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Speaker 1: of iHeart Radio in partnership with how stuff works dot Com,

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Speaker 1: and it's produced by Tyler Clang. For more podcasts my

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Speaker 1: Heart Radio, visit the iHeart Radio app, Apple Podcasts, or

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Speaker 1: wherever you listen to your favorite shows.