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Speaker 1: Welcome to brain Stuff from How Stuff Works. Hi, brain

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Speaker 1: Stuff listeners. I'm Lauren voc Obam, and today's episode is

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Speaker 1: another brain Stuff classic from our former host, Christian Sagar.

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Speaker 1: We're delving into perhaps the most important biological question known

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Speaker 1: to humankind. What are eyeboggers? A brain stuff Christian Sager Here,

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Speaker 1: Today's question is what our eyeboggers. If you've ever had

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Speaker 1: to wipe gunk out of the corner of your eyes,

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Speaker 1: it's not because you were visited by the Sandman or

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Speaker 1: a magical mucus ferry. Nope, we live in a cruelly

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Speaker 1: mundane universe, and I'm sorry if I'm the first to

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Speaker 1: break it to you, but eyeboggers are a build up

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Speaker 1: of the pre corneal or basil tier film that coats

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Speaker 1: and protects your eyes, plus any foreign particles it catches.

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Speaker 1: This tier film is just three micrometers thick, which is

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Speaker 1: less than half the diameter of a red blood cell.

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Speaker 1: But it's made up of three components, the mucin, the aqueous,

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Speaker 1: and the lipid. These are indistinct layers of stuff that

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Speaker 1: your body produces. The aqueous component is the operative one.

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Speaker 1: It nourishes, lubricates, and flushes your eyes cells. It also

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Speaker 1: smooths over microscopic lumps and bumps on the surface of

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Speaker 1: your eyes, creating a smooth lens that optimizes light transfer

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Speaker 1: into your retina. The other two components are a support

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Speaker 1: system for the aqueous one. The musing component underneath it

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Speaker 1: allows it to temporarily stick to your eye, and the

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Speaker 1: lipid component outside it holds it in place so that

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Speaker 1: you're not just you know, crying constantly. So closest to

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Speaker 1: your corneal surface cells, you've got the musing component of

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Speaker 1: the tear film. Mucins are the proteins that make mucus slimy.

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Speaker 1: They're important in your eyes because corneal cells. Your corneal

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Speaker 1: cells need water and water soluble new reents, but your

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Speaker 1: corneal cells, unhelpfully are hydrophobic, meaning they repel water like

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Speaker 1: microscopic little ducks. Mucin helps out by latching onto your

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Speaker 1: corneal cells, specifically via adhesive molecules called glycocalyx that grow

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Speaker 1: on the cell's surface, and mucans are hydrophilic, meaning that

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Speaker 1: they grab onto water molecules. Next up the aqueous component.

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Speaker 1: As you may have guessed from the name, this layer

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Speaker 1: is made up of about water plus two percent water

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Speaker 1: soluble stuff at any given time. Part of that two

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Speaker 1: percent is things your corneal cells need, like electrolytes, oxygen,

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Speaker 1: and antibacterial enzymes, and part is the cell's waste. There

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Speaker 1: are also some musans floating around in there, and usually

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Speaker 1: some dust debris, and you know sun dream microbes. Finally,

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Speaker 1: topping it all off, you've got the lipid component a

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Speaker 1: k a. The me bum. It's made mostly of wax

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Speaker 1: and cholesterol esters. These esters are slick, hydrophobic substances that

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Speaker 1: our bodies used to lubricate and waterproof various tissues in

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Speaker 1: the tear film. They float on top of the aqueous layer,

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Speaker 1: helping our eyelids glide easily over our eyes. They also

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Speaker 1: provide a strong surface tension for our basil tears. Without

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Speaker 1: the lipid layer, our tear film would drip right off

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Speaker 1: our eyeballs. But how do these components become eyeboggers and

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Speaker 1: why do they accumulate in the inner corners of your eyes. Well,

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Speaker 1: I'm gonna tell you. When you blink, your entire eyelid

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Speaker 1: doesn't close simultaneously. It shuts like a clapboard from the

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Speaker 1: outer corners of your eyes inward towards your nose, your

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Speaker 1: tear film gets pushed along by that motion. Upon reaching

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Speaker 1: the inner corner of your eye, most of the film

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Speaker 1: drains out through the tear ducts, which empty into your

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Speaker 1: nasal cavity, and some of the film, the mucin and

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Speaker 1: oils and debris, can clump together and get stuck. When

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Speaker 1: enough of that builds up, it forms the goop known

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Speaker 1: as eyeboggers, and when it accumulates and dries overnight because

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Speaker 1: you're not blinking it away, it forms the crusty gunk

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Speaker 1: known as sleep or SAM. Today's episode was produced by

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Speaker 1: Tyler Clang and written by me for brainstuffs YouTube series

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Speaker 1: in the Way Back. If you like our show and

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Speaker 1: also like not being naked, check out our merch store

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Speaker 1: at t public dot com slash brainstuff, and of course,

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Speaker 1: for more on this and lots of other gross but

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Speaker 1: fascinating topics, visit our home planet, how Stuff Works dot

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Speaker 1: com