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Our story is about a girl named Iris.

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Iris is very sensitive.

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So much that she is always in tears.

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She cries when she's sad,

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when she's happy,

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and even tears up when things just get to her.

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She has special lacrimal glands to make new tears

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and special tubes, called lacrimal puncta,

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to drain old ones away.

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And she cries so much that she goes through

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ten ounces of tears per day,

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30 gallons a year!

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In fact, if you look closely,

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you'll see that she's crying a little bit all the time.

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The basal tears that Iris constantly produces

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form a thin coating of three layers,

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that cover her and keep dirt and debris away.

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Right next to Iris is the mucus layer,

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which keeps the whole thing fastened to her.