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I'm going to take you on a journey
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into some hidden worlds inside your own body
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using the scanning electron microscope.
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These microscopes use a beam of electrons
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to illuminate things that are too small
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to be seen by the photons of visible light.
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And to put this in context,
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if you mentally divide one tiny millimeter
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into a thousand parts,
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each one of those parts is a micrometer,
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or micron for short.
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If you then divide one micron
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into another thousand parts,
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each one of those is a nanometer.
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And it's nanometers and microns
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that are the domain
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of the scanning electron microscope.
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So, let's start with something on the body
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that we can measure at about 100 microns wide,
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and that would be a human hair,
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which now you can see is covered with scales,
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just like all of our hairs,
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and in fact, just like all mammal hairs.
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We're going to plunge into the body now,
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and we've landed in the thyroid gland.
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Here we're looking at proteins
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that are being secreted into a storage chamber
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where they are going to develop
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into the mature thyroid hormones
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before being released into the body.
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And at this point you might be wondering
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if these colors are real.
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The answer is no.
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Electron images only happen in black and white.
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I often colorize my images for various reasons,
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but I don't change the structures,
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so the strucutres that you're seeing
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are all exactly as they were
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when I photographed them in the microscope.
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We're going to take a detour
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and zoom in on the heart muscle now.
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And the heart muscle has this curious structure
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that's kind of like corrugated cardboard.
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That's what allows the heart to expand and contract as it's beating.
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Let's go look at a lung with pneumonia.
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Here we've got a white blood cell
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poking around in an air sac,
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looking for something to clean out
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like a little vacuum cleaner.
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This is your immune systems at work.
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