WEBVTT - BrainStuff Classics: How Do Our Bones Grow?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff, Lauren

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<v Speaker 1>bogel Bomb here with another classic from our archives. If

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<v Speaker 1>you're anything like me, you went through a phase or

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<v Speaker 1>are still in a phase where you've been fascinated by

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<v Speaker 1>the idea that you've got a skeleton living inside you

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<v Speaker 1>all the time. So in this episode we talked about

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<v Speaker 1>how our bones grow. Hey brain Stuff, Lauren Bogelbomb here.

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<v Speaker 1>We all know that you are what you eat, but

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<v Speaker 1>how exactly do the things that you eat get turned

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<v Speaker 1>into pieces of you? I'm thinking of bones in particular here.

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<v Speaker 1>The foods we humans consume are soft, especially compared to

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<v Speaker 1>other animals diets, but from them our bodies build strong,

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<v Speaker 1>hard materials like fingernails, tooth enamel, and bones. So how

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<v Speaker 1>do we do it? How do we soft fleshy humans

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<v Speaker 1>turn soft fleshy food into bones. Let's start off by

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<v Speaker 1>zooming in all the way down to the cellular level.

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<v Speaker 1>Your body builds bone tissue with the help of specialized

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<v Speaker 1>cells called osteoblasts. Osteoblasts work together forming a tight fit

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<v Speaker 1>layer over areas where bone needs to grow or be repaired.

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<v Speaker 1>These cells secrete a particular combination of amino acids, primarily

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<v Speaker 1>glycine and proleine. These amino acids are the building blocks

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<v Speaker 1>of proteins. Not unlike voltron, they fold up with each

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<v Speaker 1>other into something more than the some of their parts,

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<v Speaker 1>though in this case it's not a space faring super robot,

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<v Speaker 1>but strong triple helix threads of protein. Your cells get

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<v Speaker 1>these amino acids from the foods that you eat. Meat, fish, dairy,

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<v Speaker 1>and lagumes contain both glycine and proline, and you can

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<v Speaker 1>also get proline from stuff like gelatine and cabbage. Once

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<v Speaker 1>your osteoblasts secrete the immuno acids and they come together

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<v Speaker 1>to form the protein threads, enzymes give those threads a

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<v Speaker 1>stabilizing polish. Vitamin C helps those enzymes work. Without it,

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<v Speaker 1>the threads can't come together to form bone tissue correctly.

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<v Speaker 1>That's what happens in scurvy, and it's one of the

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<v Speaker 1>reasons why you should eat some fruit sometimes. Cantelope, citrus, kiwi, mango,

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<v Speaker 1>and berries are all good sources. The thus stabilized threads

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<v Speaker 1>are molecules of what's called collagen, which is the most

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<v Speaker 1>abundant protein in the animal kingdom. Collogen molecules pack together

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<v Speaker 1>into long, thin fibers called fibrils. In there many types

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<v Speaker 1>fibrals create these scaffolding that bodily tissues are built upon,

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<v Speaker 1>from your corneas to your blood vessels to your skin.

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<v Speaker 1>They're sturdy and kind of flexible, like steel beams in architecture.

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<v Speaker 1>They're also relatively light weight. Adult human bones are about

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<v Speaker 1>ten percent collagen by mass, but if your bones were

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<v Speaker 1>collagen fibrils alone, you'd beat sentient silly putty. So to

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<v Speaker 1>add further support, your osteoblasts guide deposits of a strengthening

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<v Speaker 1>layer of mineral crystals along the fibrils, like pouring concrete

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<v Speaker 1>over steel beams. The mineral in question here is the

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<v Speaker 1>compound calcium phosphate. Calcium and phosphate bond in your system

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<v Speaker 1>after you consume foods that contain them. For calcium, that's

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<v Speaker 1>dairy and soy products, eggs, sh and dark leafy greens.

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<v Speaker 1>For phosphate, it's dairy, whole wheat, nuts, and lagumes. And this,

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<v Speaker 1>along with dairy's amino acid content, is why milk and

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<v Speaker 1>fortified food ads talk about how these products help build

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<v Speaker 1>strong bones, though of course all the other foods we've

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<v Speaker 1>mentioned do too, This mineral coating is just a few

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<v Speaker 1>atoms thick, but it gives bones their stiff structure, and

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<v Speaker 1>it accounts for about sixty five percent of adults bone mass. Finally,

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<v Speaker 1>the coated fibrils get gummed together with a sort of

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<v Speaker 1>shock absorbing glue made up of spiraled collagen molecules that

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<v Speaker 1>can uncoil when stress is applied and then snap back

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<v Speaker 1>into shape. This helps prevent fractures at a molecular level.

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<v Speaker 1>If you connected your steel reinforced concrete beams with springs,

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<v Speaker 1>your skeleton also contains small amounts of magnesium, sodium, and bicarbonate,

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<v Speaker 1>plus a bunch of water, like twenty five percent by mass.

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<v Speaker 1>So how does your body get a hold of all

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<v Speaker 1>of these substances. Well, your digestive system is a fancy

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<v Speaker 1>molecular ar blaster. When you eat your teeth, gastrointestinal muscles

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<v Speaker 1>and digestive juices break food down to the point that

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<v Speaker 1>it's molecules already to be harvested. Your gut bacteria helped too.

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<v Speaker 1>There are some molecules that our cells can't process by themselves.

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<v Speaker 1>Our gut bacteria eat those molecules and poop out compounds

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<v Speaker 1>that our cells can process. The cells in the walls

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<v Speaker 1>of your small intestine pass everything that they can into

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<v Speaker 1>your bloodstream to be carried on to maker cells like

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<v Speaker 1>your osteoblasts. Today's episode is based on a videoscript that

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<v Speaker 1>I wrote for Houstoffworks dot Com. Brainstuff is production of

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<v Speaker 1>iHeartRadio in partnership with Houstoffworks dot Com, and it's produced

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<v Speaker 1>by Tyler Clang. Four more podcasts from my heart Radio.

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<v Speaker 1>Visit the iHeartRadio app, Apple Podcasts, or wherever you listen

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