WEBVTT - How Do Our Bones Grow?

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<v Speaker 1>Welcome to brain Stuff from how stuff works. Hey, brain Stuff,

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<v Speaker 1>Lauren Volga bomb. Here, we all know that you are

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<v Speaker 1>what you eat, But how exactly do the things that

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<v Speaker 1>you eat get turned into pieces of you? I'm thinking

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<v Speaker 1>of bones in particular here. The foods we humans consume

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<v Speaker 1>are soft, especially compared to other animals diets. But from

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<v Speaker 1>them our bodies build strong, hard materials like fingernails, tooth enamel,

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<v Speaker 1>and bones. So how do we do it? How do

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<v Speaker 1>we soft fleshy humans turn soft fleshy food into bones.

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<v Speaker 1>Let's start off by zooming in all the way down

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<v Speaker 1>to the cellular level. Your body builds bone tissue with

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<v Speaker 1>the help of specialized cells called osteoblasts. Osteoblasts work together

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<v Speaker 1>forming a tight fit layer over areas where bone needs

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<v Speaker 1>to grow or be repaired. These cells secrete a particular

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<v Speaker 1>combination of amino acids, primarily glycine and proline. These amino

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<v Speaker 1>acids are the building blocks of proteins. Not unlike voltron,

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<v Speaker 1>they fold up with each other into something more than

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<v Speaker 1>the sum of their parts, though in this case it's

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<v Speaker 1>not a space bearing super robot, but strong triple helix

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<v Speaker 1>threads of protein. Your cells get these amino acids from

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<v Speaker 1>the foods that you eat. Meat, fish, dairy, and lagoons

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

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<v Speaker 1>proline from stuff like gelatine and cabbage. Once you're osteoblasts

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<v Speaker 1>secrete the immuno acids and they come together to form

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<v Speaker 1>the protein threads. Enzymes give those threads a stabilizing polish.

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<v Speaker 1>Vitamin C helps those enzymes work. Without it, the threads

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<v Speaker 1>can't come together to form bone tissue correctly. That's what

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

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<v Speaker 1>you should eat some fruit sometimes. Cantaloup, 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. Collagen molecules packed together

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<v Speaker 1>into long, thin fibers called fibrals. 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 lightweight. Adult human bones are about ten

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<v Speaker 1>collagen by mass, but if your bones were collagen fibrals alone,

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<v Speaker 1>you'd beat sentient silly putty. So to add further support

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<v Speaker 1>your osteoblasts, guide deposits of a strengthening layer of mineral

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<v Speaker 1>crystals along the fibrils, like pouring concrete over steel beams.

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<v Speaker 1>The mineral in question here is the compound calcium phosphate.

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<v Speaker 1>Calcium and phosphate bond in your system after you consume

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<v Speaker 1>foods that contain them. For calcium, that's dairy and soy products, eggs, shrimp,

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<v Speaker 1>and dark leafy greens. For phosphate, it's dairy, whole wheat, nuts,

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<v Speaker 1>and legumes, and this, along with dairy's amino acid content,

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<v Speaker 1>is why milk and fortified food adds talk about how

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<v Speaker 1>these products help build strong bones, though of course all

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<v Speaker 1>the other foods we've mentioned due to this mineral coating

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<v Speaker 1>is just a few atoms thick, but it gives bones

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<v Speaker 1>their stiff structure, and it accounts for about of adults

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<v Speaker 1>bone mass. Finally, the coated fibrils get gummed together with

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<v Speaker 1>a sort of shock absorbing glue made up of spiraled

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<v Speaker 1>collagen molecules that can uncoil when stress is applied, and

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<v Speaker 1>then snap back into shape. This helps prevent fractures at

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<v Speaker 1>a molecular level, like if you connected your steel reinforced

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<v Speaker 1>concrete beams with springs. Your skeleton also contains small amounts

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<v Speaker 1>of magnesium, sodium, and bicarbonate, plus a bunch of water

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<v Speaker 1>like by mass. So how does your body get ahold

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

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<v Speaker 1>a fancy molecular blaster. When you eat, your teeth, gastro

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<v Speaker 1>intestinal muscles and digestive juices break food down to the

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<v Speaker 1>point that it's molecules already to be harvested. Your gut

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<v Speaker 1>bacteria helped too. There are some molecules that are cells

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<v Speaker 1>can't process by themselves. Our gut bacteria eat those molecules

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<v Speaker 1>and poop out compounds that are cells can process. The

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<v Speaker 1>cells in the walls of your swall intestine pass everything

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<v Speaker 1>that they can into your blood stream to be carried

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<v Speaker 1>on to maker cells like your osteoblasts. Today's episode was

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<v Speaker 1>written by me and produced by Tyler Clang. For more

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<v Speaker 1>on this and lots of other reinforced topics, visit our

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<v Speaker 1>home planet Paw Stuff Works dot com