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Speaker 1: Welcome to brain Stuff from house stuff works dot com,

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Speaker 1: where smart happens him Marcial Brain with today's question, is

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Speaker 1: it harmful to breathe on oxygen? You think, since we

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Speaker 1: need oxygen to live, that it would be okay to

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Speaker 1: breathe on oxygen, And it is okay for an hour maybe,

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Speaker 1: But if you breathe on oxygen for more than an hour,

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Speaker 1: it starts to cause big problems. So the short answer

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Speaker 1: is pure oxygen is generally bad and sometimes toxic. To

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Speaker 1: understand why, you need to go a little deeper. Your

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Speaker 1: lungs are basically a long series of tubes that branch

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Speaker 1: out from your nose and mouth and end in little,

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Speaker 1: thin walled air sex called a viola. I think of

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Speaker 1: soap bubbles on the end of a straw and you'll

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Speaker 1: understand a viola. Surrounding each aviolas are small, thin walled

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Speaker 1: blood vessels called pulmonary capillaries. Between the capillaries and the

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Speaker 1: aviolas is a thin wall about point five microns thick,

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Speaker 1: through which various gases in our case, oxygen, carbon dioxide,

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Speaker 1: and nitrogen can pass. When you inhale, the aviol i

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Speaker 1: fill with this air because the oxygen concentration is high

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Speaker 1: in the aviola and low in the blood entering the

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Speaker 1: pulmonary capillaries. Oxygen diffuses from the air into the blood. Likewise,

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Speaker 1: because the concentration of carbon dioxide is higher in the

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Speaker 1: blood that's entering the capillaries than it is in the

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Speaker 1: aviolar air, carbon dioxide passes from the blood to the avioli.

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Speaker 1: The nitrogen concentration in the blood and in the aviolar

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Speaker 1: air is about the same. The gases exchange across the

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Speaker 1: aviol or wall, and the air inside the avoli becomes

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Speaker 1: depleted of oxygen and rich in carbon dioxide. When you exhale,

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Speaker 1: you breathe out this carbon dioxide enriched oxygen pour air.

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Speaker 1: Now what would happen if you breathe on oxygen? In

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Speaker 1: guinea pigs exposed one oxygen at normal air pressure for

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Speaker 1: forty eight hours, fluid accumulates in their lungs and epithelial

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Speaker 1: cells lining the avola. In addition, the pulmonary capillaries get damaged.

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Speaker 1: A highly reactive form of oxygen called the oxygen free radical,

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Speaker 1: which destroys proteins and membranes and the epithelial cells, probably

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Speaker 1: causes this damage in humans, breathing one oxygen at normal pressure,

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Speaker 1: the same kind of thing happens. First, fluid accumulates in

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Speaker 1: the lungs that causes the gas flow across the aviol

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Speaker 1: to slow down, meaning that the person has to breathe

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Speaker 1: more to get enough oxygen. Then mucus starts to plug

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Speaker 1: up local areas of collapsed a viola. The oxygen trapped

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Speaker 1: inside these plugged a viola gets absorbed into the blood

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Speaker 1: and no gas is left to keep the plugged avio

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Speaker 1: l a inflated, so they collapse. Mucus plugs are normal,

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Speaker 1: but they're cleared by coughing, but coughing doesn't work when

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Speaker 1: the avioli have collapsed. If avoli become plugged when breathing

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Speaker 1: normal air, the nitrogen trapped inside the avial i keeps

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Speaker 1: them inflated and prevents this clogging from happening. The astronauts

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Speaker 1: in the Gemini and Apollo programs breathed oxygen for up

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Speaker 1: to two weeks with no problems, So what was going

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Speaker 1: on there? That's because the pressure inside the capsule was reduced.

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Speaker 1: Today astronauts who are using spacesuits are breathing pure oxygen

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Speaker 1: as well, but the pressure inside their suits is also

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Speaker 1: reduced to improve mobility. Do you have any ideas or

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Speaker 1: suggestions for this podcast? If so, please send me an

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Speaker 1: email at podcast at how stuff works dot com. For

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Speaker 1: more on this and thousands of other topics, go to

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