200088.vtt
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WEBVTT
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Peristalsis is a series of wave-like muscle contractions
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that move food through the digestive tract.
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It starts in the esophagus
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where strong wave-like motions of the smooth muscle
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move balls of swallowed food to the stomach.
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There, the food is churned into a liquid mixture called chyme
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that moves into the small intestine where peristalsis continues.
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Stretching out a piece of intestine
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will make it easier to see the wave-like motion.
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The motion mixes and shifts the chyme back and forth.
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This lets the bloodstream absorb nutrients
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through the walls of the small intestine.
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In the large intestine peristalsis helps water
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from undigested food be absorbed into the blood stream.
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Then, the remaining waste products
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are excreted through the rectum and anus.