9781422280355

Words to Understand

absorb: a chemical or physical process of taking one substance into another. calorie: a measure of energy in food. carbohydrates: molecules from which animals derive energy; includes sugars, starches, and cellulose. gastrointestinal (GI) tract: a series of linked organs that form a long tube from the mouth to the anus; also called the digestive tract. ingest: to bring a substance into the body. nutrients: substances in food that provide the essential materials to support life and growth. peristalsis: a wave-like movement created when muscles of the intestines continually contract and relax. proteins: complex molecules made from long chains of smaller molecules called amino acids; used to build and repair cells in the body, and for energy. sphincter: a ring-like muscle at the opening of a hollow organ that tightens or relaxes to close or open the hole.

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