大学英语 综合教程 5 第二单元 let’s go veggie! 分段解析.ppt

Let’s go veggie!
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Human Nutrition:
Human beings require food to grow, reproduce, and maintain good health. Without food, our bodies could not stay warm, build or repair tissue, or maintain a heartbeat. Eating the right foods can help us avoid certain diseases or recover faster when illness occurs. These and other important functions are fueled by chemical substances in our food called nutrients. Nutrients are classified as carbohydrates, proteins, fats, vitamins, minerals, and water.
When we eat a meal, nutrients are released from food through digestion. Digestion begins in the mouth by the action of chewing and the chemical activity of saliva, a watery fluid that contains enzymes, certain proteins that help break down food. Further digestion occurs as food travels through the stomach and the small intestine, where digestive enzymes and acids liquefy food and muscle contractions push it along the digestive tract. Nutrients are absorbed from the inside of the small intestine into the bloodstream and carried to the sites in the body where they are needed. At these sites, several chemical reactions occur that ensure the growth and function of body tissues. The parts of foods that are not absorbed continue to move down the intestinal tract and are eliminated from the body as feces.
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人类需要的食物，生长，繁殖，保持身体健康。没有食物，我们的身体无法保暖，建设或修复组织，或维持心跳。吃正确的食物可以帮助我们避免某些疾病或疾病发生时，恢复更快。这些和其他重要的功能是加剧了在我们的食物称为营养素的化学物质。养分被列为碳水化合物，蛋白质，脂肪，维生素，矿物质和水。        当我们吃个饭，营养物质被释放出来，通过消化食物。开始由消化咀嚼行动和唾液，水样液体，含有酵素，可帮助分解食物中的某些蛋白质的化学活性的嘴。进一步消化食物时，通过胃和小肠，消化酶和氨基酸的食物和肌肉收缩液化推动它沿着消化道传播。养分的吸收从小肠进入血液，并进行内部在需要它们的地方机构的网站。在这些网站，一些化学反应发生，确保增长和身体组织的功能。那未被吸收继续向下移动肠道，并从粪便排出体外，作为食品的部分。
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Vegetarianism and health:
People have adopted vegetarian diets based on scientific studies showing that diets high in fatty animal foods may contribute to the early development of disease, including obesity, coronary artery disease, high blood pressure, diabetes mellitus, and colorectal cancer. The United S