英語聽力文摘 新陳代謝到底是什么？

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The Parts of Metabolism

What is metabolism really? Statements like “he can eat a lot because he has a fast metabolism” are somewhat misleading.

Metabolism isn’t about the digestion of food in your stomach; it’s the name given to all of the chemical changes that occur in an organism’s tissue cells. There are basically two kinds of chemical changes that can occur; tissue matter can be built, or it can be broken down.

These processes are called anabolism and catabolism. More specifically, anabolism is responsible for an organism’s growth, its maintenance, and the repair of its tissues. So when you cut yourself and your skin scabs over and heals, you’re seeing anabolism at work. Or if you grow taller or wider, that’s also evidence of anabolism.

In order to build tissue and repair it, however, anabolism requires energy, as well as material with which to build. This energy and building material comes from the breaking down of larger, more complex material, a process called catabolism. As well as producing energy and building material, catabolism also breaks down material for excretion from the body.

Both anabolism and catabolism are necessary for survival and good health. Understanding these processes can help one make good decisions about exercise and diet. For example, when an athlete trains, her muscle fibers break down. However, the daily recommended amount of protein is all that is needed to meet the anabolic and catabolic needs of the body and thus repair muscles fibers.

新陳代謝是什么?“他很能吃是因?yàn)樗玛惔x很快”像這樣的說法有點(diǎn)誤導(dǎo)我們。

新陳代謝不是指食物的消化能力，而是指一種在組織細(xì)胞內(nèi)發(fā)生的化學(xué)變化。基本上可分為兩類化學(xué)反應(yīng)：合成或分解組織細(xì)胞。

這些過程叫作合成代謝和分解代謝。具體地說，合成代謝負(fù)責(zé)有機(jī)組織的數(shù)量增長，維護(hù)和修復(fù)。所以，當(dāng)皮膚割傷后會自動結(jié)疤愈合，這就是合成代謝在起作用?；蛘唛L高長胖，那也是合成代謝。

要建造和修復(fù)組織細(xì)胞，合成代謝需要能量和原料。而能量和原料就來自于分解更大，更復(fù)雜的細(xì)胞，這個過程就叫分解代謝。與合成反應(yīng)一樣，分解代謝需要的能量和原料來自于身體的分泌物。

合成和分解代謝在對于身體健康很重要。而了解這些過程可以幫助我們對運(yùn)動和飲食做出更好的決定。例如，運(yùn)動員訓(xùn)練時他的肌纖維會受損。所以每日推薦的蛋白質(zhì)就是身體合成和分解代謝所需的量，這樣才能修復(fù)肌纖維。