Foods undergo changes in the body in three major periods. Listed in order of occurrence, they are as follows.
食物在體內發生變化有3個主要階段，根據其發生的順序排列如下：
occurrence [ə'kʌrəns] n. 發生；出現；事件；發現
1.The period of digestion, which occurs in the alimentary canal;
1.消化階段，在消化管內進行；
alimentary [,ælɪ'mɛntəri] adj. 滋養的；食物的
2.The period of absorption, which takes place through the intestinal mucosa into the blood and lymph;
2.吸收階段，此時食物通過腸黏膜進入血液和淋巴；
mucosa [mjʊ'kosə] n. [解剖] 黏膜
3.The period of metabolism, which occurs within the tissues themselves.
3.新陳代謝階段，在組織內進行。
metabolism [mɛ'tæbəlɪzəm] n. [生理] 新陳代謝
From the foregoing it becomes obvious that following the processes of digestion and absorption further chemical changes take place in the tissues. These changes are known collectively as metabolism.
由此可見，在消化和吸收過程之後，組織內又發生了化學變化，統稱之為新陳代謝.
foregoing ['fɔrɡoɪŋ]
adj. 前述的；前面的；在前的
v. 發生在…之前；走在…之前（forego的ing形式）
collectively [kə'lektivli] adv. 共同地，全體地
Metabolism might be defined, then, as all the chemical changes which occur in foods after they are digested and absorbed.
因此，新陳代謝可定義為：食物被消化和吸收後，其中所發生的一切化學變化。
More specifically, however, the term metabolism refers to the sum total of the chemical changes absorbed foods undergo within the body cells, or more simply, it is the utilization of foods by cells.
然而，更確切地說，新陳代謝這一術語指的是吸收了的食物在體細胞內所發生的化學變化的總和，簡言之，就是細胞對食物的利用。
term [tɝm] n. 術語；學期； vt. 把…叫做
refer to 參考；涉及；指的是；適用於
utilization [ˌjuːtəlaɪ'zeɪʃn] n. 利用，使用
Digestion and absorption are merely two preliminary steps, or preparations, for this third food process, metabolism.
消化和吸收只是新陳代謝這一第三食物變化過程的前兩個步驟或準備階段。
preliminary [prɪ'lɪmɪnɛri] n. 準備；預賽；初步措施
Now a few words about the ways in which foods are metabolized.
下面簡單談談食物是怎樣產生代謝變化的。
As is known, foods consist of six kinds of chemical compounds: carbohydrates, fats, proteins, vitamins, inorganic salts (or minerals), and water.
眾所周知，食物包括六種化學化合物；碳水化合物、脂肪、蛋白質、維生素、無機鹽（即礦物質）及水。
compound ['kɑmpaʊnd] n. [化學] 化合物；混合物；複合詞
The body utilizes, or metabolizes, these substances in three ways:
人體通過三種方式對這些物質進行利用，即使其產生代謝。
1.Burns them as fuel to supply heat and mechanical energy;
1.將食物作為燃料燃燒以提供熱能和機械能；
2.Builds body tissues out of them (growth, or repair);
2.利用食物構成體組織（生長或修復）；
3.By means of them, maintains an internal environment favorable to normal cell activity and helps to regulate the cellular activity.
3.通過這些物質，保持一個適宜的內部環境，以便於細胞正常活動並幫助調節其活動。
favorable ['fevərəbl] adj. 有利的；良好的；贊成的，讚許的；討人喜歡的
The first two types of metabolism listed bear special names.The burning, or oxidation, of absorbed foods is called catabolism; the building of body tissues, anabolism.
所列的前兩類新陳代謝各有其專門名稱，吸收了的食物的燃燒即氧化，叫作分解代謝，而體組織的構成則叫作合成代謝。
catabolism [kə'tæbəlɪzəm] n. [生化] 分解代謝
anabolism [ə'næbl,ɪzəm] n. [生化] 合成代謝；同化，同化作用
Catabolism decomposes foods into simpler compounds (wastes) and in so doing produces two kinds of energy, heat energy and mechanical energy.
分解代謝將食物分解成更簡單的化合物（廢物），從而產生兩種能量，即熱能和機械能；
Anabolism, on the other hand, uses foods as building materials with which to construct new tissues and in so doing uses up energy.
而合成代謝則是以食物為建築材料以構造新的組織，從而把能量消耗盡。
In other words, metabolism can be roughly divided into a building-up, or constructive, phase known as anabolism and a breaking-down, or destructive, phase called catabolism.
換言這，新陳代謝可大體分為合成（即建設性）階段（叫作合成代謝）和分解（即破壞性）階段（叫分解代謝）。
Therefore, catabolism must occur in order that anabolism may occur.
因此，要有合成代謝就必須有分解代謝產生。
Animal and plant tissues (eaten as foods) are transformed by the miracle of anabolism into human tissues.
動植物組織（作為食物）通過奇妙的合成代謝轉換成人體組織。
Even more miraculous are the workers of this miracle, the body’s millions of microscopic cells, the world’s tiniest and most mystifying chemistry laboratories.
更不可思議的是這一奇蹟的創造者，即人體中成千上萬的微小細胞，也是就世界上最小而最令人驚奇的化學實驗室。
Basal metabolism refers to the chemical reactions occurring when the body is at rest.
基礎代謝指的是處於靜止狀態時體內所發生的化學反應。
These reactions are necessary to provide energy for maintenance of normal body temperature, breathing, heartbeat, muscle tone, and the other essential activities of the cells and tissues of the resting body.
這些反應是指人體處於靜態時，為了保證正常體溫、呼吸、心跳、肌肉的緊張度，以及細胞和組織的其他基本活動而提供能量所必需的。
The basal metabolic rate of a healthy individual is his metabolic rate when he is lying down quietly, awake and relaxed, at an environmental temperature which is comfortable for him, having had no food in the preceding 12 hours or no significant recent exercise.
一個健康人的基礎代謝率就是他在適宜的環境溫度下於清醒和松馳狀態中靜臥著，並且在十二小時前未進過食，也未作過劇烈運動時的代謝率。
The rate of metabolism varies with age, sex, climate, with the type of clothing worn and also with the state of mind of the individual, being more highly active during nervous tension than during relaxation.
新陳代謝率因年齡，性別、氣侯及所穿衣服的樣式而有所不同，也因個體的精神狀態而異，如神經緊張時比松馳時快得多。
climate [ˈklaɪmɪt] n. 氣候；風氣；思潮；風土
It will depend also on the kind of activities in which he engages. The metabolic rate will be higher in a manual worker than in an indoor office worker leading a sedentary life.
新陳代謝率還取決於所從事活動的種類，如體力勞動者的新陳代謝率較之腦力勞動者為高。
sedentary ['sɛdntɛri] adj. 久坐的；坐慣的；定棲的；靜坐的
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《高等醫藥院校教材—英語》第二冊 第4課