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1、1,第七章 能量代谢与体温 Energy Metabolism and Temperature,2,第一节 能量代谢 Energy Metabolism,3,新陈代谢是机体生命活动的基本特征，新陈代谢包括物质代谢及相伴随的能量代谢。,4,生物体内物质代谢过程中所伴随的能量释放、转移和利用等，称为能量代谢。（energy metabolism）。,5,271.1-272.1 The term metabolism, meaning literally “change,“ is used to refer to all the chemical and energy transformations
2、 that occur in the body. The animal organism oxidizes carbohydrates, proteins, and fats, producing principally CO2, H2O, and the energy necessary for life processes.,6,In the body, oxidation is not a one-step, semiexplosive reaction but a complex, slow, stepwise process called catabolism分解代谢;异化, whi
3、ch liberates energy in small, usable amounts.,7,Energy can be stored in the body in the form of special energyrich phosphate compounds and in the form of proteins, fats, and complex carbohydrates synthesized from simpler molecules. Formation of these substances by processes that take up 吸收rather tha
4、n liberate energy is called anabolism合成代谢.,8,The energy liberated by catabolic processes in the body is used for maintaining body functions, digesting and metabolizing food, thermoregulation, and physical activity. It appears as external work, heat, and energy storage: Energy = External + Energy + H
5、eat output work storage,9,The amount of energy liberated per unit of time is the metabolic rate.,10,机体所需的能量来源于食物中的糖、脂肪和蛋白质。 能量的50%以上迅速转化为热能，用于维持体温，并向体外散发。 其余则以高能磷酸键的形式贮存于体内。,11,三磷酸腺苷(ATP)是体内能量转化和利用的关键物质。 磷酸肌酸(CP)是ATP的储存库。,12,Energy Transfer Much of the energy liberated by catabolism is not used dire
6、ctly by cells but is applied instead to the formation of bonds between phosphoric acid residues and certain organic compounds. Because the energy of bond formation in some of these phosphates is particularly high, relatively large amounts of energy (l0-12 kcal/mol) are released when the bond is hydr
7、olyzed.,13,Compounds containing such bonds are called high-energy phosphate compounds. the most important high-energy phosphate compound is adenosine triphosphate (ATP). This ubiquitous无所不在的molecule is the energy storehouse of the body.,14,Upon hydrolysis to adenosine diphosphate (ADP), ATP liberate
8、s energy directly to such processes as muscle contraction, active transport, and the synthesis of many chemical compounds.,15,Calories The standard unit of heat energy is the calorie (cal), defined as the amount of heat energy necessary to raise the temperature of 1 g of water 1 degree, from 15C to
9、16C. This unit is also called the gram calorie, small calorie, or standard calorie. The unit commonly used in physiology and medicine is the Calorie (kilocalorie, kcal), which equals 1000 cal.,16,一、能量代谢测定的原理和方法 测定在一定时间内机体所消耗的食物，或者测定机体所产生的热量与所做的外功，都可测算出整个机体的能量代谢率（单位时间内所产生的能量）,17,272.2-273.1 Energy is
10、 stored by forming energy-rich compounds. The amount of energy storage varies, but in fasting individuals it is zero or negative. Therefore, in an adult individual who has not eaten recently and who is not moving (or growing, reproducing, or lactating泌乳), all of the energy output appears as heat.,18
11、,（一）直接测热法,19,Calorimeters have been constructed that can physically accommodate human beings. The heat produced by their bodies is measured by the change in temperature of the water in the walls of the calorimeter.,20,The caloric values of the common foodstuffs, as measured in a bomb calorimeter,弹式测
12、热计：测定食物潜能的仪器，即为一中空的钢容器(弹)，内部充满纯氧，将定量的食物置于其内的铂盘上加以氧化。容器浸在一定量的水中。食物氧化产生的热被水吸收，即能从水中测定其热量are found to be 4.1 kcal/g of carbohydrate, 9.3 kcal/g of fat, and 4.1 kcal/g of protein.,21,(二）间接测热法,22,食物热价 将1g食物氧化（或在体外燃烧）时所释放出来的能量称为食物的热价（thermal equivalent of food）。,23,2呼吸商 一定时间内机体的CO2产量与耗氧量的比值称为呼吸商（respirato
13、ry quotient, RQ）。,24,The respiratory quotient (RQ) is the ratio in the steady state of the volume of CO2 produced to the volume of O2 consumed per unit of time. The RQ of carbohydrate is 1.00, and that of fat is about 0.70. Determining the RQ of protein in the body is a complex process, but an avera
14、ge value of 0.82 has been calculated.,25,3.食物的氧热价 某种食物氧化时消耗1升氧所产生的热量称为该种食物的氧热价。,26,4.非 蛋白呼吸商 在一定时间内机体中糖和脂肪氧化（非蛋白质代谢）的CO2产量和耗氧量的比值，即非 蛋白呼吸商。,27,28,间接测热法计算主要过程: 1. 实验测得的机体24小时内的耗氧量和CO2产量以及尿氮量; 2. 由尿氮量算出被氧化分解的蛋白质量。 3. 由被氧化的蛋白质量查表其产热量、耗氧量和CO2产量； 4.其次从总耗氧量和总CO2产量中减去蛋白质耗氧量和CO2产量，计算出非蛋白呼吸商。,29,5. 根据非蛋白呼吸商查
15、表的相应的非蛋白呼吸商的氧热价，计算出非蛋白代谢的产热量； 6. 最后，24小时产热量为蛋白质代谢的产热量与非蛋白代谢的产热量之和。,30,31,Indirect Calorimetry Energy production can also be calculated by measuring the products of the energy-producing biologic oxidations-ie, CO2, H2O, and the end products of protein catabolism produced-or by measuring the O2 consum
16、ed. This is indirect calorimetry. It is difficult to measure all of the end products, but measurement of O2 consumption is relatively easy.,32,Since O2 is not stored and since its consumption, except when an O2 debt is being incurred or repaid, always keeps pace with immediate needs, the amount of O2 consumed per unit of time is proportionate to the energy liberated.,33,二. 影响能量代谢的主要因素 (一) 肌肉活动 肌肉活动对能量代谢的影响最为显著。,34,（二)精神活动 无意识的肌紧张 某些激素释放增多,35,(三) 食物的特殊动力作
