生理学双语课件-代谢系统培训资料

1、生理学双语课件-代谢系统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。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）。 271.1-272.1The term metabolism, meaning literally change, is used to refer to all the chemical and energy transformations that occur in the body. The animal organism oxidizes carbohydrates, protei

2、ns, and fats, producing principally CO2, H2O, and the energy necessary for life processes. 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, which liberates energy in small, usable amounts. Energy can be stored in the bod

3、y in the form of special energy-rich phosphate compoundsand 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 than liberate energy is called anabolism合成代谢.The energy liberated by catabolic pro

4、cesses 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 + Heatoutput work storageThe amount of energy liberated per unit of time is the metab

5、olic rate. 机体所需的能量来源于食物中的机体所需的能量来源于食物中的糖、糖、脂肪和蛋白质。脂肪和蛋白质。能量能量的的50%以上迅速转化为以上迅速转化为热能热能，用，用于维持体温，并向体外散发。于维持体温，并向体外散发。其余则以其余则以高能磷酸键高能磷酸键的形式贮存于体的形式贮存于体内。内。 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。Energy TransferMuch of the energy liberated by catabolism is not used directly by cells but is applied ins

6、tead 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 hydrolyzed. Compounds containing suc

7、h 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. Upon hydrolysis to adenosine diphosphate (ADP), ATP liberates energy directly to such processes as

8、 muscle contraction, active transport, and the synthesis of many chemical compounds. CaloriesThe 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 16C. This unit is also called the gram cal

9、orie, small calorie, or standard calorie. The unit commonly used in physiology and medicine is the Calorie (kilocalorie, kcal), which equals 1000 cal. 一、能量代谢测定的原理和方法一、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，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都可测算出整个机体的能量代谢率（单位能量代谢率（单位时间内所产生的能量）时间内

10、所产生的能量）272.2-273.1Energy is 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

11、 output appears as heat. （一）直接测热法（一）直接测热法 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.The caloric values of the common foodstuffs, as measured

12、in a bomb calorimeter,弹式测热计：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. (二）间接测热法二）间接测热法食物热价食物热价将将1g食物氧化（或在体外燃烧）食物氧化（或在体外燃烧）时所释放出来的能量称为食物时所释放出来的能量称为食物的热的热价（thermal equivale

13、nt of food）。2呼吸商呼吸商一定时间内机体的一定时间内机体的CO2产量与耗氧量的比值称为呼产量与耗氧量的比值称为呼吸商（吸商（respiratory quotient, RQ）。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. Det

14、ermining the RQ of protein in the body is a complex process, but an average value of 0.82 has been calculated. 3.食物的氧热价食物的氧热价某种食物氧化时消耗某种食物氧化时消耗1升氧所产升氧所产生的热量称为该种食物的氧热价。生的热量称为该种食物的氧热价。4.非非 蛋白呼吸商蛋白呼吸商在一定时间内机体中糖和脂肪氧化在一定时间内机体中糖和脂肪氧化（非蛋白质代谢）的（非蛋白质代谢）的CO2产量和耗产量和耗氧量的比值，即非氧量的比值，即非 蛋白呼吸商。蛋白呼吸商。 间接测热法计算主要过程间接测

15、热法计算主要过程:1. 实验测得的机体实验测得的机体24小时内的耗氧量和小时内的耗氧量和CO2产量以及尿氮量产量以及尿氮量;2. 由尿氮量算出被氧化分解的蛋白质量。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、由被氧化的蛋白质量查表其产热量、耗氧量和耗氧量和CO2产量；产量；4.其次从总耗氧量和总其次从总耗氧量和总CO2产量中减去蛋产量中减去蛋白质耗氧量和白质耗氧量和CO2产量，计算出非产量，计算出非蛋白呼吸商。 5. 根据非蛋白呼吸商查表的相应的根据非蛋白呼吸商查表的相应的非蛋白呼吸商的氧热价，计算出非非蛋白呼吸商的氧热价，计算出非蛋白代谢的产热量；蛋白代谢的产热量

16、；6. 最后，最后，24小时产热量为蛋白质代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谢的产热量与非蛋白代谢的产热量之和。之和。Indirect CalorimetryEnergy 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 consumed. Th

17、is is indirect calorimetry. It is difficult to measure all of the end products, but measurement of O2 consumption is relatively easy. 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 consume

18、d per unit of time is proportionate to the energy liberated.二二. 影响能量代谢的主要因素影响能量代谢的主要因素 (一一) 肌肉活动肌肉活动肌肉活动对能量代谢的影响最为显肌肉活动对能量代谢的影响最为显著。著。（二（二)精神活动精神活动无意识的肌紧张无意识的肌紧张某些某些激素激素释放增多释放增多(三) 食物的特殊动力作用食物的特殊动力作用食物能使机体产生食物能使机体产生“额外额外”热量的热量的现象称为食物的特殊动力作用现象称为食物的特殊动力作用（specific dynamic action）。）。（四）四）环境温度环境温度安静时的能量

19、代谢，在安静时的能量代谢，在20-30度度的环境中最为稳定。的环境中最为稳定。273.2-274.3Factors Affecting the Metabolic RateThe metabolic rate is affected by many factors. The most important is muscular exertion. O2 consumption is elevated not only during exertion but also for as long afterward as is necessary to repay the O2 debt. Rece

20、ntly ingested foods also increase the metabolic rate because of their specific dynamic action (SDA). The SDA of a food is the obligatory 强制性的energy expenditure that occurs during its assimilation同化into the body. An amount of protein sufficient to provide 100 kcal increases the metabolic rate a total

21、 of 30 kcal; a similar amount of carbohydrate increases it 6 kcal; and a similar amount of fat, 4 kcal. This means, of course, that the calories available from the three foods are in effect reduced by this amount; the energy used in their assimilation must come from the food itself or from the body

22、energy stores. The cause of the SDA, which may last up to 6 hours, is uncertain.Another factor that stimulates metabolism is the environmental temperature. The curve. relating the metabolic rate to the environmental temperature is U-shaped. When the environmental temperature is lower than body tempe

23、rature, heat-conserving mechanisms such as shivering are activated and the metabolic rate rises. When the temperature is high enough to raise the body temperature, there is a general acceleration of metabolic processes, and the metabolic rate rises about 14% for each Celsius摄氏degree of elevation.三、基

24、三、基 础础 代代 谢谢基础代谢（基础代谢（basal metabolism）是指基础状态下的能量代谢。是指基础状态下的能量代谢。基础代谢率基础代谢率（basal metabolic rate,BMR）是指在）是指在基础状态基础状态下，单下，单位时间内的产热量。基础状态是指位时间内的产热量。基础状态是指人体处在清醒而又非常安静，静卧，人体处在清醒而又非常安静，静卧，室温室温2025度、食后度、食后12-14h）排除）排除精神紧张的影响。基础代谢率通常精神紧张的影响。基础代谢率通常以以kJ/m2h来表示。来表示。The metabolic rate determined at rest in a

25、 room at a comfortable temperature in the thermoneutral热平衡的zone 12-14 hours after the last meal is called the standard, or basal metabolic rate (BMR). This value falls about 10% during sleep and up to 40% during prolonged starvation. The rate in these conditions is called the minimal metabolic rate.

26、 The rate during normal daytime activities is, of course, higher than the BMR because of muscular activity and food intake and is sometimes called the field metabolic rate. The maximum metabolic rate reached during exercise is often said to be ten times the BMR, but trained athletes can increase the

27、ir metabolic rate as much as 20-fold.For convenience, the BMR is usually expressed as a percent increase or decrease above or below a set of generally used standard normal values. Thus, a value of 65 means that the individuals BMR is 65% above the standard for that age and sex.第二节第二节 体温及其调节体温及其调节一、一

28、、体体 温温（一）表层体温和深部体温（一）表层体温和深部体温人体的外周组织即表层，包括人体的外周组织即表层，包括皮肤、皮下组织和肌肉等的温皮肤、皮下组织和肌肉等的温度称为度称为表层温度（表层温度（shell temperature）。）。机体深部（心、肺、脑和腹腔内机体深部（心、肺、脑和腹腔内脏等处）的温度称为脏等处）的温度称为体核体核(深部深部)温温度度（core temperature）。）。体温是指机体深部的平均温度。体温是指机体深部的平均温度。临床上通常用临床上通常用口腔温度、直肠口腔温度、直肠温度和温度和腋窝温度腋窝温度来代表体温。来代表体温。直肠直肠 36.9 37. 9口腔口腔

29、36.7 37.7 腋窝腋窝 36.0 37.4 低低 0.2 0. 3 低低 0.3 0. 5 （二）（二）体温的正常变动体温的正常变动 在一昼夜之中，人体体温呈周在一昼夜之中，人体体温呈周期性波动。清晨期性波动。清晨2-6时体温最低，时体温最低，午后午后1-6时最高时最高。波动的幅值一。波动的幅值一般不超过般不超过1度。体温的这种昼夜度。体温的这种昼夜周期性波动称为周期性波动称为昼夜节律或日昼夜节律或日周期（周期（circadian rhythm）。）。女子的女子的基础体温基础体温随月经周期而发生随月经周期而发生变动。在排卵后体温升高，体温升变动。在排卵后体温升高，体温升高一直持续至下次月

30、经开始。高一直持续至下次月经开始。 体温也与年龄有关。体温也与年龄有关。242.3-243.2In homeothermic animals, the actual temperature at which the body is maintained varies from species to species and, to a lesser degree, from individual to individual. In humans, the traditional normal value for the oral temperature is 37 C , but in one

31、large series of normal young adults, the morning oral temperature averaged 36.7 C , with a standard deviation of 0.2 C . Therefore, 95% of all young adults would be expected to have a morning oral temperature of 36.3-37.1 C .Various parts of the body are at different temperatures, and the magnitude

32、of the temperature difference between the parts varies with the environmental temperature. The extremities are generally cooler than the rest of the body The rectal temperature is representative of the temperature at the core of the body and varies least with changes in environmental temperature. Th

33、e oral temperature is normally 0.5 C lower than the rectal temperature, but it is affected by many factors, including ingestion of hot or cold fluids, gum-chewing, smoking, and mouth breathing.The normal human core temperature undergoes a regular circadian fluctuation of 0.5-0.7 C. In individuals wh

34、o sleep at night and are awake during the day (even when hospitalized at bed rest), it is lowest at about 6 am and highest in the evenings .It is lowest during sleep, is slightly higher in the awake but relaxed state, and rises with activity. In women, there is an additional monthly cycle of tempera

35、ture variation characterized by a rise in basal temperature at the time of ovulation .Temperature regulation is less precise in young children, and they may normally have a temperature that is 0.5 C or so above the established norm标准for adults.During exercise, the heat produced by muscular contracti

36、on accumulates in the body, and the rectal temperature normally rises as high as 40 C (104 F). This rise is due in part to the inability of the heat-dissipating 散热mechanisms to handle the greatly increased amount of heat produced, but there is evidence that in addition there is an elevation of the b

37、ody temperature at which the heat- dissipating mechanisms are activated during exercise . Body temperature also rises slightly during emotional excitement, probably owing to uncoscious tensing of the muscles. It is chronically elevated by as much as 0.5 C when the metabolic rate is high, as in hyper

38、thyroidism, and lowered when the metabolic rate is low, as in hypothyroidism. Some apparently normal adults chronical have a temperature above the normal range (constitutional hyperthermia).二、体热平衡二、体热平衡 产热产热=散热散热 体温维持不变体温维持不变 产热量产热量散热量，体温升高散热量，体温升高 产热量产热量散热量散热量,体温下降体温下降 (一）产热过程一）产热过程人在寒冷环境中主要依靠寒战来增人

39、在寒冷环境中主要依靠寒战来增加产热量。加产热量。寒战寒战是骨骼肌发生不随是骨骼肌发生不随意的节律性收缩的表现。意的节律性收缩的表现。寒战前肌紧张寒战前肌紧张肾上腺素和去甲肾上腺素肾上腺素和去甲肾上腺素可使产可使产热量迅速增加；热量迅速增加；甲状腺激素甲状腺激素则使产热缓慢增加。则使产热缓慢增加。243.3-244.5A variety of basic chemical reaction contribute to body heat production at all times. Ingestion of food increases heat production because of

40、the specific dynamic action of the food ,but the major source of heat is the contraction skeletal muscle.Heat production can varied by endocrine mechanisms in the absence food intake or muscular exertion. Epinephrine and norepinephrine produce a rapid but short-lived increase in heat production; thy

41、roid hormones produce a slowly developing but prolonged increase. Furthermore, sympathetic discharge is decreased during fasting and increased by feeding.A source of considerable heat, particularly in infants, is brown fat .This fat has high rate of metabolism, and its thermogenic function has been

42、likened to that of an electric blanket.（二）散热过程二）散热过程人体的主要散热部位是人体的主要散热部位是皮肤皮肤。当环境温度低于体温时，大部分的当环境温度低于体温时，大部分的体热通过皮肤的体热通过皮肤的辐射、传导和对流辐射、传导和对流 散热。一部分热量通过蒸发来散发。散热。一部分热量通过蒸发来散发。1辐射、传导和对流散热辐射、传导和对流散热辐射（辐射（radiation）散热）散热这是机体以热射线的形式将热量这是机体以热射线的形式将热量传给外界较冷物体的散热方式。传给外界较冷物体的散热方式。传导（传导（conduction）散热）散热：是：是机体的热量直

43、接传给同它接触机体的热量直接传给同它接触的较冷物体的散热方式。的较冷物体的散热方式。对流（对流（convection）散热）散热是指通过身体周围气体散热的方是指通过身体周围气体散热的方式。式。体温调节中枢体温调节中枢通过神经控制着通过神经控制着皮肤血流量来改变皮肤温度，皮肤血流量来改变皮肤温度，从而调节散热量。从而调节散热量。Radiation is transfer of heat by infrared electromagnetic radiation from one object to another at a different temperature with which it

44、is not in contact. When an individual is in a cold environment, heat is lost by conduction to the surrounding air and by radiation to cool objects in the vicinity. Conversely, of course, heat is transferred to an individual and the heat load is increased by these processes when the environmental tem

45、perature is above body temperature. Conduction heat exchange between objects or substances at different temperatures that are in contact with one other. A basic characteristic of matter is that its molecules are in motion, with the amount of motion proportionate to the temperature. These molecules c

46、ollide with the molecules in cooler objects, transferring thermal energy to them. The amount of heat transferred is proportionate to the temperature difference between the objects in contact (thermal gradient) .Convection :an object contact with air at a different temperature changes the specific gr

47、avity of the air, and since warm air rises and cool air falls, a new supply of air is brought into contact with the object. 在在炎热环境中炎热环境中,交感神经紧张度降低交感神经紧张度降低,皮肤小动脉舒张皮肤小动脉舒张,动静脉吻合支开放动静脉吻合支开放,皮肤血流量激增皮肤血流量激增,皮肤温度升高皮肤温度升高,散散热增加。热增加。在在寒冷环境寒冷环境中中,交感神经紧张交感神经紧张度升高度升高,皮肤小动脉收缩皮肤小动脉收缩,皮肤皮肤血流量锐减血流量锐减,皮肤温度下降皮肤温度下降

48、,散散热显著减少。此时机体表层热显著减少。此时机体表层成为隔热层，减少散热。成为隔热层，减少散热。2. 蒸发（蒸发（evaporation）散热）散热 当环境温度较低时，大部分的当环境温度较低时，大部分的体热靠辐射、传导和对流的方体热靠辐射、传导和对流的方式散热，小部分体热由蒸发散式散热，小部分体热由蒸发散热；热；随着环境温度升高时，蒸发的散随着环境温度升高时，蒸发的散热作用则增强；当环境温度等于热作用则增强；当环境温度等于或与高于体温时，或与高于体温时，蒸发就成为机蒸发就成为机体唯一的散热方式。体唯一的散热方式。人体蒸发有二种形式：即不感蒸人体蒸发有二种形式：即不感蒸发和发汗。发和发汗。人体

49、皮肤和呼吸道都不断有水分渗出被蒸发掉，称为不感蒸发，其中皮肤蒸发又称为不显汗，与汗腺的活动无关。室温下人体24h的不感蒸发量为500ml。 发汗发汗 汗腺分泌汗液的活动称为发汗。汗液是低渗的。所以当机体因汗液是低渗的。所以当机体因量发汗，导致高渗性脱水。量发汗，导致高渗性脱水。发汗是反射活动。人体发汗是反射活动。人体汗腺接汗腺接受交感胆碱能纤维（交感节后受交感胆碱能纤维（交感节后纤维）支配纤维）支配,(M受体受体)。主要发汗中枢在下丘脑。主要发汗中枢在下丘脑。温热性发汗温热性发汗精神性发汗精神性发汗The other major process transferring heat from t

50、he body in humans and other animals that sweat is vaporization of water on the skin and mucous membranes of the mouth and respiratory passages. Vaporization of 1 g of water removes about 0.6 kcal of heat. A certain amount of water is vaporized at all times. This insensible water loss amounts to 50 m

51、l/h in humans. When sweat secretion is increased, the degree to which the sweat vaporizes depends upon the humidity of the environment. It is common knowledge that one feels hotter on a humid day. This is due in part to the decreased vaporization of sweat, but even under conditions in which vaporiza

52、tion of sweat is complete, an individual in a humid environment feels warmer than an individual in a dry environment. During muscular exertion in a hot environment, sweat secretion reaches values as high as 1600 ml/h, and in a dry atmosphere, most of this sweat is vaporized. Heat loss by vaporizatio

53、n of water therefore varies from 30 to over 900 kcal/h.三、体温调节三、体温调节体温调节机制通过调节产热过程体温调节机制通过调节产热过程和散热过程，维持体温相对稳定。和散热过程，维持体温相对稳定。 体温调节自动控制示意图体温调节自动控制示意图（一）温度感受器（一）温度感受器1. 外周外周温度感受器温度感受器 冷感受器冷感受器 温觉感受器温觉感受器大鼠阴囊皮肤冷觉和温觉感受器大鼠阴囊皮肤冷觉和温觉感受器中枢中枢温度感受器温度感受器 在视前区在视前区-下丘脑前部（下丘脑前部（preoptic anterior hypothalamus, PO/

54、AH） 热敏神经元热敏神经元 冷敏神经元冷敏神经元下丘脑局部加温时热敏神经元放电的记录 由下丘脑视前区导出的温度敏感神经元的放由下丘脑视前区导出的温度敏感神经元的放电活动电活动（二）体温调节中枢（二）体温调节中枢调节体温的基本中枢在调节体温的基本中枢在 下丘脑下丘脑，视前区视前区-下丘脑前部下丘脑前部PO/AH是体是体温调节的基本部位。温调节的基本部位。环境温度的信息上传到体温调节环境温度的信息上传到体温调节中枢，通过后者的中枢，通过后者的整合整合作用，形作用，形成决策。然后成决策。然后改变产热和散热改变产热和散热过过程程,以调节体温。以调节体温。245.1-6The reflex therm

55、oregulatory reponses in human include autonomic, somatic, endocrine, and behavioral changes. One group of responses increases heat loss and decreases heat production; the other decreases heat loss and increases heat production. In general, exposure to heat stimulates the former group of responses and inhibits the latter, whereas exposure to cold does the opposite.Table14-5.Temperature-regulating mechanisms. Mechanisms activated by cold Increase heat production Shivering Hunger Increased voluntary activity Increased secretion of norepinephrine and epinephrineDecrease heat loss Cutaneous vas