生理學(xué)雙語(yǔ)課件-代謝系統(tǒng)培訓(xùn)資料

1、生理學(xué)雙語(yǔ)課件-代謝系統(tǒng)新陳代謝是機(jī)體生命活動(dòng)的基本特征，新陳代謝包括物質(zhì)代謝及相伴隨的能量代謝。生物體內(nèi)物質(zhì)代謝過(guò)程中所伴隨的能量釋放、轉(zhuǎn)移和利用等，稱為能量代謝。（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分解代謝;異化, 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合成代謝.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. 機(jī)體所需的能量來(lái)源于食物中的機(jī)體所需的能量來(lái)源于食物中的糖、糖、脂肪和蛋白質(zhì)。脂肪和蛋白質(zhì)。能量能量的的50%以上迅速轉(zhuǎn)化為以上迅速轉(zhuǎn)化為熱能熱能，用，用于維持體溫，并向體外散發(fā)。于維持體溫，并向體外散發(fā)。其余則以其余則以高能磷酸鍵高能磷酸鍵的形式貯存于體的形式貯存于體內(nèi)。內(nèi)。 三磷酸腺苷(ATP)是體內(nèi)能量轉(zhuǎn)化和利用的關(guān)鍵物質(zhì)。磷酸肌酸(CP)是ATP的儲(chǔ)存庫(kù)。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無(wú)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、能量代謝測(cè)定的原理和方法一、能量代謝測(cè)定的原理和方法測(cè)定在一定時(shí)間內(nèi)機(jī)體所消耗的食物，或測(cè)定在一定時(shí)間內(nèi)機(jī)體所消耗的食物，或者測(cè)定機(jī)體所產(chǎn)生的熱量與所做的外功，者測(cè)定機(jī)體所產(chǎn)生的熱量與所做的外功，都可測(cè)算出整個(gè)機(jī)體的都可測(cè)算出整個(gè)機(jī)體的能量代謝率（單位能量代謝率（單位時(shí)間內(nèi)所產(chǎn)生的能量）時(shí)間內(nèi)

10、所產(chǎn)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）直接測(cè)熱法（一）直接測(cè)熱法 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,彈式測(cè)熱計(jì)：測(cè)定食物潛能的儀器，即為一中空的鋼容器(彈)，內(nèi)部充滿純氧，將定量的食物置于其內(nèi)的鉑盤(pán)上加以氧化。容器浸在一定量的水中。食物氧化產(chǎn)生的熱被水吸收，即能從水中測(cè)定其熱量are found to be 4.1 kcal/g of carbohydrate, 9.3 kcal/g of fat, and 4.1 kcal/g of protein. (二）間接測(cè)熱法二）間接測(cè)熱法食物熱價(jià)食物熱價(jià)將將1g食物氧化（或在體外燃燒）食物氧化（或在體外燃燒）時(shí)所釋放出來(lái)的能量稱為食物時(shí)所釋放出來(lái)的能量稱為食物的熱的熱價(jià)（thermal equivale

13、nt of food）。2呼吸商呼吸商一定時(shí)間內(nèi)機(jī)體的一定時(shí)間內(nèi)機(jī)體的CO2產(chǎn)量與耗氧量的比值稱為呼產(chǎn)量與耗氧量的比值稱為呼吸商（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.食物的氧熱價(jià)食物的氧熱價(jià)某種食物氧化時(shí)消耗某種食物氧化時(shí)消耗1升氧所產(chǎn)升氧所產(chǎn)生的熱量稱為該種食物的氧熱價(jià)。生的熱量稱為該種食物的氧熱價(jià)。4.非非 蛋白呼吸商蛋白呼吸商在一定時(shí)間內(nèi)機(jī)體中糖和脂肪氧化在一定時(shí)間內(nèi)機(jī)體中糖和脂肪氧化（非蛋白質(zhì)代謝）的（非蛋白質(zhì)代謝）的CO2產(chǎn)量和耗產(chǎn)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。 間接測(cè)熱法計(jì)算主要過(guò)程間接測(cè)

15、熱法計(jì)算主要過(guò)程:1. 實(shí)驗(yàn)測(cè)得的機(jī)體實(shí)驗(yàn)測(cè)得的機(jī)體24小時(shí)內(nèi)的耗氧量和小時(shí)內(nèi)的耗氧量和CO2產(chǎn)量以及尿氮量產(chǎn)量以及尿氮量;2. 由尿氮量算出被氧化分解的蛋白質(zhì)量。由尿氮量算出被氧化分解的蛋白質(zhì)量。3. 由被氧化的蛋白質(zhì)量查表其產(chǎn)熱量、由被氧化的蛋白質(zhì)量查表其產(chǎn)熱量、耗氧量和耗氧量和CO2產(chǎn)量；產(chǎn)量；4.其次從總耗氧量和總其次從總耗氧量和總CO2產(chǎn)量中減去蛋產(chǎn)量中減去蛋白質(zhì)耗氧量和白質(zhì)耗氧量和CO2產(chǎn)量，計(jì)算出非產(chǎn)量，計(jì)算出非蛋白呼吸商。 5. 根據(jù)非蛋白呼吸商查表的相應(yīng)的根據(jù)非蛋白呼吸商查表的相應(yīng)的非蛋白呼吸商的氧熱價(jià)，計(jì)算出非非蛋白呼吸商的氧熱價(jià)，計(jì)算出非蛋白代謝的產(chǎn)熱量；蛋白代謝的產(chǎn)熱量

16、；6. 最后，最后，24小時(shí)產(chǎn)熱量為蛋白質(zhì)代小時(shí)產(chǎn)熱量為蛋白質(zhì)代謝的產(chǎn)熱量與非蛋白代謝的產(chǎn)熱量謝的產(chǎn)熱量與非蛋白代謝的產(chǎn)熱量之和。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. 影響能量代謝的主要因素影響能量代謝的主要因素 (一一) 肌肉活動(dòng)肌肉活動(dòng)肌肉活動(dòng)對(duì)能量代謝的影響最為顯肌肉活動(dòng)對(duì)能量代謝的影響最為顯著。著。（二（二)精神活動(dòng)精神活動(dòng)無(wú)意識(shí)的肌緊張無(wú)意識(shí)的肌緊張某些某些激素激素釋放增多釋放增多(三) 食物的特殊動(dòng)力作用食物的特殊動(dòng)力作用食物能使機(jī)體產(chǎn)生食物能使機(jī)體產(chǎn)生“額外額外”熱量的熱量的現(xiàn)象稱為食物的特殊動(dòng)力作用現(xiàn)象稱為食物的特殊動(dòng)力作用（specific dynamic action）。）。（四）四）環(huán)境溫度環(huán)境溫度安靜時(shí)的能量

19、代謝，在安靜時(shí)的能量代謝，在20-30度度的環(huán)境中最為穩(wěn)定。的環(huán)境中最為穩(wěn)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 強(qiáng)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攝氏degree of elevation.三、基

24、三、基 礎(chǔ)礎(chǔ) 代代 謝謝基礎(chǔ)代謝（基礎(chǔ)代謝（basal metabolism）是指基礎(chǔ)狀態(tài)下的能量代謝。是指基礎(chǔ)狀態(tài)下的能量代謝?；A(chǔ)代謝率基礎(chǔ)代謝率（basal metabolic rate,BMR）是指在）是指在基礎(chǔ)狀態(tài)基礎(chǔ)狀態(tài)下，單下，單位時(shí)間內(nèi)的產(chǎn)熱量?；A(chǔ)狀態(tài)是指位時(shí)間內(nèi)的產(chǎn)熱量?；A(chǔ)狀態(tài)是指人體處在清醒而又非常安靜，靜臥，人體處在清醒而又非常安靜，靜臥，室溫室溫2025度、食后度、食后12-14h）排除）排除精神緊張的影響?；A(chǔ)代謝率通常精神緊張的影響?；A(chǔ)代謝率通常以以kJ/m2h來(lái)表示。來(lái)表示。The metabolic rate determined at rest in a

25、 room at a comfortable temperature in the thermoneutral熱平衡的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.第二節(jié)第二節(jié) 體溫及其調(diào)節(jié)體溫及其調(diào)節(jié)一、一

28、、體體 溫溫（一）表層體溫和深部體溫（一）表層體溫和深部體溫人體的外周組織即表層，包括人體的外周組織即表層，包括皮膚、皮下組織和肌肉等的溫皮膚、皮下組織和肌肉等的溫度稱為度稱為表層溫度（表層溫度（shell temperature）。）。機(jī)體深部（心、肺、腦和腹腔內(nèi)機(jī)體深部（心、肺、腦和腹腔內(nèi)臟等處）的溫度稱為臟等處）的溫度稱為體核體核(深部深部)溫溫度度（core temperature）。）。體溫是指機(jī)體深部的平均溫度。體溫是指機(jī)體深部的平均溫度。臨床上通常用臨床上通常用口腔溫度、直腸口腔溫度、直腸溫度和溫度和腋窩溫度腋窩溫度來(lái)代表體溫。來(lái)代表體溫。直腸直腸 36.9 37. 9口腔口腔

29、36.7 37.7 腋窩腋窩 36.0 37.4 低低 0.2 0. 3 低低 0.3 0. 5 （二）（二）體溫的正常變動(dòng)體溫的正常變動(dòng) 在一晝夜之中，人體體溫呈周在一晝夜之中，人體體溫呈周期性波動(dòng)。清晨期性波動(dòng)。清晨2-6時(shí)體溫最低，時(shí)體溫最低，午后午后1-6時(shí)最高時(shí)最高。波動(dòng)的幅值一。波動(dòng)的幅值一般不超過(guò)般不超過(guò)1度。體溫的這種晝夜度。體溫的這種晝夜周期性波動(dòng)稱為周期性波動(dòng)稱為晝夜節(jié)律或日晝夜節(jié)律或日周期（周期（circadian rhythm）。）。女子的女子的基礎(chǔ)體溫基礎(chǔ)體溫隨月經(jīng)周期而發(fā)生隨月經(jīng)周期而發(fā)生變動(dòng)。在排卵后體溫升高，體溫升變動(dòng)。在排卵后體溫升高，體溫升高一直持續(xù)至下次月

30、經(jīng)開(kāi)始。高一直持續(xù)至下次月經(jīng)開(kāi)始。 體溫也與年齡有關(guān)。體溫也與年齡有關(guān)。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標(biāo)準(zhǔn)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 散熱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、體熱平衡二、體熱平衡 產(chǎn)熱產(chǎn)熱=散熱散熱 體溫維持不變體溫維持不變 產(chǎn)熱量產(chǎn)熱量散熱量，體溫升高散熱量，體溫升高 產(chǎn)熱量產(chǎn)熱量散熱量散熱量,體溫下降體溫下降 (一）產(chǎn)熱過(guò)程一）產(chǎn)熱過(guò)程人在寒冷環(huán)境中主要依靠寒戰(zhàn)來(lái)增人

39、在寒冷環(huán)境中主要依靠寒戰(zhàn)來(lái)增加產(chǎn)熱量。加產(chǎn)熱量。寒戰(zhàn)寒戰(zhàn)是骨骼肌發(fā)生不隨是骨骼肌發(fā)生不隨意的節(jié)律性收縮的表現(xiàn)。意的節(jié)律性收縮的表現(xiàn)。寒戰(zhàn)前肌緊張寒戰(zhàn)前肌緊張腎上腺素和去甲腎上腺素腎上腺素和去甲腎上腺素可使產(chǎn)可使產(chǎn)熱量迅速增加；熱量迅速增加；甲狀腺激素甲狀腺激素則使產(chǎn)熱緩慢增加。則使產(chǎn)熱緩慢增加。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）散熱過(guò)程二）散熱過(guò)程人體的主要散熱部位是人體的主要散熱部位是皮膚皮膚。當(dāng)環(huán)境溫度低于體溫時(shí)，大部分的當(dāng)環(huán)境溫度低于體溫時(shí)，大部分的體熱通過(guò)皮膚的體熱通過(guò)皮膚的輻射、傳導(dǎo)和對(duì)流輻射、傳導(dǎo)和對(duì)流 散熱。一部分熱量通過(guò)蒸發(fā)來(lái)散發(fā)。散熱。一部分熱量通過(guò)蒸發(fā)來(lái)散發(fā)。1輻射、傳導(dǎo)和對(duì)流散熱輻射、傳導(dǎo)和對(duì)流散熱輻射（輻射（radiation）散熱）散熱這是機(jī)體以熱射線的形式將熱量這是機(jī)體以熱射線的形式將熱量傳給外界較冷物體的散熱方式。傳給外界較冷物體的散熱方式。傳導(dǎo)（傳導(dǎo)（conduction）散熱）散熱：是：是機(jī)體的熱量直

43、接傳給同它接觸機(jī)體的熱量直接傳給同它接觸的較冷物體的散熱方式。的較冷物體的散熱方式。對(duì)流（對(duì)流（convection）散熱）散熱是指通過(guò)身體周圍氣體散熱的方是指通過(guò)身體周圍氣體散熱的方式。式。體溫調(diào)節(jié)中樞體溫調(diào)節(jié)中樞通過(guò)神經(jīng)控制著通過(guò)神經(jīng)控制著皮膚血流量來(lái)改變皮膚溫度，皮膚血流量來(lái)改變皮膚溫度，從而調(diào)節(jié)散熱量。從而調(diào)節(jié)散熱量。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. 在在炎熱環(huán)境中炎熱環(huán)境中,交感神經(jīng)緊張度降低交感神經(jīng)緊張度降低,皮膚小動(dòng)脈舒張皮膚小動(dòng)脈舒張,動(dòng)靜脈吻合支開(kāi)放動(dòng)靜脈吻合支開(kāi)放,皮膚血流量激增皮膚血流量激增,皮膚溫度升高皮膚溫度升高,散散熱增加。熱增加。在在寒冷環(huán)境寒冷環(huán)境中中,交感神經(jīng)緊張交感神經(jīng)緊張度升高度升高,皮膚小動(dòng)脈收縮皮膚小動(dòng)脈收縮,皮膚皮膚血流量銳減血流量銳減,皮膚溫度下降皮膚溫度下降

48、,散散熱顯著減少。此時(shí)機(jī)體表層熱顯著減少。此時(shí)機(jī)體表層成為隔熱層，減少散熱。成為隔熱層，減少散熱。2. 蒸發(fā)（蒸發(fā)（evaporation）散熱）散熱 當(dāng)環(huán)境溫度較低時(shí)，大部分的當(dāng)環(huán)境溫度較低時(shí)，大部分的體熱靠輻射、傳導(dǎo)和對(duì)流的方體熱靠輻射、傳導(dǎo)和對(duì)流的方式散熱，小部分體熱由蒸發(fā)散式散熱，小部分體熱由蒸發(fā)散熱；熱；隨著環(huán)境溫度升高時(shí)，蒸發(fā)的散隨著環(huán)境溫度升高時(shí)，蒸發(fā)的散熱作用則增強(qiáng)；當(dāng)環(huán)境溫度等于熱作用則增強(qiáng)；當(dāng)環(huán)境溫度等于或與高于體溫時(shí)，或與高于體溫時(shí)，蒸發(fā)就成為機(jī)蒸發(fā)就成為機(jī)體唯一的散熱方式。體唯一的散熱方式。人體蒸發(fā)有二種形式：即不感蒸人體蒸發(fā)有二種形式：即不感蒸發(fā)和發(fā)汗。發(fā)和發(fā)汗。人體

49、皮膚和呼吸道都不斷有水分滲出被蒸發(fā)掉，稱為不感蒸發(fā)，其中皮膚蒸發(fā)又稱為不顯汗，與汗腺的活動(dòng)無(wú)關(guān)。室溫下人體24h的不感蒸發(fā)量為500ml。 發(fā)汗發(fā)汗 汗腺分泌汗液的活動(dòng)稱為發(fā)汗。汗液是低滲的。所以當(dāng)機(jī)體因汗液是低滲的。所以當(dāng)機(jī)體因量發(fā)汗，導(dǎo)致高滲性脫水。量發(fā)汗，導(dǎo)致高滲性脫水。發(fā)汗是反射活動(dòng)。人體發(fā)汗是反射活動(dòng)。人體汗腺接汗腺接受交感膽堿能纖維（交感節(jié)后受交感膽堿能纖維（交感節(jié)后纖維）支配纖維）支配,(M受體受體)。主要發(fā)汗中樞在下丘腦。主要發(fā)汗中樞在下丘腦。溫?zé)嵝园l(fā)汗溫?zé)嵝园l(fā)汗精神性發(fā)汗精神性發(fā)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、體溫調(diào)節(jié)三、體溫調(diào)節(jié)體溫調(diào)節(jié)機(jī)制通過(guò)調(diào)節(jié)產(chǎn)熱過(guò)程體溫調(diào)節(jié)機(jī)制通過(guò)調(diào)節(jié)產(chǎn)熱過(guò)程和散熱過(guò)程，維持體溫相對(duì)穩(wěn)定。和散熱過(guò)程，維持體溫相對(duì)穩(wěn)定。 體溫調(diào)節(jié)自動(dòng)控制示意圖體溫調(diào)節(jié)自動(dòng)控制示意圖（一）溫度感受器（一）溫度感受器1. 外周外周溫度感受器溫度感受器 冷感受器冷感受器 溫覺(jué)感受器溫覺(jué)感受器大鼠陰囊皮膚冷覺(jué)和溫覺(jué)感受器大鼠陰囊皮膚冷覺(jué)和溫覺(jué)感受器中樞中樞溫度感受器溫度感受器 在視前區(qū)在視前區(qū)-下丘腦前部（下丘腦前部（preoptic anterior hypothalamus, PO/

54、AH） 熱敏神經(jīng)元熱敏神經(jīng)元 冷敏神經(jīng)元冷敏神經(jīng)元下丘腦局部加溫時(shí)熱敏神經(jīng)元放電的記錄 由下丘腦視前區(qū)導(dǎo)出的溫度敏感神經(jīng)元的放由下丘腦視前區(qū)導(dǎo)出的溫度敏感神經(jīng)元的放電活動(dòng)電活動(dòng)（二）體溫調(diào)節(jié)中樞（二）體溫調(diào)節(jié)中樞調(diào)節(jié)體溫的基本中樞在調(diào)節(jié)體溫的基本中樞在 下丘腦下丘腦，視前區(qū)視前區(qū)-下丘腦前部下丘腦前部PO/AH是體是體溫調(diào)節(jié)的基本部位。溫調(diào)節(jié)的基本部位。環(huán)境溫度的信息上傳到體溫調(diào)節(jié)環(huán)境溫度的信息上傳到體溫調(diào)節(jié)中樞，通過(guò)后者的中樞，通過(guò)后者的整合整合作用，形作用，形成決策。然后成決策。然后改變產(chǎn)熱和散熱改變產(chǎn)熱和散熱過(guò)過(guò)程程,以調(diào)節(jié)體溫。以調(diào)節(jié)體溫。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