1、Chapter 7 Energy Metabolism & Body Temperature,Department of Physiology School of Preclinical and Forensic Medicine Sichuan University,1. Guyton AC Textbook of Medical Physiology 20th edition 北京医科大学出版社 2002 Page 815-833 2. Lingappa, V.R. 医学生理学科学出版社 2005 Page 315-322 3. 姚泰主编 人体生理学 第三版人卫出版社 2001 Page
2、1754-1770Page 1787-1821 4. Ganong WF Review of Medical Physiology 20th edition 北京医科大学出版社 2001 Page 271-278 5. Robert M. Berne Physiology 5th 北京医科大学出版社 2005 Page 743-765,References,Part 1 Energy Metabolism,Source and utilization of energy in the bodyMeasurement of the energy metabolismFactors affecti
3、ng the energy metabolismBasal metabolism,Topics in this part:,Definition of energy metabolism:Energy metabolism is used to refer to all processes of liberation, storage, transformation and utilization of energy produced by the material metabolism in the body.,energy metabolism of whole body,Muscle c
4、ontraction Nerve conduction Anabolism Active transport Digestion and secretion Etc.,Foods (carbohydrate, fat and protein),CO2, H2O, urea,(50%),I. Source and Utilization of Energy,Energy output:Heat External mechanical work,Energy metabolism rate: The amount of energy liberated per unit of time.,. Me
5、asure of Energy Metabolism,How to measure energy metabolism?,Question:,Principle 1: the first law of thermodynamics,Energy intake = Energy output,The amount of energy liberated by food = The amount of heat + external mechanical work + energy stored,The amount of energy liberated by food = The amount
6、 of heat,Method 1 Direct calorimetry,Principle 2: the law of definite proportion,20世纪初，Atweter-Benedict,1. Thermal equivalent of food:The amount of energy liberatedby oxidation or combustion of 1g of such food.,physical caloric valuebiologic caloric value,Heat (whole-body) = DH (glucose) + DH (fat)
7、+ DH (protein),2. Thermal equivalent of oxygen:The amount of energy liberated per liter of oxygen consumed in the body.,Heat = thermal equivalent of oxygen the amount of O2 consumed,3. Respiratory quotient ( RQ ):The ratio of the volume of CO2 produced to the volume of O2 consumed per unit of time.,
8、thermal equivalent of food thermal equivalent of oxygenthe amount of the food oxidationthe amount of O2 consumption,Data used to measure energy:,Non-protein respiratory quotient(NPRQ),The ratio of the volume of CO2 produced to the volume of O2 consumed per unit of time that carbohydrate and fat are
9、oxidized.,4. Methods of measuring O2 consumption and CO2 production open type, closed type,5. Measure of energy metabolismthe classic way：,Heat (whole-body) = DH (glucose) + DH (fat) + DH (protein),A simple way in clinic (简略法)： NPRQ = 0.82，thermal equivalent of oxygen = 20. 20kJ，Heat = 20.20 O2 cons
10、umed,Muscle activity:,III. Factors Affecting the Energy Metabolism,3. Environmental temperature,20-30 , energy metabolism stablyT 30, energy metabolism ,2. Mental activitysympathetic nerve activationE, NE, thyroid hormone secretion energy metabolism,shivering thermogenesis, EM sweating, EM,the oblig
11、atory energy expenditure that occurs during its assimilation into the body (last for 3-12 hours),4. Specific dynamic action of foods,Specific dynamic action of foods,protein,carbohydrate,fat,time,6. Individual factors 1) Body surface area: Energy metabolism rate: kJ/(m2 . h)2) Sex and Age7. Others,B
12、asal metabolism: the energy metabolism in basal conditions.Basal condition:,IV. Basal Metabolism,not have eaten food for at least 12hours after a night of restful sleep the temperature in a room 2025 No mental and physical activity,Basal metabolism rate (BMR):the basal metabolism per unit of time,(k
13、J / m2.h),Normal basal metabolism rate: the normal average value1015%,Abnormality of basal metabolism rate:,Part 2 Body Temperature and its Regulation,Body temperature Heat production and heat loss Regulation of body temperature,Topics in this part:,I. Body Temperature,1. Concept of body temperature
14、 Body temperature is the constantcorn temperature (mean T) of the deep tissues in the body.,20,35,the rectal T. 36.9 - 37.9 the oral T. 36.7 - 37.7 the axillary T. 36.0 - 37.4 ,2. Normal body temperature,3. Factors affecting normal body temperature,Diurnal variations: circadian rhythmsuprachiasmatic
15、 nucleus ( 视交叉上核 )biological clockAge and Sex,Curve of basal body temperaturein the menstrual cycle of female,Muscle contractionOthers,the follicular phase,the luteal phase,. Heat Production and Heat Loss of the Body,Basal metabolism Muscle activity Specific dynamic action of food,RadiationConductio
16、nConvection Evaporation,Principal organs of heat production in rest: visceral organs, skeletal musclein activity: skeletal muscle,Ways of heat production shivering thermogenesis,1. Heat production,Origin of heatbasal metabolism, muscle activity specific dynamic action of food,non-shivering thermogen
17、esis: brown fat,2. Heat loss,Ways of heat loss: skin, expiration, fecesMost important position (the major organ) of heat loss: skin Methods of heat loss:,radiation conduction convection evaporation,evaporation,Skin T.Environmental T.,conduction (3%),convection(15%),evaporation (22%),( 21 ),1) Radiat
18、ion: Heat loss by radiation means lossof heat in the infrared heat rays.,Factors affecting radiation:skin T- environmental Teffective radiation area of the body surface,2) Conduction:Heat loss by direct conduction from the surface of the body to contact objects. Factors affecting conduction:skin T-
19、environmental Theat conduction character of the object:cotton, fat, water, iron,In clinic, ice bag (ice cap) is used to reduce body temperature for fever case,3) Convection:Heat loss by convection of air or liquid currents.,Factors affecting convection:skin T- environmental Twind,Methods of evaporat
20、ion:insensible perspiration ( 1000ml/d )sensible evaperation ( sweating ),4) Evaporation:Heat is lost by water evaporation.,Factors affecting evaporation:environmental T, humidity in the air, wind, clothing, muscle activity,Types of Sweating: thermal sweating (relation to heat loss)mental sweatinggu
21、statory sweating,The center of sweating: hypothalamusInnervation of sweat glands: sympathetic cholinergic nerve fibers,III. Regulation of Body Temperature,Temperature receptor 1) Peripheral temperature receptor cold receptor/warm receptor located on the skin, muscle, visceral organ,2) Central temper
22、ature receptor:spinal cord, medulla, reticular formationof brainstem, hypothalamuswarm-sensitive neuroncold-sensitive neuronlocated in preoptic and anteriorhypothalamus, PO/AH,2. Mechanism of body temperature regulation,Negative feedbackSet-point theory:a “set-point” for temperaturecontrol in PO/AHF
23、eedback gain for body temperature control,A: cold-sensitive neuron B: warm-sensitive neuron,Temperature receptor （skin and central temperature receptor）,PO/AH Set-point,Body temperature,Muscle Visceral organs Brown fat,Skin Lung Urine,Heat production,Heat loss,Mechanism of body temperature control,f
24、eed forward,3. Reaction of body temperature regulation,Heat loss,Skin vasodilatation: Thermotaxic vasodilatation,Sweating,2) Heat production,Skin vasoconstrictionShivering: the important reaction in cold winterSympathetic activationE, NE, Thyroid hormone secretion,Mechanism of fever,1. Explain: ener
25、gy metabolism, basal metabolism, thermal equivalent of food, thermal equivalent of oxygenbody temperature, thermal radiation, thermal conductionthermal convection, evaporation. 2. Can you give me a few examples of measuring of energy metabolism? 3. What is specific dynamic action of food? How is it produced? 4. Describe the factors influencing energy metabolism.,Review Question,
