1. Body Temperature Huang Qin Huang Qin （ Tel 2995285 ）

2. Major Topics First Normal Body Temperature Second Heat Balance Heat BalanceHeat Balance Thermogenesis ThermogenesisThermogenesis Thermolysis ThermolysisThermolysis Third Thermoregulation Thermoregulation Thermo reflex Thermo reflex Set Point Theory Set Point TheorySet Point TheorySet Point Theory Temp Regulation Example Temp Regulation ExampleTemp Regulation ExampleTemp Regulation Example

3. Normal Body Temp. core temp. is the temp. in deep tissues of the body. core temp. is the temp. in deep tissues of the body. Fluctuates very little in normal Fluctuates very little in normal shell temp. is the surface Temp. of the body. shell temp. is the surface Temp. of the body. Fluctuates widely in normal Fluctuates widely in normal 20 ℃ ~40 ℃ 20 ℃ ~40 ℃ 1. Body core temp. & surface temp.

4. skin subcutaneous tissue fat 寒冷环境 炎热环境 体热模式

5. Body Temp. Body Temp. refers to the average core temp. T ＜ 22 ℃ → 心跳停止 T ＞ 43 ℃ → 酶变性死 T = 27 ℃ → 低温麻醉

6. Temp. unit : Usually measured in degrees Centigrate Usually measured in degrees Centigrate (  C). (  C). degrees Fahrenheit (  F). degrees Fahrenheit (  F).

7. 环境温度体热温度

8. Normal Body Temp. In normal, the body temp. remains almost exactly constant (±1.0 ℃ ) In normal, the body temp. remains almost exactly constant (±1.0 ℃ ) Environment temp. rise rise fall fall endotherm (warm-blood Animal) endotherm (warm-blood Animal) Body temp. constant

9. Normal range of body temp. axillary temp. 36.0-37.4 ℃ axillary temp. 36.0-37.4 ℃ oral temp. 36.7-37.7 ℃ oral temp. 36.7-37.7 ℃ rectal temp. 36.9-37.9 ℃ rectal temp. 36.9-37.9 ℃ Esophagus Esophagus Tympanic membrane Tympanic membrane Temp. measuring equipment Temp. measuring equipment Mercurial thermometer Mercurial thermometer Recording thermometer Recording thermometer

10. 3. Body temp varies physiologically 1. circadian rhythm: 2~6 AM, lowest 1~6 PM, highest 1~6 PM, highest (±1 ℃ ) (±1 ℃ ) 2. Sex difference: the female average body temp. is higher than the male’s ( 0.3 ℃ ) 3. Age difference: newborn baby old person (slightly) old person (slightly) 4. Emotion, physical work, menses : (> 2 ℃ ) (> 2 ℃ )

12. Heat balance: thermogenesis and thermolysis Heat balance: thermogenesis and thermolysis Heat is continuously being produced in the body as a by-product of metabolism Heat is continuously being produced in the body as a by-product of metabolism thermogenesis thermogenesis Heat is continuously being lost to the surroundings Heat is continuously being lost to the surroundings thermolysis thermolysis Body temp. is closely related to the balance between thermogenesis and thermolysis: Body temp. is closely related to the balance between thermogenesis and thermolysis:

13. rate of heat production = the rate of loss rate of heat production = the rate of loss (the person is in heat balance, body temp. is stable.) (the person is in heat balance, body temp. is stable.) Reversely ： the body temp. is increasing/decreasing. Reversely ： the body temp. is increasing/decreasing. 图 8-2 体热平衡模式 热输出 辐射 传导 对流 蒸发 热来源 代谢 环境

14. 1. Thermogenesis Organs of thermogenesis Organs of thermogenesis In rest : viscera (liver) and brain In rest : viscera (liver) and brain 56% 16% 56% 16% In sport : skeletal muscle In sport : skeletal muscle 90% 90%

15. Means of thermogenesis Means of thermogenesis 1) Basal metabolism (clear-headed,quiet) 1) Basal metabolism (clear-headed,quiet) 2) Shivering(chill) 2) Shivering(chill) flexor and extensor contract flexor and extensor contract 3) Non-shivering thermogenesis 3) Non-shivering thermogenesis neural and hormonal ： sympathetic nervous neural and hormonal ： sympathetic nervous norepinephrine norepinephrine brown fat catabolism brown fat catabolism 4) Specific dynamic effect 4) Specific dynamic effect

16. 2. Thermolysis Organs of thermolysis Organs of thermolysis 1) skin : major organ 85% 1) skin : major organ 85% 2) respiratory tract 2) respiratory tract digestive tract digestive tract urinary tract urinary tract

17. 2. Heat transfers ： from body core to skin Heat conducts directly from body core to skin. Heat conducts directly from body core to skin. efficiency: Fat < skeletal muscle efficiency: Fat < skeletal muscle Heat transfers along with blood flow to the skin. Heat transfers along with blood flow to the skin.

18. Skin structure E. epidermis F. dermis G. subcutaneous tissue J. sweat gland I. Arterial and venous vessel.

19. Features of skin vessel Arteria, capillary and vein. Arteria, capillary and vein. many connections between arteria and vein : A-V connecting vessel. many connections between arteria and vein : A-V connecting vessel. The vessel is controlled by sympathetic nerve, and the postganglionic fiber is cholinergic (not adrenergic): The vessel is controlled by sympathetic nerve, and the postganglionic fiber is cholinergic (not adrenergic): Ach (Acetylcholine) as transmitter Ach (Acetylcholine) as transmitter

20. Effect of sympathetic nerve on skin blood flow Sympathetic nerve excites Sympathetic nerve excites the end release Ach (Acetylcholine) the end release Ach (Acetylcholine) Ach is vasodilating Ach is vasodilating skin blood vessel dilate skin blood vessel dilate skin blood flow skin blood flow Heat exchanges Heat exchanges Not Noradrenalin

21. 3. Means of Thermolysis Evaporation Radiation Convection Conduction nude person at room temperature

22. 1. Radiation: heat transfers between two bodies that are not in direct contact. Main form is infrared rays. Main form is infrared rays. body temp. Radiation body temp. Radiation ( 60% of total heat lost) ( 60% of total heat lost) person room person room

23. 2. Conduction: transfer of heat between 2 bodies in direct contact (solid, liquid or gas). Heat flows down thermal gradient. conduction to objects: conduction to objects: person 3% chair person 3% chair person 15% air person 15% air

24. 3. Convection: heat transfer by movement of fluid (liquid or gas). Depends on the speed of mass movement. air/water : temp. air/water : temp. movement movement

25. way principle affected factor example way principle affected factor example radiation infrared difference in temp. dressing rays area of body rays area of body conduction direct difference in temp. Ice transfer ability to conduct heat refrigerate transfer ability to conduct heat refrigerate convection direct difference in temp. fan transfer velocity of air transfer velocity of air Compare : radition, conduction and evaporation

26. 4. Evaporation: 4. Evaporation: evaporation of water requires evaporation of water requires a lot of heat. a lot of heat.

27. Insensible perspiration Insensible perspiration water evaporates insensibly: skin and lung water evaporates insensibly: skin and lung 600ml/d 600ml/d Sensible perspiration (Sweating) Sensible perspiration (Sweating) when bodies becomes overheated, large amount of sweat are secreted onto the surface of skin by the sweat gland : evaporative cooling of the body. when bodies becomes overheated, large amount of sweat are secreted onto the surface of skin by the sweat gland : evaporative cooling of the body. temp. of surroundings temp. of surroundings velocity of air movement velocity of air movement humidity of air humidity of air influencing factors

28. Sweat gland 1)A deep coiled portion that secretes the sweat. Sodium, chloride Sodium, chloride 2)A duct portion passing outward through the dermis, by which sweat flow onto the skin surface. **osmotic pressure of end-sweat is lower than plasma

29. Sweating reflex afferent nerve afferent nerve center of sweating (hypothalamus) center of sweating (hypothalamus) efferent nerve efferent nerve

30. Conclusion of thermolysis Radiation, conduction and convection is the major way of thermolysis When body temp. is Higher than surroundings Radiation, conduction and convection is the major way of thermolysis When body temp. is Higher than surroundings Evaporation is the only way of thermolysis when body temp. is lower than surroundings. Evaporation is the only way of thermolysis when body temp. is lower than surroundings.

31. Thermoregulation Thermoregulation The body temp. keep constant is important for life. The body temp. keep constant is important for life. Autonomic thermoregulation Autonomic thermoregulation nervous regulation: receptor, afferent nerve, center, efferent nerve, effector nervous regulation: receptor, afferent nerve, center, efferent nerve, effectorreceptorcentereffectorreceptorcentereffector Behavioral thermoregulation: dressing, fan Behavioral thermoregulation: dressing, fan

32. Temp. Receptor 1. Peripheral Thermal Receptor Warmth Receptor Cold Receptor Warmth Receptor Cold Receptor 2. central thermal receptors classified into warmth-sensitive neuron classified into warmth-sensitive neuron cold-sensitive neuron cold-sensitive neuron spinal cord, hypothalamus spinal cord, hypothalamus Cold >> Warmth, more concerned with hypothermia 10 : 1 10 : 1

33. Thermoregulation Centre Hypothalamus : Hypothalamus : the central integrator of thermoregulation, called “thermostat” the central integrator of thermoregulation, called “thermostat” Preoptic anterior hypothalamus (PO/AH) Preoptic anterior hypothalamus (PO/AH) 视前区 - 下丘脑前部 视前区 - 下丘脑前部 warmth-sensitive / cold-sensitive neurons warmth-sensitive / cold-sensitive neurons **receives input from peripheral and deep tissue thermal receptors when body temp. is low / high.

34. Temp. Effector 1. blood vessels 2. sweat glands 3. skeletal muscle

35. Set Point theory Normal homeostasis operates to keep the body temperature within a very narrow range ， called the set point. This set point acts as a "trigger" for the body to respond in a manner, which activates physiologic processes that influence temperature elevation or decrease. Normal homeostasis operates to keep the body temperature within a very narrow range ， called the set point. This set point acts as a "trigger" for the body to respond in a manner, which activates physiologic processes that influence temperature elevation or decrease. Similar to Air conditioner Similar to Air conditioner 40 37 36 Set Point Body Temp. 37 Normal Body Temp. 40“Normal”

36. Mechanism of increased heat loss when the body becomes overheated 1. Skin vessel dilated. 2. Sweating 3. Heat production reduce

37. Mechanism of heat conserving when the body becomes cooled 1. Skin vessel constricted. 2. Increasing of heat production shivering, sympathetic excitation and thyroxin releasing. 3. other : Piloerection

38. Behavioral control of body temp. thermostatic control thermostatic control human being——behavioral control human being——behavioral control body temp. high/low feeling overheated /cooled and discomforted feeling overheated /cooled and discomforted Less/more clothing, etc. Less/more clothing, etc.

39. Set Point change Fever Fever Pyrogens act on the anterior hypothalamus to raise the set point to a higher level. Pyrogens act on the anterior hypothalamus to raise the set point to a higher level. Pyrogen : some protein increase set point Body Temp. 37 40 37 36 Set Point

43. Summary Normal body temp range. Normal body temp range. Ways of thermolysis. Ways of thermolysis. Center, receptor and effector of thermoregulation. Center, receptor and effector of thermoregulation. Mechanism of body regulating the temp. to normal when the body temp. is higher or lower than set point. Mechanism of body regulating the temp. to normal when the body temp. is higher or lower than set point.