THERMOREGULATION DIVISION OF PHYSIOLOGY DEPARTMENT OF ANATOMY, PHYSIOLOGY AND PHARMACOLOGY FACULTY OF VETERINARY MEDICINE IPB 2017 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 1
Regulation of the total body energy balance The energy produced during a chemical reaction appears as body heat or work (by product of the metabolic process) Total Energy Production = Body heat production + Energy for work + Energy stored Heat Productian (K) Food types Per gram of food Per liter of O 2 consumed Per liter of CO 2 produced Carbohydrates 4.1 5.05 5.05 Fat 9.6 4.75 6.67 Proteins (to urea) 4.2 4.60 5.57 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 2
BALANCE OF BODY ENERGY Energy from food = Heat production + Energy for work + Energy stored CONDITION Incoming energy = (heat production + energy for work) Incoming energy > (heat production + energy for work) Incoming energy < (heat production + energy for work) RESULT Body energy will remain constant (body fat remains constant) Body energy will increase (body fat will increase) Body energy will decrease (body fat will decrease) 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 3
INCOMING ENERGY = OUTCOMING ENERGY Carbohydrate Fat Protein Mechanical work: Muscle contraction; cell movement Synthesis reaction: Storage; tissue formation; molecular function Membrane transport: Mineral; organic; amino acid Generating and propagating electric signal: chemical; mechanical Heat production: body temperature regulation; Inefficiency of chemical reaction Detoxication/Degradation : urea synthesis; conjugation; oxidation, reduction 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 4
Temparature Regulation Body temperature Main factor for tissues function < 34 o C loss of thermoregulation ability 27-29 o C cardiac fibrillation and death > 45 o C brain damage Homeotherms Poikilotherms Body temperature regulation different Body temperature: depends on the balance between incoming and outcoming heat 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 5
Body temperature Core temp Skin temp Factors BMR Muscle activities almost all constant depends on the ambient temp Work hard, emotion, etc Normal Range Oral (36.7 0 C-37 0 C) Metabolism, additional Metabolism, additional Metabolism, additional { { { Early morning, etc 104 102 100 98 96 0 F 0 C 40 } 39 38 37 36 35 } } } Work hard Except fever Emotion, Mild physical wrk, normal adult, active children Reguler normal range Early morning, cold weather, etc Rectal (0.6 0 C) thyroxine, GH, testostosterone The function of the skin as a place to release heat epinephrine, norepinephrine, sympathetic activities Chemical activities of the cells
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HEAT SOURCES : Metabolism }Food Energy Working External sources (environment) Heat 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 8
Animal type based on body temperature: 1 Homeotherms = warm-blooded Using body metabolism to regulate the temperature can survive over a wide range of temperature Have good insulation 2 Poikilotherms = cold-blooded Body temperature depends on the ambient temperature Poor insulation searching for a suitable environment and behavioral adaptation optimum body temperature 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 9
BMR of homeothermy > poikilothermy Metabolic rate per kg BB small individual > big individual Ratio of surface area/volume of small animal > big animal Surface area >> heat loss >> Metabolic rate heat production heat released 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 10
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Lizard Behavioral Thermoregulation 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 12
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Heat Production The main by product of metabolism process Mostly produced in the liver, brain, heart, skeletal muscle during work Factors: BMR of all body cells The rate of reserve metabolism by muscle RMR by thyroxine, GH, testosterone Additional metabolism by epinephnerine effect Additional metabolism by chemical activity in the cell because of temperature 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 14
Heat Loss 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 15
Body heat will be released through: Radiation Infrared heat wave (electromagnetic 5-20 μm) Convection Conduction Evaporation (sweat, respiration) Urination, defecation 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 16
Radiation Conduction Evaporation} Heat loses heat from the skin to the environment Radiation: - 60 % of the total heat loss - In the form of infrared heat wave Conduction: - To other object 3% of heat loss - 15 % to the air Convection: transfer of heat from the body though air convection preceded by conduction 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 17
Sun = most important source of radiant heat: Photons from the sun excite molecules in the atmosphere, warming them by radiant heat. 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 18
Heat Loss: Heat from the internal organs is passed to the skin via the circulation Factors : - The rate of heat conduction to the skin - The rate of heat transfer from the skin to its surroundings Insulator : Skin, subcutaneous tissues, particularly fat from subcutaneous tissue it is not effective for heat distribution low thermal conductivity 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 19
Effect of clothes - The rate of heat loss through conduction & convection is depressed - Clothes made of ordinary materials decreases the rate of heat loss ½ x from the naked body - Polar clothes 1/6 X - Heat from skin to clothes radiation - The effectiveness of maintaining of body temperature is almost lost when the clothes are wet 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 20
Internal Insulator External Insulator 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 21
Circulatory convection the ability of circulation system to take and drain the heat to maintain the temperature of brain and visceral organ 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 22
Response to Heat Stress: 1. Dilatation of skin arteriol capillary blood flow 2. Opening of arteriovena anastomose in the leg, ear, and mouth blood flow and heat to the peripheral skin temperature increases (heat loss ) 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 23
Response to Cold Stress: 1. Constriction of skin arteriol capillary blood flow 2. Anastomose arteriovenous closure in the legs, ears, and mouth Heat loss from the skin 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 24
Control of Conductance by Regional Heterothermy Cold-climate homeotherms can allow their appendages to cool to reduce heat loss. Countercurrent heat exchange occurs between warm out-flowing blood in a central artery and cold inflowing blood in surrounding veins. 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 25
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Cooling effect by the wind The air layer adjacent to the skin is immediately replaced by new air convection Conduction & convention by water Water has special heat several thousand times > air Rate of heat loss to the water > air at the same temperature air = udara At very cold temperatures the rate of heat loss to water = to the air 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 27
Evaporation Evaporation of 1 liter of water to water vapor needs 580 kkal If skin temperature > environment temperature Heat will loss through radiation and conduction If environment temperaure > skin temperature The body will obtain heat radiation and conduction Body heat releases through evaporation The ability of evaporation decreases when the humidity 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 29
Sweat regulation by the autonomic nervous system Stimulation of the preoptic area in the anterior of hypothalamus impuls to the spinal cord through autonomic pathway To the skin through sympathetic pathway sweat Sweat gland Innervation by the cholinergic nerve (secretes acetylcholine) 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 30
Initial secretion is isosmotic to plasma (Na + 142mEq/L and Cl - 104 meq/l) Mild stimulation Na + and Cl - reabsorption 5 meq/l osmotic pressure water reabsorption Strong stimulation electrolites reabsorption Acclimatisation role of aldosterone to prevent electrolite loss 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 31
Temperature sensor Brain Increaset/decrease Heat loss/heat production Heat-sensitive neuron in the preoptic area of anterior hypothalamus monitore body and brain temperatures Temperature-sensitive neuron in the skin active in the cold (more active) and in the hot temperature alteration of environment temperature can be quickly detected before change the body temperature shivering, sweating Core temperature receptor spinal cord, internal organ in the abdomen and surrounding large veins Information from the anterior hypothalamus and the peripheral receptors are then integrated in the posterior hypothalamus Heat production/ heat conservation 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 32
Mechanism of Thermoregulation Thermoreceptor in the skin and in the body give information to the hypothalamus (set point) conservation/ heat production 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 33
In the range of thermoneutral zone, body temperature is regulated through the vasomotor mechanism ( and blood flow) then follwed by convection and radiation 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 35
Posterior Hypothalamus Receives sensoric signal for temperature from the core and peripheral receptors Shivering - Primary motoric center is located in the posterior hypothalamus inhibited by the high temperature signal from the preoptic area and stimulated by the cold signal from the skn and spinal cord Fever - Body temperature > normal - Causa: brain abnormality, toxic materials 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 36
Mechanism of Temperature Regulation Cold environment activates : - Shivering - Hungry - Conscious activities heat production - Norepinephrine/epinephrine - Thyroxine & cathecolamine secretion}increase o Cutaneous vasoconstriction } o Curled up Decrease heat loss o Horripilation Control : Posterior Hypothalamus 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 37
Physiological Response to the Cold Temperature 1. Decreases heat loss (vasoconstriction, curled up, piloerection, fur growth, fat deposition) 2. Increases heat production: - Increases food intake - Muscle contraction (shivering) - Non-shivering thermogenesis, calorigenic effect of epinephrine/norepinephrine - Brown fat uncouple reaction heat production 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 38
Shivering Primary motoric center is located in the posterior hypothalamus inhibited by the signal from hot center in the preoptic area and stimulated by the cold signal from the skin and spinal cord Chemical energy used for the shivering process is transferred to the body in the form of heat (can increase heat production 4x higher) 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 39
Non Shivering Thermogenesis The ability to produce metabolic heat when exposed to the cold temperature in the long periode Effect of thyroid hormone and effect of calorigenic of cathecolamine on the lipid (Brown Fat) 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 40
High Temperature Environment activates: - Cutaneus vasodilatation - Sweating - Respiration } Increase heat loss (initial response) o Anorexia o Sluggish } Decrease heat production Control : Anterior Hypothalamus Posterior Hypothalamus: combining the temperature sensoric signal from the core and the peripheral 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 41
Vasodilatation only is not able to maintain body temperature supported by evaporation (sweating and panting) Evaporation is the only mechanism to release heat when environment temperature > body temperature and in low humidity 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 42
Physiological Response to the High Temperature 1. Decrease heat production (decrease food intake) 2. Increase heat loss: - a. Regulate cisculation increase heat loss - b. Increase evaporation: - Sweating (cattle, antelope) - Panting: polipnea + salivation (dog) - Gular flutter (birds) 3. Behaviour: sand shower, take shelter, sitting back toward the sun, etc 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 43
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Panting 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 46
Fever Is a form of adaptation/evolution to fight infection Pyrogen stimulates fever enters the incoming bloodstream to hypothalamus alters set point produces and conserves heat until body temperature reaches new set point 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 48
Mechanism of Fever
Frostbite 6/21/2017 MATERI AJAR FISIOLOGI VETERINER II (TERMOREGULASI) 50