Thermoregulation - wikipedia Thermoregulation `` Body heat '' redirects here. For other uses, see Body Heat ( disambiguation ). `` Body temperature '' redirects here. For information regarding normal human body temperature, see Human body temperature. For the 2011 Japanese film, see Body Temperature ( film ). Thermoregulation in animals Ectotherm Endotherm Mesotherm Poikilotherm Homeothermy Heterothermy Stenotherm Eurytherm Thermolabile Thermostability Gigantothermy Kleptothermy Bradymetabolism Tachymetabolism Thermogenesis Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation. The internal thermoreegulation process is one aspect of homeostasis : a state of dynamic stability in an organism 's internal conditions, maintained far from thermal equilibrium with its environment ( the study of such processes in zoology has been called physiological ecology ). If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs. For humans, this occurs when the body is exposed to constant temperatures of approximately 55 ° C ( 131 ° F ), and with prolonged exposure ( longer than a few hours ) at this temperature and up to around 75 ° C ( 167 ° F ) death is almost inevitable. Humans may also experience lethal hyperthermia when the wet bulb temperature is sustained above 35 ° C ( 95 ° F ) for six hours. The opposite condition, when body temperature decreases below normal levels, is known as hypothermia. It results when the homeostatic control mechanisms of heat within the body malfunction, causing the body to lose heat faster than producing it. Normal body temperature is around 37 ° C ( 99 ° F ), and hypothermia sets in when the core body temperature gets lower than 35 ° C ( 95 ° F ). Usually caused by prolonged exposure to cold temperatures, hypothermia is usually treated by methods that attempt to raise the body temperature back to a normal range. It was not until the introduction of thermometers that any exact data on the temperature of animals could be obtained. It was then found that local differences were present, since heat production and heat loss vary considerably in different parts of the body, although the circulation of the blood tends to bring about a mean temperature of the internal parts. Hence it is important to identify the parts of the body that most closely reflect the temperature of the internal organs. Also, for such results to be comparable, the measurements must be conducted under comparable conditions. The rectum has traditionally been considered to reflect most accurately the temperature of internal parts, or in some cases of sex or species, the vagina, uterus or bladder. Occasionally the temperature of the urine as it leaves the urethra may be of use in measuring body temperature. More often the temperature is taken in the mouth, axilla, ear or groin. Some animals undergo one of various forms of dormancy where the thermoregulation process temporarily allows the body temperature to drop, thereby conserving energy. Examples include hibernating bears and torpor in bats. Contents 1 Classification of animals by thermal characteristics 1.1 Endothermy vs. ectothermy 1.2 Ectotherms 1.3 Ectothermic cooling 1.4 Ectothermic heating ( or minimizing heat loss ) 1.5 Endothermy 1.6 Homeothermy compared with poikilothermy 2 Vertebrates 2.1 Brain control 2.2 In birds and mammals 2.3 In humans 3 In plants 4 Behavioral temperature regulation 4.1 Hibernation, estivation and daily torpor 5 Variation in animals 5.1 Normal human temperature 5.2 Variations due to circadian rhythms 5.3 Variations due to women 's menstrual cycles 5.4 Variations due to fever 5.5 Variations due to biofeedback 6 Low body temperature increases lifespan 7 Limits compatible with life 7.1 Arthropoda 8 See also 9 References 10 Further reading 11 External links Classification of animals by thermal characteristics This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. ( March 2016 ) Endothermy vs. ectothermy Thermoregulation in organisms runs along a spectrum from endothermy to ectothermy. Endotherms create most of their heat via metabolic processes, and are colloquially referred to as warm - blooded. When the surrounding temperatures are cold, endotherms increase metabolic heat production to keep their body temperature constant, thus making the internal body temperature of an endotherm more or less independent of the temperature of the environment. One metabolic activity, in terms of generating heat, that endotherms are able to do is that they possess a larger number of mitochondria per cell than ectotherms, enabling them to generate more heat by increasing the rate at which they metabolize fats and sugars. Ectotherms use external sources of temperature to regulate their body temperatures. They are colloquially referred to as cold - blooded despite the fact that body temperatures often stay within the same temperature ranges as warm - blooded animals. Ectotherms are the opposite of endotherms when it comes to regulating internal temperatures. In ectotherms, the internal physiological sources of heat are of negligible importance ; the biggest factor that enables them to maintain adequate body temperatures is due to environmental influences. Living in areas that maintain a constant temperature throughout the year, like the tropics or the ocean, have enabled ectotherms to develop a wide range of behavioral mechanisms that enable them to respond to external temperatures, such as sun - bathing to increase body temperature, or seeking the cover of shade to lower body temperature. Ectotherms Main article : Ectotherm Seeking shade is one method of cooling. Here sooty tern chicks are using a black - footed albatross chick for shade. Ectothermic cooling Vaporization : Evaporation of sweat and other bodily fluids. Convection : Increasing blood flow to body surfaces to maximize heat transfer across the advective gradient. Conduction : Losing heat by being in contact with a colder surface. For instance : Lying on cool ground. Staying wet in a river, lake or sea. Covering in cool mud. Radiation : releasing heat by radiating it away from the body. Ectothermic heating ( or minimizing heat loss ) Convection : Climbing to higher ground up trees, ridges, rocks. Entering a warm water or air current. Building an insulated nest or burrow. The red line represents the air temperature. The purple line represents the body temperature of the lizard. The green line represents the base temperature of the burrow. Lizards are ectotherms and use behavioral adaptations to control their temperature. They regulate their behavior based on the temperature outside, if it is warm they will go outside up to a point and return to their burrow as necessary. Conduction : Lying on a hot surface. Radiation : Lying in the sun ( heating this way is affected by the body 's angle in relation to the sun ). Folding skin to reduce exposure. Concealing wing surfaces. Exposing wing surfaces. Insulation : Changing shape to alter surface / volume ratio. Inflating the body. Thermographic image of a snake around an arm To cope with low temperatures, some fish have developed the ability to remain functional even when the water temperature is below freezing ; some use natural antifreeze or antifreeze proteins to resist ice crystal formation in their tissues. Amphibians and reptiles cope with heat loss by evaporative cooling and behavioral adaptations. An example of behavioral adaptation is that of a lizard lying in the sun on a hot rock in order to heat through conduction. Endothermy Main article : Endotherm An endotherm is an animal that regulates its own body temperature, typically by keeping it at a constant level. To regulate body temperature, an organism may need to prevent heat gains in arid environments. Evaporation of water, either across respiratory surfaces or across the skin in those animals possessing sweat glands, helps in cooling body temperature to within the organism 's tolerance range. Animals with a body covered by fur have limited ability to sweat, relying heavily on panting to increase evaporation of water across the moist surfaces of the lungs and the tongue and mouth. Mammals like cats, dogs and pigs, rely on panting or other means for thermal regulation and have sweat glands only in foot pads and snout. The sweat produced on pads of paws and on palms and soles mostly serves to increase friction and enhance grip. Birds also counteract overheating by gular fluttering, or rapid vibrations of the gular ( throat ) skin. Down feathers trap warm air acting as excellent insulators just as hair in mammals acts as a good insulator. Mammalian skin is much thicker than that of birds and often has a continuous layer of insulating fat beneath the dermis. In marine mammals, such as whales, or animals that live in very cold regions, such as the polar bears, this is called blubber. Dense coats found in desert endotherms also aid in preventing heat gain such as in the case of the camels. A cold weather strategy is to temporarily decrease metabolic rate, decreasing the temperature difference between the animal and the air and thereby minimizing heat loss. Furthermore, having a lower metabolic rate is less energetically expensive. Many animals survive cold frosty nights through torpor, a short - term temporary drop in body temperature. Organisms when presented with the problem of regulating body temperature have not only behavioural, physiological, and structural adaptations but also a feedback system to trigger these adaptations to regulate temperature accordingly. The main features of this system are stimulus, receptor, modulator, effector and then the feedback of the newly adjusted temperature to the stimulus. This cyclical process aids in homeostasis. Homeothermy compared with poikilothermy Homeothermy and poikilothermy refer to how stable an organism 's deep - body temperature is. Most endothermic organisms are homeothermic, like mammals. However, animals with facultative endothermy are often poikilothermic, meaning their temperature can vary considerably. Most fish are ectotherms, as most of their heat comes from the surrounding water. However, almost all fish are poikilothermic. Vertebrates By numerous observations upon humans and other animals, John Hunter showed that the essential difference between the so - called warm - blooded and cold - blooded animals lies in observed constancy of the temperature of the former, and the observed variability of the temperature of the latter. Almost all birds and mammals have a high temperature almost constant and independent of that of the surrounding air ( homeothermy ). Almost all other animals display a variation of body temperature, dependent on their surroundings ( poikilothermy ). Brain control Thermoregulation in both ectotherms and endotherms is controlled mainly by the preoptic area of the anterior hypothalamus. Such homeostatic control is separate from the sensation of temperature. In birds and mammals Kangaroo licking its arms to cool down on a very hot day In cold environments, birds and mammals employ the following adaptations and strategies to minimize heat loss : Using small smooth muscles ( arrector pili in mammals ), which are attached to feather or hair shafts ; this distorts the surface of the skin making feather / hair shaft stand erect ( called goose bumps or pimples ) which slows the movement of air across the skin and minimizes heat loss. Increasing body size to more easily maintain core body temperature ( warm - blooded animals in cold climates tend to be larger than similar species in warmer climates ( see Bergmann 's Rule ) ) Having the ability to store energy as fat for metabolism Have shortened extremities Have countercurrent blood flow in extremities -- this is where the warm arterial blood travelling to the limb passes the cooler venous blood from the limb and heat is exchanged warming the venous blood and cooling the arterial ( e.g., Arctic wolf or penguins ) In warm environments, birds and mammals employ the following adaptations and strategies to maximize heat loss : Behavioural adaptations like living in burrows during the day and being nocturnal Evaporative cooling by perspiration and panting Storing fat reserves in one place ( e.g., camel 's hump ) to avoid its insulating effect Elongated, often vascularized extremities to conduct body heat to the air In humans Main article : Thermoregulation in humans Simplified control circuit of human thermoregulation. As in other mammals, thermoregulation is an important aspect of human homeostasis. Most body heat is generated in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid. High temperatures pose serious stresses for the human body, placing it in great danger of injury or even death. For example, one of the most common reactions to hot temperatures is heat exhaustion, which is an illness that could happen if one is exposed to high temperatures, resulting in some symptoms such as dizziness, fainting, or a rapid heartbeat. For humans, adaptation to varying climatic conditions includes both physiological mechanisms resulting from evolution and behavioural mechanisms resulting from conscious cultural adaptations. The physiological control of the body 's core temperature takes place primarily through the hypothalamus, which assumes the role as the body 's `` thermostat. '' This organ possesses control mechanisms as well as key temperature sensors, which are connected to nerve cells called thermoreceptors. Thermoreceptors come in two subcategories ; ones that respond to cold temperatures and ones that respond to warm temperatures. Scattered throughout the body in both peripheral and central nervous systems, these nerve cells are sensitive to changes in temperature and are able to provide useful information to the hypothalamus through the process of negative feedback, thus maintaining a constant core temperature. There are three avenues of heat loss : convection, conduction, and radiation. If skin temperature is greater than that of the surroundings, the body can lose heat by radiation and conduction. But, if the temperature of the surroundings is greater than that of the skin, the body actually gains heat by radiation and conduction. In such conditions, the only means by which the body can rid itself of heat is by evaporation. So, when the surrounding temperature is higher than the skin temperature, anything that prevents adequate evaporation will cause the internal body temperature to rise. During intense physical activity ( e.g. sports ), evaporation becomes the main avenue of heat loss. Humidity affects thermoregulation by limiting sweat evaporation and thus heat loss. Play media A dog panting after exercise In plants Thermogenesis occurs in the flowers of many plants in the Araceae family as well as in cycad cones. In addition, the sacred lotus ( Nelumbo nucifera ) is able to thermoregulate itself, remaining on average 20 ° C ( 36 ° F ) above air temperature while flowering. Heat is produced by breaking down the starch that was stored in their roots, which requires the consumption of oxygen at a rate approaching that of a flying hummingbird. One possible explanation for plant thermoregulation is to provide protection against cold temperature. For example, the skunk cabbage is not frost - resistant, yet it begins to grow and flower when there is still snow on the ground. Another theory is that thermogenicity helps attract pollinators, which is borne out by observations that heat production is accompanied by the arrival of beetles or flies. Behavioral temperature Regulation Animals other than humans regulate and maintain their body temperature with physiological adjustments and behavior. Desert lizards are ectotherms and so unable to metabolically control their temperature but can do this by altering their location. They may do this, in the morning only by raising their head from its burrow and then exposing their entire body. By basking in the sun, the lizard absorbs solar heat. It may also absorb heat by conduction from heated rocks that have stored radiant solar energy. To lower their temperature, lizards exhibit varied behaviors. Sand seas, or ergs, produce up to 57.7 ° C ( 135.9 ° F ), and the sand lizard will hold its feet up in the air to cool down, seek cooler objects with which to contact, find shade or return to their burrow. They also go to their burrows to avoid cooling when the sun goes down or the temperature falls. Aquatic animals can also regulate their temperature behaviorally by changing their position in the thermal gradient. During cold weather many animals increase their thermal inertia by huddling. Animals also engage in kleptothermy in which they share or even steal each other 's body warmth. In endotherms such as bats and birds ( such as the mousebird and emperor penguin ) it allows the sharing of body heat ( particularly amongst juveniles ). This allows the individuals to increase their thermal inertia ( as with gigantothermy ) and so reduce heat loss. Some ectotherms share burrows of ectotherms. Other animals exploit termite mounds. Some animals living in cold environments maintain their body temperature by preventing heat loss. Their fur grows more densely to increase the amount of insulation. Some animals are regionally heterothermic and are able to allow their less insulated extremities to cool to temperatures much lower than their core temperature -- nearly to 0 ° C ( 32 ° F ). This minimizes heat loss through less insulated body parts, like the legs, feet ( or hooves ), and nose. An ostrich can keep its body temperature relatively constant, even though the environment can be very hot during the day and cold at night. Hibernation, estivation and daily torpor To cope with limited food resources and low temperatures, some mammals hibernate during cold periods. To remain in `` stasis '' for long periods, these animals build up brown fat reserves and slow all body functions. True hibernators ( e.g., groundhogs ) keep their body temperatures low throughout hibernation whereas the core temperature of false hibernators ( e.g., bears ) varies ; occasionally the animal may emerge from its den for brief periods. Some bats are true hibernators and rely upon a rapid, non-shivering thermogenesis of their brown fat deposit to bring them out of hibernation. Estivation is similar to hibernation, however, it usually occurs in hot periods to allow animals to avoid high temperatures and desiccation. Both terrestrial and aquatic invertebrate and vertebrates enter into estivation. Examples include lady beetles ( Coccinellidae ), North American desert tortoises, crocodiles, salamanders, cane toads, and the water - holding frog. Daily torpor occurs in small endotherms like bats and hummingbirds, which temporarily reduces their high metabolic rates to conserve energy. Variation in animals Chart showing diurnal variation in body temperature. Normal Human temperature Main article : Normal human body temperature Previously, average oral temperature for healthy adults had been considered 37.0 ° C ( 98.6 ° F ), while normal ranges are 36.1 ° C ( 97.0 ° F ) to 37.8 ° C ( 100.0 ° F ). In Poland and Russia, the temperature had been measured axillary. 36.6 ° C was considered `` ideal '' temperature in these countries, while normal ranges are 36 ° C to 36.9 ° C. Recent studies suggest that the average temperature for healthy adults is 36.8 ° C ( 98.2 ° F ) ( same result in three different studies ). Variations ( one standard deviation ) from three other studies are : 36.4 -- 37.1 ° C ( 97.5 -- 98.8 ° F ) 36.3 -- 37.1 ° C ( 97.3 -- 98.8 ° F ) for males, 36.5 -- 37.3 ° C ( 97.7 -- 99.1 ° F ) for females 36.6 -- 37.3 ° C ( 97.9 -- 99.1 ° F ) Measured temperature varies according to thermometer placement, with rectal temperature being 0.3 -- 0.6 ° C ( 0.5 -- 1 ° F ) higher than oral temperature, while axillary temperature is 0.3 -- 0.6 ° C ( 0.5 -- 1 ° F ) lower than oral temperature. The average difference between oral and axillary temperatures of Indian children aged 6 -- 12 was found to be only 0.1 ° C ( standard deviation 0.2 ° C ), and the mean difference in Maltese children aged 4 -- 14 between oral and axillary temperature was 0.56 ° C, while the mean difference between rectal and axillary temperature for children under 4 years old was 0.38 ° C. Variations due to circadian rhythms In humans, a diurnal variation has been observed dependent on the periods of rest and activity, lowest at 11 p.m. to 3 a.m. and peaking at 10 a.m. to 6 p.m. Monkeys also have a well - marked and regular diurnal variation of body temperature that follows periods of rest and activity, and is not dependent on the incidence of day and night ; nocturnal monkeys reach their highest body temperature at night and lowest during the day. Sutherland Simpson and J.J. Galbraith observed that all nocturnal animals and birds -- whose periods of rest and activity are naturally reversed through habit and not from outside interference -- experience their highest temperature during the natural period of activity ( night ) and lowest during the period of rest ( day ). Those diurnal temperatures can be reversed by reversing their daily routine. In essence, the temperature curve of diurnal birds is similar to that of man and other homoeothermal animals, except that the maximum occurs earlier in the afternoon and the minimum earlier in the morning. Also, the curves obtained from rabbits, guinea pigs, and dogs were quite similar to those from man. These observations indicate that body temperature is partially regulated by circadian rhythms. Variations due to women 's menstrual cycles During the follicular phase ( which lasts from the first day of menstruation until the day of ovulation ), the average basal body temperature in women ranges from 36.45 to 36.7 ° C ( 97.6 to 98.1 ° F ). Within 24 hours of ovulation, women experience an elevation of 0.15 -- 0.45 ° C ( 0.2 -- 0.9 ° F ) due to the increased metabolic rate caused by sharply elevated levels of progesterone. The basal body temperature ranges between 36.7 -- 37.3 ° C ( 98.1 -- 99.2 ° F ) throughout the luteal phase, and drops down to pre-ovulatory levels within a few days of menstruation. Women can chart this phenomenon to determine whether and when they are ovulating, so as to aid conception or contraception. Variations due to fever Fever is a regulated elevation of the set point of core temperature in the hypothalamus, caused by circulating pyrogens produced by the immune system. To the subject, a rise in core temperature due to fever may result in feeling cold in an environment where people without fever do not. Variations due to biofeedback Some monks are known to practice Tummo, biofeedback meditation techniques, that allow them to raise their body temperatures substantially. Low body temperature increases lifespan It has been theorised that low body temperature may increase lifespan. In 2006, it was reported that transgenic mice with a body temperature 0.3 -- 0.5 C lower than normal mice lived longer than normal mice. This mechanism is due to overexpressing the uncoupling protein 2 in hypocretin neurons ( Hcrt - UCP2 ), which elevated hypothalamic temperature, thus forcing the hypothalamus to lower body temperature. Lifespan was increased by 12 % and 20 % for males and females, respectively. The mice were fed ad libitum. The effects of such a genetic change in body temperature on longevity is more difficult to study in humans ; in 2011, the UCP2 genetic alleles in humans were associated with obesity. Limits compatible with life There are limits both of heat and cold that an endothermic animal can bear and other far wider limits that an ectothermic animal may endure and yet live. The effect of too extreme a cold is to decrease metabolism, and hence to lessen the production of heat. Both catabolic and anabolic pathways share in this metabolic depression, and, though less energy is used up, still less energy is generated. The effects of this diminished metabolism become telling on the central nervous system first, especially the brain and those parts concerning consciousness ; both heart rate and respiration rate decrease ; judgment becomes impaired as drowsiness supervenes, becoming steadily deeper until the individual loses consciousness ; without medical intervention, death by hypothermia quickly follows. Occasionally, however, convulsions may set in towards the end, and death is caused by asphyxia. In experiments on cats performed by Sutherland Simpson and Percy T. Herring, the animals were unable to survive when rectal temperature fell below 16 ° C. At this low temperature, respiration became increasingly feeble ; heart - impulse usually continued after respiration had ceased, the beats becoming very irregular, appearing to cease, then beginning again. Death appeared to be mainly due to asphyxia, and the only certain sign that it had taken place was the loss of knee - jerks. However, too high a temperature speeds up the metabolism of different tissues to such a rate that their metabolic capital is soon exhausted. Blood that is too warm produces dyspnea by exhausting the metabolic capital of the respiratory centre ; heart rate is increased ; the beats then become arrhythmic and eventually cease. The central nervous system is also profoundly affected by hyperthermia and delirium, and convulsions may set in. Consciousness may also be lost, propelling the person into a comatose condition. These changes can sometimes also be observed in patients suffering from an acute fever. Mammalian muscle becomes rigid with heat rigor at about 50 ° C, with the sudden rigidity of the whole body rendering life impossible. H.M. Vernon performed work on the death temperature and paralysis temperature ( temperature of heat rigor ) of various animals. He found that species of the same class showed very similar temperature values, those from the Amphibia examined being 38.5 ° C, fish 39 ° C, reptiles 45 ° C, and various molluscs 46 ° C. Also, in the case of pelagic animals, he showed a relation between death temperature and the quantity of solid constituents of the body. In higher animals, however, his experiments tend to show that there is greater variation in both the chemical and physical characteristics of the protoplasm and, hence, greater variation in the extreme temperature compatible with life. Arthropoda The maximum temperatures tolerated by certain thermophilic arthropods exceeds the lethal temperatures for most vertebrates. The most heat - resistant insects are three genera of desert ants recorded from three different parts of the world. The ants have developed a lifestyle of scavenging for short durations during the hottest hours of the day, in excess of 50 ° C ( 122 ° F ), for the carcasses of insects and other forms of life which have succumbed to heat stress. In April 2014, the South Californian mite Paratarsotomus macropalpis has been recorded as the world 's fastest land animal relative to body length, at a speed of 322 body lengths per second. Besides the unusually great speed of the mites, the researchers were surprised to find the mites running at such speeds on concrete at temperatures up to 60 ° C ( 140 ° F ), which is significant because this temperature is well above the lethal limit for the majority of animal species. In addition, the mites are able to stop and change direction very quickly. See also Innate heat Human body temperature Thermal neutral zone Insect thermoregulation References Jump up ^ `` Global Warming : Future Temperatures Could Exceed Livable Limits, Researchers Find ''. Jump up ^ `` Hypothermia ''. Mayo Clinic. Retrieved 2017 - 05 - 01. Jump up ^ `` Hypothermia : Causes, Symptoms, and Treatment ''. WebMD. Retrieved 2017 - 05 - 01. Jump up ^ Chisholm 1911, p. 48. ^ Jump up to : Chisholm 1911, p. 49. ^ Jump up to : `` Khan Academy ''. Khan Academy. Retrieved 2017 - 04 - 03. ^ Jump up to : Boundless ( 2016 - 09 - 20 ). `` Homeostasis : Thermoregulation ''. Boundless. ^ Jump up to : Romanovsky, AA ( 2007 ). `` Functional architecture of the thermoregulatory system ''. Am J Physiol Regul Integr Comp Physiol. 292 ( 1 ) : R37 -- 46. doi : 10.1152 / ajpregu. 00668.2006. PMID 17008453. Jump up ^ Swan, K.G. ; R.E. Henshaw ( March 1973 ). Lumbar sympathectomy and cold acclimatization by the arctic wolf. Analysis of Surgery. 177. pp. 286 -- 292. doi : 10.1097 / 00000658 - 197303000 - 00008. PMC 1355529. PMID 4692116. Jump up ^ Adaptations for an Aquatic Environment. SeaWorld / Busch Gardens Animal Information Database, 2002. Last accessed 27 November 2006. Jump up ^ Introduction to Penguins. Mike Bingham, International Penguin Conservation Work Group. Last accessed 27 November 2006. Jump up ^ Kanosue, K. ; Crawshaw, L.I. ; Nagashima, K. ; Yoda, T. ( 2009 ). `` Concepts to utilize in describing thermoregulation and neurophysiological evidence for how the system works ''. European Journal of Applied Physiology. 109 ( 1 ) : 5 -- 11. doi : 10.1007 / s00421 - 009 - 1256 - 6. Jump up ^ Guyton, A.C., & Hall, J.E. ( 2006 ). Textbook of Medical Physiology ( 11th ed. ). Philadelphia : Elsevier Saunders. p. 890. CS1 maint : Multiple names : authors list ( link ) Jump up ^ `` Heat Exhaustion : Symptoms and Treatment ''. WebMD. Retrieved 2017 - 03 - 01 Jump up ^ Harmon, Katherine. `` How Does a Heat Wave Affect the Human Body ? ''. Scientific American. Retrieved 2017 - 03 - 01 Jump up ^ Harrison, G.A., Tanner, J.M., Pilbeam, D.R., & Baker, P.T. ( 1988 ) Human Biology : An introduction to human evolution, variation, growth, and adaptability. ( 3rd ed ). Oxford : Oxford University Press Jump up ^ Weiss, M.L., & Mann, A.E. ( 1985 ) Human Biology and Behaviour : An anthropological perspective. ( 4th ed ). Boston : Little Brown Jump up ^ `` Thermoregulation ''. www.unm.edu. Retrieved 2017 - 03 - 01. Jump up ^ Boundless ( 2016 - 05 - 26 ). `` Thermoreception ''. Boundless. Jump up ^ Tansey, Etain A. ; Johnson, Christopher D. ( 2015 - 09 - 01 ). `` Recent advances in thermoregulation ''. Advances in Physiology Education. 39 ( 3 ) : 139 -- 148. doi : 10.1152 / advan. 00126.2014. ISSN 1043 - 4046. PMID 26330029. Jump up ^ `` Temperature Regulation of the Human Body ''. hyperphysics.phy-astr.gsu.edu. Retrieved 2017 - 03 - 01. Jump up ^ Guyton & Hall ( 2006 ), pp. 891 -- 892 Jump up ^ Wilmore, Jack H., & Costill, David L. ( 1999 ). Physiology of sport and exercise ( 2nd ed ). Champaign, Illinois : Human Kinetics. Jump up ^ Guyton, Arthur C. ( 1976 ) Textbook of Medical Physiology. ( 5th ed ). Philadelphia : W.B. Saunders ^ Jump up to : Minorsky, Peter V. ( May 2003 ). The Hot and the Classic. Plant Physiol. 132. pp. 25 -- 26. doi : 10.1104 / pp. 900071. PMC 1540311. PMID 12765187. Jump up ^ Plants Thermoregulation ( PDF ). Google. Archived from the original ( PDF ) on 2012 - 05 - 07. Retrieved 24 October 2013. Jump up ^ Holdrege, Craig ( 2000 ). Skunk Cabbage ( Symplocarpus foetidus ). The Nature Institute. pp. 12 -- 18. Jump up ^ Kenneth A. Nagy ; Daniel K. Odell & Roger S. Seymour ( December 1972 ). Temperature Regulation by the Inflorescence of Philodendron. Science. 178. pp. 1195 -- 1197. doi : 10.1126 / science. 178.4066. 1195. PMID 17748981. Jump up ^ Gibernau, Marc ; Barabé, Denis ( 2000 ). Thermogenesis in three Philodendron species ( Araceae ) of French Guiana ( PDF ). Canadian Journal of Botany. 78. p. 685. doi : 10.1139 / cjb - 78 - 5 - 685. Jump up ^ Westhoff, Jacob ( 9 Oct 2014 ). `` Behavioural thermoregulation and bioenergetics of riverine smallmouth bass associated with ambient cold - period thermal refuge ''. Ecology of Freshwater Fish. 25 : 72 -- 85. doi : 10.1111 / eff. 12192. Jump up ^ Arends, A ; Bonaccorso, FJ ; Genoud, M ( 1995 ). `` Basal rates of metabolism of nectarivorous bats ( Phyllostomidae ) from a semiarid thorn forest in Venezuela ''. J. Mammal. 76 : 947 -- 956. doi : 10.2307 / 1382765. Jump up ^ Brown, C.R. ; Foster, G.G. ( 1992 ). `` The thermal and energetic significance of clustering in the speckled mousebird, Colius striatus ''. Journal of Comparative Physiology B. 162 ( 7 ) : 658 -- 664. doi : 10.1007 / BF00296648. Jump up ^ Ancel A, Visser H, Handrich Y, Masman D, Le Maho Y ( 1997 ). Energy saving in huddling penguins. Nature. 385. pp. 304 -- 305. doi : 10.1038 / 385304a0. Jump up ^ Canals, M ; Rosenmann, M ; Bozinovic, F ( 1989 ). `` Energetics and geometry of huddling in small mammals ''. J. Theor. Biol. 141 : 181 -- 189. doi : 10.1016 / S0022 - 5193 ( 89 ) 80016 - 5. Jump up ^ Ehmann, H ; Swan, G ; Swan, G ; Smith, B ( 1991 ). `` Nesting, egg incubation and hatching by the heath monitor Varanus rosenbergi in a termite mound ''. Herpetofauna. 21 : 17 -- 24. Jump up ^ Knapp, CR ; Owens, AK ( 2008 ). `` Nesting Behavior and the Use of Termitaria by the Andros Iguana ( Cyclura Cychlura Cychlura ) ''. Journal of Herpetology. 42 ( 1 ) : 46 -- 53. doi : 10.1670 / 07 - 098.1. Jump up ^ Kenneth S. Hagen ( 1962 ). `` Biology and ecology of predaceous Coccinellidae ''. Annual Review of Entomology. 7 : 289 -- 326. doi : 10.1146 / annurev. en. 07.010162. 001445. Jump up ^ Bob Moore ( 29 September 2009 ). `` Estivation : The Survial Siesta ''. Audubon Guides. Retrieved 24 October 2013. Jump up ^ F.H. Pough, R.M. Andrews, J.E. Cadle, M.L. Crump, A.H. Savitzky and K.D. Wells ( 2001 ). Herpetology, second edition. Upper Saddle River, New Jersey : Prentice Hall. CS1 maint : Multiple names : authors list ( link ) Jump up ^ Starr, Cecie ( 2005 ). Biology : Concepts and Applications. Thomson Brooks / Cole. p. 639. ISBN 0 - 534 - 46226 - X. Jump up ^ Wong, Lena ; Forsberg, C ; Wahren, LK ( 2005 ). `` Temperature of a Healthy Human ( Body Temperature ) ''. Scandinavian Journal of Caring Sciences, The Physics Factbook. 16 ( 2 ) : 122 -- 128. doi : 10.1046 / j. 1471 - 6712.2002. 00069. x. PMID 12000664. Retrieved 24 October 2013. Jump up ^ Rectal, ear, oral, and axillary temperature comparison. Yahoo Health. Jump up ^ Deepti Chaturvedi ; K.Y. Vilhekar ; Pushpa Chaturvedi ; M.S. Bharambe ( 17 June 2004 ). `` Comparison of Axillary Temperature with Rectal or Oral Temperature and Determination of Optimum Placement Time in Children '' ( PDF ). Indian Pediatrics. 41 ( 6 ) : 600 -- 603. PMID 15235167. Jump up ^ Quintana, E.C. ( June 2004 ). How reliable is axillary temperature measurement ?. Annuals of Emergency Medicine. 43. pp. 797 -- 798. doi : 10.1016 / j. annemergmed. 2004.03. 010. Jump up ^ Simpson, Sutherland ; Galbraith, J.J. ( 1905 ). An investigation into the diurnal variation of the body temperature of nocturnal and other birds, and a few mammals ( PDF ). The Journal of Physiology Online. Jump up ^ Swedan, Nadya Gabriele ( 2001 ). Women 's Sports Medicine and Rehabilitation. Lippincott Williams & Wilkins. p. 149. ISBN 0 - 8342 - 1731 - 7. Jump up ^ Cromie, William J. ( 2002 ). Meditation changes temperatures : Mind controls body in extreme experiments. Harvard Gazette. Jump up ^ Transgenic Mice with a Reduced Core Body Temperature Have an Increased Life Span, by Bruno Conti et al. Science, 3, November 2006 Jump up ^ Reduced Body Temperature Extends Lifespan, Study Finds Jump up ^ Bee cool, live long Jump up ^ `` OMIM entry on human UnCoupling Protein 2 ( UCP2 ) ''. ^ Jump up to : Simpson S, Herring PT ( 1905 - 05 - 09 ). `` The effect of cold narcosis on reflex action in warm - blooded animals ''. J. Physiol. 32 ( 5 Suppl 8 ) : 305 -- 11. doi : 10.1113 / jphysiol. 1905. sp001084. PMC 1465681. PMID 16992777. ^ Jump up to : Chisholm 1911, p. 50. ^ Jump up to : Federation of American Societies for Experimental Biology ( FASEB ) ( 27 April 2014 ). `` Mite sets new record as world 's fastest land animal ''. Featured Research. ScienceDaily. Retrieved 28 April 2014. Jump up ^ Sherwood, Van ( 1 May 1996 ). `` Chapter 21 : Most heat tolerant ''. Book of Insect Records. University of Florida. Retrieved 30 April 2014. Further reading Blatteis, Clark M, ed. ( 2001 ) ( First published 1998 ). Physiology and Pathophysiology of Temperature Regulation. Singapore & River Edge, NJ : World Scientific Publishing Co. ISBN 981 - 02 - 3172 - 5. Retrieved 8 September 2010. Charkoudian, Nisha ( May 2003 ). Skin Blood Flow in Adult Human Thermoregulation : How It Works, When It Does Not, and Why. Mayo Clinic Proceedings. 78. pp. 603 -- 612. doi : 10.4065 / 78.5. 603. PMID 12744548. full pdf This article incorporates text from a publication now in the public domain : Chisholm, Hugh, ed. ( 1911 ). `` Animal Heat ''. Encyclopædia Britannica. 2 ( 11th ed. ). Cambridge University Press. pp. 48 -- 50. This cites work of Simpson & Galbraith Green, Charles Wilson ( 1917 ). Kirke 's Handbook of Physiology. North American Revision. New York : William Wood & Co. Retrieved 8 September 2010. Other Internet Archive listings Hall, John E. ( 2010 ). Guyton and Hall Textbook of Medical Physiology with Student Consult Online Access ( 12th ed. ). Philadelphia : Elsevier Saunders. ISBN 978 - 1 - 4160 - 4574 - 8. see Table of Contents link ( Previously Guyton 's Textbook of Medical Physiology. Earlier editions back to at least 5th edition 1976, contain useful information on the subject of thermoregulation, the concepts of which have changed little in that time ). Hardy, James D ; Gagge, A. Pharo ; Stolwijk, Jan A, eds. ( 1970 ). Physiological and Behavioral Temperature Regulation. Springfield, Illinois : Charles C Thomas. Havenith, George ; Coenen, John M.L ; Kistemaker, Lyda ; Kenney, W. Larry ( 1998 ). Relevance of individual characteristics for human heat stress response is dependent on exercise intensity and climate type. European Journal of Applied Physiology. 77. pp. 231 -- 241. doi : 10.1007 / s004210050327. Kakuta, Naoto ; Yokoyama, Shintaro ; Nakamura, Mitsuyoshi ; Mabuchi, Kunihiko ( March 2001 ). Estimation of Radiative Heat Transfer Using a Geometric Human Model. IEEE Transactions on Biomedical Engineering. 48. pp. 324 -- 331. doi : 10.1109 / 10.914795. PMID 11327500. link to abstract Marino, Frank E ( 2008 ). Thermoregulation and Human Performance : Physiological and Biological Aspects. Medicine and Sport Science. Vol. 53. Basel, Switzerland : Karger. ISBN 978 - 3 - 8055 - 8648 - 1. Retrieved 9 September 2010. Mitchell, John W ( 1 June 1976 ). Heat transfer from spheres and other animal forms. Biophysical Journal. 16. pp. 561 -- 569. doi : 10.1016 / S0006 - 3495 ( 76 ) 85711 - 6. PMC 1334880. PMID 1276385. Milton, Anthony Stewart ( 1994 ). Temperature Regulation : Recent Physiological and Pharmacological Advances. Switzerland : Birkhäuser Verlag. ISBN 0 - 8176 - 2992 - 0. Retrieved 9 September 2010. Selkirk, Glen A & McLellan, Tom M ( November 2001 ). Influence of aerobic fitness and body fatness on tolerance to uncompensable heat stress. Journal of Applied Physiology. 91. pp. 2055 -- 2063. PMID 11641344. Retrieved 9 September 2010. Simpson, S. & Galbraith, J.J ( 1905 ). Observations on the normal temperatures of the monkey and its diurnal variation, and on the effects of changes in the daily routine on this variation. Transactions of the Royal Society of Edinburgh. 45. pp. 65 -- 104. doi : 10.1017 / S0080456800011649. Helmut Tributsch ( Author ), Miriam Varon ( Translator ) ( May 1985 ). How Life Learned to Live : Adaptation in Nature. Mit Pr. ISBN 978 - 0262700283. Weldon Owen Pty Ltd. ( 1993 ). Encyclopedia of animals - Mammals, Birds, Reptiles, Amphibians. Reader 's Digest Association, Inc. Pages 567 - 568. ISBN 1 - 875137 - 49 - 1. External links Australian Government Bureau of Meteorology. Thermal Comfort Observations. Retrieved 28 January 2013. Royal Institution Christmas Lectures 1998 Wong, Lena ( 1997 ). `` Temperature of a Healthy Human ( Body Temperature ) ''. The Physics Factbook. Retrieved 24 October 2013. Thermoregulation at the US National Library of Medicine Medical Subject Headings ( MeSH ) Library resources about Thermoregulation Resources in your library hide Human homeostasis Blood composition Blood sugar Osmoregulation Pressure : Renin -- angiotensin system Acid -- base Fluid balance Hemostasis Other Predictive Thermoregulation Retrieved from `` https://en.wikipedia.org/w/index.php?title=Thermoregulation&oldid=845894383 '' Categories : Human homeostasis Animal physiology Heat transfer Thermoregulation Mathematics in medicine Hidden categories : CS1 maint : Multiple names : authors list CS1 : Julian -- Gregorian uncertainty Use dmy dates from October 2013 All articles with unsourced statements Articles with unsourced statements from June 2011 Articles needing additional references from March 2016 All articles needing additional references Articles with unsourced statements from October 2009 Wikipedia articles incorporating a citation from the 1911 Encyclopaedia Britannica with Wikisource reference Wikipedia articles incorporating text from the 1911 Encyclopædia Britannica Articles containing video clips Talk Contents About Wikipedia Беларуская Български Bosanski Català Čeština Dansk Deutsch Eesti Español Esperanto فارسی Français Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Italiano עברית Қазақша Lietuvių Magyar Македонски Bahasa Melayu Nederlands ਪੰਜਾਬੀ Polski Português Română Русский Scots Simple English Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska ไทย Українська Tiếng Việt 中文 35 more Edit links This page was last edited on 14 June 2018, at 21 : 12. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: hypothermia is a state of body temperature lower than
Answer: 35 °C (95 °F)