WThermoregulation 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 thermoregulation 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. If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs. 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.
WBradyaerobic is a term used in biology that describes an animal that has low levels of oxygen consumption.
WBradymetabolism refers to organisms with a high active metabolism and a considerably slower resting metabolism. Bradymetabolic animals can often undergo dramatic changes in metabolic speed, according to food availability and temperature. Many bradymetabolic creatures in deserts and in areas that experience extreme winters are capable of "shutting down" their metabolisms to approach near-death states, until favorable conditions return (see hibernation and estivation).
WCold-stunning, also known as hypothermic stunning, is a hypothermic reaction experienced by marine reptiles, notably sea turtles, when exposed to cold water for prolonged periods, which causes them to become weak and inactive. Cold-stunned sea turtles may float to the surface and be further exposed to cold temperatures, which can cause them to drown. A water temperature threshold of 8–10 °C has been associated with mass turtle stunning events. After cold-stunning has taken place, there is only a very short period of time when sea turtles can be safely rescued.
WAn ectotherm is an organism in which internal physiological sources of heat are of relatively small or of quite negligible importance in controlling body temperature. Such organisms rely on environmental heat sources, which permit them to operate at very economical metabolic rates.
WAn endotherm is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine metabolism, but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production. Examples include special-function muscular exertion such as shivering, and uncoupled oxidative metabolism such as within brown adipose tissue. Only birds and mammals are extant universally endothermic groups of animals. Certain lamnid sharks, tuna and billfishes are also endothermic.
WGigantothermy is a phenomenon with significance in biology and paleontology, whereby large, bulky ectothermic animals are more easily able to maintain a constant, relatively high body temperature than smaller animals by virtue of their smaller surface-area-to-volume ratio. A bigger animal has proportionately less of its body close to the outside environment than a smaller animal of otherwise similar shape, and so it gains heat from, or loses heat to, the environment much more slowly.
WHeat stroke, also known as sun stroke, is a type of severe heat illness that results in a body temperature greater than 40.0 °C (104.0 °F). Other symptoms include red skin, headache, dizziness, and confusion. There is generally a lack of sweating in classic heat stroke while sweating is generally present in exertional heatstroke. The start of heat stroke can be sudden or gradual. Heatstroke is a life-threatening condition characterized by severe hyperthermia and multiorgan-dysfunction resulting from exposure to heat. Medical complications may include seizures, rhabdomyolysis, or kidney failure.
WHeterothermy or heterothermia is a physiological term for animals that vary between self-regulating their body temperature, and allowing the surrounding environment to affect it. In other words, they exhibit characteristics of both poikilothermy and homeothermy.
WHomeothermy, homothermy or homoiothermy is thermoregulation that maintains a stable internal body temperature regardless of external influence. This internal body temperature is often, though not necessarily, higher than the immediate environment. Homeothermy is one of the three types of thermoregulation in warm-blooded animal species. Homeothermy's opposite is poikilothermy. A poikilotherm is an organism that does not maintain a fixed internal temperature but rather fluctuates based on their environment and physical behaviour.
WHyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme temperature elevation occurs, it becomes a medical emergency requiring immediate treatment to prevent disability or death. Almost half a million deaths are recorded every year from hyperthermia.
WHypothermia is defined as a body core temperature below 35.0 °C (95.0 °F) in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe hypothermia, there may be paradoxical undressing, in which a person removes their clothing, as well as an increased risk of the heart stopping.
WInsect thermoregulation is the process whereby insects maintain body temperatures within certain boundaries. Insects have traditionally been considered as poikilotherms as opposed to being homeothermic. However, the term temperature regulation, or thermoregulation, is currently used to describe the ability of insects and other animals to maintain a stable temperature, at least in a portion of their bodies by physiological or behavioral means. While many insects are ectotherms, others are endotherms. These endothermic insects are better described as regional heterotherms because they are not uniformly endothermic. When heat is being produced, different temperatures are maintained in different parts of their bodies, for example, moths generate heat in their thorax prior to flight but the abdomen remains relatively cool.
WKleptothermy is any form of thermoregulation by which an animal shares in the metabolic thermogenesis of another animal. It may or may not be reciprocal, and occurs in both endotherms and ectotherms. One of its forms is huddling. However, kleptothermy can happen between different species that share the same habitat, and can also happen in pre-hatching life where embryos are able to detect thermal changes in the environment.
WA mesotherm is a type of animal with a thermoregulatory strategy intermediate to cold-blooded ectotherms and warm-blooded endotherms.
WA poikilotherm is an animal whose internal temperature varies considerably. Poikilotherms have to survive and adapt to environmental stress. One of the most important stressors is temperature change, which can lead to alterations in membrane lipid order and can cause protein unfolding and denaturation at elevated temperatures. It is the opposite of a homeotherm, an animal which maintains thermal homeostasis. While the term in principle can apply to all organisms, it is generally only applied to animals, and mostly to vertebrates. Usually the fluctuations are consequence of variation in the ambient environmental temperature. Many terrestrial ectotherms are poikilothermic. However some ectotherms remain in temperature-constant environments to the point that they are actually able to maintain a constant internal temperature. It is this distinction that often makes the term "poikilotherm" more useful than the vernacular "cold-blooded", which is sometimes used to refer to ectotherms more generally.
WTachyaerobic is a term used in biology to describe the muscles of large animals and birds that are able to maintain high levels or physical activity because their hearts make up at least 0.5-0.6 percent of their body mass and maintain high blood pressures. A reptile displaying equal size to a tachyaerobic mammal does not have the same capabilities. Tachyaerobic animals' hearts beat more quickly, produce more oxygen, and distribute blood at a quicker rate than reptiles.
WWarm-blooded is an informal term referring to animal species which can maintain a body temperature higher than their environment. In particular, homeothermic species maintain a stable body temperature by regulating metabolic processes. The only known living homeotherms are birds and mammals, though ichthyosaurs, pterosaurs, plesiosaurs and non-avian dinosaurs are believed to have been homeotherms. Other species have various degrees of thermoregulation.