Editing Warm-blooded (section)

==Heat generation==
{{Main Article|Thermogenesis}}

Body heat is [[thermogenesis|generated]] by [[metabolism]].<ref>{{Citation |last1=Yousef |first1=Hani |title=Physiology, Thermal Regulation |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK499843/ |access-date=2024-02-28 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29763018 |last2=Ramezanpour Ahangar |first2=Edris |last3=Varacallo |first3=Matthew}}</ref> This relates to the chemical reaction in [[cell (biology)|cell]]s that break down [[glucose]] into water and [[carbon dioxide]], thereby producing [[adenosine triphosphate]] (ATP), a high-energy compound used to power other cellular processes. Muscle contraction is one such metabolic process generating heat energy,<ref>{{Cite journal |last1=Periasamy |first1=Muthu |last2=Herrera |first2=Jose Luis |last3=Reis |first3=Felipe C. G. |title=Skeletal Muscle Thermogenesis and Its Role in Whole Body Energy Metabolism |journal=Diabetes & Metabolism Journal |language=en |publication-date=October 24, 2017 |volume=41 |issue=5 |pages=327–336 |doi=10.4093/dmj.2017.41.5.327 |pmid=29086530 |pmc=5663671 }}</ref> and additional heat results from friction as blood circulates through the vascular system in premise to their specialized fat [[Cell (biology)|cells]] which produce heat through uncoupled [[Respiration (physiology)|respiration]], contributing to [[thermoregulation]].

All organisms metabolize food and other inputs, but some make better use of the output than others. Like all energy conversions, metabolism is rather inefficient, and around 60% of the available energy is converted to heat rather than to ATP.<ref>{{Cite journal |last1=Macherel |first1=David |last2=Haraux |first2=Francis |last3=Guillou |first3=Hervé |last4=Bourgeois |first4=Olivier |date=2021-02-01 |title=The conundrum of hot mitochondria |journal=Biochimica et Biophysica Acta (BBA) - Bioenergetics |volume=1862 |issue=2 |pages=148348 |doi=10.1016/j.bbabio.2020.148348 |pmid=33248118 |issn=0005-2728|doi-access=free |url=https://hal.science/hal-03102332/file/Version%20HAL%20BBABIOv2.pdf }}</ref> In most organisms, this heat dissipates into the surroundings. However, endothermic homeotherms (generally referred to as "warm-blooded" animals) not only produce more heat but also possess superior means of retaining and regulating it compared to other animals. They exhibit a higher basal metabolic rate and can further increase their metabolic rate during strenuous activity. They usually have well-developed insulation in order to retain body heat: fur and [[blubber]] in the case of mammals and [[feather]]s in birds. When this insulation is insufficient to maintain body temperature, they may resort to [[shivering]]—rapid muscle contractions that quickly use up ATP, thus stimulating cellular metabolism to replace it and consequently produce more heat. Additionally, almost all [[eutheria]]n mammals (with the only known exception being [[swine]]) have [[brown adipose tissue]] whose [[Mitochondrion|mitochondria]] are capable of [[non-shivering thermogenesis]].<ref>{{Cite journal |last1=Berg |first1=Frida |last2=Gustafson |first2=Ulla |last3=Andersson |first3=Leif |date=2006-08-18 |title=The Uncoupling Protein 1 Gene (UCP1) Is Disrupted in the Pig Lineage: A Genetic Explanation for Poor Thermoregulation in Piglets |journal=PLOS Genetics |volume=2 |issue=8 |pages=e129 |doi=10.1371/journal.pgen.0020129 |doi-access=free |pmid=16933999 |pmc=1550502 |issn=1553-7404}}</ref> This process involves the direct dissipation of the mitochondrial gradient as heat via an [[uncoupling protein]], thereby "uncoupling" the gradient from its usual function of driving ATP production via [[ATP synthase]].<ref>{{Cite journal |last1=Cannon |first1=Barbara |last2=Nedergaard |first2=Jan |date=2004-01-01 |title=Brown Adipose Tissue: Function and Physiological Significance |url=https://www.physiology.org/doi/10.1152/physrev.00015.2003 |journal=Physiological Reviews |language=en |volume=84 |issue=1 |pages=277–359 |doi=10.1152/physrev.00015.2003 |pmid=14715917 |issn=0031-9333}}</ref>

In warm environments, these animals employ evaporative cooling to shed excess heat, either through [[sweating]] (some mammals) or by [[Thermoregulation#Endothermy|panting]] (many mammals and all birds)—mechanisms generally absent in poikilotherms.