Lecture notes chapter 40

Can transfer heat between objects that are not in

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Unformatted text preview: in environments with stable temperatures Are endotherms always homeotherms? No, some animals will enter inactive states in which they maintain lower body temperatures Hummingbirds decrease temperature set point at night – torpor Balancing heat loss and gain Four physical processes allow for the exchange of heat between an organism an its environment RadiaBon: Emission of electromagneCc waves. Can transfer heat between objects that are not in direct contact ConvecBon: Transfer of heat by movement of air or liquid past a surface blood, wind EvaporaBon: Removal of heat from the surface of a liquid that is loosing some of its molecules as gas ConducBon: Direct transfer of heat between molecules of objects in direct contact with each other Note: heat is transferred from an object of high temperature to one of lower temperature Several mechanisms are involved in thermoregula2on Several of these mechanisms involve the Integumentary System: Skin, Hair, and nails Outer layer of skin Inner layer of skin Raised Feathers InsulaBon: Hair, feathers, layers of fat – major thermoregulatory adapCon in birds and mammals Marine mammals that live in near freezing water have a thick layer of fat called blubber * heat transfer in water occurs 50 to 100x faster than heat transfer in air Blubber allows marine mammals to maintain a body temperature between 36 and 40 °C without acquiring more food energy than land animals of similar size Circulatory AdapBon: VasodilaBon: increase the diameter of blood vessels found near the body surface (superficial) Example: An increase is the diameter of blood vessels size will increases the transfer of body heat to the environment that occurs by radiaCon, conducCon and convecCon. VasoconstricBon: decrease in the diameter of the superficial blood vessels Example: A decreases in the diameter of blood vessels will decrease the transfer of heat from the environment to the body that occurs by radiaCon, conducCon and convecCon Countercurrent Heat Exchangers: involves the anCparallel arrangement of blood vessels Arteries transfer heat to veins Heat exchange occurs along the enCre length of the exchanger As blo...
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