1 14 1 Thermoregulation Introduction to Thermoregulation BIO 361T Fall 2014 1 In the Arctic tundra land temperatures fluctuate from an average of 12 C in the summer to 28 C in the winter The Arctic fox releases vasoconstrictors at blood vessels that are close to the surface a Does this mechanism increase or decrease H Explain your answer Minimizes heat loss so it increases H brings it closer to zero to maintain Tb decrease blood going to surface which carries heat with it that can radiate out b Which of the four processes of heat exchange will this affect Explain your answer Conduction to surroundings convection if moving or there is wind radiation of heat from body to environment c What variables are being regulated that contribute to the process es in b such as area of contact path distance wavelength distribution etc Path distance 2 During winter the pelage of the Arctic fox changes from brown to white a Does this mechanism increase or decrease H Explain your answer Will result in less heat absorbed so it decreases H Light will be reflected b Explain how this change in coat color is a trade off It is not adaptive for thermoregulation but it provides camouflage c Which of the four processes of heat exchange will this affect Explain your answer Radiation is white because it is reflecting all wavelengths absorbing none 2 d Wavelength distribution 3 What variables are being regulated that contribute to the process es in c During winter the ground squirrel hibernates lowering its body temperature from 37 C to 0 C a Does this mechanism increase or decrease H Explain your answer Minimizes heat loss so it increases H brings it closer to zero to maintain Tb Keep Tb lower closer to Ta b Which of the four processes of heat exchange will this affect Explain your answer Conduction to surrounding soil Radiation of heat through air to soil combined with conduction when it hits nearby objects No convection due to stagnant media around it c What variables are being regulated that contribute to the process es in b Temperature gradient by bringing Tb lower closer to Ta http research uleth ca rgs hib physiol cfm 4 The ground squirrel also experiences massive neuron cell death during hibernation which is followed by regrowth within two hours of arousal a Does this mechanism increase or decrease H Explain your answer Minimizes heat loss so it increases H brings it closer to zero to maintain Tb Less ATP synthesis to keep cells alive releases less heat b Which of the four processes of heat exchange will this affect Explain your answer Conduction to surrounding soil Radiation of heat through air to soil combined with conduction when it hits nearby objects No convection due to stagnant media around it 3 c What variables are being regulated that contribute to the process es in b Temperature gradient by bringing Tb lower closer to Ta 5 The beluga whale lives in deep waters around the Arctic ice cap for most of the year Instead of a dorsal fin like other Odontocetes toothed whales as opposed to baleen whales the beluga has a dorsal ridge a Does this mechanism increase or decrease H Explain your answer Minimizes heat loss so it increases H brings it closer to zero to maintain Tb Reduce heat loss from extremity b Which of the four processes of heat exchange will this affect Explain your answer Conduction convection radiation c What variables are being regulated that contribute to the process es in b Area of contact 6 Air temperatures in Antarctica may go as low as 40 C and the water where Emperor penguins forage is roughly 2 C The internal temperature of an Emperor penguin is 39 C For each method of heat transfer suggest two plausible adaptations the Emperor penguin has to minimize heat loss H a Conduction huddling minimize surface area of feet high feather density 4 b Convection countercurrent exchangers in circulation increase fat layer to decrease heat loss via wind c Radiation Dark coat color to absorb light huddling d Why is the method of evaporation irrelevant Ta Tb Penguins diverged from ancestors 71 million years ago Antarctica was green until 35 million years ago when South America and Australia drifted away from it The exact evolutionary history of Emperor penguins is not clear yet but it seems that their flightlessness is due to a trade off between diving and flying Each winter Emperor penguins Aptenodytes forsteri travel from the pack ice on the coast of Antarctica to a breeding colony some 30 75 miles away After the adults mate the female lays a single egg leaves it with her mate and walks back to the coast to forage in the water Her mate stands in a huddle of other males throughout the Antarctic winter incubating his egg atop his feet until it hatches During this 64 day incubation the male does not eat due to this fast as well as not eating during his trip he will have fasted for an average of 115 days and loses approximately 1 3 of his body mass The males and offspring wait for the females to return from their two month foraging trip at which time the females relieve their mates of their parenting duties feed the chick some of their foraged food and allow the males to walk back to the closest coast to forage often 60 miles away 7 Why do you think there are more species of mammals than lizards or amphibians in the Arctic Leads into next section mammals have endothermic mechanisms for homeothermy
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