IMG_0001_NEW_001 - close contact with veins carrying cool...

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Depends on the animals niche and lifestyle: A barnacle has no need to be warm or have a high rate of metabolism since it just sits there (its muscle does not need to be warm) and is in water (any heat generated would be immediately lost). 4. Thermoregulation in endotherms involves several mechanisms: High metabolic rate at rest Change in the rate of metabolic heat production by shivering, increased muscular activity and nonshivering thermogenesis (fats broken down but no ATP, just heat) Adjustments to rate of convective heat exchanged with the environment by vasodilation or vasoconstriction and piloerection (insulation : fu r, feathers, fat). Adjustments to rate of evaporative heat loss by panting, sweating and spreading of saliva or urine over body surface (e.g. bats). I Behavioral responsds, e.g. relocation. 5. Heat conservation in some animals living in cold environments operates on a countercurrent exchange mechanism: 1 Arteries carrying warm blood from core are in
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Unformatted text preview: close contact with veins carrying cool blood from periphery 2 Near the end of the leg cooled arterial blood can still transfer heat to the even colder blood in adjacent vein 3 As blood in veins returns to the body core it is now warmed, retaining heat and minimizing heat loss 6. The body's thermostat in endothermic mammals is a group of nerve cells located in the hypothalamus of the brain: Hypothalamus is capable of initiating two thermoregulatory mechanisms: 1)heat conserving mechanisms e.g. vasoconstriction, piloerection, shivering and nonshivering thermogenesis 2) heat releasing mechanisms e.g. vasodilation and sweating 7. Living with cold: Hibernation Types of dormancy: Hibernation, Torpor, Winter sleep, Carnivore lethargy, Estivation Hibernators : Chipmunks, Squirrels, Bats, Skunks, Garter snakes, Bull frogs Hibernation: abandoning maintenance of high Tb but not abandoning homeostasis (Fig. a0.21)...
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This note was uploaded on 12/27/2011 for the course MBB 222 taught by Professor Briscoe during the Fall '10 term at Simon Fraser.

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