BIO 203 Lecture Notes - Lecture 4: Thermostat, Bes, Aestivation
2 Nov 2016
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As ambient temperature gets colder, mr increases to produce heat and maintain body temperature. They can also increase metabolic rate when not in the thermal neutral zone. Shivering thermogenesis- muscle contraction to produce heat. Spread to the rest of the body through circulatory system: groups of antagonistic muscles are activated - little net movement other than shivering, muscle contraction is only 25% efficient-energy for the body - 75% of energy expended is released as heat. Non-shivering thermogenesis- metabolism of fat to produce heat: very little energy is conserved in the form of atp, produces heat right away instead of atp. Found in mammals (e. g. , bats) usually in neck and between shoulders. Heat spreads to other parts of the body via the circulation. Decrease driving force: counter-current exchange mechanism in limbs, pulsatile blood flow to limbs (e. g. , artic fox) Decrease surface area (e. g. , small ears, short limbs) curl up into a ball- you can behaviorally reduce sa.
