BIO 203 Lecture Notes - Lecture 4: Thermostat, Autonomic Nervous System, Torpor
13 Jan 2016
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As t,amb gets colder, mr increases to produce heat and maintain t,b (lower than tz) Metabolic rate: not increased/used for thermoregulation when in tz. Increase mr -> heat production -> energetically costly. Thermogenesis: convert chemical energy into heat: shivering thermogenesis: muscle contraction to produce heat. Groups of antagonistic muscles are activated - little net movement other than shivering. Muscle contraction is only 25% ef cient - 75% of energy expended is released as heat (circulatory system spreads the heat produced to rest of body: nonshivering thermogenesis - metabolism of fat to produce heat. Very little energy is conserved in the form of atp. Brown (adipose tissue) fat specialized fat for heat production. Thursday, september 3, 2015: a specialization for fat-fueled thermogenesis. Found in mammals (e. g. , bats) usually in neck and between shoulders. Adaptation for rapid, massive heat production heats up very quickly. Highly vascularized heat spreads to other parts of the body via the circulatory system.
