BIO 203 Lecture Notes - Lecture 4: Freezing-Point Depression, Hydrophile, Osmosis
18 Sep 2017
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I. e. large endotherms have lower sa/v ratios and are better able to retain heat on a cold environment. Make behavioral and physiological changes to alter heat exchange with the environment. Manipulate the transport equation (i. e. increase insulation) Larger animals use less energy per unit mass to stay warm. (cid:313) mr (cid:314) (cid:313) heat production (cid:314) energetically costly. Thermogenesis : convert chem energy into heat. Shivering thermogenesis : muscle contraction to produce heat. Groups of antagonistic muscles are activated (cid:314) little net movement other than shivering. Muscle contraction is only 25% e(cid:130)(cid:128)cient (cid:314) 75% of energy expended is released as heat. Nonshivering thermogenesis : metabolism of fat to produce heat. Very little energy is conserved in the form of atp. Found in mammals (i. e. bats) usually in neck and between shoulders. Heat spreads to other parts of the body via circulation. Avoidance (cid:314) great savings cost in terms of energy. Endothermsmoderate heat stress (t b > t amb )
