BIOL 1902 Lecture Notes - Lecture 3: Rete Mirabile, Beaver, Muskrat
28 Jan 2016
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Document Summary
Ectotherms collect their heat from the environment. Mammals stay warm by growing more hair. Contour feathers on the outside and more down feathers underneath. Animals add more layers on the inside too. Subcutaneous fat fir insulation, internal brown fat for burning for warmth. Shivering is an important means of thermogenesis. Colour can provide warmth pale colours retain body heat better. Glogers rule a tendency for animals which are father north to be paler is generate heat. winter. Body shape: short extremities are better allen"s rule. Low surface area: volume ratio bergmann"s rule. Countercurrent heat exchanger the heat is being exchanged between veins that are touching, in the rete mirabile or wonderful net. This keeps the animal"s feet from freezing, and conserving energy. Tucking extremities under a wing can also help keep warmth. How an animal breathes in winter also converses heat and energy. Mouth closed, breathes through the nostrils counter-current in snout.
