BIOL 1902 Lecture Notes - Subcutaneous Tissue, Brown Adipose Tissue
21 Mar 2014
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Document Summary
Stay warm by growing more hair; guard hairs grow longer and thicker. Birds; grow bulkier feathers; contour feathers on the outside; down feathers underneath. Birds add subcutaneous fat for fuel; wing muscles used to keep birds warm; muscles start to vibrate to generate heat; they shiver to generate heat. Birds fluff up to trap more air for insulation. Feathers that are white tend to hold more heat; little hollow spots within the feathers to hold air/heat. Showshoe hares gain 27% in the coat"s insulation value. Low surface area: volume ratio; bergmann"s rule. Countercurrent heat exchanger; rete mirabile or wonderful net. How an animal breathes in winter also conserves heat and energy. Tucking extremities under a wing can also help keep them warm. Where a bird roosts can be important; choice of roost site is important; coniferous trees offer more warmth, especially when covered with snow. Woodpeckers stay inside cavities overnight, small owls go inside cavities, so do black-capped.
