BIOL 1902 Lecture Notes - Lecture 6: Pennaceous Feather, Subcutaneous Tissue, Fluffing
31 Jan 2019
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Document Summary
Second challenge that all living things face environmental stress. The internal body temperature is controlled by the external temperature around them. Internal body temperature is mostly controlled by themselves. Sub-zer0 conditions (general solutions: add layers externally. Mammals grow more hair: guard hairs grow longer and thicker, dense underfur traps the heat. Birds grow more and bulkier feathers: contour feathers on outside, down underneath, add layers internally. Mammals have two types of fat subcutaneous fat a layer of fat just under skin for insulation (white) internal brown fat that generates more heat internally (internal) (only mammals) Birds only have one fat + generate heat by shivering: add subcutaneous fat for fuel not insulation (burning the fat = heat, shivering is an important means of thermogenesis, fluffing feathers help retain body heat. Whenever heat is generated by the body it is called thermogenesis: coloration.
