Controlling the Internal Environment I - Regulation of Body Temperature
Keywords (reading p. 865-873)
Temperature
Temperature affects the rates of reactions, e.g. enzyme catalyzed reaction
Illustrated by gas molecules in a balloon slowing down if they are cooled
What is the magnitude of temperature effects for physiological processes or biochemical reactions?
PPT Slide
Q10 values differ for different physiological processes or biochemical reactions
Temperature affects characteristics of macromolecules
Lipid bilayer
Structure of an unsaturated phospholipid
Bilayer with unsaturated phospholipid stays fluid at lower temperatures
Since temperature has such a fundamental influence on biochemistry and physiology, animals:
Endotherms vs. Ectotherms
Example of endotherm and ectotherm
Homeostasis
Thermoregulation
Behavioral thermoregulation
Example of physiological: countercurrent heat exchange
Arteries and veins in appendages are closely associated
Blood vessels in a bird leg
Similar mechanism in flippers of marine mammals
Blood flow can be controlled so that heat is lost. Blood goes to alternate veins close to the surface.
Countercurrent exchange is a trick used by many animals
Tuna heat exchanger
Great white shark
Other tricks: shivering
Brown fat
Short-circuiting the mitochondria
Insect preflight warmup
Another trick: reduce heat loss
Insulating fat (blubber)
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