BIO 226 LAB 7
Observe thermoregulatory mechanisms in mouse, an endotherm
Observe relationship between ambient T and metabolic rate, indicated by rate of O2
Observe behavioral response of mouse to changing environmental temperatures.
Describe thermal characteristics of endotherms to changing environmental T.
Thermoregulate : maintain body T within narrow range Ectotherms depend on environmental
temperature since they have high thermal conductance and no insulation.
Endotherms have low thermal conductance and high insulationthey depend on metabolic rate to
maintain body T within a narrow range.
Endotherms can extend their environmental and activity ranges beyond that of ectotherms.
Cost = tenfold increase in metabolic rate for an endotherm when compared to an ectotherm of
similar body weight and body T. (way higher metabolic rates)
Maintaining high metabolic rates = high aerobic energy production.
Endotherms + ectotherms seek microclimates + postural adjustments to aid in thermoregulation
In vertebrates = thermoregulation controlled by hypothalamus.
Ambient temperature range, the thermoneutral zone (TNZ), within which endotherms have a low
* In TNZ, metabolic rates are constant and low leveled in response to T changes.
* In TNZ, endotherms maintain body T without altering MR significantly
* TNZ =lower and upper T limits = lower critical temperature LCT and upper critical T UCT
* Outside these limits, endotherms raise MR to increase heat when cold
* + decrease MR to release heat when exposed to hot temperatures
Adjusting the body posture = alter the rate of heat loss and through physiological processes such
as piloerection (goosebumps or fluffing of fur/feathers) to alter thermal conductance, shivering
increases heat production, peripheral vasoconstriction to maintain higher core body T.
Peripheral vasodilation = sweating = lose heat
When T is too extreme = LLT = lower lethal T and ULT = upper lethal T (hypothermic (too much
heat loss) or hyperthermi