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Chapter 9 Animal Physiology
Thermal Relations Thermoregulatory Classifications
Terms in this set (63)
is a measure of intensity of random molecular motions of a substance
is a form of energy. Heat is the amount of energy a substance contains as a result of its random molecular motions
A large object and small object
can have the same temperature but different amounts of heat energy.
can have the same amount of heat energy but different temperature.
Heat (energy) flows
from areas of high temperatures to areas of low temperatures, regardless of the amount of heat in the two areas.
What are the four mechanisms of heat transfer?
Dry Heat Transfer:
Wet Heat Transfer:
heat diffusion by contact, no macroscopic motion
movement carries heat macroscopically. More movement=more transfer.
infrared, electromagnetic emissions, no macroscopic motion, no contact or fluid needed.
change of water from liquid to gas carries away
Rate of conductive heat transfer (H)
TB-TA/L is the thermal gradient
k is the thermal conductivity of the insulation layer
L is the thickness of the layer
At night the sky radiates _____ back to the animals than do surrounding trees.
Less heat... the net heat loss to the sky is greater than to the trees.
body temperature is generated from within (metabolic processes)
body temperature is determined from the environment
body temperature is relatively constant
body temperature is variable
Endothermy: no....... thermoregulation:no
Nonthermoregulating poikilotherms or ectotherms
Endothermy: no......... thermoregulation: yes
Thermoregulation poikilotherms or ectotherms.
Endothermy:yes....... thermoregulation: no
Endothermy: yes....... thermoregulation: yes
Ectotherms need ______ energy than endotherms
less. At the same body size, an endotherm needs 4-10 times the amount of food energy as an ectotherm
immediate physiological response (e.g. metabolic rate, moving into the shade)
days, weeks, or months (e.g. adjustments in mitochondrial volume)
chronic response of an individual to changes in a natural environment
In response to temperature variation (e.g. seasons) an ectotherm will acclimatize to that temperature. Acclimatization of metabolic rate (sometimes called metabolic compensation) is a widely employed strategy.
generations (e.g. fur or naked skin)
an animals that can function only over a relatively small range of temperatures
an animal that can function over a relatively broad range of temperatures
Which of the following is not one of the mechanisms by which animals exchange heat with their environment?
D. Metabolic heat production
E. Thermal radiation
D. Metabolic heat production
Besides temperature, the factor that is important for conduction, convection, and thermal radiation is
When thermal radiation strikes an object, it can be
reflected, absorbed, transmitted (passes through)
On an overcast night, as compared to a night with a clear sky, the thermal environment experienced by a desert rodent will by _____, because, _____________.
warmer; there is less radiant heat lost to an overcast sky
Poikilothermy and metabolic rate
the Q10 effect: metabolic rate increases exponentially with increasing body temperature
Q10= Rt/ (Rt-10)
Q10 values are normally near 2-i.e. reaction rates approximately double when increasing temperature by 10 degrees C.
Behavioral thermoregulation depends on ______ of the thermal environment and ______ within the environment.
heterogeneity; preferential selection of particular sites
In response to long-term temperature variation an ectotherm will acclimate to that temperature acclimate to that temperature. Acclimation of metabolic rate (sometimes called metabolic compensation) is a widely employed strategy.
the chronic response of an individual to a change in one or two environmental variables.
allows species to maintain near constant fluidity at different temperatures
Overheating in Poikilothermy
Animals can repair damaged proteins using heat shock proteins (HSPs)
HSPs only repair reversibly denatured enzymes
HSPs require ATP to operate
generally decreases with increasing temperature
Some animals can survive freezing and others cannot. What is associated with the ability of animals to survive freezing?
Freezing of the extracellular fluids only
Ectotherms can tolerate freezing or prevent it
Tolerance involves managing ice crystal formation
ice formation is self-limiting, due to osmosis and colligative properties of water
Extracellular ice crystals can coexist in equilibrium with surrounding aqueous solution
Homeothermy in Birds and Mammals
regulate their body temperature by mainly physiological means. They can also use behavioral means as well.
Are more independent from environmental temperature than ectotherms.
Deep body temperatures are about 37C in placental mammals, regardless of where they live.
Cellular functions occur at a relatively constant, reliable temperature
An endotherm's metabolic rate
rises in both hot and cold environments
In winter, winter flounder have a ___________ concentration in their blood plasma, and therefore have a _____________.
higher protein antifreeze; lower freezing point
Linear Hear Equation
C=Thermal conductance 1/I (I=insulation)
Below the thermoneutral zone (TNZ), TB-TA determines the ____________, and therefore the metabolic rate.
dry heat transfer
Dry heat transfer refers to heat exchange by
conduction, convection and thermal radiation
With respect to heat flow between animals and their environments, high conductance corresponds to _____ insulation and to _____ resistance to heat loss.
As temperature drops within the TNZ insulation is
As temperature drops below the TNZ, insulation
cannot be further increase. MR must increase to generate more heat
(winter fur or feather) is a way to acclimatize to winter for birds and mammals. Peak metabolic rate remains the same
Uncoupling protein 1 is critical for which of the following?
A. Freeze tolerance
B. Brown adipose tissue
C. Mitochondria in birds
D. Temperature sensitive neurons
B. Brown adipose tissue
Brown Adipose Tissue (BAT)
is thermogenic. BAT is found in cold acclimated animals, hibernators, and newborns, including humans.
Increasing peak metabolic rate, often with more BAT, is one response to cold. Insulation remains the same.
In winter, some birds stand on frozen ponds and lakes. How do they prevent their feet from freezing while simultaneously preventing excessive heat loss?
Through the mechanism of countercurrent heat exchange in their legs, while the temperature of the foot is maintained above zero.
Countercurrent heat exchange
outgoing arterial blood gives up heat to incoming venous blood by virtue of the proximity of the vessels
reduces heat transfer to extremities that have a lot of surface area and are often relatively naked.
Accomplished by vasomotor responses and counterheat exchange
allowing the body temp. to drop close to ambient temp. for several days, at least, during winter
same as hibernation but in the summer
like hibernation, but daily. Used by many small endotherms, like mice and hummingbirds, to escape high energy demands of homeothermy each night
As temperature rises above the TNZ in mammals and birds
insulation cannot be further decreased acutely
Above the TNZ, enhancing evaporative cooling is a common strategy
Mechanisms: Gular fluttering, panting, and sweating
Behavioral thermoregulation (dry)
moving to shade, changing orientation to sun, lying on cool earth burrow
In a very hot environment, the benefit of hyperthermia is that it
saves water and reduces heat gain
Peripheral vasodilation (dry)
increase blood flow to ear pinna, tongue, extremities
Cycling body temperature & hyperthermia (dry)
Cycling-allowing body temperature to rise during the hot day and drop at night. Reduces water loss by evaporative cooling during the day , and by conducting to ground during night. This reduces thermal gradient.
Hyperthermia-Common in birds, but rarer in mammals.
Allow body temp. to increase to profoundly high temperatures (Decreases TB-TA and therefore reduces heat gain and need to cool by evaporative means)
THIS SET IS OFTEN IN FOLDERS WITH...
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