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72 Cards in this Set
- Front
- Back
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What is temperature?
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a measure of the speed of the random motions of the atoms or molecules in a substance?
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What is heat?
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the TOTAL ENERGY that a substance posesses by virtue of the sum of the random motions ofits atoms or molecules
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How do organisms acquire the heat they have? What's the Heat exchange equation?
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T body =
Tambient + H metabolism +/- H radiation +/- H conduction +/- H convection - H evaporation |
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What is H met?
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Heat of metabolism; it's always gained due to the inefficiency of biochemical reactions
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When converting glucose to ATP, if it's 65% efficient, what's the rest?
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it's heat.
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What's the conversion of ATP into work? How does this explain shivering?
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<30%. Shivering is even lower so it produces more Hmetabolism
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What's important about metabolic heat and surface area?
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H met is created in the volume of the body but lost through the surface
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What is radiation and who radiates?
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Anything above absolute zero radiates heat. Heat is infrared electromagnetic waves.
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What is the expression for H radiation?
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Hrad is proportional to sigma, e1e2(Ts2^4-Ts1^4) (Areasurface1)
where sigma equals the stefan-boltzmann constant, e is emissivity, T is the surface temp in Kelvin, and A is effective radiating surface area |
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What is conduction?
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the transfer of heat through stationary materials by atomic-molecular agitation
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What does +/- sign of conduction depend on?
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The difference in temperature at the contact area
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What is the expression for conduction?
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Hconduction is proportional to kA(T1-T2)/d
where k is the coefficient of thermal conductivity, A is the surface area of contact T is the surface temp and D is the distance of separation |
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What's an example of an animal adaption to affect H conduction?
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A lizard lifting its feet and tail off the hot desert sand. This decreases A, increases D, decreasing H conduction
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Can animals modify k or d? (thermal conductivity)
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yes, via evolution
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What's an evolutionary adaption to affect k?
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Qiviut is musk ox fur under their coat. It is 8 times warmer than sheep wool
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What is convection?
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Loss of heat through bulk flow of a material (water, air, etc)
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What affects H convection?
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The difference in temperature, wind velocity, etc
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What is the mathematical expression for H conduction?
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Hcond is proportional to hsubc(Tsurface-Tambient)
where h sub c is the coefficient of convection |
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How to animals decrease or increase convective heat exchange?
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Lizards stilt to decrease heat, creatures move towards black smokers to increase heat, humans fan to decrease heat
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How does evaporation work?
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Evaporation always takes heat as water takes energy to go from liquid to gas phases
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What factors affect evaporation?
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Temperature, relative humidity, volume of H2O
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What is the mathematical expression for Hevap?
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H evap is proportional to
V/(Ta times RH) where V is volume of water vaporized, Ta is ambient temp RH is relative humidity |
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How do honey bees use evaporation?
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The regurgitate some nectar from the honey stomach which will cool the body down
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Why doesn't evaporation always work?
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Water doesn't evaporate in 100% relative humidity because the air is saturated
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What is endothermy?
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If an animal's tissues are warmed by its metabolic production of heat, the animal exhibits endothermy.
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What is an ectotherm?
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An animal whose body temperature depends mostly on the environment
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What kind of thermoregulation might an ectotherm engage in?
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Behavioral thermoregulators like mud baths or stilting legs
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Most ectotherms do/don't regulate their body temperature at all.
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Don't. Fish, bugs, etc
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What's a nonthermoregulating endotherm?
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naked mole rat
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What is a thermoregulating endotherm?
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most homeotherms are thermoregulating endotherms. Most birds/mammals
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What is thermoregulation?
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the maintenance of a relatively constant tissue temperature
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What does ecto mean?
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outside
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Most animals are capable/incapable of endothermy. What is endothermy?
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Endothermy is metabolic thermoregulation. Most are incapable.
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What does poikilo mean
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variable
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What are ectotherms and poikilotherms?
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animals that can't regulate their body temp through metabolism
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what is the difference between an endotherm and a homeotherm?
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Homeotherms regulate temperature by physiological means, not just by behavior
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What ectotherms regulate Tb or Tsome organ and how?
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Bluefin tuna keep muscles in thermal excess over a wide range of ambient temperatures
Bees keep their thorax and head above ambient temperature |
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What is gigantothermy?
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An animal so big that its surface area to volume ratio is small. Thus, when an animal heats up, it doesn't lose heat fast. It becomes essentially endothermic and it can thermoregulate.
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What does eurythermal mean?
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eury means broad or wide
eurythermal means a species that can function over a wide range of body temperatures |
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what does stenothermal mean?
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steno means narrow or restricted
stenothermal means a specie can only function in comparatively narrow ranges of body temperature |
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How is the SMR affected by temperature in poikilotherms?
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SMR is an approximately exponential function of body temperature
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What is Qsub10?
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Qsub10 is the temperature coefficient as given by:
Rt/(Rt-10) where Rt is any given body temperature, Rt-10 is rate at a temperature 10 degrees lower. |
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What is Q10 for most poikilotherms?
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between 2-3.
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What is a homeothermic endotherm?
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Endo = within, therm = heat.
An organism that maintains its heat largely by its metabolic activity. Homeothermic, homeo=similar. It keeps its body temperature consistent regardless of T ambient |
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What are the benefits of being a homeothermic endotherm?
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-activity levels can be kept higher (for biochem, foraging, escape)
-greater independence from external thermal conditions -more flexibility in exploiting different habitats |
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What are the costs of being a homeothermic endotherm?
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-energetically expensive, especially in lower T ambient
-need regulatory machinery (like sensors, receptors, hormones, effectors) |
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What is a conformer?
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An organism that conforms to the ambient temperature, it exists at T ambient
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Compare the metabolism of bluefin vs yellowfin tuna.
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Bluefin regulate Tmuscle and can inhabit colder water than conformer yellowfin tuna
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How much more does homeothermy cost than being an ectotherm?
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the metabolic rate is >100x greater
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Why do humans consume so many calories?
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Because of the high cost of human homeothermy
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What affects the cost of homeothermy?
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T ambient is the greatest determiner of the cost of homeothermy
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What is the Thermoneutral Zone?
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The TNZ is a range of T ambient over which BMR is stable and the animal is most comfortable
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What happens when T ambient falls above or below TNZ?
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The animal's metabolic activity goes up
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What is the mathematical expression for dry heat transfer rate?
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C times (Tbody-Tambient)
where C is the animal's thermal conductance |
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What is the opposite (inverse) of conductance C?
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Insulation
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What are ways the body copes with changes in temperature within the TNZ?
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It decreases its conductance through acts like fluffing up feathers, getting out of the wind, adapting a more compact posture
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How is Tb regulated?
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Tb internal set point is monitored by the thermostat in the hypothalamus
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How is homeostasis maintained?
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by opposing negative feedback loops
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What is thermogenesis?
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The production of heat in organisms
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What does shivering accomplish?
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Its random co-activation of muslce units within antagonistic skeletal muscles produces but no mechanical work. This is a form of thermogenesis
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What is non-shivering thermogenesis?
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Brown adipose tissue (BAT) generates heat
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Where is BAT found?
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along the spine and clavicles and between the scapulas.
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How does BAT work?
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it has more lipid droplets, many mitochondria, and rich vascularization
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What is thermogenin in Bat and what does it do?
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Thermogenin is a transport protein that uncouples ETC to form little ATP and instead, the proteins leaking from the inner mitochondrial membrane go through thermogenin and produce heat instead of ATP
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What affects our Tbody?
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sleeping, torpor, hibernation, fever, illness
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What is torpor?
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a state of decreased physiological activity in an animal, usually by a reduced body temperature and rate of metabolism
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Deep body temperature is / is not constant
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Is not. Daily torpor occurs when organisms sleep
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How does hibernation work?
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It saves energy by reducing Tbody and metabolism
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What is regional heterothermy?
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The ability for regions of the body to regulate Tbody of an area
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What is a countercurrent system?
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Appendages will use blood vessels that are closer to the core of the flesh to keep the heat centralized whereas sending blood closer to the skin will accelerate heat loss.
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What happens if Tappendage << Tbody?
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Countercurrent mechanisms will either try to maintain heat in the appendage or will just focus on preserving the essential body core
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What happens if T appendage >> Tbody?
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mechanisms sometimes move heat to the periphery appendages to hopefully lose heat faster. Think bunny ears
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