Water balance and heat load in mammals

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136ºF
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-132ºF
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• Birds and mammals in cold environments
• The thermoneutral zone (TNZ)

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Endothermic homeotherms and the thermal
environment
increased blood flow sweating panting urination/sa
livation melon rinds heat exhaustion heat stroke
BTR
piloerection thigmotaxis increased
MR (NST) shivering hypothermia
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solstice
equinox
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Heterothermy
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Hibernation
cyclic prolonged protected regulated
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Hibernation
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Torpor
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Tb
fall spring
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Energy Use during hibernation Torpor
16.6 Arousal 19.0 Intertorpor Homeothermy
51.6 Reentry into torpor 12.8
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brown fat
body size
white fat
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Water balance and heat load in mammals
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• the Kangaroo Rat
• adaptive syndrome
• Burrowing
• Nocturnal
• Granivorous

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Water balance and heat load in mammals

• Burrowing
• microhabitat
• latrine
• urine

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Water balance and heat load in mammals

• turbinate bones

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Water balance and heat load in mammals

• Nocturnal

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Water balance and heat load in mammals

• Granivores
• Atkins diet?
• water?
• store seeds
• store seeds

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Water balance and heat load in mammals
burrowing nocturnal granivores - works for
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Water balance and heat load in mammals
Dromedary Camel can go without water organisms
are Camels can drink 100 l of water in about 10
minutes
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Water balance and heat load in mammals

• Camels lose 25 of their body mass in water
• a 500 kg camel can lose 125 l of water
• a human?

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Water balance and heat load in mammals
Hydrated camels evaporate 23 l per day
Tb 41 39 36 34
night Time day
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Water balance and heat load in mammals
When under water stress
Tb 41 39 36 34
night Time day
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Water balance and heat load in mammals

• a hot pan
• circadian temperature fluctuation
• storage of heat
• convective heat loss

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Water balance and heat load in mammals What does
this accomplish?

• reduced heat loading from env
• reduced metabolic rate at night
• increased storage capacity
• reduced water loss
• storage of heat saving of water
• water is necessary for dissipation of heat

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Water balance and heat load in mammals

• How much water do camels save?
• The SHC of camel flesh is 0.83 cal g-1 oC-1 (or
  0.83 kcal kg-1 oC-1)
• 500 kg camel each degree of temperature increase
  415 kcal of stored heat (500 x 0.83 415)
• How much water would be needed?

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Water balance and heat load in mammals

• What is the HV of water?
• 540 cal g-1 (540 kcal l-1)
• so for each 415 kcal
• 415 kcal /540 kcal l-1 0.768 l
• 0.768 l per degree x 7 degrees 5.38 l of water
  saved per day
• What does this do for them?

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Water balance and heat load in mammals

• camels evaporate 23 l per day
• can lose 125 l of water
• 125 l /23 l day-1 5.5 days

23 l - 5.28l 17.62l 125/17.62 7.1 d
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Water balance and heat load in mammals

• an extra day and a half

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What is up with the hump?
furry
Other camel strategies