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Lecture 27

BIOL 3070 Lecture Notes - Lecture 27: Torpor, Rete Algorithm, Countercurrent Exchange

2 pages90 viewsWinter 2017

Course Code
BIOL 3070

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Lecture 27:
Tb = body temperature
Ta= ambient temperature
1) temporal: periods of heat gain and loss change by a factor of time
2) regional: the control of heat gain and loss change by factor of regions (such as tissues in the
organism where we have tissues losing heat and some are always producing heat)
o A) cold environment
o B) warm environment
Insects flying in cool environments need to warm up their thoracic muscles
Done by isometric contraction of the thorax antagonistic muscles that
gives of heat without doing work until they reach 30 degrees take off
They drop their body temperature to the ambient temperature of
where the bears are hiding during the winter
Bears only drop their body temperature by 5 degrees below normal
Daily torpor:
Decreased physiological activity reduction of body temp and
metabolic rate
Regional heterotherm:
o Specific portions of the body temperature is elevated while the remaining portion is
kept at ambient temperature
o Done by specific vasculature
o RETE MIRABILE countercurrent
The main arteries are under the skin (peripheral) and it would infiltrate the core
of the body and would maintain a higher core temperature compared to
another animal where it has its arteries in the middle and infiltrates the
peripheral (more loss of energy)
Endotherms thermal regulation
o Heat input + heat production = heat loss
Regulation of heat:
Heat dissipation sweating
Metabolic heat production
Blood flow in skin
o Thermal neutral zone: no change in the metabolic rate
o Above upper critical temperature would lead to increase in heat dissipation can lead
to death if temp keeps on increasing
o Below lower critical temperature increase metabolic rate so heat can be produced
Thermal neutral zone:
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