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AP Bio- Energy 2: Thermoregulation
Transcript of AP Bio- Energy 2: Thermoregulation
Animals are really the only organisms who are able to regulate their temperature.
Even among animals, there is a wide diversity of abilities to regulate temperature.
Many animals are
c, which essentially makes them
(though even ectotherms can affect their termperature by changing their environment.
Endotherms & Ectotherms
Able to maintain internal temperature at a different level than ambient temperature
Birds and mammals
Internal temperature conforms to ambient temperature
All other animals.
Metabolic activity is the major source of heat production in organisms.
Endothermic organisms have a higher metabolic rate than ectothermic organisms.
Heat is exchanged between an organism and the environment in 4 major ways.
Controlling Heat Exchange
is the major mechanism of heat exchange between animals and the environment
Organisms that live in pronounced heat sink environments (like the ocean) utilize
to decrease heat loss in extremities.
Mammals utilize circulatory, integumentary (skin), and muscular processes to maintain temperature within a homeostatic range.
& constriction of skin capillaries.
& dilation of skin blood vessels.
Some examples of heat exchange strategies:
Metabolism can be measured in organisms by measuring heat exchange and metabolic indicators (respiratory rate, heart rate, etc.)
Basal Metabolic Rate
: the minimum metabolic rate of an endotherm at rest (not correlated to temperature).
Basal Metabolic Rate (
) is a function of body size, with larger organisms consuming more oxygen per hour than smaller organisms (note the logarithmic scales)....
However, when adjusted for metabolism as a function of mass, it becomes apparent that smaller animals consume exponentially more oxygen per unit of mass than larger animals...
Metabolic rate is a function of temperature. The higher the ambient temperature, the greater an animal's metabolic rate.
Standard metabolic rate
: The metabolic rate of an ectotherm at rest at a particular temperature.
Comparison of energy requirements for three different endotherms and an ectotherm.
Notice that the ectotherm (snake) has to spend no energy on thermoregulation. Also notice that compared to the comparatively sized endotherm (penguin), the ectotherm has a greatly reduced energy requirement.
Refers to a state of decreased activity and metabolism, which enables organisms to expend less energy during times when food acquisition is unfavorable or dangerous.
Common in small endotherms (usually during
: Long-term winter torpor.
: Long-term summer torpor.
Data from an experiment monitoring RNA levels of two "clock genes" (Per2 & Bmal1) involved in regulating daily activity ("
") in active (
) and hibernating European hamsters.
Harbor Seal- Endothermic
What's the Strategy?
Make Sure You Can:
Why do organisms need to regulate their internal conditions?
How is regulation accomplished?
Explain why organisms need to regulate their temperature.
Compare the thermoregulatory strategies of ectotherms and endotherms.
Explain the advantages of ectothermy and endothermy.
Explain how metabolism is measured in ectotherms and endotherms.