Mechanisms for Maintaining Homeostasis

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Mechanisms for Maintaining Homeostasis

• Thermoregulation
• Osmoregulation and Excretion

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Cold-blooded vs. Warm-blooded

• Body temperature can fluctuate
• Body temperature determined by environment

• Body temperature stable
• Body temperature determined by metabolism

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Thermoregulation
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Polar Bear Cold or Warm-blooded?

• Absorbs heat from the sun through its CLEAR hair
  on its BLACK skin
• Maintains consistently warm body temperature

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Grizzly Bear Warm or cold-blooded?

• Hibernates drops body temperature significantly
• Derives most of its heat from its own metabolism

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Confused?
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Thermoregulation depends on heat production,
heat gain, and heat loss.

• Heat production METABOLISM
• Heat exchange (gain and loss) Radiation,
  Conduction, Convection, Evaporation

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Mechanisms of heat exchange with the environment
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Behaviors
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Reduction of Metabolic Rate
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Osmoregulation

• Hypotonic
• Isotonic
• Hypertonic

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Swell and Burst or Shrivel and Die
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Sea Dwellers Isotonic Why?
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Fresh Water and Land Dwellers must regulate How?
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Animals must also dispose of nitrogen waste from
protein metabolism

• Ammonia soluble and toxic aquatic animals
• Urea soluble and less toxic mammals and
  amphibians
• Uric Acid insoluble birds, insects, reptiles

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What organ is responsible for osmoregulation and
removal of nitrogen waste?