Comparative Vertebrate Physiology

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Comparative Vertebrate Physiology

• Temperature regulation

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Temperature regulation

• O2 consumption depends on temperature

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Heat production

• At rest
• 70 - 80 from organs
• 20 - 30 from skeletal muscle
• During exercise
• Skeletal muscle produces 30 - 40X more heat than
  rest of body

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Control of heat

• Metabolism plus heat transfer

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Heat transfer

• Conduction
• Transfer of heat from physical contact
• Convection
• Transfer of heat by warming a layer of air or
  water. Replacement of layer increases heat
  transfer

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Heat transfer

• Radiation
• Transfer of infrared rays (thermal heat)
• 50 of heat transfer
• Evaporation
• Liquid turning into a gas transfers heat
• Lungs and skin

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Thermal strategies

• Based on stability of body temperature
• Homeotherms (birds, mammals)
• Poikilotherms (fish, amphibians, reptiles)

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Thermal strategies

• Based on ability to produce heat
• Endotherms (birds and mammals)
• Ectotherms (fish, amphibians, reptiles)

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Thermal strategy summary
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Thermal strategy

• Heterothermy
• Temporal (monotremes)
• Regional (fish)

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Heat production

• 1. Vasoconstriction of cutaneous vessels
• Restrict blood flow to the core
• Short vs. long term (frostbite)

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Heat production

• 2. Increase metabolic rate
• Norepinephrine from sympathetic fibers
• 3. Thyroxine release

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Heat production

• 4. Shivering
• As a last resort
• Involuntary muscle contraction
• 5. Behavioral
• Huddling

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Heat loss

• 1. Vasodilation
• Increase loss via heat transfer
• 2. Perspiration
• If dry its efficient, if not its inefficient
• 3. Behavior