Thermoregulation

Question 1

Basic information about thermoregulation

Answer 1

Most biochemical and physiological reactions are temperature dependent
▪ Every species has an optimal temperature
range
- Modifications in physiology or behavior maintain temperature within that range
- All animals generate some metabolic heat

Question 2

Types of regulation

Answer 2

• Endotherms
  ▪ Generate heat to maintain optimal body temperature
• Ectotherms
  ▪ Rely on environment to maintain optimal body temperature
• Homeotherms
  ▪ Maintain stable body temperature
• Poikilotherms
  ▪ Allow body temperature to fluctuate with environment

Question 3

Heat exchange

Answer 3

1. Radiation: Heat transfer via the emission
   of electromagnetic waves
2. Evaporation: Cooling via surface liquids
   changing into water vapor. e.g. panting, sweating, gular birds (moist membranes), urohidrosis in Birds (Defecation onto scaly portions of legs)
3. Convection: Heat transfer via the
   movement of water or air. e.g. gular birds (speed of air increased), vasodilation of skin vessels (Requires thin layer for diffusion of heat)
4. Conduction: Heat transfer between
   neighboring molecules

Question 4

Raising body temperature

Answer 4

1. Insulation
   - Skin, hair, blubber, fur, feathers in mammals and birds
   - Reduces flow of heat into or out of the
   organism
2. Countercurrent Blood Flow
   - Dolphins, sharks
3. Shivering
   - Produces ~500 joules
   - Individuals exposed to -3 ◦C for 15 min had a 200% increase in O2 consumption and 300% increase in heat production
   *Negative feedback loops to maintain stable body temperature

Question 5

Metabolic rate

Answer 5

• Metabolic rate: the amount of energy an animal uses during a given time interval
  ▪ Measured in joules or kilocalories (1 kilocalorie = 4184 joules)
  ▪ Determined directly by the amount of heat generated by metabolism (direct calorimetry) or indirectly by the amount of oxygen consumed or carbon dioxide produced (indirect calorimetry)
  ▪ Larger animals have higher metabolic rates than smaller animals (but smaller animals have higher metabolic rates per gram than larger animals)

Question 6

Ectotherms

Answer 6

Body temperature can change with the ambient temperature. Or…body temperature can fluctuate with behavioral
modifications
- Detect thermal stimuli and decide to gain or lose heat
▪ Ex. basking in the sun, cooling off with water, seeking shade, huddling

Question 7

Lizard graph

Answer 7

Draw graph

Question 8

Regional Endothermy

Answer 8

Some ectotherms (fast swimmers in cold water = tuna, sharks, etc.) can regulate body temperature to an extent

Question 9

Extra

Answer 9

• Ectotherms can change their range as ambient temperature changes (with climate change)
• so can endotherms