Energy for Thermoregulation

Question 1

heat gained or lost by radiation, convection or conduction

Answer 1

• depends on a temperature gradient
• sensible heat flow
• heat flows from warmer body to cooler body

can’t loose heat if environment is warmer than animal

Question 2

heat gained or lost by evaporation

Answer 2

• depends on vapour pressure gradient
• latent heat flow
• energy loss occurs with a phase change

can’t loose heat at 100% humidity (air is fully saturated)

Question 3

Radiation

Answer 3

heat transfer (warm to cool) via electromagnetic waves

• all animals radiate heat- infrared/longwave radiation
• the sun radiated heat= solar/shortwave radiation
• infrared, visible, UV

all radiation can be absorbed or reflected
- animals absorb about 95% of infrared/longwave radiation
black animals absorb up to 90% of solar/shortwave radiation
white animals only absorb ~50% of solar shortwave radiation

Question 4

Convection

Answer 4

heat transfer through moving air (or water)

• heating air/water= it expands, becomes less dense and rises
• cooling air/water= it becomes denser and sinks

when air/water moves more rapidly, the rate of heat loss by convection increases

Question 5

Conduction

Answer 5

heat transfer between animals and contact surfaces

• when on land- rate of heat loss/gain comes down to surface area
• perching
• standing
• incubating eggs
• lying down

Question 6

Evaporation

Answer 6

heat transfer required for a phase change to occur

• sweating
• panting
• gular fluttering (birds)
• saliva spreading
• mucus secretions

Question 7

Insulative Layers- BOUNDARY

Answer 7

still air surrounding animal
affected by air movement
approximately 0.35 cm (still animal, no air movement)

Question 8

Insulative Layers- COVER

Answer 8

pelage or plumage
trapper still air

effectiveness depends on

• hair/feather type
• hair density
• cover length
• shedding or molting- response to seasonal day length changes
• pilo/ptero-erection- increase trapped air
• wind/water- will reduce depth of pelage/plumage

Question 9

Insulative Layers- TISSUE

Answer 9

muscle, skin, fat, blood vessels

insulation affected by blood flow - body core heat gets to skin via circulatory convection

Question 10

Insulative Layers - BODY CORE

Answer 10

site of metbolic heat production
when you are hot –> appetite decreases
when you are cold–> appetite increases