Thermoregulation Flashcards
Homeothermy
Maintenance of a constant body temperature typically Warner than the environment
Endothermy
Elevated metabolism (internally generated heat) in response to changes in ambient temperature
Ectothermy
Use of external heat source (solar radiation) to maintain an elevated body temperature
Poikilothermy
Conformance to ambient temperature
What are some difficulties that marine animals encounter when thermoregulating in water?
- Water has a high specific heat capacity
- You loose heat more easily in water than in air
How do seabirds thermoregulate?
Endothermy
What is the thermoneutral zone?
The optimal temperature where an organism can thermoregulate without fluctuations in metabolic rate (requires less energy)
Do bigger objects have a lower or higher surface area to volume ratio?
Lower
How does the Surface area to volume ratio affect an organisms ability to retain heat?
- Organisms with a higher surface area to volume ratio loose less heat than organisms with smaller surface are to volume ratios
- Smaller organisms have a higher surface area to loose heat
How do feathers help seabirds thermoregulate?
Semiplume and down feathers add insulation
Describe the function of preen glands
Secrete wax that waterproof feathers
Describe the function of brood patches
- Patch of heavily vascularized skin that lacks feathers in order to facilitate heat transfer to egg or chicks
- Present in breeding birds
How do penguins maintain their thermoneutral zone?
Insulation (feather and fat)
What is a more effective insulator fat or feathers?
- Feathers
- Fat is heavier than feathers and more energetically costly
Describe the structure of penguin feathers
- Down is located near the bottom of the shaft
- When immersed in water feathers flattened
- On land down feathers become erect and trap air (adds insulation)
- Feather overlap makes them impenetrable to wind and water
What affect do oil spills have on seabirds?
- Interferes with their ability to thermoregulate
- Oil disrupts water-repellent properties of plumage
- Water penetrates feathers and removes layer of trapped air
- More susceptible to hypothermia in cold waters
Why is preening important in penguins?
It allows them to rearrange their feathers adding insulation by changing the angle of the feather shaft
Regional heterothermy
Different regions of the body are maintained at different body temperatures
How do seabirds conserve heat through regional heterothermy
- Conservation of core temperature
- Peripheral vasoconstriction
- Counter-current exchange
Describe counter-current exchange
Close proximity of arteries and veins allows heat from warm arterial blood (coming from the body core) to warm colder venous blood (coming from extremities). Heat is conserved by recirculating blood to the warmer body core.
How can penguins use their nasal passage to recapture heat lost through exhalation?
- During inhalation walls of nasal passage cool
- During exhalation, moist air from lungs cools and condenses in the surface of nasal walls
- Nasal passage becomes narrow
- Water loss and energy expenditure are limited
How do seabirds behaviorally thermoregulate?
- Basking
- Tipping up feet to reduce contact to ice
- Huddling
- Seeking shade
- Burrowing
- Nocturnal behavior
- Constant movement (shivering, walking, swimming)
What are some advantages of homeothermy?
- Organisms can live in a wide range of ambient temperatures
- Faster growth rate
- High activity rates
- Faster digestion
- Faster healing from injury
What are some disadvantages of homeothermy/
- Larger food requirements
- 75% of all energy gained from food is used to thermoregulate
- less energy for growth and reproduction
