Thermoregulation essay Flashcards
Endothermic
Animals generate heat by metabolism. Maintain body temperature despite the external temperature . Requires energy to keep functions normal
Ectothermic
Animals gain heat from external sources. Can tolerate temperature fluctuations, less energy is required
Thermoregulation
Process by which animals maintain an internal temperature within a tolerable range
Adaptations that help animals thermoregulate
- Insulation
- Circulatory adaptations
- Cooling by evaporative heat loss
- Behavioral responses
- Adjusting metabolic heat production
Insulation
Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment (especially important in marine mammals such as whales and walrus)
Circulatory adaptations
Regulation of blood flow near the body surface affects thermoregulation
- Vasodilation: blood blow in the skin increases, facilitating heat loss
- Vasoconstriction: blood flow in the skin decreases, lowering heat loss
- Countercurrent exchange: transfer heat between fluids flowing in opposite directions and thereby reducing heat loss
Cooling by evaporative heat loss
- Animals lose heat through evaporation of water from their skin
- Sweating or bathing moistens the skin, helping to cool an animal down
- Panting increases the cooling effect in many birds and mammals
Behavioral responses
- Some invertebrates have postures that minimize or maximize absorption of solar heat (dragonfly maintains a certain posture to absorb sunlight)
- Honeybees huddle together during cold weather to retain heat
Adjusting metabolic heat production
Thermogenesis: adjustment of metabolic heat to maintain body temp
(shivering, moving, hormones etc)
Part of the body responsible for thermoregulation
Hypothalamus, triggers heat loss or heat generating mechanisms (negative feedback)
