Responses to the Environment Flashcards
Regulate
using internal control mechanisms to minimize internal physiological damages
Conform
allows certain internal conditions to vary with external changes
Body Temperature
- affects body activities and functions
- enzyme activity increases and body temp increases
- for every 10 degrees above C, enzyme activity doubles
- proteins will denature and lose function with high heat
Source of Body Heat
- Endotherms
- Ectotherms
Endotherms
obtain heat from metabolic activity within their own cells; typically have high metabolic rates, high nutritional needs, and a relatively narrow range of survivable temperatures
- EX: mammals and birds
Ectotherms
obtain heat from external sources; typically have lower metabolic rates, lower nutritional needs, and a wider range of survivable temperatues
- EX: fish, amphibians, reptiles, invertebrates
Mechanisms of Body Temperature Regulation
- Homeotherms
- Poikilotherms
- Heterotherms
Homeotherms
maintain a relatively constant body temperature even as external temperatures vary; may be endo or ecto thermic
Homeothermic Endotherms
most birds and mammals
Homeothermic Ectotherms
most polar marine fish and invertebrates
Poikilotherms
allow body temp to fluctuate with the environment and typically are also ectotherms
- most amphibians, reptiles, freshwater fish, and terrestrial + freshwater invertebrates
Heterotherms
can switch between homeothermic + poikilothermic; maintain a relatively constant body temp with periods of fluctuation with the environment
- animal enters seasonal “tupors” with decreased activity and metabolic activity
Hibernation
winter turpor; hibernating animals are heterotherms
- hibernating mammals are heterothermic endotherms
- hibernating reptiles are heterothermic ectotherms
Thermoregulation Tradeoffs
endotherms + homeotherms have much higher metabolic rates, requiring more food per day compared to ectotherms + poikilotherms
Radiation
transfer of heat between 2 bodies not in direct contact; via the emission of electromagnetic heat waves
Evaporation
loss of heat associated with a phase change (L to G); heat can be removed with liquid from a surface
- EX: mammal sweat
Convection
transfer of heat between a body + moving gas/liquid
- EX: wind removes heat from the surface of dry skin as air passes over it
Conduction
transfer of heat between two bodies in direct contact
- EX: lizard laying on a warm rock
Insulation
reduces the flow of heat between an animal and its environment
- present in many endothermic animals
- feathers, fur, blubber
- goose bumps cause small hairs to erect increasing body temp
- mammals use fat to increase body temp
Circulatory Adaptation
help maintain body temp of endotherms:
1. Vasodilation
2. Vasoconstriction
3. Countercurrent Heat Exchange
4. Metabolic Waste Heat
Vasodilation
brings more flood and heat to the body surface, facilitating radiation and evaporative heat loss that cools the body
Vasoconstruction
reduces blood flow in peripheral blood vessels; forces blood toward the core and vital organs to conserve heat
Countercurrent Heat Exchange
enables the circulatory system to transfer heat from the arteries to veins, warming blood returning to the heart
- prevents cold blood from cooling down organs
- can shut down in some animals to prevent overheating
- EX: dolphins, sharks, fish, bees, humminbirds
Metabolic Waste Heat
when muscles contract, most energy from ATP in muscle actions is wasted energy that translates into heat
- mammals, severe cold and shivering reflex
