Homeostasis Flashcards
What are the choices/trade-offs an individual must make?
(1) Fecundity (reproduction)
(2) Growth
(3) Longevity
Fecundity
Reproduction. How many offspring can you produce and with what investment?
Growth
Size/defense (survival). How big and strong or well defended?
Longevity
How long will the individual survive?
Adaptation
Altering the physiology of a population through changes in gene frequencies over generations.
Acclimation
Changing INDIVIDUAL physiology to accommodate environmental change
How can organisms change to sustain optimal performance?
(1) Acclimation–changing individual physiology to accomodate emnvironmental change in short term
(2) Regulation–behavior, morphology, or physiology that maintains internal temperature and chemistry in a narrow range (e.g. day vs night)
Ectotherm
Derives body temperature from EXTERNAL heat source (e.g. lizard)
Endotherm
Derives body temperature from INTERNAL heat production (e.g. birds)
Poikilotherm
Body temperature = ambient temperature (e.g. fish)
Homeotherm
Controls body temperature, keeps constant as ambient temperature changes (e.g. zebras)
Stenotherm
Organism only capable of living or surviving within a very narrow temperature
Conduction
Diffusion of heat through liquid/solid
Convection
Diffusion of heat through gas
Radiation
Electromagnetic movement of heat
Thermal neutral zone
(Homeotherms) The range of temperatures over which the metabolic rate does not change, lessens the need for swings in energy demand
Counter current heat exchange
Blood flows in loops to the cold extremities, so warm blood flowing out warms up the cold blood flowing back in.
Thermal inertia
Reducing the rate of heat loss (reducing surface to volume ratio, e.g. curling up)
Bradycardia
Slowing of heart rate (dive reflex)
Vasoconstriction
When in cold environments, heat tends to get pulled to the core. Blood is shunted from the periphery to minimize exposure to cold temperatures and maintain core temperature.
Heat balance in animals
Total stored = metabolism + conduction + convection + radiation + evaporation
Heat balance in plants
Total stored = conduction + convection + radiation
Water balance in animals
Balance = Ingestion + metabolism + absorption + secretion + evaporation
Water balance in plants
Balance = precipitation + evaporation + transpiration
Transpiration
Evaporation of water from plant into the air (from leaves)
Potential evapotranspiration (PET)
amount of water lost in the environment from evapotranspiration
