ENERGY AND ENERGY EXPENDITURE Flashcards
energy
the capacity of a physical system to perform work
exists in many forms
food energy
chemical energy that animals derive from certain nutrient in a food
energy derived from carbohydrates, proteins and fats
nutrients are metabolized, during which energy is released/absorbed
is required to sustain an animal’s metabolism during…
- maintenance
- growth
- reproduction
- physical activity
Endotherm
body temperature primarily determined by heat derived from metabolic activity
- more mitochondria per cell than ectotherms
- increased metabolic rate
How does an endotherm COOL down
- eating less- lower metabolism
- reduce physical activity
- panting/sweating
- vasodilation
how does an endotherm WARM up
- eating more
- increase physical activity
- shivering
- insulation
- vasoconstriction
Ectotherm
body temperature primarily determined by heat derived from the environment
- body temperature fluctuated with environment temperature
- metabolic heat production is minor/ negligible
- lower metabolic rate than endotherms
- eat less
- usually live in consistent temperature
how does an ectotherm COOL down
- reduce physical activity
- seek shelter/ shade/ water
- vasodilation- efficient due to no hair/fur/feathers
- mucus secretions- evaporative cooling
how does an ectotherm WARM up
- increase physical activity
- seek external sources of heat
- countercurrent heat exchange
- keep arms/legs warm by moving cool blood into body and warm blood out to limbs
Pros and Cons of Ectothermy
PROs
- require less food
- larger carrying capacity in a given environment
CONs
- no one functions well when they are cold
Homeotherm
maintains a relatively constant body temperature (regardless of environmental temperature)
- typically considered ‘warm blooded’ animals
- mammals and birds (mostly)
not necessarily endothermic (some tropical or deep water fish)
Poikilotherm
body temperature that fluctuates considerably (usually according to environmental temperature)
- typically considered ‘cold blooded’ animals
- fish, reptiles, and most amphibians
- naked mole rat is the only mammalian poikilotherm
Thermoneutral Zone
environmental termpertature range where endotherms do not warm/cool themselves
basal metabolic heat production = heat loss to the environment
many factors influence an animals TNZ
- body compostion
- fur/pelage
- life stage
- body size
Upper Critical Temperature
the environmental temperature at the upper limit of an endotherms TNZ
if above UCT for too long, heat stress ensures:
- anorexia
- excessive sweating/panting
- cellular dysfunction leading to organ failure
- death if severe
Lower Critical Temperature
the environmental temperature at the lower limit of an endotherms TNZ
if below the LCT for too long cold stress ensures:
- excessive shivering
-bodily processes may slow
- cellular dysfunction leading to organ failure
- death if severe
Basal Metabolic Rate
the minimal amount of energy required by an endothermic animal each day to maintain homeostasis
the minimal amount of energy required by endothermic animals that is…
- at rest (but awake)
- is a post-absorptive state (12h since food)
- in a thermoneutral environment
- without stress
