metabolism and body temp regulation Flashcards
for humans what is daily energy spent on
~70% in basic organ function
~20% on physical activity
~10% for thermoregulation
what are organic substrates that are absorbed form the digestive system in to blood delivered to tissue for
-immediate conversion to ATP (&heat)
-synthesis into structural molecules
-storage for later conversion to ATP
what do heterotrophs derive energy form
other organisms (food)
what is the energy flow diagram
-food energy
-metabolic pool in body<->energy storage
-external work/internal work–>thermal energy (heat)
metabolism
body processes that use or produce energy; occurs at multiple scales
metabolic rate
the rate at which body energy is used in metabolism
what is body metabolism adjusted to do
meet specific needs
more body activity
=higher overall energy use (metabolic rate)
what is metabolism and metabolic rate regulated by
-the CNS and various hormones in mammals
-motor NS increases skeletal muscle activity
-autonomic NS switches between PNS and SNS
-epinephrine increase metabolism
-T3 directly stimulates cellular ATP and heat production indirectly through verious chemical signals (cortisol, leptin)
a change in metabolic rate results form a change…
ATP usage by individual cells
how is a change in metabolic rate seen at a whole body level
-altered O2 consumption
-altered CO2 production
-altered production of H+ and other byproducts
-altered heat production
why have some animals evolves a high rate of metabolism
just to maintain elevated body temps
how is metabolic rate usually measured indirectly
as the rate of O2 consumption
what does the whole body energy use depend on
body mass (slope=0.80)
what does SA/vol have to do with physiology
it plays role in physiology because some properties vary in relation to volume (measured in body mass) and other properties vary in relation to SA
e.g heat production (V) versus heat dissipation (SA)
why are large animals more efficient in maintaining body temp
because of low SA/V (thus less heat loss) but cools down slower (requires structural adaption)
why do smaller lose body heat faster and cool down faster
due to greater SA/V
endotherms:
generate heat internally (thermogenesis) to maintain a steady body temp
example: mammals and birds
ectotherms
depend on external sources of body heat
example: reptiles, amphibians, fish, inverts
homeotherms
maintain a near constant body tem
poikilotherms
do not maintain a steady body temps
what body things are greatly influenced by temperature
enzymatic and other cellular activities
why do endothermic animals generate excess metabolic heat
excess metabolic heat to thermoregulate
what do ectothermic animals rely on
the external environment to govern their body temprature
what happens to endo and ectotherms at low tempratures
endo=metabolic rate rises to generate extra body heat
ecto=animals rely on the external environment to govern their body temp
hibernation vs torpor
hybornation metabolic rate drops in the cold for multiple months
torpor metabolic rate drops for only a few hours
what are bears
endothermic pikotherm
what animals are ectotherms
invertebrates, fish, amphibians, reptiles
what do ectothermic animals rely on
the external environment to govern their body temp
what can modulate ectothermic animals body temp
behavior
how do enzymes change in ectotherms
different forms of body enzymes may have different activities depending on temp
what are advantages to ectotherms
less food needed, lower body energy expenditures
what are disadvantages to ectotherms
optimal temprature is limited, need to cope with fluctuations in body temps, limited body complexity, limited environmental range, periods of inactivity
what are some examples of endothermic animals
birds and mammals
what are some advantages to endotherms
always an optimal temprature for body biochemistry
what things do endotherms use to maintain a stable body temp
behavioural, homeostasis, and anatomical adaptions (fur, sweat glands)
what are some disadvantages to endotherms
need a constant supply of hight quality food; complex homeostasis to cool and warm body
why do endothermic animals generate excess metabolic heat
to thermoregulate
what happens if there is a change in skin temp
-triggers peripheral thermochemoreceptors in skin
-signals to the hypothalamic centers for body thermoregulation (bodys thermostat)
-effects include triggering; volentary change in behaviour, motor neurons, and symphathetic nerves
when there is a decrease in temp detected by thermoreceptors and the hypothalums triggers motor neurons what does this do
skeletal muscle->muscle tone shivering->adjustments in muscle activity (in metabolic output)
what happens if there is a change in core temprature
-central thermochemoreceptors in hypothalamus, abdominal organs, and else where
-signals to the hypothalamic centers for body thermoregulation (bodys thermostat)
-effects include triggering; volentary change in behaviour, motor neurons, and symphathetic nerves
when there is a change in tepm detected by thermoreceptors and the hypothalums triggers sympathetic nerves what does this do
1) smooth muscle in arterioles in skin->vasoconstriction/dilation->adjustment loss or conservation of heat
2) sweat glands->sweating->adjustment in heat loss
3)smooth muscle in skin->piloerection(goose bumps)->adjustment in conservation or loss of heat
what does a negative feedback loop do for endotherms
maintains a balance between heat loss and heat gain
explain the feed back loop if the body temperature gets too low
-temp too low
-temperature receptors in hypothalamus stimulate heat producing mechanisms
-which is: superfical arteries are constricted reducing heat loss to the air blood flow to digestive system decreases, shivering increases aerobic respiration in the muscles releasing heat, thyroid stimulates cells to increase metabolic heat production
-body temp increses
explain the feed back loop if the body temperature gets too high
-body temp gets too high
-temperature receptors initiate heat releasing mechanism
-which is: superficial arteries are dilated, causing flushing and increasing heat loss to air blood flow in not diverted away form digestive system, sweating initiated in skin, thyroid stimulates cells to decrease metabolic heat
-body temperature decreases
what are thyroid hormones important for
important cellular regulators of metabolism in endotherms (especially T3)
what happens if T3 and T4 levels are low
-hypothalamus releases TRH this triggers TSH release by pituitary
-effects of TSH release: triggers release of T3 and T4 by thyroid follicle cells
-effects of T3 and T4 release: increased metabolic rate of body cells, rise in body temp
-then if there is high levels of T3 and T4 it inhibits the release of TRH and TSH
what is the active form of thyroid hormone
T3
what happens when we have a fever? does the thermoregulation stop working?
-no
-hypothalamus sets the temp higher metabolically to fight off infections
