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THERMOREGULATION :thermometer: - Coggle Diagram
THERMOREGULATION :thermometer:
thermal classification of animals
homeotherm
poikilotherm
ectotherm
endotherm
variations in body temperature
spatial
metabolic rates of different organs
core temp
shell temp
temporal
diurnal vs nocternal
phylogenetic
different species
heat vs temperature
heat
= measure of thermal energy or rate of heat exchange
calorimeter
temperature
= measure of thermal molecular intensity
thermometer
heat exchange w/ enviro
convection
transfer of heat in mass flow (bulk movement) of fluids
acc. heat flow by conduction btwn solids & fluids by reducing boundary layer thickness
liquids & gases
free convection
forces convection
electromagnetic radiation
intensity inversely related to distance from emitting surf
intensity of radiation depends on temp of emitting surf
emitted by all objects above 0 K
wavelength of radiation depends on temp of emitting surface - hotter = shorter wavelengths
transfer of heat in absence of direct contact btwn objects
reflection & absorption -- pigment, fur, feathers
conduction
high temp to low temp
solids, liquids & gases
transfer of heat btwn physical bodies in contact w/ each other due to direct transfer of kinetic E of molecular motion
evapouration
amt heat absorbed slightly dependent on temp of evaporating surface
evaporation rate related to saturation deficit - diff btwn vapor pressure of free water & vapor pressure of surr air
water vapourizes - absorbs heat
heat balance
heat gain > heat loss - incr. body temp
heat gain < heat loss - decr. body temp
heat gain = heat loss - stable body temp
H store = + H metab +/- H cond +/- H conv +/- H rad +/- H evap/conde
H store = 0 = stable bt H store = + = incr bt
H store = - = decr bt
temp effects rates of physiological processes
BSM
TNZ
regulating body temp in TNZ
heat loss to enviro by conduction
varying conductance
vary boundary thickness for heat loss
engage & disengage a countercurrent heat exchanger
vary SA for heat loss
ambient temp = no effect on metabolic rate
regulating body temp in cold
incr. heat gain by metabolism
shivering thermogenesis - NS activayes groups of antagonistic skel mus - continuous m contractions liberate heat
non-shivering thermogenesis - sympath NS = release norepinephrine - binds to receptors on fat cells = stim enzyme systems for lipid catabolism - white fats broken & oxidized w/ most E converted and brown fats broken & oxidised & pace accel by uncoupling proteins in inner mito mem = free passage of protons to leak down electrochem gradient w/out being used for phosphorylation
regulating body temp in hot
incr. heat loss by enviro
conductance @ max & body temp held constant by incr. evaporative cooling
panting & gular fluttering
hypothalamus - resp centers - resp muscles
electrolyte recovery & evaporating surf guaranteed
risk of alkalosis
sweating
hypothalamus - sympathetic nerves - sweat glands
no risk of alkalosis & no muscular work
risk of electrolyte depletion & no guarantee of air flow
spreading saliva / urinating
thermoreg pathways
hypothalamus
receives info from central hot & cold thermoreceptors (w/in hypothalamus)
receives info from peripheral hot & cold thermoreceptors
depolarization of hot & cold thermoreceptors - proportional to temp
input sigs integrated & response (autonomic) output sigs to effector sites to stim heat gain or loss
heat loss
autonomic
pilorelaxation
vasodilation
sweating
behavioral
stretching out
panting
heat gain
autonomic
shivering
piloerection
vasoconstriction
behavioural
curling up
hypothermia
2-4 C below normal core temp
CNS anesthesia
muscle rigidity, violet shivering, low BR, low HR ---- organ failure
torpor & hibernation
physio state - body temp reduced & regs @ levels close to ambient temp
low ambient temp &/or food shortage
animals w/ high SA to vol ratio OR high mass-specific metabolic rate
hyperthermia
2-3 C above core temp
dizziness, abdom cramps, delirium, loss conciousness
heat stroke - dehydraton & high humitidty
fever
exogenous pyrogens = thermally-stable polysac produced by bact or virus
endogenous pyrogens = thermally-labile proteins released by leukocytes - resp to circulating exogenous pyrogens
act on thermoreg center