lecture 9 Flashcards
what are the types of heat exchanges
conduction, convection, radiation, evaporative het loss
how do fish thermoregulate
closer to homeotherm (take on temp of deep sea that is at constant temp) closer to surface = poikilotherm
how do birds thermoregulate
heterothermy - during hibernation, reduce body temp in the cold to save resources
how do aquatic ectotherms thermoregulate (and exceptions)
take on temp of water
large fish like sharks and tuna can thermoregulate
how do terrestrial ectotherms thermoregulate
by behavioural means
how is global warming affecting antarctic borks
borks = poikilotherms, can only live in between 1-2 degrees
enzyme acetylcholesterase - breaks down acetylcholine into choline and CoA only functions at 1-2 degrees
without breaking down, overstimulation die
binding affinity of acetylcholesterase in borks drops significantly compared to mullets
what is sarin gas
nerve gas that inhibits acetylcholesterase
how do lizards (ectotherm) thermoregulate
behavioural
at night, in burrow
in the day, move in the sun/shade, off the ground, into trees
how do ectotherms tolerate freezing
freeze only ECF and not intracellular so organelles still work
how do ectotherms avoid freezing
1) antifreeze compounds that prevent freezing. a higher concentration = more effective. ex. sugar alcohol
2) glycoproteins = proteins with AA backbone attached to sugar residue - prevents ice crystals from getting too big
can antifreeze be measured in molarity
no, it is not biological
what do endotherms use (in the brain) to thermoregulate
the hypothalamus
what happened in the experiment testing for the hypothalamus
electrode inserted into hypo to trick it into thinking it is too hot or cold, it will make body temp cool or increase
what is the temperature set point
the body temp that the hypo works to maintain
what happens when body temp goes below temp set point
hypo - heat producing centre, shivering, vasoconstriction
what happens when body temp goes above temp set point
hypo - heat loss centre, sweat glands, vasodilation
what are insulator defences against the cold
beaver dam - going inside the lodge to become warm t
what are insulator defences against the heat
camels, pelage, reflect the sun and heat during the day
what is the adaptations to climate of species in regards to TNZ
arctic animals have a lower lower crtiical tempeature and a wider TNZ
tropical animals are more temp dependent
what is cutaneous blood flow against the heat
vasodilation
what is cutaneous blood flow against the cold
vasoconstriction
if hypo is the control, what are the effectors of cutaneous blood flow
blood arterioles
what is temperature recycling against the heat
camels, let themselves heat up during the day, cool off during the night
if they thermoregulated during the day, there would be evaporative heat loss and they would lose too much water
squirrel - going in and out of the burrow to heat up and cool down - periodic activity of temperature
how does brain cooling in some animals work
arterial (warm) blood - carotid artery - carotid rete mirabile - brain
venous (cool) blood, cooled from nostrils in nasal region - nasal vein - pools at sinus - cools blood at carotid rete mirabile (or to facial vein - jugular vein - body)
what is shivering thermogenesis
uncoordinated contraction of muscle
con: disturb air flow, may transfer heat by convection
what is non-shivering thermogenesis
brown fat/brown adipose with a lot of mitochondria with small lipid vacuoles
hypo - detect cold - activate sympathetic nerves - adrenal gland releases noradrenaline - activate heat production in brown fat
neonatal/hibernating
adults, white fat, large lipid vacuole and little mitochondria
what is heterothermy - torporwhat
depression of MR, heat production, body temp, O2 use to save energy
mini hibernations in circadian rhythms
MR drops less than 70%, body temp remains above12 degrees
what is heterothermy - hibernation
90%+ drop in MR, low body temp
what is a hibernation bout and what is it used for
animal drops body temperature for long period then increases it for a few days before going back down
temp going up is for sleeping
describe bear hibernation
hibernate because of food shortages more than for the cold, easily aroused, body temp remains above 31 degrees
