thermal physiology Flashcards
what are the rate enhancing and destructive effects of increasing temperature
rate enhancing - kinetic energy of molecules
destructive - denaturing
what re the 2 equations for temperature quotient
Q10 = rate at T / (rate at T - 10)
Q10 = (k2 / k1) ^ (10 / (t2 - t1))
where k = rate and t = time
what is the equation for logQ10
(logk2 - logk1) * (10 / (t2 - t1))
what are the 2 types of classifying thermo-regulation stratergies
based on the source of body heat (ecto and endo therms)
based on the stability of body temperature (poikilothermy and homeothermy)
what are ectotherms
body temp dependent on heat transfer from / to environment
what are endotherms
body temp dependent on internal (metabolic) sources of heat
what is poikilothermy
body temp varies with environment
what is homeothermy
body temp maintained within narrow range
are most ectotherms poikilotherms or homeotherms
poikilotherms
how can homeotherms control their temperature
behaviourally
name a common regulatory ectotherm (homeotherm)
lizards
what behaviour can homeotherms engage in to increase temperature
basking
what is the role of the capillaries in controlling temperature of homeotherms
vasoconstriction - constriction of capillaries to reduce heat loss
vasodilation - more blood to external capillaries encourages heat loss to environment
how is the phospholipid membrane affected by temperature change
too viscous when too cold and too fluid when too warm
what is the name of the adaptation to combat phospholipid membranes being impacted by temperature change and what does it involve
homeoviscous adaptation to saturate and desaturate lipids in the membrane
what advantage do unsaturated phospholipids provide
membrane can’t pack as tightly, making it more fluid
what would a warm adapted animals phospholipid membrane look like
have more saturated fatty acids and cholesterol for stability - giving the membrane more rigidity
reference for homeoviscous adaptation
fly experiment - Cooper et al, 2012
what animal was used to demonstrate seasonal enzyme activity
alligator
what happens to metabolic enzyme activity when colder
metabolic rate decreases when cold causing compensatory increase in enzyme activity
what proteins offers thermal protection
heat shock proteins
what are the main heat shock proteins
Hsp40, 70 ans 90
what is the role of heat shock proteins
re-fold damaged proteins
reference for freeze-tolerance
wood frog in Alaska - Larson et al. 2014
give an example of animals which use freeze-avoidance
polar fish and invertebrates
what allows the wood frog to be freeze-tolerant
glucose and urea are effective cryo-protectants allowing the frog to be completely frozen and immobile
how does freeze-avoidance work
anti-freeze glycoproteins prevent uncontrollable ice crystal growth
advantage and disadvantage of endothermy
adv - high constant metabolic rate
dis - high energetic cost
what is special about endothermy evolution
independently evolved in mammals, birds and other taxa
do birds or mammals have higher body temperature and why
birds are higher due to energy expensive flying making it easier to be warm than cool down
3 ways endotherms gain external heat
basking,
migration / movement
increase absorbance e.g. being darker in colour, fur and feathers
give an example of an animal which uses migration to stay warm
humpback whale moving from the North in summer and moving down to warmer climates in winter to rear offspring
3 ways endotherms retain internal heat
vasoconstriction,
insulation,
counter-current exchange
give 2 examples of insulation
anatomical - increased fat and fur
behavioural - huddling and burrows
give another name for counter-current exchange
rete mirabile
how does counter-current exchange work
counter-current flow of veinal and arterial blood
arterial blood flows close to vein blood, heat transferred to returning vein blood
3 ways endotherms can generate more internal heat
higher base metabolic rate,
muscular activity e.g. shivering,
non-shivering thermogenesis
what is responsible for non-shivering thermogenesis in mammals and birds
brown adipose tissue (BAT) in mammals
white muscle in birds
how does non-shivering thermogenesis work
breakdown of triglycerides into free fatty acids
interact with uncoupling protein 1 causing mitochondria to directly produce heat instead of ATP
5 ways to reduce excess heat
reduce insulation e.g. shed fur,
vasodilation,
evaporation e.g. sweating or panting,
counter-current exchange,
avoidance
give an example of counter-current exchange to remove excess heat
gazelles cool arterial blood going to the brain
what are heterotherms
generate internal heat but have variable body temperature
give an example of a heterotherm and how it uses counter-current exchange
tuna - preserves warmth in aerobic swimming muscles usingn counter-current rete system
give an example of a temporal heterotherm
deer mouse
what happens in temporal heterothermy
daily torpor - high body temperature and metabolic rate when active, drops when not
what general trends are occuring as a result of climate change
smaller body size,
shifts in timing of reproduction,
changes in species distribution
what are 2 constraints of adapting to climate change
energetic trade-offs e.g. reproductive fitness and immunity
reduced capacity to tolerate other environmental stressors e.g. pathogens and pollution
