Temperature and Thermoregulation Flashcards
Thermal strategies
Behavioural
Chemical
Physiological
Behavioural strategies
migration
hibernation
Chemical strategies
Cell membrane - phospholipids
Cholesterol: too hot is a liquid and too cold it hardens
Physiological strategies
can build reserve from fat
Insulation
what do physiological mechanisms need
to be charged
what areas have more dramatic increases in temperature
big cities
what is the ring of fire in Northern Canada
machines that melt permafrost
Conduction
energy transfer from one object to another
Convection
energy transfer between the animals and the moving mileu
evaporation
thermal energy absorbed by the water on the surface of an object
Radiation
emission of electromagnetic energy frmo an object
thermal conduction
heat is conducted from internal tissues, throughout other tissues and fluids and into the surroundings
High thermal conductivity
heat sink
water has higher thermal conductivity in air which is why it would loose heat faster
what is heat lost too
moving fluid (water/air)
Shiver
a muscle contraction to heat the boundary layer
Bergmanns rule
states that animals living in cold environments tend to be larger than animals in warmer environments
(applies more to ectotherms)
Allens rule
states that animals living in colder climates tend to have shorter extremities than animals in warmer climates
what is insulation for animals
fur
feathers
blubber
Fur and Feathers
- restricts movement between surface of animal and environment
- keratin
- traps air in between which keeps it warm
- thickness and density changes (better traps air)
- black bird controls piloerection at different temperatures
- thermal conductance through trapped air
- black absorbs wavelength but no reflects
- white reflects but absorbs heat
- polar bear (white absorbs and black causes less damage, hair is hollow)
cons of fur and feathers
- uncommon to be main form of insulation for mammals
- compressible
- energy expensive
blubber
- lipid layer distrupts the flow of thermal energy from the core to external surface of animal
- thicker layer = more insulation
- common insulation for marine mammals
- non compressible
- energy store
poikilotherm
cannot regulate body temp and uses behaviour methods
homeotherm
maintains body temp ( helps their nervous system)
endothermic
animal generates internal heat to maintain a high body temperature
ectothermic
environment determines the animals body temperature
regional endothermy
heat will increase with MR
allow certain parts of the body to be warm during vasoconstriction
- aquatic animals have a system to regulate temperature in the body : rete mirabile
they favour heat production with lots of mitochondria and vasoconstriction
temporal heterotherms
-partial endotherms
- when MR is reduced by the seasons or overnight - torpor
- hibernating animals drop their temperature
- while digesting prey the body temp will increase
partial endotherm because they are internally generating heat
regional heterotherm
- fish like marlin and sword fish can heat specific areas of their environment
- Rete mirabile system used to maintain internal temperature
- heat is generated through the digestive system and moved around by the body to the thermal exchange cells so that heat can be generated
thermotolerance
animals have a characteristic degree of thermotolerance
- ectotherms: changes in their TA alter body temperature directly changing rate of many biological processes
- endotherms: respond to changes in TA by inducing regulatory responses
thermal neutral zone
endotherm temperature tolerance range
- optimal temperature in which heat production is in equilibrium (heat loss and gain are the same)
temperature effects on metabolism
- ectotherms: change in the TA affects body temperature and directly affects various biological processes
- endotherms: a change in the TA induces a compensatory response
- membrane must be given time to allow the membrane to be functionally at different temperature
- phospholipids become more saturated during warmer temperatures while becoming less saturated in colder temperatures (homeoviscus adaptation)
homeoviscus adaptation
- fatty acid chain length and saturated double bond
- polar head phosphatidylcholine (PC) in heat
- polar head phosphatidylethanol (PE) in cold
- cholesterol: membranes are more liquid when external conditions change
what are the two classes of macromolecules that are affected by temperature
proteins and lipids
Ice crystals in tissues can have two harmful effects
- break membranes
- take water and causes a hyper osmotic stress
ice nucleators
- affect calcium and salts will reduce temperature again
- help with freezing of membrane with changes from phospholipids
ambient temperature
- how it varies is realized by thermoreceptors
- thermoreceptors are in the abdominal regions, muscles and one more
- controlled by sensors
panting
found in many mammals
important in species living in warm regions
- gazelles, camels, canines, felines
- absent in horses, rodents, primates and humans
sleeping
- functioning of the brain
- reduce body temperature
- we go to sleep and sometimes wake up cold
- use strategies in order to cool it down for sleeping
torpor
- body temp is reduced
- BMR is reduced
- many different individuals
- humming bird = small surface area and they lose heat at a higher rate
temp drops to 13ºC
estivation
- practiced by some mammals such as squirrels who spends the hottest part of summer sleeping in their burrows with body temp close to ambient temp
hibernation
- physiological adaptation
- survive when food availability is poor and cause a decrease in body temp and metabolism
- accompanies by a significant decrease of internal temp to 1ºC
only hibernating animals can survive this because for any other animal if it goes below 17ºC it is lethal - interrupted by periodic arousals of ‘unpredictable’ nature and temp increases to 37ºC
- 75% time in orthodox sleep
- awakeness is constant
- pay attention to length of day, changes in temp and food availability to prepare for hibernation
- bouts where they change from high to low
- gets to a point where they need to get up to get energy.
