Exam 1-Thermal Relations Flashcards
conduction
heat transfer between two objects (solids)
convection
heat transfer between solid and surrounding air
evaporation
heat causing H2O to go into gas phase
radiation
heat transfer
endothermy
heat is internally produced
ectothermy
refers to the influence of the environment on the internal body temperature of an animal
poikilothermy
refers to the ability of an animal to survive at a variety of internal body temperatures
eurythermal
refers to poikilotherms who can function over a wide range of internal and external temperatures
stenothermal
refers to poikilotherms who can function over a narrow range of internal and external temperatures
behavioral thermoregulation
poikilotherms
maintenance of a relatively constant internal temperature via certain behaviors
behavioral thermoregulation
homeotherms
the use of behavior to assist in the maintenance of a relatively constant internal temperature
expanding thermoneutral zone
- in order to not have to increase metab.
- insulation: make heat transfer more difficult [fat, pilomotor (fur), ptilomotor (feathers)]
- vasomotor: blood vessels (hot-exposed, dilated at skin; cold-less exposed, constricted)
- postural: taking up space (hot) vs curling up (cold)
Thermoreceptors
cold: phasic, 12-35oC
warm: phasic, 25-4oC
* mammals respond
(regulation of temperature)
hypothalamus
- controls much of homeostasis
- input from peripheral temp. receptors
- directly detects temp.
(regulation of temperature)
posterior region
- cold response: shiver (muscle contractions), restrict blood vessels, hair stands up, insulate, change environ., posture change)
- damage: won’t be able to sense cold or do anything about it
(regulation of temperature)
anterior region
- warmth response: blood vessels dilate, sweat, change posture, change environment, lower metabolism, less active
- damage: can’t sense when we’ve gone above set-point, can’t make changes (always making heat, difficult to cool down)
performance curve
-pejus range: things go to pieces (avalanche) doubtful that the individual will survive (enzymes moving so fast that they’re not really binding)
chronic physiological response
- poikilotherm’s recent thermal history will determine its acute response to temp. changes
- acclimatization
- acclimation
chronic metabolism-temperature curve
if change is less extreme, less stress is placed upon the system (able to make changes in the system)
fever
ectotherms and poikilotherms
-cold response (deliberately increasing temp.-posterior)
-increasing set-point by pyrogens (body feels cold until reaching set-point-get shivers and put layers on)
when fever breaks-sweaty
why fevers?
- invaded cells likely to die
- reduces Fe (required by bacteria)
- increasing enzyme activity (somewhat)
poikilothermic response to high temp.
avoidance: shade, dens, circadian rhythm
(poikilothermic response to freezing temp.)
production of antifreeze compounds
- colligative (concentration higher can survive lower temp.) (invertebrates)
- noncolligative: glycoproteins (prevent crystals)
(poikilothermic response to freezing temp.)
supercooling
- cooling of a solution below its freeing point without ice formation
- ice-nucleating agents: particles that can act as a foci for freezing initiation (ice needs a substance to crystallize on)-(used by shallow fish)
(poikilothermic response to freezing temp.)
tolerance of freezing
ice (pure H2O) forms in tissues around cells increasing conc. of solutes around ice (hypertonic); then solutes move into cell—decreases freezing point
core body temperature
-has much tighter regulation than peripheral body temp.
37oC
-circadian rhythm: increase of 1.5-2oC during active phase
-in TNZ (changes won’t affect internal)
responding to temp. above TNZ
-active evaporation cooling: increased heat loss via accelerated water evaporation (sweating, pantin, gular fluttering)
(responding to temp. above TNZ)
sweating
- increase cutaneous evaporation by 50 fold
- Na, Cl loss
- humans, horses, camels, kangaroos
(responding to temp. above TNZ)
panting
- increased breathing rate in response to heat stress
- blood CO2 (less in blood when taking in more new air than old air-messes with pH and breathing desire)
- breathing patterns
(responding to temp. above TNZ)
gular fluttering
-rapid up/down oscillation of mouth, cavity floor to enhance rate of evaporation cooling by increasing air flow over moist membranes in mouth
responding to temp. below TNZ
- thermogenic mechanism: used to deliberately generate heat (shivering and nonshivering)
- heat conservation (regional heterothermy and countercurrent heat exchange)
(responding to temp. below TNZ)
nonshivering
-brown fat: in young, metabolically active, uncoupling of oxidative phosphorylation (instead of using energy to make ATP its used to generate heat)
(responding to temp. below TNZ)
shivering
- high frequency, unsynchronized (constant forming/breaking bonds) contractions and relaxations of skeletal-muscle motor units
- increases heat production 4-5x resting levels
(responding to temp. below TNZ)
regional heterothermy
- certain regions of the body exhibit different thermal relations than other regions
- wider temp. range (usually appendages)
(responding to temp. below TNZ)
concurrent heat exchange
normally: loosing heat as leaves core
concurrent: blood next to each other, as heat given off its absorbed by next door blood vessel (requires flow of fluids in opposite directions to help maintain a heat gradient)
