thermoregulation 1 Flashcards
external heat source
the sun, burning organic material
internal heat source
cellular metabolism
cellular metabolism
energy extracted from food and converted partially into heat
anabolic
building complex structures from small monomers
catabolic
breaking down complex structures into small monomers
mass specific metabolic rate
sum catabolic + anabolic
oxyregulators
Mr maintained at a lower level during hypoxia
hypoxia tolerant
can survive low o2 - produces lactic acid
oxyconformers
Mr decreases rapidly during hypoxia
hypoxia intolerant
core body temperature (Tc)
internal Tc roughly in the center of the body
can be dependent or independent of environment
optimized for physiology
TRP channels
open and close as a function in C
detect internal T
poikilotherm
Tc varies considerably with environmental changes
reptiles, fish, insects
homeotherms
Tc does not vary with environmental changes
mammals, birds
heterotherms
Tc has characteristics between the two
endotherm
capable of self generation to maintain Tc
midway between freezing and boiling
more complex
more mitochondria
endotherm
capable of self generation to maintain Tc
midway between freezing and boiling
more complex
more mitochondria
ectotherm
requires external heat sources to maintain Tc
small or negligible internal heat production
rely on environmental heat sources
greater tolerance of T extremes
need less food to survive
mesotherm
can use metabolic rate to raise Tc above ambient
gigantotherm
low metabolic rate able to elevate Tc as a result of high body mass and increased capacity to maintain heat
change in conduction and convection
basoendotherm
Tc <35C
lowest body temp of any mammal
primarily nocturnal
factors that affect Tc
metabolic activity - o2 consumption
environment
size
tissue placement
counter-current heat exchanger
blood vessels placed next to each other
warm blood moves in one direction, cool blood in the other
specific heat capacity
the amount of heat required to raise the T of 1kg of any substance 1C
how easy it is to gain and lose heat
K
ability to transfer heat
higher K indicates rapid heat transfer
materials with low K are effective insulators
what causes a change in K
reducing blood flow to the skin surface
posture (fetal position)
changing skin
hair and feather coloration
decreases K
feather lubrication with oil
fluffing feathers
posture (minimizing s/v ratio)
changing skin color (lizards)
seasonal hair
heat balance eqaution
HE + HC + HR (losses) = HT + HC + HS (gains)
maintaining internal Tc at an optimal T by balancing heat gain and heat loss
HE
evaporation of water
sweat glands, panting
HT
thermogenesis - brown adipose tissue
heat produced as product of metabolism
through muscular activity (shivering)
thermogenesis
increased metabolic activity
reduced metabolic efficiency - uncoupling proteins (UCP)
all energy is lost as heat
[no coupling of ATPase –> energy has to be lost somewhere –> heat]
brown adipose tissue
high number of mitochondria, iron - brown
high number of capillaries, high oxygen demand
UP1 expression
HC
heat flow from animal to environment
insulation - fur, feathers, subcutaneous fat, trapped air
possible causes of death from lethal T (TL)
protein denaturation
enzyme inactivation - Q10
inadequate o2 supply - lack of o2 to support Mr
cascade failure - disruption of biosynthetic pathways
membrane fluidity - changes in the cell membrane
