Homeostasis 2 Flashcards
what is the definition of homeostasis?
the condition of a relatively stable internal environment, maintained with narrow limits
what internal conditions need to be controlled?
carbon dioxide, oxygen
waste
temperature
water salts
PH
glucose
what is a negative feedback loop?
an increase in one thing leads to an decrease in another eg glucose
how does the human body decrease heat loss in cold?
Vasoconstriction, reducing sweating conscious behaviours, reduction of surface area
how does the human body decrease heat production in heat ?
decrease movement, metabolic rate
how does the human body increase heat production in cold?
shivering increased movement and metabolic rate
how does the human body increase heat loss in heat?
vasodilation sweat, conscious behaviour, increased surface area
why does the body’s limits need to be maintained ?
enzyme activity
cellular functioning
nerve transmission
muscle contraction
what are the methods that heat is gain or loss?
radiation=waves of energy
conduction =contact from one molecule to another
convection=the movement of air
evaporation = water molecules get evaporated
what is and ectotherm ?
an organism that gains heat from the external environment and there body temperature fluctuates and may regulate temperature through behaviour
what are advantages of ectotherms ?
little energy requirement
can feed less often
stay in shelters longer
what are disadvantages of ectotherms ?
inactive in cold and the night
more likely to be prey
restricted by geographical range
what is an endotherm?
an organisms that gains body heat from metabolism and have a consistant temperature
what are advantages of endotherms ?
body temperature is consistent
often predators
what are disadvantages of endotherms ?
large energy requirements
need insulation or cooling mechanisms
what are physiological adaptations to heat?
sweating or panting
coat thinning
vasodilation
decreased metabolic rate
what are structural adaptations to heat?
insulating fur=shades skin
large surface are to volume ratio
what are behavioural adaptations to heat?
wallowing in water
staying out of direct sunlight
decreasing physical activity
increasing surface area
what are physiological adaptations to cold?
Vasoconstriction
increased metabolic rate
Torpor : hibernation long term inactivity, diurnation short term inactivity
shivering
piloerection
what are structural adaptations to cold?
small surface area to volume ratio
insulating fat
insulating fur
counter current heat exchange
what are behavioural adaptations to cold?
huddling/clusters
staying in burrows create a microclimate
basking in the sun
migration to avoid cold
what is the relationship between SA:VOL and shape?
- spheres are shapes that have the smallest SA:VOL
- longer and thinner shapes have the highest SA:VOL
what is the relationship between SA:VOL and size?
the smaller the size the greater the SA:VOL
what is the relationship between SA:VOL and heat loss?
heat is loss at a set rate per area
the higher the SA:VOL ratio the greater loss of heat
what is the relationship between SA:VOL and metabolism?
the smaller the organism the greater the SA:VOL therefore the greater the metabolism to maintain homeostasis
why do marine mammals not have fur?
water compresses fur pushing out the air
it is not hydrodynamic
how does blubber prevent heat loss?
-poor conductor of heat
-little blood flow
-reduces the heat gradients
-reducing heat loss by conduction
counter current heat exchange?
- artery and vein are touching or close
- arterial blood loses heat to venous blood
- cooler arterial blood means the difference between foot temperature and ambient temperature is less which means lower rate of heat loss
- foot temperature kept slightly above ambient temperature
- venous blood returning to core is warmed by the arterial blood
6.venous blood is almost back to core temperature therefore little energy is required to reheat blood
what is nitrogenous waste ?
a product (ammonia) of breaking down amino acids