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Animal Form and Function Notes – Thermoregulation
Surface Area to Volume Ratio
There is a lot of activity happening inside a cell
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Cell needs resources from the outside world in order to live
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As the cell uses these resources it will generate waste products
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Activity inside the cell generates THERMAL energy which must be dissipated
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Question: As cell gets bigger what happens to the surface area to volume ratio?
AS THE VOLUME OF A CELL INCREASES THERE IS LESS SURFACE AREA PER UNIT
VOLUME
This makes the exchange of resources and waste more difficult
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o This helps to achieve a higher surface area to volume ratio
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Disadvantage: when it is cold all the metabolism/enzymes inside body goes
slow, warm themselves up using sun
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Disadvantage: have to constantly eat to maintain energy levels to keep body
temp constant
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E
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Putting your finger IN a flame

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Flame interacts with your finger to heat it up
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E
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Holding your finger ABOVE a flame
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More likely to burn your finger using this method
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E
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Having a VACUUM BETWEEN your finger and a flame

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The heat waves from the flame move through the vacuum and make their way
to your finger where you can feel the heat
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RESPIRATION – as living things we can generate heat through respiration
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Heat of respiration is a process by which oxygen and carbohydrates are
assimilated by a substance also when CO2 and H2O are given off by a
substance
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If our temp is too HIGH:
o Hypothalamus senses it and we react in several ways:
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We start to SWEAT

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We start to VASODILATE – capillaries start to dilate, move more
blood near the surface of our body so we can lose the heat,
which will bring down our temp
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Reason for THERMOREGULATION:
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We are constantly doing this

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Keep our body as close to OPTIMAL temp as possible, which is the perfect
temp for all the enzymes inside our body for function optimally
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o they cool down in muddy water which gets trapped in the folds and
keeps moisture near the skin
o the moisture gradually evaporates and cools the elephant over time –
similar to sweat

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Elephants EARS radiates a lot of heat:
o when it is hot the blood vessels in the ears VASODIALTE allowing more
blood to flow into the vascular ears allowing the blood to cool down in
their very thin ears when they are fanned
o all the blood in an elephant can be pumped through its ears in about
20min
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Thermoregulation in penguins:
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Penguins live in the coldest place on earth

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They need to conserve heat energy

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In Antarctica, temps rarely rise above freezing (0°C)

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Emperor penguins have developed a number of ways to keep warm:

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One way is through SOCIAL THERAMLREGULATION:
o they stick close to each other in clusters during harsh cold and winds
o they take turns standing in the middle
o the insulation of others helps them to reduce heat loss by almost half

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A penguin’s feathers are densely packed overlapping and waterproof:
o when temperatures drop it lifts its feathers upright to trap a layer of
INSULATING AIR close to its body

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Penguins have no choice but to stand on the ice with their bare feet, however:
o their feet are SMALL and lined with FAT
o by standing on their HEELS, they keep their contact with the ice to a
MINIUM
o as their blood circulates, they absorb some of the heat before the
blood reaches their feet



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