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Today
• Q10 revisited
• Enzyme adaptation Biochemical Adaptation to
Temperature Change – enzymes, membranes and
heat shock proteins
• Mechanics of heat gain and loss
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Convection
Conduction
Evaporation
Radiation
• Definitions of the “therms”
• Keeping Warm --- the extremes
Membrane Changes
• In heat – more cholesterol, more satuated
fatty acids
• In cold – more polyunsaturated fatty acids
(PUFAs),
Stress Proteins or Heat Shock Proteins are produced when an
organism is subjected to environmental stresses including heat, high
salinity, desiccation, heavy metal pollution. Hsp 70 and hps 60
proteins act to protect enzymes by folding around them to prevent
changes in weak bonds and denaturation.
Conduction
varies with
the area
exchanging
heat, the
distance
between the
source and
the sink and
the types of
materials in
contact.
Q = kA(t2-t1)
l
Convection is the special case of conduction
where one or both of the exchangers are fluid and
moving. In animal systems, concurrent
conduction systems are modified to form very
efficient counter current systems.
Radiation
Bodies radiate electromagnetic energy proportional to the 4th
power of the absolute temperature of the surface. The hotter
the surface, the shorter the wavelength radiated. At
biological temperatures, approximately 300oK, our bodies
emit energy in the infrared range, but visible light.
Evaporation
One of the most effective ways to loose heat is to use it to heat
water from a liquid to a gaseous state. This requires a lot of heat
energy, 585 calories/ gram. Many animals sweat, or pant to remove
heat.
Camels will sweat when they are well watered, but a dry
camel instead allows it body temperature to fluctuate + 3.5o.
Extremophiles – bacteria, diatoms and protozoa
have been found living in sea ice in the arctic and
antarctic. The presence of these organisms suggests
that there may also be live on ice covered plants
like Europa shown here.
Temperature Regulation in
Heterotherms and Homeotherms
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First Response – Behavioral
Conduction and Anatomy – Big Ears
Counter Current circulation in Fish
Sexy Dolphins
Insect Flight Warm-up
Brown Fat and Hibernation
Fever
The Thermostat