Laboratory Exercise Number 2
Assignment Statements and Functions
enough for you?
It ain’t the heat, it’s the
Yes, I know it’s 122
here in Phoenix, but it’s a
This laboratory and its associated homework exercise (#1) are intended to continue our
introduction to programming and gain experience in writing assignment statements. Additionally,
the exercise is intended to make you more familiar with the interactions of m files and functions
Introduction: Equivalent Temperatures
An important topical area in biological engineering (specifically, human factors engineering)
is environmental biophysics. You may ask, what is environmental biophysics? Well, it's the study
of how physical factors in an organism’s environment affect its behavior, well-being, and life.
The factors may be, for example, temperature, humidity, visible light, smog aerosols, sound
level, wind speed, water balloons, you name it.
Homeothermic animals are those creatures that must maintain constant internal body
temperatures. People, cows, hamsters, gnus, whales and penguins are all homeothermic. Some
dinosaurs may have been. Furbies were not.
Metabolic processes continuously produce heat, heat that must be transferred to the
environment if the organism is to survive, whether the environment wants it or not! Heat stroke
and death follow if metabolic heat can not be transferred rapidly enough. On the other hand, body
temperature can not be maintained and life is threatened if heat is lost too rapidly (as in a very
cold environment .
.. think, Libe Slope in February).
(Trivia item for the next dull stretch in the conversation – a shrew is so small and loses heat
to its environment so rapidly that metabolic processes are pushed to the limit – which means
homeothermic animals much smaller than the smallest shrew are probably not possible unless
heavily insulated ( ThinsulShrews™?). Why? A shrew has a very large surface area
(where heat is lost)
relative to its volume
(where heat is generated) – also known as specific
surface area. It also means a shrew can eat a
and never have a weight problem (“shrew-out”?).
Furthermore, some of the smallest birds go semi-dormant at night to drop their body
temperatures enough to slow their metabolic rates and lower their heat losses to the point where
they will not starve to death before dawn. Fascinating, isn’t it?)
People exchange heat with their environments by simple convection (warming the air in
contact with the body, called sensible heat exchange), evaporation of perspiration when needed