[BIOL 104] - Midterm Exam Guide - Everything you need to know! (12 pages long)

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BIOL 104
MIDTERM EXAM
STUDY GUIDE
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BIOL 104 003
WEEK 1 (HOMEOSTASIS NOTES)
HOMEOSTASIS
Definition: the steady-state environment of the body
In particular, we are interested in how this steady-state is maintained
If the internal environment changes too much, it can be fatal
EXAMPLE: you’re thirsty, why? “oe reeptor soewhere seses your eed for water.
Why? Because increase in body temperature can be dangerous.
Temperature regulation:
Heat can be exchanged (figure 25.2 on page 506)
o Conduction heat is conducted from one structure to another
EXAMPLE: getting into a got bathtub, heat goes from water to you.
Similarly, picking up heat from surrounding structures such as a hot rock.
o Convection movement of air or water past body surface
EXAMPLE: wind-chill is caused by wind sucking heat out of body
o Radiation electro-magnetic waves coming from a warm substance to body
EXAMPLE: it’s hotter i the su tha i the shade
o Evaporation evaporation of water from body surface causing cooling
EXAMPLE: feeling cold coming out of a pool or shower. Humans are very
efficient at this. One of the few animals with sweat glands over most of
the body surface (horses are another example of this)
Some terminology describing how an animal adapts to or regulates temperatures
Ectotherm heat is absorbed from environment, little or no internal mechanism for
controlling body temperature
Endotherm heat is generated by organism, organism can (within limits) control
internal body temperature regardless of environmental temperature regardless of
environmental temperature
Poikilotherm body temperature varies a lot
Homeotherm body temperature is reasonable steady
In general, cold-blooded and warm-blooded are terms that everyone understands right away,
even though they may not be that accurate.
Some behavioral and physiological methods to adapt to temperature changes:
Behavioral kind of obvious (if hot get out of the sun, or be active at night, etc.)
Physiological
o Regulate blood flow to skin
o Sweat
o Shiver
o Counter current systems
EXAMPLES: endotherms for above
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o (figure 20.15 on page 426) hypothalamus reacts to small changes in body
temperature
o response to cold constrict skin capillaries and start shivering
o response to heat dilate skin capillaries and activate sweat glands
Some specific methods by which animals adapt to hostile temperatures:
If endothermic, animal will need a constant supply of high-energy food even in bad climates.
One reason so many animals may starve during the winter.
Another possibility is to hibernate. When an endothermi hierates, it’s ody
temperature and metabolism drop drastically, thus, it needs very little food and can
usually survive off of stored energy reserves (fat). Incidentally, a surprising conservation
problem is bats in the winter.
Bears not true hibernators (i.e. their body temperature does not drop that much), but
do have many of the physiological adaptations that allow them to survive, including a
high tolerance for metabolic wastes in the blood
If etotheri, aial eters a hieratio stage almost automatically. When the
temperature drops below a certain level, metabolism and food requirements are
lowered automatically. There comes a point when behavioral adjustments are no
longer adequate, and the animal will seek out a sheltered location in which to spend the
winter.
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