temperature ppt notes Flashcards
Heat is a form of what?
energy (kinetic energy)
Heat can be transfered from a hotter substance to a colder one, but never what?
cold to hot
what is the measured thermal state of a substance whch quantifies the energy distribution among the molecules in a system?
Temperature
what properties of a substance change with temperature changes?
physical properties
what is the standard unit of temperature?
kelvin
K
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0 K= what C
0 C= what K
0 k = what
how do u convert C to K
-273.15 C
273 K
absolute 0
add 273.15
what is 1 calorie
the amt of heat needed to raise the temp of 1 g of h20 by 1 degree C
what occurs to kenetic energy during freezing and thawing
decreases when cools (freezing)
Increases when warms (thawing)
The majority of the body’s heat is locted where?
core
- brain
- thorax
- abdomen
since core temp is the gold standard where are some common sites to measure this
pulm artery
esophagus
rectum
bladder
tympanic
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metabolic rate increases by ___ - _____% for each degree C increase in core temp
6-7%
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CO increases by ________ per degree C
3L/min
the body compensates for excessive heat loss by what 2 ways
- decreasing rate of loss
- increasing rate of heat production
Heat is a product of what?
and thus heat can be increased by increasing what?
metabolism
metabolism
what is an effective way of increasing metabolism?
shivering
The down fall of shivering is an increase in O2 consumption by 400-500%, this emphesizes the importance of us doing what?
keeping out pt’s warm to prevent stressful increases in metabolism
What is non-shivering thermogenesis?
complex mechanism not involving ATP
triggers brown fat metabolism
what effects does Anesthesia have on thermoregulation
- general and regional anesthesia blunt the normal thermoregulatory mechanism
- Potent inhaled agents cause vasodilation and disrupt normal hypothalmic shivering regulation
- inhalation agents, propofol induction, vasodilating drugs, and regional anesthetics induce vasodilation
- regional- heat loss due to loss of sympathetic tone
The greatest decrease in core body temp occurs when during anesthesia
1st hour of operative time
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4 routes of heat loss
Radiation
Convection
Conduction
Evaporation