temperature regulation ranm
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TEMPERATURE REGULATION
Rayvita Meagratia
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Normal body temperature
96.0F (35.5C) in the morning to 99.9F (37.7C)
in the evening Average 98.2F (36.7C)
According circardian rhythm
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WHY DO WE NEED TO
REGULATE INTERNAL BODY
TEMPERATURE?
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Thermoregulation aims to:
frees biochemical reactions from fluctuating with theexternal temperature
provide the optimum conditions for enzyme-catalysed
reactions to be carried out
because the structure and reactivity of the chemicalsthat compose the body are temperature sensitive
Temperatures abovenormal: denature enzymes and block metabolic pathways
Temperatures belownormal : slow down metabolism and affect the brain
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Range of Core Temperature
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Women tend to have wider fluctuation that follow
menstrual cycle, with a sharp rise in temperature
within the ovulation
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Monitoring Temperature
Oral and axillary temperaturescomparable
Rectal temperaturehigher about 1F (0.56C)
Heat generated by the eardrumconverts into
an oral equivalent
Temporal scannerscans heat in temporal
artery
the best determinant of core temperature because it
is nearly identical to the temperature of the blood
exiting the heart
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Heat Loss
Evaporation
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Heat Production
Factors determine the rate of heat production Basal rate of metabolism of all the cells
Extra rate of metabolism caused by muscle activityshivering
Extra metabolism caused by the effect of thyroxine,other hormones, such as GH and testosterone
Extra metabolism caused by the effect ofepinephrine,norepinephrine,and sympathetic
stimulation on the cells extra metabolism caused by increased chemical activity
in the cells themselves
extra metabolism needed for digestion,absorption,and
storage of food (thermogenic effect of food)
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Hypothalamus: Preoptic area neurons hypothalamic thermostat:
Heat-losing center (anterior region) Heat-promoting center (posterior region)
Core temperature is below set point Heat-generating mech
Increased metabolism, shivering, vasoconstriction ofcutaneous vessels
Core temperature is above set point
Mech for heat loss Vasodilatation of cutaneous vessels, increased
symphatethic outflow to sweat glands
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Shivering thermogenesis:spinal reflex of alternating
contractions in antagonisticmuscles
Every muscle contraction
release heat from ATP.
Shivering can increase the
bodys heat production as
much as fourfolds.
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Non shiveringthermogenesis:
Long-term mechanism
stimulating thyroid hormonerelease T3 and T4.
We have greater appetite inthe winter than in thesummer..
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Thermoregulation is a function of multiple organs:the brain, the
autonomic nerves, thyroid glands, skin, blood vessels and
skeletal muscles
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Disturbances in thermoregulation
Fever:which means a body
temperature above
the usual range of
normal.
Is a normal protective mechanism
that should be allowed to run its
course if it is not excessively high,however it can be very dangerous.
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Hypothermia: is where the body
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Hypothermia: is where the body
temperature falls drastically
because of exposure to cold.
It can occur when someone is outin the cold too long without
adequate clothing or immersion
in icy water
If the core body
temperature falls below
33C, the metabolic rate
drops so low that heatproduction cannot keep
pace with heat loss.
Death from cardiacfibrillation may occur
below 32C
The elderly can
be much more
susceptible tohypothermia.
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CONCLUSION??
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