Temperature Regulation Ranm

8/12/2019 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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Temperature Regulation Ranm

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