k-51 & 55 pengaturan & pengukuran suhu tubuh

8/9/2019 K-51 & 55 Pengaturan & Pengukuran Suhu Tubuh

1/43

BODY TEMPERATURE

Departemen Fisiologi

Fakultas Kedokteran USU


2/43

Homeostasis

Poikilotherms : body

temperature dictated by

the environment .

Homeotherms :

homeostatically maintain

body temp. at a level that

is optimal for cellular

metabolism.


3/43

Thermographic image of a snake around an arm

http://en.wikipedia.org/wiki/Image:Wiki_stranglesnake.jpg


4/43

Why is maintenance of body temperature

important? Rate of enzyme activity isrelated to temperature

Temperature Temperature

ActivitActivityy ReversiblReversibl

eeNon-Non-

ReversibleReversible

37°C37°C43°C43°C

55°C55°C


5/43

Normal body temp.Normal body temp. → homeostatic→ homeostatic

→ cells metabolism is stable→ cells metabolism is stable ↑↑ body tempbody temp. (41. (41ooC) → seizureC) → seizure

(neuron dysfunction)(neuron dysfunction)

(43(43ooC) →C) → irreversible proteinirreversible proteindenaturation → deathdenaturation → death

body tempbody temp. →. → metab. activity metab. activity !!"" consumptionconsumption


6/43

Temperature (C)Temperature (C)

SymptomsSymptoms

"#"# muscle failuremuscle failure

3$3$ loss of body temp.loss of body temp. controlcontrol

3333 loss ofloss of consciousnessconsciousness

3%3% normalnormal

4"4" central nervous systemcentral nervous systembrea&do'nbrea&do'n

4444 deathdeath


7/43

Thermoregulatory

Central oreBrain

T!ora"# a$domen# muslesOuter s!ellSkin % su$ utis

Range & oral '(#) * '+#, oC

retal '(#) * '+#- oC


8/43


9/43

Body Temperatures: Core

and kin

COLD HOT

kin temperature tends to be colder than core temperature at a normal state

!ormal

""#"$o C

%&o C $&o C"&o C

%&o C $&o C"&o C

!ormal

"&o C

Core Temperature

kin Temperature


10/43

Central core variation :

Biological clock

' (orning ) *#& am +, - evening ) #& pm+

(enstrual cycle

ovulation / menstruation : - 0,oC

12ercise

12posure by e2treme ambient temperature


11/43

Hypothalamic Regulation of

Core Temperature T!e !ypot!alamus contains t!e central

coordination center for temperature

re"ulation#

$t initiates t!e responses t!at %eep t!ebody from over!eatin" or overcoolin"


12/43

The Anterior hypothalamic preoptic area contains

thermodetectors that are responsive to increased

hypothalamic temperature and hypothalamic cooling.


13/43

Heat#regulating mechanisms are activated by

either:

Thermal receptors central 3 peripheral

Temperature changes in the blood

4ree nerve endings in the skinrespond to heat and cold and relay the

senses to the hypothalamus and

cerebral corte2.


14/43


15/43


16/43

4actors That 5ffect Heat 6ain

B(7(uscular activity )during sustainedvigorous e&ercise in aerobically fitindividuals : increase %0 to % times +

Hormones : thyro2in 3 catecholamine

Thermic effect of food

Postural changes

and environment (radiation, conduction)

'!iverin"


17/43

SHIVERING

7hythmic, oscillating skeletal muscle

contractions )about 80#%0 per second+

9ncrease the tone of skeletal muscle

(ay increase internal heat production %#times.

Center : dorsomedial portion of posterior

hypothalamus


18/43

Brown Fat

4ull of mitochondria, rich blood supply and

innervation. 4ound primarily in the chest and

behind shoulder blades Bron fat is o2idised and heat is produced to

arm the animals.

Bron fat is also found in neborn humans.Babies cannot shiver at birth and bron fat is

used to produce heat


19/43

716;T1(P175T;71T1(P175T;71


20/43

HEA BA!ANCE RESE"B!ES

ENERG# BA!ANCE

INPUT - OUTPUT = + >>RISE IN TEMPERATURE

INPUT - OUTPUT = - >>FALL IN TEMPERATURE

INPUT - OUTPUT = 0 >>NO CHANGE IN

TEMPERATURE


21/43

"ec$ani%m% o&

Bod'

emerature

Reulation

Fiure *+*-


22/43

Bod' re%on%e% to temerature

c$ane%

omatic

5utonomic Hormonal

Behavior


23/43

Heat./romotin "ec$ani%m%


24/43

Heat.!o%% "ec$ani%m%

When the core temperature rises, the heat#

loss center is activated to cause:

@asodilation of cutaneous blood vessels

1nhanced seating

7educing activity and seeking a cooler

environment

Wearing light#colored and loose#fitting clothing


25/43

Fiure **.*0: Homeo%tatic re%on%e% to environmental e1treme%


26/43

Thermoneutra !one

The range of ambient

temperatures beteen

the seating and

shivering thresholds isknon as the

thermoneutral zone.


27/43

Sweatin

;nacclimatiAed person produces more than

about 8 liter of seathour. When this person

is e2posed to hot eather for 8 to * eeks,

he or she begins to seat more profusely,often increasing ma2imum seat production

to as much as % to "


28/43

Sweat land


29/43

S"#n Tem$erature Can S#%ht& Ater the

Set-Po#nt 'or Core Tem$erature Contro

Thermoregulation: homeostatic Balancing of Body Temperature


30/43

g g y p

Fiure **.23: $ermoreulator' re&le1e%


31/43

Evaporative Heat Loss atHigh Ambient Temperatures

$ncreased temperatures reduces t!e

e(ectiveness of !eat loss by conduction)convection) and radiation#

*!en temperatures e&ceed t!e body+stemperature) t!ese mec!anisms

contribute to !eat "ain# *!en t!is occurs) t!e only avenue to

dissipate !eat is t!rou"! evaporation#


32/43

,arious'ites to

easure'%in

Temperatur

e


33/43

ody *emperatureody *emperature

+ariations +ariations Afebrile: Afebrile: normal body temperaturenormal body temperature

Pyrexia:Pyrexia: a body temperature abovea body temperature above

normalnormal Hyperpyrexia:Hyperpyrexia: hi,h fever usuallyhi,h fever usually

above 41above 41°°CC

HypothermiaHypothermia- decreased body- decreased bodytemperature death may occurtemperature death may occur

belo' 34belo' 34°°CC


34/43

DenitionsDenitions

(cont.)(cont.)

/ever 0ithout a /ocus/ever 0ithout a /ocus fever fever

'ith no clear cause determined'ith no clear cause determined

by history and2or physical eamby history and2or physical eam /ever of n&no'n !ri,in/ever of n&no'n !ri,in (/!)(/!)

prolon,ed fever lastin, over % prolon,ed fever lastin, over %

1$ days 'ithout identi5ed 1$ days 'ithout identi5edcausecause


35/43

!"!# !"!#

6levation of body temperature above6levation of body temperature abovethe normal ran,e as the result of athe normal ran,e as the result of a

chan,e in the thermore,ulatorychan,e in the thermore,ulatorycenter located in the anteriorcenter located in the anteriorhypothalamus.hypothalamus.

6levation in temperature results from6levation in temperature results fromeither increased heat productioneither increased heat production(shiverin,) or decreased loss(shiverin,) or decreased loss(peripheral vasoconstriction).(peripheral vasoconstriction).


36/43

Release interleukin-1 (endogenous pyrogens)

reset

the hypothalamic

thermostatD

to a higher set#point

Formation of theProstaglandin

HPOTHALA!"#

Viruses,bacteria

Immune complexesTumor cells

hagocyti!e" by leu#ocytes$ macrophages $

lymphocytes

antipyretics


37/43

Pathophysiology of fever


38/43

.ypert!ermia

.ypert!ermia is c!aracterized by anunchanged (normothermic) setting of thethermoregulatory center in con/unction 0it!an uncontrolled increase in bodytemperature t!at e&ceeds t!e body1s abilityto lose !eat#

2&o"enous !eat e&posure and endo"enous!eat production are t0o mec!anisms by0!ic! !ypert!ermia can result indan"erously !i"! internal temperatures#


39/43

.ypert!ermia

Normal !eat loss processes becomeine(ective and elevated body

temperatures depress t!e !ypot!alamus T!is sets up a positive-feedbac%

mec!anism) s!arply increasin" bodytemperature and metabolic rate

T!is condition) called !eat stro%e) canbe fatal if not corrected


40/43


41/43

Hypothermia


42/43


43/43

Comparison : hyperthermia, hypothermia 3 fever
http://en.wikipedia.org/wiki/Image:Fever-conceptual.svghttp://en.wikipedia.org/wiki/Image:Fever-conceptual.svg

k-51 & 55 pengaturan & pengukuran suhu tubuh

Documents