Temperature is a measure of the thermal state of a substance and determines whether it will give or receive heat. Heat is a form of energy transferred between substances at different temperatures. There are various methods to measure temperature, including liquid expansion thermometers like mercury thermometers, electrical methods like resistance thermometers, and chemical indicators. The human body tightly regulates its core temperature within a narrow range through mechanisms that increase or decrease heat loss and production in response to temperature changes. Temperature monitoring has clinical applications to detect changes in peripheral perfusion, unintentional temperature changes, and hyperthermia or hypothermia.

1. Temperature

3. Temperature &Heat
Temperature :Is the thermal state of a substance that
determines whether it will give heat to another substance
or receive.
Heat :Is a form of energy transferred from a hotter
subset. to a colder one

4. Temperature Scales

6. Temperature Measurement
A. Non_electrical Methods
1. Liquid Expansion Thermometers
i. Mercury Thermometers
Advantages :it has linear scale&
cheap
disadv.:
1. unsuitable for remote readings &
for measurement of very low temp.
2. Response time is long (2-3min.)
3. Rigid & made of glass which is
liable to break.

8. Temp.Measurement(cont)
ii. Alcohol thermometers
Adv:
 cheaper than mercury
 Suitable for use at very low temp
Disadv:
 Unsuitable for remote reading or
 recording results
 Non linear scale
 Unsuitable for high temp

9. 2. Dial expansion Thermometers
 Bimetallic strip thermometers
i. It is used for measuring air temp.
ii. It depends on 2 dissimilar metals with diff. coefficients
of expansion fixed together as a coil.
iii. temp diff. in length of the 2 metals moving a
pointer on a scale.
Adv: cheap
disadv:not accurate

11.  Bourdon gauge thermometers
i. Used for measuring large temp changes e.g.
autoclaves
ii. Small bulb cont. volatile fl. to a small coiled
tube attached to a pointer.
iii. Temp bulb pr. Straighten the coiled
tube moving the pointer on a scale.
Adv:Cheap
Disadv.:not accurate

13. 3.Chemical thermometers
 Arise of temperature increases the number
of cells which release the chemical dyes
which appear indicating the temperature
 Adv :It detect the change temperature on
the skin
 Disadv: It disposable
:It not accurate
:It dose not allow continuous
reading

14. B.Electrical methods
1. Resistance Thermometer;
based on the fact that :the electrical resistance of a
metal increases with the increase of temp.
Adv:- can be used for calibration of other
thermometers accurately
-remote &continuous reading
-linear scale
Disadv.;-long response time
-expensive& fragile

15. 2-thermistor
• The electrical resist. decreases with the
increase of temp.It is formed of a small
bead of metal oxide e.g.zinc oxide.
Adv. :-the bead is of very small size &
diff. shapes,fixed on a needle. very
accurate with remote & continuos
reading.cheap. than platinum resis.therm.
Disadv.the is not linear &resistance
changes with time.

17. 3-Thermocouple
• Based on the seebeck effect,2 diff. metals are
joined to form a circle the potential diff. bet. the 2
junctions is proportional to the diff.in their temps.
• The 2 metals may be copper or iron & constantan.

18. Thermocouple

19. • 4-Transistor thermometer The
voltage across transistor js.is temp.-dependent
&more sensit.than thermocouple
• 5-Optical thermometer objects
emits electro magnetic radiations,the wave lengths
of these radiations are temp. dependent.
Types; a-infrared ear thermometer.
B-tympanic membrane thermometer

20. 6-Liquid crystal thermometer
• temp. organic.comp. from solid to liq.passing
by intermed. State with optically active properties
• Exposure of such material (intermed.state) to light
at certain temp. iridescent colors &the
remaining of light transmitt. By the crystals
• The colors form letters & numbers& black
background.

21. • It consists of a flexible adhesive –backed strip
with plastic-encased liq. Crystals on a black
background.
• To use ,the covering over the adhesive is removed
&the strip placed on the skin.
• Advs.;convenient,non-invasive,easy to
apply&read,unbreakable,disposable&inexpensive.
• Disadvs.;infrared lamps&sun exposure give high
readings &less accurate

23. Clinical Applications
• Humans are homeothermic i.e. control body temp.
within a narrow range despite a wide range of
environmental temp.
• Body temp. :
 a-Core temp. i.e.temp. of deeper tissues(2.5 cm
from the skin).It includes brain ,thoracic&
abdominal organs(37˚C).
 b-Shell temp.:temp.of tissues within 2.5 cm.from
the skin(32-35˚C).

25. Thermoregulation of human bodys

26. Mechanisms activated by heat
• Increased heat loss
• Cutaneous vasodilation
• Sweating
• Increased respiration
• Decreased heat production

27. Mechanisms activated by cold
• Shivering
• Hunger
• Increased voluntary activity
• Increased secretion of norepinephrine and
epinephrine
• Decreased heat loss
• Cutaneous vasoconstriction
• Curling up
• Horripilation

28. Sites Of Temp. Monitoring
• Core temp.
1. Tympanic memb. Brain temp.
2. Nasopharynx.
3. Oesophagus Cardiac temp.
4. Rectum(risk of perforation)
5. Pulmonary a. catheter
6. Urinary bladder
• Peripheral temp.:at the skin by liq.
Crystal adhesive strip

29. Indication of temp. monitoring
1. Detection of peripheral perfusion (core-
peripheral temp.gradient is 5C )
2. Detection of unintentional hypothermia
3. Detection of elective hypothermia
4. Detection of hyperthermia

30. Definitio
n and
scales
Measure
menta of
tamptem
p
Linical
applica
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