This document discusses temperature effects on animal physiology. It begins by noting that active animal life is limited to a narrow temperature range, typically between -5°C and 50°C. It then defines several terms related to temperature regulation, including homeotherms, poikilotherms, ectotherms, and endotherms. It explains that temperature has striking effects on physiological processes like oxygen consumption. It also discusses the limits of temperature tolerance for different organisms, mechanisms of heat transfer, and temperature regulation in humans and other animals.

1. VIJAYANAGARA SRIKRISHNADEVARAYA UNIVERSITY, BALLARI
DEPARTMENT OF STUDIES IN ZOOLOGY
Dr. Nagabhushan CM
Assistant Professor, DOZ,
VSK University, Ballari
ANIMAL PHYSIOLOGY
TEMPERATURE EFFECTS

2. ENVIRONMENT AND TEMPERATURE
ACTIVE ANIMAL LIFE IS LIMITED TO A NARROW RANGE OF
TEMPERATURES
-5 oC (in polar regions)to +50 oC (in hot springs)
human = 37 oC whether in SUB-FREEZING weather or
SAUNA with air temperature of 100 oC.
Some organisms can tolerate extensive freezing, Some can survive submersion
in liquid nitrogen at -196 °C or even liquid helium at -269 °C (about 4 K), but
some animals are so sensitive to cold that they die at temperatures far above
freezing.

3. TERMINOLOGY
Homeotherms : animals having well regulated body temperatures.
Homeotherms maintain high body temp. and thus remain
active in COLD as well as HOT surroundings.
Poikilotherms : temp. fluctuates with the change in surrondings.
Poikilotherms become more inactive as temp. decreases.
Ectotherms : temperature of the body is dependent upon external heat
souces (solar)
Endotherms : able to maintain high body temperature by internal heat
production.
Heterotherms :homeotherms behaving as poikilotherms

4. EFFECTS OF TEMPERATURE CHANGE
TEMPERATURE HAS STRIKING EFFECT ON MANY PHYSIOLOGICAL
PROCESSES:
Oxygen consumption INCREASES with INCREASE in temp. and
STEEPS up further with FURTHER INCREASE and AT EVEN HIGHER
INCREASE IN TEMPERATURE (lethal) the Oxygen consumption DIMINISHES.

5. EXTREME TEMPERATURES: LIMITS TO LIFE
ANIMALS DIFFER IN THE RANGE OF TEMPERATURES THEY TOLERATE:
SOME have NARROW tolerance range,
SOME have WIDE tolerance range,
SOME can be ADAPTED to cross the tolerance range.
SOME are MORE SENSITIVE to EXTREME temperatures.
It is difficult to determine the LETHAL TEMP. for a given organism because
DURATION OF EXPOSURE is of great importance.

6. TOLERANCE TO HIGH TEMPERATURE
NO ANIMAL IS KNOWN TO LIVE AT A TEMP. OVER 50 OC.
EXCEPTIONS ARE:
75 OC is the upper limit for photosynthetic Synecossus sp (BGA),
92 OC is the heat tolerable limit to thermophilic bacteria in hot springs,
100 OC is the tolerable limit to bacteria in hydrothermal vents.
LETHAL TEMPERATURE:
it is the temperature at which 50% of the animals die and
50% of the animals survive = T L50
%
survival
temperature
100
50
00 T L50

7. TOLERANCE TO HIGH TEMPERATURE
NO ANIMAL IS KNOWN TO LIVE AT A TEMP. OVER 50 OC.
ADVANTAGES ARE:
Apis cerana japonica when attacked by predator hornet, Vespa japonica,
over 500 bees MOB the hornet the RAISES THE TEMP by 48 oC (lethal to the
hornet but not to bees)
EXCEPTIONS:
organisms at the INTERTIDAL ZONE have wide range of TOLERANCE.

8. HEAT DEATH
1. Denaturation Of Proteins (Thermal Coagulation at 45-55 oC)
2. Thermal Inactivation Of Enzymes (thermolabile at +6 oC)
3. Inadequate supply of Oxygen,
4. Different temperature affects on interdependent metabolic reactions.
ABCDE (C may require more temp. than D/E etc.)
5. Temperature effects on membrane protein-lipid structure.

9. VISE VERSA

10. TOLERANCE TO LOW TEMPERATURES
The effects of low temperature are at least as perplexing as those of high
temperature.
Some organisms can tolerate extensive freezing, but most animals cannot.
Some can survive submersion in liquid nitrogen at —196 °C or even liquid
helium at —269 °C (about 4 K), but some animals are so sensitive to cold that
they die at temperatures far above freezing.
death is
caused by cold depression of the respiratory center, followed by damage from
anoxia, for an increase in the oxygen content or the water improves survival, and
a decrease in the oxygen content in
creases susceptibility to cold.

11. Cold tolerance and freezing tolerance
Animals that live in temperate and cold regions withstand long periods
of winter temperatures that are far below the freezing point.
They can escape cold injury by two means:
supercooling and freezing tolerance.
The former is the lowering of the temperature of a fluid to below its
freezing point without formation of ice;
the latter is a tolerance to freezing of water and formation of ice in the
body. Those animals that cannot tolerate ice formation in the body are
called freezing-susceptible; those that survive freezing are
FREEZING TOLERANT.
are freezing-tolerant.

12. SUPER COOLING
Pure water can be cooled far below 0°C without any ice formation.
Such supercooled water will freeze depends on three important
variables:
the temperature,
the presence of nuclei for ice formation,
and time.
In the absence of foreign nucleating materials, pure water is readily
supercooled to - 20 °C before it freezes, and if extraordinary
precautions are taken, water can be supercooled to near - 40 °C.
The moment an initial ice nucleus is formed, freezing progresses
rapidly throughout the sample.
The presence of certain solutes not only lowers the freezing point, but
also influences supercooling before freezing occurs.

13. SUPER COOLING
tidal animals shows that they indeed freeze rather than become
supercooled, and that there is a remarkable distortion of muscles
and internal organs by the ice.
The ice crystals, however, are generally located outside the cells,
which are shrunken and possibly have no ice formed within them.
Within a few seconds of thawing, the tissues again assume a normal
appearance.

14. SUPER COOLING
In addition to the DEGREE OF COOLING the duration of exposure is
important for determining whether freezing takes place or not.
A plant-feeding wasp, Cephus ductus when these larvae are kept at
constant subfreezing temperature, no freezing takes place at
temperatures above -15 °C.BUT as the temp is lowered further,
FREEZING takes place more and more readily so that -30oC freezing
occurs in about a second whereas at -17oC it takes nearly 1 YEAR for
50% of the larval samples to FREEZE.

15. SUPER COOLING in gametes
Glycerol protects red blood cells and mammalian spermatozoa from
injury caused by freezing.
Glycerol is widely used for this purpose, and samples of human or bull
sperm can be kept frozen and remain viable for several years if
glycerol is added in a suitable concentration before freezing.
Without such treatment, freezing is lethal to spermatozoans.
Glycerol influences the cold resistance of insects in two ways:
(1) by its protective action against freezing damage, glycerol could
help insects that do freeze to survive, and (2) by lowering
the freezing point and increasing the degree of supercooling, glycerol
prevents ice formation.

16. SUPER COOLING in fishes
increase in the major dissolved ions, sodium and chloride; the most
important contribution to lowering the freezing point

17. SUPER COOLING in antarctic fish
The antifreeze in the blood of an Antarctic fish, Trematomus, has
been isolated and its chemical nature studied in detail. Chemically,
this antifreeze is a glycoprotein that occurs in the blood with three
distinct molecular weights: 10 500, 17 000, and 21 500.
At low concentrations (6 g per liter) this glycoprotein is more effective
than sodium chloride in preventing formation of ice in water.
the glycoprotein inhibits the growth of ice crystals by being absorbed
to their surfaces.

18. TEMPERATURE REGULATION
Dr. Nagabhushan CM
Assistant Professor, DOZ,
VSK University, Ballari

19. THERMAL REGULATION
How do animals that keep their body temperature
more or less constant is
independent of the environment

20. What is body temperature?
It is necessary to know what is the body
temperature.
In order to maintain the constant body
temperature, HEAT TRANSFER must be balanced
so that THE GAIN OF HEAT ARE EQUAL.

21. What is body temperature?
It is necessary to know what is the body
temperature?
In order to maintain the constant body
temperature, HEAT TRANSFER must be balanced
so that THE GAIN OF HEAT ARE EQUAL.

22. PHYSICS OF HEAT TRASNFER
In a cold environment
heat balance can be achieved by manipulating the heat loss
and/or the heat gain.
Most mammals and birds do this very successfully,
but some mammals and a few birds appear to give up and
permit their temperature to drop precipitously; they go into
torpor or hibernation.
But they have not fully abandoned temperature regulation;
on the contrary, hibernation is a well-regulated and controlled
physiological state.

23. PHYSICS OF HEAT TRASNFER
In a hot environment
the problems of maintaining the body temperature are
reversed:
The animal must keep the body temperature from rising and
is often compelled to cool itself by evaporation of water.

24. What is body temperature?
The heat produced by an animal must be transported to the
surface before it can be transferred to the environment.
Therefore, the surface of the organism must be at a lower
temperature than the inner parts, for if the temperature were
the same throughout, no heat could be transferred.
The conclusion is that the temperature of an organism of
necessity cannot be uniform throughout.

25. Organ wise heat production in man
ORGAN WEIGHT (%) HEAT PRODUCTION (%)
KIDNEY 0.45 07.7
HEART 0.45 10.7
LUNGS 0.9 04.4
SPLANCHNIC ORGANS 3.8 33.6
BRAIN 2.1 16.0
MUSCLE 42 15.7
OTHER 43 10.0

26. During exercise, the situation is different, for the total
metabolic rate may increase 10-fold or more. Most of this
increase occurs in the muscles (including the diaphragm and
other respiratory muscles).
During exercise, then, for the internal temperature to remain
constant, more than 10 times as much heat as was
produced at rest must be transported to the surface of the
organism.

27. TEMPERATURE
DISTRIBUTION IN
HUMAN BODY

28. The surface temperature
of a man who is in heat
balance is always lower
than the core temperature.
This means that the
arterial blood which flows
to the shell loses heat and
returns as colder venous
blood.
This is, of course, how
most of the heat
produced in the core is
brought to the surface and
the core organs are cooled.

29. A change in the temperature of the shell means that the total
heat content of the body changes, although the core
temperature may remain constant.
If a man moves from a room temperature of 35 °C to 20 °C,
the drop in shell temperature may involve a heat loss of 200
kcal from the shell.

30. Diurnal and nocturnal fluctuations
The core temperature of man and of other mammals and
birds undergoes regular daily fluctuations.
Within 24 hours these fluctuations are between 1 and 2°C.
Diurnal animals show a temperature peak during the day
and a minimum at night;
nocturnal animals show the reverse pattern.

31. Lethal temperature
The approximate lethal body temperatures for the various
groups of warm-blooded vertebrates is roughly 6 °C above
the normal core temperature

32. FEVER temperature
Fever is an increase in body temperature that is usually
associated with bacterial or virus infections.
Similar increases in body temperature can be produced by
the injection of killed bacteria. (pyrogens)

33. FEVER temperature
An experiment on Dipsosaurus (five groups of lizards) were
infected with bacteria (Aeromonas hydrophila) and placed
in a neutral environment (38°C),
at lower temperatures (36 and 34°C),
and at higher temperatures (40 and 42°C).
There was a striking correlation between survival and
temperature; all the animals at lowest temperature died in
less than 4 days; survival increased with temperature and
was highest in the animals at 42°C.

34. TEMPERATURE, HEAT, AND HEAT TRANSFER
Temperature is usually measured in degrees Celsius (°C),
In thermodynamics we use absolute temperature expressed
in KELVIN (K).
In biology heat is measured in K Cal (calories)
The amount of heat needed to raise the temperature of 1
g water by 1 °C is 1 calory. IT IS THE SPECIFIC HEAT
CAPACITY OF THE SUBSTANCE. (1.0 Cal g-1 oC-1)

35. Specific heat capacity
The specific heat capacity of water is 1.0
cal g_1°C_1, which compared with that of other substances
is very high.
The specific capacity of rubber is 0.5, of wood 0.4, and of
most metals 0.1 or less.
The specific heat capacity of air is 0.24 cal g_1°C_1,
and because the density of air is 1 . 2 g per liter (at 20 °C),
the heat capacity of 1 liter air is 0.3 cal.

36. Specific heat capacity
The amount of heat needed to increase the temperature of
the animal body is slightly less than the amount needed to
heat the same weight of water.
The mean specific heat capacity of the mammalian body is
about 0.8. Thus, to increase the temperature of a 1000 g
mammal by 1 °C requires about 800 cal

37. HEAT TRANSFER
For an animal to maintain a constant temperature, heat
must be lost from the body at the same rate it is produced by
metabolic activity.
Whenever physical materials are at different
temperatures, heat flows from a region of higher
temperature to one of lower temperature. This
transfer of heat takes place by conduction & RADIATION

38. HEAT TRANSFER
however, a third way to remove heat: the evaporation of
water. These three ways of heat transfer - conduction,*
radiation, and evaporation - are the only means available for
the removal of the heat produced in the metabolic activity of
living organisms.

39. EVAPORATION
The evaporation of water requires a great deal of heat. To transfer 1
g water at room temperature to water vapor at the same temperature
requires 584 cal (2443 J). This is an amazingly large amount of heat.
The amount of heat required to achieve the phase change from liquid
water to vapor is known as the heat of vaporization.
In physiology it is customary to use the figure 580 cal per gram water,
which is an approximation of the value for vaporization of water at the
skin temperature of a sweating man, about 35°C.

40. HEAT BALANCE
The three components of heat exchange - conduction, radiation, and evaporation -
depend on external factors, among which the most important single factor is
temperature. It is obvious that heat losses increase when the external temperature
falls.
If, on the other hand, external temperature rises, the heat losses decrease, and if
external temperature exceeds body surface temperature, both conduction and
radiation heat exchange may be from the environment to the organism. The total
heat gain is then the sum of heat gain from metabolism plus heat gain from the
environment. This situation still permits the maintenance of a constant body
temperature (storage = 0), provided evaporation is increased sufficiently to
dissipate the entire heat load.

41. THANK YOU