Understanding the Impact of Temperature on Animals and Plants

 
Temperature relations
 
Temp very important factor – effects not only
animals but also have influence on plants
Varies considerably geographically
Temp variations effects the animal historically
but also induce adaptations in them.
Also have certain biochemical effects
 
Temperature classification of animals
 
Animals are categorized into groups according to the
temperature inhabit and their patters of temperature
regulation.
Historical classification
Cold blooded -  animals having body temp below 5 oC
Warm blooded – birds & mammals
b/c of few exceptions –certain mammals below 5 C
during hybernation e.g squirrels
So this terminology was excluded & alternate
classification was made
 
 
Poikilotherm
 (poikilo =“varied”) - body temperature
approximates the ambient temperature.  Not capable
of controlling body temperature as ambient
temperature varies. Cold blooded animals. Their body
temperature fluctuates along with the environment so
thermoconformers– do not have efficient source of
heat production.b/c of low metabolic activities
Homeotherm
 (homeo = “same”) - controls body
temperature, keeping it relatively constant as ambient
temperature varies.  There fore thermoregulators.
Efficient source of heat production due to high
metabolic activity& by hormonal control
 
 
 
These terminologies were found to be
ambigious b/c poikilotherms do resist the
ambient temperature but to regulate the
temperature they depend upon the ambient
temperature.
New terminologies are
Ectothermy
Endothermy
heterothermy
 
 
Ectotherm
 (ecto = “outside”) - An animal that
derives body temperature from an external heat
source.
Animals have low metabolic heat production
Have efficient heat conduction system
Higher thermal conductivity
Importance of heat exchange with environment
Some insects, reptiles, amphibians
Classified as 
Heliotherms
: take heat directly from
sunlight  e.g lizards & insects – basking of insects
Thigmotherms 
receive heat from substance or
immediate environment.
 
 
Endotherm
 (endo = “inside”) - An animal
that derives body temperature from internal
heat production.
Hav an efficient endogenous heat production
Have good insulation of their body from
environment
thermoregulators
 
 
Heterotherm
 
(hetero = “different”) -
regulates body temperature when active, but
allows body temperature to fluctuate with the
environment when inactive.
Certain insects & birds, rodents, marsupials
When the birds have made enormous flight
they warm up their body by muscular activity
under hormonal control and body
temperature may rise to 40 C & at other time
it fails to do so.
Is of two types
 
Regional Homeothermy
 
 
Core body temperature
Temperature at the interior of the body (thoracic and abdominal
cavity, brain, etc.)
Maintained within narrow margins
Peripheral body temperature
Temperature of integument, limbs, is not different from
surrounding
Tends to vary considerably
Another example ---- scrotum of certain animals
keep the  temperature 5 C below the body
temperature – due to  pempiniform plexus in the
testis.
 
Temporal heterothermy
 
The exhibition of widely different body temperatures at
different times or under different conditions, as certain
species of birds, marsupials, or hibernation.
During these conditions animals maintain their body
temp below their normal phase f activity. Metabolic
heat production is reduced,
Humoral agents causes the lowering of temperature.
If ambient temp. decreases more than body temp.
then animal start producing heat & maintain low temp.
Blood supply decreases except head and brown fat---
low blood supply to pulmonary area, less oxygenation--
-acidity & decrease PH & enzymatic activity decreases.
 
Heat Exchange Between an
Animal and its Environment
 
Temperature effects
 
Temperatre effects both biochemical and metabolic changes.
Thermophilic organisms can survive at very high temp. 94 – 95.
Where as animal life prevails from -30 to 55
Temp. effects at various levels
COLDER EFFECTS:
Water essential component --- life ranges b/w 10 – 40C.
Water has fascinating characteristics of freezing due to contraction and
expansion properties
Ice formation --- major hazards----cold death occurs
 
WARM EFFECTS:
At high temp. 02 curve goes against conditions. Its availability
decreases to the tissues. Heat death
High temperature strongly effects the enzyme activity and cause heat
death.
 
 
A
D
A
P
T
A
T
I
O
N
S
 
I
N
 
E
C
T
O
T
H
E
R
M
S
 
In Cold Environment
1.
PREVENT crystal formation
The crystal formation in the cells is lethal b/c it destroys the
cells.
Problem is minimized in certain animals like beetles that an
with stand the freezing temperature. Due to the presence
of a substance in extracellular that accelarates nucleation.
As a result extracellular fluid crystalize before the
intracellular fluid, as water leaves the extra cellular fluid
to form crystal the fluid becomes concentrated & draws
water out of the cell. Which lowers intracellular freezing
point. – cell is avoided from destruction.
Chironomus larvae can survive as low as -32C. Animals not so
active ---hybernating conditions.
 
 
2. super cooling
Some animlas – supercooling—body cooled below freezing
point. Yet remain unforzen b/c of absence of ice crystals.
Crystal will fail to form as long as  they hav no seeds.
Certain fishes at bottom of arctic live in supercooled state
unless come in contact with ice cystal.
3. antifreeze substance
Advanced type of adaptation
Antifreeze substances like
Glycerol
NaCl
Sugar sorbitol, inositol
Antifreeze proteins
Glycoproteins
 
The conc. Of glycerol increases during winter
& animal survive at -17C
Several glycoprotein has been isolated from
arctic pecific & atlantic region. 200- 500 times
more effective than equivalent conc. Of NaCl.
Polymer of analyl-amalyl theronine also act as
antifreeze substance which form glycoprotein
b/c thy have N- aceyl galactose amine
galactose.
 
ECTOTHERMS IN HOT ENVIRONMENT
 
Evaporative Cooling– depends upon ambient
temp. & humidity. At high temp. low humidity
high evaporation occurs.
In dry conditions sweating brings more cooling.
At 50C with low humidity can easily be managed
as compared to 35C but high humidity.
At low humidity – dehydration--- animals
dependent upon environment, lizards use that in
high humidity, frogs secrete mucous–
evaporation slowly—that causes cooling
 
 
2. heart rate and vascular supply
Animals are poor conductor of heat. If internal
tissue has high temperature then heart rate and
vascular supply increases which in turn removes the
heat e.g in lizards.
3. Behavioral adaptations to bask.
If internal temperature is high then animals move
to colder places & if feel low moves towards high
temperature.
Lizards use all three types of adaptations to avoid
high temp.
 
 
Advantages – not need to manage
endogenous heat production manage with
minimum budget
Urothermy
Stenothermy
 
Endotherms
 
Generate most body heat physiologically
Tend to be 
homeothermic
regulate body temperature (T
b
) by adjusting heat
production therefore thermoregulators e.g birds,
mammals.the body temperature of primates is 37
which is most appropriate for endogenous heat
production and enzymatic activity.  Tb 35 – 42 C.
In endotherms temp regulation occurs through
  
CNS hypothalamus
  
Thermoreceptors in spinal cord
Peripheral thermoreceptors in skin.
 
 
ENDOTHERMS IN COLD
ENVIRONMENT
 
Endotherms respond to low ambient temperatures by:
Increasing heat production (thermogenesis)
Limiting heat loss
Lose ability of thermoregulation.
Mechanism of reducing heat.
1.
Decrease thermal conductance---through lower surface
to volume ratio. Temperature thermoconductivity
decreases with increase in size.
 
2.
Postural adjustment. Birds – retracting the head under
the wings
Body Heat Retention
 
Increased body size
 surface area/volume ratio
Generally thicker coats
Bergmann’s Rule
 
 size w/ 
 latitude
 
 
3. external insulation – nesting or homing
abalities, live in caves etc, arctic bear in ice
caves
4. Huddling together--- live in community—
antarctic pegunins
5. Thick fur under skin surface
6. Reduce blood supply
 
Increase in endogenous heat
production.---Thermogenesis
 
Shivering
Rapid contractions in groups of antagonistic muscles
No useful work generated
Heat liberated by hydrolysis of ATP
Non-shivering Thermogenesis
Enzyme systems activated that oxidize fats to produce heat
Virtually no ATP production
 
Nutritional fermentation –ruminents hv efficient nutritional
fermentation system bacteria digest cellulose& liberate
heat energy.
Non-shivering Thermogenesis
 
Brown Adipose Tissue (BAT)
Highly vascularized, with large
numbers of mitochondria
Inner mitochondrial membranes
contain 
thermogenin
Allows H
+
  to bypass ATP synthase
Protons re-enter mitochondrial
matrix and bind to O
2
, generating
heat and water
Heat absorbed by blood in
vasculature and distributed
throughout the body
Body Heat Retention
 
Circulation
Reduced skin perfusion
Limit heat loss from blood
Countercurrent Exchange
Heat transferred from arteries to veins
Limit heat loss from extremities
 
Absorb heat through basking
Lose ability of thermoregulation and becomes heterotherms.
Endotherms in hot environment
 
Endotherms respond to high ambient
temperatures by:
1.
Limiting heat gain
2.
Increasing heat dissipation
Limiting Heat Gain
 
Increased Size
Large animals have large heat capacities and
low surface area/volume ratios
Take longer to heat up
Large animals tend to have thicker pelage
Insulate body from external heating
Increasing Heat Dissipation
 
Specific heat exchange surfaces
Enable heat loss through
conduction/convection/radiation
Thin cuticle
Highly vascularized
Lightly insulated
Large surface areas
Allen’s Rule
The warmer the climate, the larger the
size of appendages
Evaporative Cooling
 
Sweating
Extrusion of water through sweat glands onto
the skin
Panting
Evaporative cooling through the respiratory
system surfaces
Gular Flitter-
 
heat loss from throat surface e.g chickens,
pigeons, it has considerably supplied with
blood supply
Sweating vs. Panting
 
Sweating
Passive (little energy expenditure)
High salt loss
No convection
No effect on blood pH
Panting
Active (requires muscle contraction)
No salt loss
Convection – increases cooling
Increased ventilation 
 
pH
Panting and Brain Cooling
 
Panting can cool brain during
high levels of activity
Rete mirabile
heat exchange between warm
arterial blood and cooled venous
blood from nasal cavity
Maintain brain temperature
despite abnormally high body
temperature
 
 
ESTIVATION
Several vertebrates & invertebrates have
estivation. It may be long or short. E.g snail
close their shells due to enzymatic activity &
remain inactive for summer.
Fishes go in mud and remain inactive
Similar to hibernation but differ in seasonal
timing.
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Temperature plays a crucial role in influencing animals and plants, affecting their adaptations and biochemical processes. Animals are classified based on their ability to regulate body temperature, with terms like poikilotherm and homeotherm being redefined as ectothermy and endothermy. Ectotherms rely on external heat sources, while endotherms generate internal heat, showcasing different thermal adaptation strategies in the animal kingdom.


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  1. Temperature relations Temp very important factor effects not only animals but also have influence on plants Varies considerably geographically Temp variations effects the animal historically but also induce adaptations in them. Also have certain biochemical effects

  2. Temperature classification of animals Animals are categorized into groups according to the temperature inhabit and their patters of temperature regulation. Historical classification Cold blooded - animals having body temp below 5 oC Warm blooded birds & mammals b/c of few exceptions certain mammals below 5 C during hybernation e.g squirrels So this terminology was excluded & alternate classification was made

  3. Poikilotherm (poikilo =varied) - body temperature approximates the ambient temperature. Not capable of controlling body temperature as ambient temperature varies. Cold blooded animals. Their body temperature fluctuates along with the environment so thermoconformers do not have efficient source of heat production.b/c of low metabolic activities Homeotherm (homeo = same ) - controls body temperature, keeping it relatively constant as ambient temperature varies. There fore thermoregulators. Efficient source of heat production due to high metabolic activity& by hormonal control

  4. These terminologies were found to be ambigious b/c poikilotherms do resist the ambient temperature but to regulate the temperature they depend upon the ambient temperature. New terminologies are Ectothermy Endothermy heterothermy

  5. Ectotherm (ecto = outside) - An animal that derives body temperature from an external heat source. Animals have low metabolic heat production Have efficient heat conduction system Higher thermal conductivity Importance of heat exchange with environment Some insects, reptiles, amphibians Classified as Heliotherms: take heat directly from sunlight e.g lizards & insects basking of insects Thigmotherms receive heat from substance or immediate environment.

  6. Endotherm (endo = inside) - An animal that derives body temperature from internal heat production. Hav an efficient endogenous heat production Have good insulation of their body from environment thermoregulators

  7. Heterotherm (hetero = different) - regulates body temperature when active, but allows body temperature to fluctuate with the environment when inactive. Certain insects & birds, rodents, marsupials When the birds have made enormous flight they warm up their body by muscular activity under hormonal control and body temperature may rise to 40 C & at other time it fails to do so. Is of two types

  8. Regional Homeothermy Core body temperature Temperature at the interior of the body (thoracic and abdominal cavity, brain, etc.) Maintained within narrow margins Peripheral body temperature Temperature of integument, limbs, is not different from surrounding Tends to vary considerably Another example ---- scrotum of certain animals keep the temperature 5 C below the body temperature due to pempiniform plexus in the testis.

  9. Temporal heterothermy The exhibition of widely different body temperatures at different times or under different conditions, as certain species of birds, marsupials, or hibernation. During these conditions animals maintain their body temp below their normal phase f activity. Metabolic heat production is reduced, Humoral agents causes the lowering of temperature. If ambient temp. decreases more than body temp. then animal start producing heat & maintain low temp. Blood supply decreases except head and brown fat--- low blood supply to pulmonary area, less oxygenation-- -acidity & decrease PH & enzymatic activity decreases.

  10. Heat Exchange Between an Animal and its Environment

  11. Temperature effects Temperatre effects both biochemical and metabolic changes. Thermophilic organisms can survive at very high temp. 94 95. Where as animal life prevails from -30 to 55 Temp. effects at various levels COLDER EFFECTS: Water essential component --- life ranges b/w 10 40C. Water has fascinating characteristics of freezing due to contraction and expansion properties Ice formation --- major hazards----cold death occurs WARM EFFECTS: At high temp. 02 curve goes against conditions. Its availability decreases to the tissues. Heat death High temperature strongly effects the enzyme activity and cause heat death.

  12. ADAPTATIONS IN ECTOTHERMS In Cold Environment 1. PREVENT crystal formation The crystal formation in the cells is lethal b/c it destroys the cells. Problem is minimized in certain animals like beetles that an with stand the freezing temperature. Due to the presence of a substance in extracellular that accelarates nucleation. As a result extracellular fluid crystalize before the intracellular fluid, as water leaves the extra cellular fluid to form crystal the fluid becomes concentrated & draws water out of the cell. Which lowers intracellular freezing point. cell is avoided from destruction. Chironomus larvae can survive as low as -32C. Animals not so active ---hybernating conditions.

  13. 2. super cooling Some animlas supercooling body cooled below freezing point. Yet remain unforzen b/c of absence of ice crystals. Crystal will fail to form as long as they hav no seeds. Certain fishes at bottom of arctic live in supercooled state unless come in contact with ice cystal. 3. antifreeze substance Advanced type of adaptation Antifreeze substances like Glycerol NaCl Sugar sorbitol, inositol Antifreeze proteins Glycoproteins

  14. The conc. Of glycerol increases during winter & animal survive at -17C Several glycoprotein has been isolated from arctic pecific & atlantic region. 200- 500 times more effective than equivalent conc. Of NaCl. Polymer of analyl-amalyl theronine also act as antifreeze substance which form glycoprotein b/c thy have N- aceyl galactose amine galactose.

  15. ECTOTHERMS IN HOT ENVIRONMENT Evaporative Cooling depends upon ambient temp. & humidity. At high temp. low humidity high evaporation occurs. In dry conditions sweating brings more cooling. At 50C with low humidity can easily be managed as compared to 35C but high humidity. At low humidity dehydration--- animals dependent upon environment, lizards use that in high humidity, frogs secrete mucous evaporation slowly that causes cooling

  16. 2. heart rate and vascular supply Animals are poor conductor of heat. If internal tissue has high temperature then heart rate and vascular supply increases which in turn removes the heat e.g in lizards. 3. Behavioral adaptations to bask. If internal temperature is high then animals move to colder places & if feel low moves towards high temperature. Lizards use all three types of adaptations to avoid high temp.

  17. Advantages not need to manage endogenous heat production manage with minimum budget Urothermy Stenothermy

  18. Endotherms Generate most body heat physiologically Tend to be homeothermic regulate body temperature (Tb) by adjusting heat production therefore thermoregulators e.g birds, mammals.the body temperature of primates is 37 which is most appropriate for endogenous heat production and enzymatic activity. Tb 35 42 C. In endotherms temp regulation occurs through CNS hypothalamus Thermoreceptors in spinal cord Peripheral thermoreceptors in skin.

  19. ENDOTHERMS IN COLD ENVIRONMENT Endotherms respond to low ambient temperatures by: Increasing heat production (thermogenesis) Limiting heat loss Lose ability of thermoregulation. Mechanism of reducing heat. 1. Decrease thermal conductance---through lower surface to volume ratio. Temperature thermoconductivity decreases with increase in size. 2. Postural adjustment. Birds retracting the head under the wings

  20. Body Heat Retention Increased body size surface area/volume ratio Generally thicker coats Bergmann s Rule size w/ latitude

  21. 3. external insulation nesting or homing abalities, live in caves etc, arctic bear in ice caves 4. Huddling together--- live in community antarctic pegunins 5. Thick fur under skin surface 6. Reduce blood supply

  22. Increase in endogenous heat production.---Thermogenesis Shivering Rapid contractions in groups of antagonistic muscles No useful work generated Heat liberated by hydrolysis of ATP Non-shivering Thermogenesis Enzyme systems activated that oxidize fats to produce heat Virtually no ATP production Nutritional fermentation ruminents hv efficient nutritional fermentation system bacteria digest cellulose& liberate heat energy.

  23. Non-shivering Thermogenesis Brown Adipose Tissue (BAT) Highly vascularized, with large numbers of mitochondria Inner mitochondrial membranes contain thermogenin Allows H+ to bypass ATP synthase Protons re-enter mitochondrial matrix and bind to O2, generating heat and water Heat absorbed by blood in vasculature and distributed throughout the body

  24. Body Heat Retention Circulation Reduced skin perfusion Limit heat loss from blood Countercurrent Exchange Heat transferred from arteries to veins Limit heat loss from extremities Absorb heat through basking Lose ability of thermoregulation and becomes heterotherms.

  25. Endotherms in hot environment Endotherms respond to high ambient temperatures by: 1. Limiting heat gain 2. Increasing heat dissipation

  26. Limiting Heat Gain Increased Size Large animals have large heat capacities and low surface area/volume ratios Take longer to heat up Large animals tend to have thicker pelage Insulate body from external heating

  27. Increasing Heat Dissipation Specific heat exchange surfaces Enable heat loss through conduction/convection/radiation Thin cuticle Highly vascularized Lightly insulated Large surface areas Allen s Rule The warmer the climate, the larger the size of appendages

  28. Evaporative Cooling Sweating Extrusion of water through sweat glands onto the skin Panting Evaporative cooling through the respiratory system surfaces Gular Flitter- heat loss from throat surface e.g chickens, pigeons, it has considerably supplied with blood supply

  29. Sweating vs. Panting Sweating Passive (little energy expenditure) High salt loss No convection No effect on blood pH Panting Active (requires muscle contraction) No salt loss Convection increases cooling Increased ventilation pH

  30. Panting and Brain Cooling Panting can cool brain during high levels of activity Rete mirabile heat exchange between warm arterial blood and cooled venous blood from nasal cavity Maintain brain temperature despite abnormally high body temperature

  31. ESTIVATION Several vertebrates & invertebrates have estivation. It may be long or short. E.g snail close their shells due to enzymatic activity & remain inactive for summer. Fishes go in mud and remain inactive Similar to hibernation but differ in seasonal timing.

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