This document discusses thermoregulation in various vertebrates. It explains that animals are classified as either ectotherms, which rely on external heat sources, or endotherms, which generate internal heat. Ectotherms like fish, amphibians, and reptiles rely on behavioral and physiological adaptations to regulate temperature, while endothermic birds and mammals maintain a constant internal temperature through metabolic heat production and thermoregulatory mechanisms like sweating, vasodilation, insulation, and shivering. The document provides examples of temperature regulation strategies across different vertebrate groups.

1. 1

3. Presented to:
Sir Akash Ali
Presented by:
Sanya Yaseen
(4010)

4. Topic
Thermoregulation
in Vertebrates

5. Introduction

6. Page 6
 Animals divided into two main
categories:-
1. Pikilotherms: (cold blooded)
change their body temp.
according to environment e.g. fishes,
amphibians & reptiles
2. Homeotherms: (warm blooded)
Maintain their body temp. e.g.
birds and mammals

7. Page 7
Modern classification of
animals
1. Ectotherms:
take heat from outside e.g. fish
amphibian & reptiles also invertebrates
2. Endotherms:
take heat from inside e.g.
mammals, birds and some fishes
3. Heterotherms:
take heat from inside but body
temp. change e.g. bat, humming bird

8. Thermoregulation
in Fishes

9.  cold blooded but Ectotherms as well
 Core body temp. close to environment
 2 types of thermoregulation:
a) Behavioral thermoregulation
b) Physiological thermoregulation

10. Behavioral thermoregulation
 Occurs when it seeks out areas of water with higher
or lower temperature.
 Move from surface to downward or reverse
 E.g.
juveniles of the Bear Lake Sculpin lives in bottom
(5°C in day time) eat food and move to the surface at
night (14°C) to digest their stored food.

11.  Another example is Sockeye Salmon
o Feed only at dawn to dusk
o At dusk, they move 11m down(15°C)
o At dawn, move 37m down(5°C)
o Because night is short and day is long in Canada
o In doing so they reduce their metabolic costs

12. Physiological thermoregulation
 occurs in only a few species, all of which are marine
and swim constantly
 controls its core body temperature by means of
internal physiological and metabolic activities
 Network of blood capillaries (rete mirabile) b/w
swimming red muscles, act as heat exchanger
 Heat from muscle transported to blood
 Oxygen-depleted blood is sent to gills.

13.  In gills, thin blood vessels takes heat and thus blood
becomes warmer
 Blood in both vessels move in opposite direction due
to which process becomes more efficient
 No body heat is lost
 Body temp. rise from 5-14°C to environment
 Especially done in sharks and tuna

15. Thermoregulation in
Amphibians

16. Are Ectotherms
Face daily and seasonal changes
Produce little heat from metabolism and
lose it rapidly
Show behavioral adaptation
Have moist skin which helps in
evaporative cooling in warm temp.

17. To get moist, live in shady areas mostly
Bullfrog secrete mucus for evaporating
cooling
Sun basking early in dawn
Change their color darker in cooling
envior.
Lighter color in warmer envior

18. Thermoregulation in
Reptiles

19. Have dry skin, reduce water loss
 have extensible rib cage, provides efficient
ventilation
Conserve body heat into the center of body
Increase heat production in response to
hormones thyroxine and epinephrine
tortoises and land turtles can cool themselves
through salivating and frothing at the mouth

20. Thermoregulation in Birds

21.  Are endothermic
 All energy demands are
generated by metabolic process
 Regulate their body temp.
 Don’t have sweat gland, lose heat
from gular pouches present in
throat.
 Their fluttering increase
evaporation from respiratory
system

22.  In some spp., feathers
provides insulation
 Downy type feather trap air
next to body to prevent
body heat loss
 Aquatic species has “rete
mirabile” process in their
legs & feet
 As temp. fluctuates they
sun themselves or seek
shades.

23. Thermoregulation
in Mammals

24. ѬMammals in cooler regions have
exchange vessels in their ears, nose, legs
and tails
ѬIn warmer regions, get rid of heat by
sweating
ѬIn Aquatic climates, thick layer of
insulating fat “blubber”.
ѬIn tail & flippers, blubber is absent,
countercurrent system helps in
conservation of heat lose.

26. Heat production in Birds &
Mammals
o Can generate heat by:
1. Muscle contraction
2. ATPase pump enzymes
3. Oxidation of Fatty acids in brown
fats
4. Basal metabolic rate

27.  In each muscle contraction, actin
and myosin fiber slide over each
other and hydrolysis of ATP
generate heat
 Both voluntary and involuntary
muscular work generate heat
 Called “Shivering
thermogenesis”

28. • ATPase pump in cell membrane
helps in generation of heat
• When body cools, thyroid gland
releases thyroxine
• It increases the permeability of
NA+ ions into cells
• In the process, ATP is
hydrolyzed & generate heat
• Called “non-shivering
thermogenesis”

29. • Brown fat, special type of protein
found in youngness in cold climate
• Brown color is due to large amount
of mitochondria with their
iron-containing cytochromes
• Deposit in ribs & shoulders
• Large amount of heat is produced
• Blood passing through them is
heated and warm the body

30. FEEDBACK MECHANISM

31. Control of
thermoregulation
• It is controlled by 3 ways in
humans:
a) By sweat gland
b) By blood circulation
(vasoconstriction/
vasodilation)
c) By hairs