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
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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
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
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
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
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.
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.
25.
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
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