Biology Form 5 Chapter 3 - Coordination & Response Part 5 - Body Temperature Regulation

1. BIOLOGY FORM 5
CHAPTER 3
COORDINATION & RESPONSE PART 5

2. LEARNING OBJECTIVES
3.4 Synthesising the concept of homeostasis in humans
LEARNING OUTCOMES
 explain the necessity to maintain an optimal physical and chemical
condition in the internal environment
 state the meaning of homeostasis,
 design an experiment to study the effect of different quantities of
water intake on urine output,
 relate changes in blood osmotic pressure to urine output,
 describe the formation of urine,
 relate the formation of urine to excretion,
 describe briefly the mechanism of osmoregulation,
 predict the consequences of impaired kidney function,
 describe the regulation of blood sugar level,
 describe the regulation of body temperature,
 conceptualise homeostasis.

4. THERMOREGULATION
How we keep (or maintain) a steady body temperature.
Mammals are
endothermic
homeotherms
(warm
blooded)
They regulate
their own
body
temperature.

5.  To provide the optimum conditions for
enzyme-catalysed reactions to be
carried out.
Why do we need to regulate:
Internal body temperature

6. In humans it is the core
body temperature
which is maintained by
homeostasis.
Temperature Regulation

7. Body Temperature
 Normal internal body temperature
is 370C.
 Temperatures above this:
denature enzymes and block
metabolic pathways
 Temperatures below this:
slow down metabolism and affect
the brain.

8. Body Temperature Control
 The hypothalamus
acts as a thermostat
and receives nerve
impulses from heat
and cold
thermoreceptors in
the skin.
 There are also
receptors in the
hypothalamus- called
central
thermoreceptors.
These detect changes in
blood temperature.

9. SKIN STRUCTURE

10. IT’S HOT

11. Correction of overheating
1. Detected by thermoreceptors in the
hypothalamus impulses thermo
regulatory centre in hypothalamus 
triggers effectors
2. Causes vasodilation.
3. Sweating
4. Hair lies flat

12. If the temperature
rises, the blood
vessel dilates (gets
bigger).
Vasodilation
This means more heat is lost from the surface of
the skin

13. Sweating
 When your body is hot,
sweat glands are stimulated
to release sweat.
 The liquid sweat turns into a
gas (it evaporates)
 To do this, it needs heat.
 It gets that heat from your
skin.
 As your skin loses heat, it
cools down.

14. Sweating
The
skin

15. Cooling down
 When it's hot and you
need to cool down,
muscles at each hair
relax.
 Hairs lie close to the
skin.
 Air does not act as an
insulating layer.

17. ITS COLD

18. If you are cold,
What mechanisms are there to
warm the body up?

19. Correction of overcooling
1. Detected by thermoreceptors in the
hypothalamus  impulses thermo regulatory
centre in hypothalamus  triggers effectors
2. Causes vasoconstriction.
3. Decreased sweating
4. Shivering

20. If the temperature
falls, the blood
vessel constricts
(gets shut off).
This means less heat is lost from the surface of the skin

21. Keeping warm
 When it's cold, the
muscle contracts
pulls the hair up.
 A layer of warm air
accumulates around
the hair and
insulates the
organism.
 Heat retained

23. No Sweating

24. Shivering
How does it work?

25. Penguins huddling to keep warm

26. Animation

29. Metabolic changes
Adrenal gland
secretes adrenaline
Thyroid gland
secretes thyroxine
Metabolic rate increases  more heat released
Converts
glycogen
 glucose

30. ANIMATION

31. Fill in the blanks

32. Regulating Body Temperature - on a Hot Day

33. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 34
Stimulus
Blood and skin
temperatures rise
Regulating Body Temperature - on a Hot Day

34. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 35
Stimulus
Blood and skin
temperatures rise
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Regulating Body Temperature - on a Hot Day

35. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 36
Stimulus
Blood and skin
temperatures rise
blood capillaries
hair follicle
hair
arteriole
erector muscle
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Regulating Body Temperature - on a Hot Day

36. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 37
Stimulus
Blood and skin
temperatures rise
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
arteriole
capillariesskin surface
Arterioles in
skin dilate
1
More blood flows to
capillaries in skin
2
3
Greater heat loss
4
Shunt vessels constrict
Regulating Body Temperature - on a Hot Day

37. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 38
Stimulus
Blood and skin
temperatures rise
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
sweat duct
sweat pore
sweat gland
Sweat glands
more active
Sweat
production
increases
More latent heat lost as sweat evaporates
6
7
5
Regulating Body Temperature - on a Hot Day
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain

38. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 39
Stimulus
Blood and skin
temperatures rise
Hair erector
muscles in
skin relax
erector muscle
blood capillaries
hair follicle
hair
arteriole
8
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Regulating Body Temperature - on a Hot Day

39. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 40
Stimulus
Blood and skin
temperatures rise
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Corrective Mechanism
Increase in heat loss and
decrease in heat
production
Regulating Body Temperature - on a Hot Day

40. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 41
Stimulus
Blood and skin
temperatures rise
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Corrective Mechanism
Increase in heat loss and
decrease in heat
production
Decreased
metabolic rate
reduces heat
production
Regulating Body Temperature - on a Hot Day

41. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 42
Stimulus
Blood and skin
temperatures rise
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Corrective Mechanism
Increase in heat loss and
decrease in heat
production
Blood temperature
returns to normal levels
Decreased
metabolic rate
reduces heat
production
Regulating Body Temperature - on a Hot Day

42. 8 June 2016Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 43
Stimulus
Blood and skin
temperatures rise
Receptor
Temperature receptors
detect changes and send
nerve impulses to the brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Corrective Mechanism
Increase in heat loss and
decrease in heat
production
Blood temperature
returns to normal levels
Negative
feedback
Decreased
metabolic rate
reduces heat
production
Regulating Body Temperature - on a Hot Day

43. Regulating Body Temperature - on a Cold Day

44. Stimulus
Blood and skin
temperatures fall
Regulating Body Temperature - on a Cold Day

45. Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Regulating Body Temperature - on a Cold Day

46. blood capillaries
arteriole
hair hair follicle
Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
erector muscles
Regulating Body Temperature - on a Cold Day

47. Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Less blood flows to
capillaries in skin
Arterioles in
skin constrict
Shunt vessels dilate
skin surface
capillaries
arteriole
1
2
3
Less heat loss
4
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Regulating Body Temperature - on a Cold Day

48. Sweat glands
less active
Sweat
production
decreases
Less latent heat lost
sweat pore
sweat duct
sweat gland
Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
56
7
Regulating Body Temperature - on a Cold Day

49. Hair erector
muscles in
skin contract
erector muscles
blood capillaries
arteriole
hair hair follicle
Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
8
Regulating Body Temperature - on a Cold Day

50. Shivering occurs when
insufficient heat is produced
Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Hypothalamus of brain
is
stimulated and sends
nerve impulses to
relevant body parts
Corrective Mechanism
Decrease in heat loss
and increase in heat
production
Regulating Body Temperature - on a Cold Day

51. Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Corrective Mechanism
Decrease in heat loss
and increase in heat
production
Increased
metabolic rate
increases heat
production
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Regulating Body Temperature - on a Cold Day

52. Blood temperature
returns to normal levels
Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Corrective Mechanism
Decrease in heat loss
and increase in heat
production
Increased
metabolic rate
increases heat
production
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts
Regulating Body Temperature - on a Cold Day

53. Regulating Body Temperature - on a Cold Day
Corrective Mechanism
Decrease in heat loss
and increase in heat
production
Increased
metabolic rate
increases heat
production
Blood temperature
returns to normal levels
Negative
feedback
Stimulus
Blood and skin
temperatures fall
Receptor
Temperature receptors
detect changes and send
nerve impulses to the
brain
Hypothalamus of brain
is stimulated and sends
nerve impulses to
relevant body parts

54. 1. Receptors
Nerve endings in skin send
message to the brain about
the external environment.
Blood temperature changes
detected by temperature
receptors in brain
Body
Temperature
Above 37°C
3. Effectors produce response
•Sweating
•Hairs lie flat
•Vasodilation
(blood vessels closest to surface
of the skin widen)
Body
Temperature
Below 37°C
3. Effectors produce response
•Shivering
•Hairs stand up
•Vasoconstriction
(blood vessels closest to the
surface of the skin narrow)
2. Processing Centre
The hypothalamus
processes the information
from the temperature
receptors and co-ordinates
the response.
2. Processing Centre
The hypothalamus
processes the information from
the temperature receptors
and co-ordinates the
response.
4. Levels return to
Normal 37°C

55. The EnD