The document outlines the mechanisms of temperature regulation within the human body, emphasizing the role of the hypothalamus and thermoreceptors in monitoring and adjusting body temperature. It explains the processes of vasodilation and sweating for cooling down, and vasoconstriction and shivering for warming up. Additionally, it highlights the voluntary responses that individuals can take to maintain an optimal temperature for enzyme activity and metabolism.

1. Temperature Regulation
Temperature Regulation
 By the end of the lesson you should
know
 How the body corrects overheating
 How the body corrects overcooling
 What thermocreceptors do?
 What volutary responses are carried out
to control temperature

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

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

6. Water Bath
Temperature set on thermostat
Too cool? Heater kicks on and temperature goes up
Too warm? Heater stays off until bath cools down
Constant checking and turning on and off

7. Control of homeostasis through
Control of homeostasis through
feedback
feedback
 Feedback system- cycle of events in which the
status of a body condition is continually
monitored, evaluated, changed, re-monitored,
re-evaluated, etc.

8.  1) receptor
– sensor that responds to changes (stimuli)
 2) control centre
– sets range of values, evaluates input and sends
output
 3) effector
– receives output from control centre and
produces a response
3 basic components of a feedback system

9. 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.

10. Vasoconstriction and
Vasoconstriction and
Vasodilatation
Vasodilatation

11. Correction of overheating
Correction of overheating
1. Detected by thermoreceptors in the
hypothalamus.
2. Causes vasodilation.
3. Sweating

12. Cooling down
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.

13. Sweating
Sweating
How does it work?
Heat energy in the
body is used to
convert the water
in sweat to vapour
cooling down the
body.

14. Correction of overcooling
1. Detected by thermoreceptors in the
hypothalamus.
2. Causes vasoconstriction.
3. Decreased sweating
4. Shivering

15. Keeping warm
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

16. Shivering
How does it
work?

17. Voluntary responses
Voluntary responses
 In humans the cerebrum “makes”
people feel cold or hot.
 They can then e.g. put on more
clothes, eat a hot meal, exercise etc
as appropriate.

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