1. 11.9 The brain and our senses

2. - The order of making a response:
Sense organ
Stimulus
Brain
Muscle
Response
message

3. p.116
response
muscle
brain
sense organ
stimulus

4. - The functions of different parts of
body in making a response:
Body part
Function
detect stimuli in the environment
sense organs
nerves
carry messages to brain
interprets messages, gives sensations
brain
make a response
muscles

5. interprets messages received
Functions of the brain
p.116
interprets messages received
Sensory function
(感覺功能)
gives sensations
Motor function
(運動功能)
decides what to do
sends messages along nerves

6. Sensory function Motor function response muscles brain sense organ
stimulus

7. Reaction time (反應時間) - The time taken for our body to react to
p.118
- The time taken for our body to react to
a stimulus.
- different among individuals.
Sense organ
Stimulus
Brain
Muscle
Response
message

8. Experiment Centre 11.9
p.118
Who reacts faster?

9. > Taking alcohol and drugs increases it.
- The following factors can affect
reaction time:
> Training shortens it.
> Tiredness increases it.
> Taking alcohol and drugs increases it.
p.119

10. - The brain consists of three main parts.
Cerebellum
(小腦)
Cerebrum
(大腦)
Medulla
(延腦)
Different parts of the brain do different jobs.

11. - Top view of
the brain:
> Divided into two hemispheres.
> Highly folded to increase surface
area for accommodating more cells.

12. - Longitudinal section
cerebrum
at the back of brain
cerebellum
medulla
at the bottom of brain, linking to spinal cord

13. action controlled by thinking
Function of cerebrum
p.120
- related to intelligence, memory and thought.
(隨意動作).
- controls voluntary action
action controlled by thinking
E.g. talk, shake hands...

14. Do you know ? Function of cerebellum - controls balance.
- controls muscle coordination.
E.g. walk, run...
Do you know ?
If the cerebellum is damaged, what will be the result?

15. Not controlled by thinking
Function of medulla
(不隨意動作)
- controls involuntary action
Not controlled by thinking
E.g. heartbeat, breathing

16. Do you know ?
The brain is about 1/50 of the total body weight, but it uses 1/5 of the body’s energy.

17. Activity Corner M 1 a Are the darker lines parallel?
Is the brain always correct?
b Use a ruler to check you answer.
What do you find?

18. b Use a pencil to trace its path.
2 a Is it a spiral?
b Use a pencil to trace its path.
What do you find?

19. 3 a Which column of the grey bars is
darker?
b Hide away the black bars.
Are all the grey bars in the same shade?

20. 4 How many legs does this elephant have?
Sometimes the brain interprets messages incorrectly. This results in illusions.