Transcript 11.9e

11.9
The brain and
our senses
p.117
- The order of making a response:
Stimulus
message
Sense
organ
Muscle
message
Brain
Response
p.116
muscle
brain
stimulus
sense organ
response
- The functions of different parts of
body in making a response:
Body part
Function
sense organs
detect stimuli in the
environment
nerves
carry messages to brain
brain
interprets messages,
gives sensations
muscles
make a response
Functions of the brain
• interprets messages received
• gives sensations
• decides what to do
• sends messages along
nerves
p.116
Sensory
function
(感覺功能)
Motor
function
(運動功能)
response
muscles
Sensory
function
brain
sense organ
stimulus
Motor
function
Reaction time (反應時間)
p.118
- The time taken for our body to react to
a stimulus.
- different among individuals.
Stimulus
message
Sense
organ
Muscle
message
Brain
Response
Experiment Centre 11.9
Who reacts faster?
p.118
- The following factors can affect
reaction time:
> Training shortens it.
> Tiredness increases it.
> Taking alcohol and drugs increases it.
p.119
- The brain consists of three
main parts.
Cerebrum
(大腦)
Medulla
(延腦)
p.120
Cerebellum
(小腦)
Different parts of the brain do
different jobs.
- Top view of
the brain:
> Divided into two hemispheres.
> Highly folded to increase surface
area for accommodating more cells.
- Longitudinal section
cerebrum
at the back
of brain
cerebellum
medulla
at the bottom of brain,
linking to spinal cord
Function of cerebrum
p.120
- related to intelligence, memory and thought.
- controls voluntary action (隨意動作).
action controlled by thinking
E.g. talk, shake hands...
Function of cerebellum
- controls balance.
- controls muscle coordination.
E.g. walk, run...
If the cerebellum is damaged,
what will be the result?
Function of medulla
- controls involuntary action (不隨意動作)
Not controlled by thinking
E.g. heartbeat, breathing
The brain is about 1/50 of the
total body weight, but it uses
1/5 of the body’s energy.
Activity Corner M
p.121
Is a
theAre
brain
alwayslines
correct?
1
the darker
parallel?
b Use a ruler to check you answer.
What do you find?
2 a Is it a spiral?
b Use a pencil to trace its path.
What do you find?
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?
4 How many legs does this elephant have?
Sometimes the brain interprets messages
incorrectly. This results in illusions.