Revision Part 1
...but what do they mean?
 Sense organs
 Receptors
 Stimuli
 Sensory neurones
 Motor neurones
 Central nervous system
 Reflex arc
 Synapses
 Relay neurone
 Effectors
 Response
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There are different kinds of receptors. How
many can you name?
Light
Sound
Balance
Smell
Taste
Touch
Pressure
Temperature change
There are five of them. What are they?
 Eyes
 Ears
 Nose
 Tongue
 Skin
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Sense organs contain receptors – Don’t get the
two mixed up!
Receptors change stimulus energy into an
electrical (nervous) impulse.
We need to be able to react quickly to certain
situations in order to survive and not get hurt.
The central nervous system (CNS) is made up
of the brain and the spinal cord.
1.
2.
Nerve cells or n_________ transmit e_________
impulses from our sense organs to the CNS.
Message from the CNS are sent to e__________,
which are muscles or g________. The impulses
are carried along m___________ and
s___________ neurones.
Which of the following in not an example of a
stimulus?
Pressure Chemical Hearing
Change in position Change in temperature
In each sentence, copy it out and then underline
the sense organ and say what type of receptor is
involved.
3a) Phillip puts a piece of lemon on his tongue. It
tastes sour.
3b) Ella wrinkles her nose as she smells something
unpleasant in a baby’s nappy.
3c) Emily covers her eyes when she sees the man in
the mask jump out during a scary film.
3d) Charlie’s ears were filled with the sound of the
crowd cheering his outstanding goal.
4. Give two reasons why it is important for
animals to be able to detect changes in their
surroundings.
5. Explain why a man with a damaged spinal cord
may not be able to feel someone touching his
toe.
6. Some parts of the body are known as the CNS.
a) What does CNS stand for?
b) Name the two main parts of the CNS.
c) What type of neurone carries information to the
CNS?
d) What type of neurone carries information from
the CNS?
7. Anna and Amelia investigated how sensitive
different parts of the body are to pressure. The
stuck two pins into a cork 0.5cm apart. The
pins were placed on different parts of the body.
10 pupils took part – they were blindfolded
and reported “yes” or “no” to feeling both
points. The results of the experiment are shown
in the table on the following slide.
7.
a)
b)
c)
d)
Area of the body tested
Number of pupils saying
“yes”
Sole of foot
2
Knee
3
Fingertip
10
Back of hand
5
Lip
9
Which part of the body do the results suggest is
most and least sensitive?
From the results above, which body part do
you think contains the most pressure receptors?
Explain your answer.
The girls took it in turns to test the pupils. Their
teacher suggested it would have been fairer if
only one of the boys had done the testing.
Explain why.
Each pupil was tested once. Suggest how you
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The reflex arc goes through the CNS. It doesn’t
go as far as the brain because it would take too
long... REMEMBER reflexes are designed
primarily for protection!
Stimulus
Receptor Sensory neurone
Relay neurone Motor neurone
Response
Effector
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A synapse is the tiny gap between two
neurones in the nervous system.
The nervous impulse is transmitted across the
gap by diffusion of chemicals from one
neurone to the next.
The signal goes from electrical to chemical back
to electrical.
1)
Copy out the following sentences, choosing the
correct word to make the statement true.
a)
Reflexes happen more quickly/slowly than
considered responses.
b)
The vertebrae/spinal cord can coordinate a
reflex response.
a)
The main purpose of a reflex is to
protect/display the body.
b)
Reflexes happen with/without you thinking
about them.
c)
A synapse is a connection between two
effectors/neurones.
2) Look carefully at the diagram showing the two
eyes above.
a) Describe the difference you can see in the
appearance of the two eyes.
b) Which diagram do you think shows an eye in
bright light? Explain your answer.
a)
Is the response illustrated above a reflex
response or a considered response?
b)
Explain why it is an advantage to have this
type of response controlling the action of the
eye.
3) Why is a reflex reaction quicker than a
voluntary reaction?
4) Explain what a reflex arc is.