CO-ORDINATION AND CONTROL

Revision Part 1

Key words...

...but what do they mean? Sense organs Receptors Stimuli Sensory neurones Motor neurones Central nervous system Reflex arc Synapses Relay neurone Effectors Response

The Nervous System

Receptors

There are different kinds of receptors. How many can you name?

Light Sound Balance Smell Taste Touch Pressure Temperature change

Sense organs

There are five of them. What are they? Eyes Ears Nose Tongue Skin

Remember...

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.

Questions...

1. 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.

2. Which of the following in not an example of a stimulus?

Pressure Chemical Hearing Change in position Change in temperature

Questions...

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.

Questions...

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.

Questions...

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?

Questions...

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) Which part of the body do the results suggest

is most and least sensitive?b) From the results above, which body part do

you think contains the most pressure receptors? Explain your answer.

c) 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.

d) Each pupil was tested once. Suggest how you might make the results more accurate.

Area of the body tested

Number of pupils saying “yes”

Sole of foot 2

Knee 3

Fingertip 10

Back of hand 5

Lip 9

The Reflex Arc

The Reflex Arc

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 Effector

Response

Synapses

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.

Questions...

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.

Questions...

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.

Questions...

3) Why is a reflex reaction quicker than a voluntary reaction?

4) Explain what a reflex arc is.