1. The Nervous System

2. Objective questions Lesson 1
Can you name the five senses and the sense organs?
Are you able to describe the main parts of the CNS and PNS?
Lesson 2
Can you describe a reflex action?
Higher Tier
Can you fully label a diagram of a reflex arc?
Can you fully label a diagram of the eye?

3. The nervous system is made up of the central
Medical RF.Com/Science Photo Library
The nervous system is made up of the central
nervous system (CNS) and the peripheral
nervous system.

4. Nervous system- sense organs

5. The Nervous System
We have 5 sense organs that help us detect our surroundings
Ears- Sound and balance
Nose- Chemicals (smell)
Tongue- Chemicals (taste)
Skin- Touch, heat, pressure
Eyes- Light

6. Stimulus Receptor Coordinator Effector Response
The Nervous System
The NERVOUS SYSTEM consists mainly of the brain, the spinal cord, nerve cells (“neurones”) and receptors. CNS Central Nervous System is made up of the brain and spinal cord.
Types of receptor:
Light receptors in the eyes
Sound receptors in the ears
Chemical receptors on the tongue and in the nose
Touch, pressure and temperature receptors in the skin
Changes of position receptors in the ears (balance)
Stimulus Receptor Coordinator Effector Response

7. Examples of reactions Bright light Sour taste Losing balance
Stimulus
Receptor
(i.e. the thing that detects the stimulus)
Effector
(i.e. the thing that will do the reaction)
Response
(i.e. action taken)
Bright light
Eye
Pupil
Pupil constrict
Sour taste
Taste bud
Salivary Gland
Produce saliva
Losing balance
Ear
Muscles
Movement (stop you falling down)
Sit on a drawing pin
Touch receptors
Movement

8. Structure of a motor neurone. The nerve impulse is
carried along the nerve fibre.

9. Background
If you notice a ball moving towards your head, the time it takes from when you first notice the ball to when your arm reaches up to catch it is an example of reaction time. Even though nervous impulses travel very quickly through your nervous system, your body doesn’t react instantly. In this activity, you will conduct a simple, measurable experiment to study reaction time and investigate the hypothesis that reaction time improves with practice.

11. Method- assigned practical from teachers guide
1. Ask your first volunteer to sit in the chair with good upright posture and eyes looking across the room. 2. Have the volunteer place their forearm (the part of the arm from elbow to hand) so it extends over the edge of the table. 3. Ask the volunteer to place their thumb and index (pointer) finger on either side of the bottom of the vertically placed ruler. The number “1” should be on the bottom, the “30” near the top. 4. Let your volunteer practice holding the ruler with those two fingers. 5. Now, ask your volunteer to remove their fingers from the ruler while you continue to hold it so that the bottom of the ruler is at a height of 2 cm above the fingers. 6. Tell your volunteer that you will release the ruler without warning. Their job will be to catch it with their thumb and forefinger as soon as they sense it dropping. 7. Drop the ruler. When your volunteer catches it, record the number on the ruler displayed just over the thumb. The lower the number, the faster the reaction time. 8. Conduct five trials with the same volunteer, dropping the ruler from 2 cm above their fingers each time. 9. Repeat the experiment with at least five other volunteers and record your results in a suitable table

14. Objective questions Lesson 1
Can you name the five senses and the sense organs?
Are you able to describe the main parts of the CNS and PNS?
Lesson 2
Can you describe a reflex action?
Higher Tier
Can you fully label a diagram of a reflex arc?
Can you fully label a diagram of the eye?

15. straightens. This reflex is used when we walk.
What happens next??
Iofoto/Shutterstock
The knee-jerk reflex test. When the leg is tapped just below the knee, the leg
straightens. This reflex is used when we walk.

16. Muscle strands (effector)
Types of nerve cell
Nucleus
Muscle strands (effector)
Cell body
Nerve cells (neurones) are elongated with branched endings to connect to many muscles fibres.
1) Motor neurone
2) Sensory neurone
3) Relay neurone
Impulse
Impulse

17. Receptor
Sensory Neurone
Spinal cord
Synapse
Relay Neurone
Motor Neurone
Effector
Reaction

18. A reflex arc

19. The impulse goes from receptor to CNS and then to effector to bring about the response. The relay neurone (purple) inside the spinal cord coordinates the response by connecting the sensory neurone to an appropriate motor neurone (green). The information travels from one neurone to another across a small gap called a synapse.

20. receptor: which sense organ?
Keeping in touch
Coordination
receptor: which sense organ?
response: ……………
stimulus:……………
effector: …………….
coordinator:
brain or spinal cord?
itch
skin receptors
brain and spinal cord
arm muscle
scratch

21. Stimulus Receptor Coordinator Effector Response

22. Keeping in touch
Reflex arc 1 2 4 3 5
Spinal cord.
Nerve ………… arrives from ………… along the sensory neurone.
…….. neurone.
…………
Nerve impulse travels to the effector along the ……… ………

23. Exercise Write out the actions for the following
1) peeling an onion and chemicals from them getting into your eye
2) Pepper particles get up your nose
3) You put your hand on a hot plate

24. Withdrawal reflex stimulus: ………………………………. pain receptor: ……………………………….
Keeping in touch
Withdrawal reflex
receptor: ……………………………….
coordinator:……………………………
response: ……………………………..
stimulus: ……………………………….
effector: ……………………………….
pain
skin heat sensor
relay neurone in spinal cord
arm + shoulder muscles
withdrawal

25. Objective questions Lesson 1
Can you name the five senses and the sense organs?
Are you able to describe the main parts of the CNS and PNS?
Lesson 2
Can you describe a reflex action?
Higher Tier
Can you fully label a diagram of a reflex arc?
Can you fully label a diagram of the eye?

27. The functions include:
sclera – protective, tough white outer coat
cornea – clear part of sclera allows
light to enter and refracts light
entering
pupil – hole in centre of iris which
allows light to enter
iris – muscles that alter size of pupil to
control amount of light entering
lens – changes shape to focus light
onto retina
choroid – a pigmented layer which
absorbs light to prevent reflection,
also contains blood vessels
retina – light sensitive layer , an image
is formed here, impulses sent to optic
nerve
blind spot – where the optic nerve leaves
the eye, there are no light sensitive cells
here
optic nerve – carries impulses from retina
to brain