1. What can I remember? What is a synapse?
What are neurotransmitters? Give two examples and what they do
How is the removal of noradrenaline different to that of acetylcholine?
Why is it important that neurotransmitters are removed at a synapse?
Explain how an impulse is determined as excitatory or inhibitory
Two possible revision of last lesson – slide with 6 Qs or Multiple choice series of Qs

2. A synapse is … A. a space between two neurones
B. a region of contact between a vesicle and a dendrite
C. a region of functional contact between axon ending and dendrite
D. a space between a neurotransmitter and a vesicle

3. What is a neurotransmitter?
A. a chemical which travels from the presynaptic neuron to the post synaptic neuron
B. a chemical which travels from the post synaptic neuron to the pre synaptic neuron
C. a chemical which stays in the synaptic cleft
D. a chemical which stays in the post synaptic neuron

4. Examples of two neurotransmitters are …
A. Acetyl Co A and morphine
B. Acetylcholine and Strychnine
C. Noradrenaline and Acetyl Co A
D. Noradrenaline and acetylcholine

5. Which organelle is required to provide energy for synthesis?
A. Ribosome
B. Vesicle
C. Nucleus
D. None of the above

6. Acetylcholine is removed from the synapse by …
A. re-uptake by the pre synaptic neuron
B. re-uptake by the post synaptic neuron
C. enzyme degradation and reabsorption by post synaptic neuron
D. enzyme degradation and reabsorption by pre synaptic neuron

7. What dictates whether impulse is excitatory of inhibitory?
A. receptors on the pre synaptic neuron
B. receptors on the post synaptic neuron
C. receptors on both the pre and post synaptic neurones
D. receptors and the neurotransmitter

8. Neurones and Neural Pathways Part 2
Higher Human Biology
Neurones and Neural Pathways Part 2

9. Complex neural pathways
Learning intentions:
What are converging neural pathways and their involvement in light sensitivity?
What are diverging neural pathways and their involvement in fine motor control?
What are reverberating pathways and their function?
What is the plasticity response and its importance in the nervous system?

10. What are converging neural pathways and their involvement in light sensitivity?
Converging neural pathways come together and meet at a common point.
Nerve impulses from several sources are channelled together and meet at one destination

11. What are converging neural pathways and their involvement in light sensitivity?
3 neurones sending impulses from different sources N
Single cell body of neurone receiving the converging nerve impulses

12. Converging neural pathways continued
Converging neural pathways help us to see in the ‘dark’
Rods and cones are the visual receptor cells which distinguish between daylight and dim light. They are found in the retina of our eyes.
The cones have a pigment which is broken down in the presence of bright light (daylight).
Rods also have a pigment but it is extremely sensitive to light therefore the pigment can be broken down in very dim light.

13. Convergent pathway of rod cells in the eye
Many rods are needed to produce enough of an impulse to ensure it is passed on
The nerve impulse of one rod in dim light is too weak
The convergent arrangement of several rods enables several impulses to be transmitted at the same time ensuring the threshold of the postsynaptic neurone is raised and transmits the nerve impulse to the optic nerve

14. What are diverging neural pathways and their involvement in fine motor control?
Diverging neural pathways branch out from a common point
As a result one single impulse can be transmitted to several destinations
This type of pathway is crucial in fine motor control

15. Divergent pathways and fine motor control
Movement of the skeletal muscles is controlled by the motor area of the cerebrum
Impulses are sent from this area of the brain along motor neurones to effector cells in the skeletal muscles
A single motor neurone can carry the impulse for hand movement
The impulse is passed on in the form of a diverging neural pathway along the hand to the tips of the fingers and the thumb to allow them to move in unison

16. Diverging neural pathways and temperature control
Diverging neural pathways carry impulses from the hypothalamus to effector cells in the skin (hair erector muscles), sweat glands and skin arterioles
The hypothalamus is therefore able to exert a co-ordinated control over the structures involved in temperature control. Such as:

17. Reverberating Pathways
Tuning fork
Hit on the desk gently
The sound you hear appears to go on repeatedly
This is reverberation
Shouting in a valley produces an echo = reverberation
Nerve impulse reverberation means repeating the impulse

18. How do reverberating pathways work?
A neuron later in the pathway has axons connecting it to neurones earlier in the pathway
The nerve impulse can then be recycled
Thought to be involved in -
breathing – reverberating pathway for a lifetime
short term memory – reverberating for minutes or hours

19. What is the plasticity response of the nervous system?
Plasticity: the ability of parts of the brain to take on different jobs as well as their own
Plasticity enables new neural pathways to form:
- during early development of the brain
- learning new skills
- response to brain injury

20. Stroke patients for example may have damage which stops them from speaking however over the months following the stroke they begin to regain normal speech
Brain damage cannot be repaired so another part of the brain has taken on the role of co-ordinating speech = major plasticity
Various simple experiments can demonstrate minor plasticity of the brain

21. Plasticity of the brain cont’d
Suppressing a reflex
- reflex action is an involuntary automatic response to a stimulus
- blinking of the eye is a reflex response when someone/something comes close to your eye

22. How many of you know someone who appears to switch off?
Suppressing sensory distraction
- ever tried having a conversation with someone who is watching their favourite programme on the TV and they do not respond
- they are suppressing the auditory stimulus of your voice and are able to concentrate on the TV
What a ping!
He hasn’t heard a word I just said

23. Plasticity cont’d
Plasticity is thought to occur because conflicting messages are being sent to the brain
In suppressing the urge to blink your brain is being told to make you blink and to resist the urge to blink
If the overall effect is excitatory then you blink
If the overall effect is inhibitory you don’t blink

24. From today what have I learned?
What are converging neural pathways and their involvement in light sensitivity?
What are diverging neural pathways and their involvement in fine motor control?
What are reverberating pathways and their function?
What is the plasticity response and its importance in the nervous system?

25. Activities Testing your knowledge Qs p256 No’s 3 and 4
Homework
Chapter 14 past paper Qs
Pre-reading – Chapter 18