1. The structure and function of Neurons
Aim:
To be able to identify and label a neuron
Describe the functions of the 3 types
Understand how they work to pass on information (synaptic transmission)

2. Have you ever wondered what it feels like to be a neuron?
Your task is to work in threes (fours – narrator) to demonstrate how the 3 different types of neurons work to pass information from one dendrite to the other
Decide who will be which neuron
Figure out something that will represent the electrical impulse.
You will need to narrate what is happening. You should introduce yourself.
Label yourselves (post its)
I am a sensory neuron – ‘ here are my dendrites….here is my myelin sheath, I can be found in…..
Sensory neuron
Relay Neuron
Motor Neuron

3. Become neurons Neurons one: You have touched something really hot
Neurons two:
You have heard an alarm
Neurons three:
You have stood on something really sharp.

4. Can you label a neuron correctly?
On mini whiteboards:
1. What type of neuron is this?
2. Write the key structures of each neuron and identify what is the direction of impulse ( i.e. which way is the signal travelling?). We will check your answers at the end. 2 1 3 6 5 4 7

5. And this one…number 2 1 2 3 5 6 4 7

6. Cell body Axon Synaptic endings dendrites2 1 3
How did you get on? 4

7. Check answers… Sensory neuron Motor Neuron Relay Neuron
1.Synaptic endings
2.Cell body
3.Skin receptors
4. Myelin Sheath
5.Node of Ranvier
6. Dendrites
7. Axon
Motor Neuron
1.Cell body
2.Schwann cell nucleus
3.Myelin Sheath
4. Motor end plates
6. Axon
7.Dendrites
Relay Neuron
1. Cell body
2. Dendrites
3. Axon
4. Synaptic endings

8. Bringing your knowledge together – on paper or MWB can you fill out the grid?
Which direction are these impulses sent?
Where are these neurons found?
What is the function of these neurons?
Sensory Neuron
Relay Neuron
Motor Neuron

9. Bringing your knowledge together – on paper or MWB can you fill out the grid?
Which direction are these impulses sent?
Where are these neurons found?
What is the function of these neurons?
Sensory Neuron
Skin to spinal and brain
Eyes, ears, tongue, skin… (PNS)
Convert info from receptors into neural impulse
Relay Neuron
Between sensory and motor
Brain and spinal cord (CNS)
Allow communication
Motor Neuron
Spine to muscles
CNS and PNS muscles
Releases neurotransmitters to bind to muscle receptors
to trigger movement.

10. Neurons (part 2)- Synaptic transmission
Prep for Monday..
Flip 4 - Localisation of Brain function for Wednesday.

11. But first…quick recap from previous lessons
The Nervous System –
On Mini White Boards, individually draw out the structure of the Nervous System – try and label it as accurately as you can. To start you off, it’s divided into the CNS and PNS…Go!
Next, Neurons – in pairs on BWB sketch out the sensory neuron, motor neuron and relay neuron and label them.

12. Synaptic transmission
In your flip on neurons you would have noted they don’t touch each other and the way they ‘communicate’ is via a process called synaptic transmission. Can you remember what this process involves? Label the diagrams on the sheet. And describe what is happening in each of these – bullet points are fine.

13. Synaptic vesicles
Pre-synaptic nerve ending
Synaptic nerve ending
Neurotransmitters
Receptor
Synaptic Cleft

15. The neurotransmitters bind to and activates receptor sites
The neurotransmitters bind to and activates receptor sites. The activation results in either a excitatory or inhibitory effect.
The transmission stops when the neurotransmitter is taken-up again by the pre-synaptic neuron (or broken by enzymes). The effects are therefore determined by how quickly re-uptake occurs.
As the action potential reaches the end of the nerve axon it causes vesicles to release neurotransmitters that are chemical messengers.
The vesicles bond with the nerve membrane and are released into the synaptic cleft. This is called Exocytosis

16. An important part of the process…excitatory or inhibitory
Neurotransmitters that get released across the synapse can have either an excitatory effect on the receiving neuron (making them more likely to fire) or an inhibitory effect (making them less likely to fire).
Watch the following short clip

17. GABA being inhibitory will make the post synaptic neuron LESS likely to have an action potential (fire).
Acetylcholine (a-seat-oh-coal-line), glutamate etc will make post synaptic neuron MORE likely to have an action potential.

18. In summary…excitatory & inhibitory neurotransmitters
The ‘on switches’
They cause excitation of post synaptic neurons
Makes the mind ‘busy’
Neurotransmitter examples: Adrenaline, acetylcholine
Inhibitory
The ‘off switches’
They cause inhibition of post synaptic neurons
Makes the mind ‘calm’
Neurotransmitter examples: GABA, serotonin

19. Will the post synaptic neuron fire?
One post synaptic neuron is connected to many other presynaptic neurons at the same time.
Each presynaptic neuron may be transmitting a different neurotransmitter. In this example (green, blue & black) are excitatory. The red is inhibitory.
What do you think the ‘net’ result would be on the postsynaptic neuron. To fire or not?
Excitatory post synaptic potential
Inhibitory post synaptic potential
The net result of the calculation is referred to as spatial summation

20. Researchers tested synaptic transmission in slices of rat brain
Researchers tested synaptic transmission in slices of rat brain. They stimulated different combinations of presynaptic neurons, and found that an action potential was sometimes produced, but not always. Use your knowledge of excitatory and inhibitory neurotransmitters to explain this finding (4 marks)
If the researchers stimulated several neurons which all caused an EPSP in the post-synaptic neuron then spatial summation would mean that an action potential is produced. On the other hand, if they stimulated a combination of neurons some of which caused IPSP’s then the post synaptic neuron may not fire.

21. Treating abnormal neurotransmission.
What do you think would happen if someone did not produce enough Serotonin or GABA?
What do you think would happen if someone had too much excitatory neurotransmission?
What can we do to aid its action?
We will learn about this in psychopathology. BZ’s increase the channels receiving GABA, SSRI’s block serotonin’s reuptake. Both boost the action.

22. Exam practice
Have a go on at least one of the following questions. Be accurate and detailed in your response.
1. Outline the structure and processes involved in synaptic transmission (6 marks)
2. Explain how information travels from a sense organ (such as the eye) to an effector (such as a bicep) – (6 marks)

23. Outline the structure and processes involved in synaptic transmission (6 marks)
The structure of synaptic transmission begins with the presynaptic and postsynaptic neuron. Electrical impulses are conducted into the cell body via dendrites and run along the axon. Myelin is a fatty insulative tissue surrounding the axon and helps speed up the rate the impulse passes along the axon. The impulse reaches towards the synaptic terminal but cannot access the synaptic cleft. The impulse causes calcium to be released and trigger vesicles containing neurotransmitters to cross the synapse. The neurotransmitters then bind to the receptors on the post synaptic neuron. Neurotransmitters can have an excitatory effect on the receiving neuron or inhibitory effect. Acetylcholine for example, has an excitatory effect, making the postsynaptic neuron more likely to fire. In contrast, GABA causes an inhibition in the receiving neuron making it less likely to fire. Furthermore, this action will occur depending on the ‘net’ or summation of the neurons being excitatory or inhibitory.

24. Notice the amount of key terminology. This is expected for 6 marks
Explain how information travels from a sense organ (such as the eye) to an effector (such as a bicep) – (6 marks)
Notice the amount of key terminology. This is expected for 6 marks
Information is received from a sense organ and passes through the sensory neuron. It is detected by the dendrites and an electrical impulse is passed towards the CNS via the cell body. The impulse is then passed along the axon to the terminal axons, where neurochemicals are released across the synapse and detected by the receptor sites in the dendrites of the relay neurons. The impulse continues across the dendrites, cell body, axon and axon terminals of the relay neuron, and chemicals are released across the synapse between the relay and the motor neuron. The electrical impulse then moves away from the CNS towards the important effector via the dendrites, cell body and axon of the motor neuron, until chemicals are released at the motor end plate which inform the muscle to act.

25. If time allows
-Now in pairs create 5 questions to test your classmates on based on the lesson. It could be on types of neurons, how they work, asking them to draw them, synaptic transmission etc. You have to make the questions increasing more difficult as they go along.
-Everybody stand up! Now pair up with another pair on a different table and take it in turns to ask each other a question. Who got the most correct?
-Now each pair grab a whiteboard. Each pair will ask one of their questions to the whole class who have to write on MWB. Hold up answer and the pair have to check boards to see if the class is right and tell us the right answer if not.
No repeating of questions so the last pair have to be creative!