1. Neurones or nerve cells
part of module one of
unit F214
Communication, homeostasis and energy

2. Independent work for Monday 16th Nov
a) Draw and fully label a sensory neurone and a motor neurone to show their structure.
b) State the function of sensory and motor neurones.
2) Describe and explain at least 4 ways in which neurones are adapted for their function.
3) Write a definition for each of these terms:-
relay neurone b) CNS
c) polarised membrane d) resting potential
4) a) Name at least 4 types of sensory receptors in humans, their position and the stimulus detected;
b) Explain why receptors can be called transducers?
5) State at least 5 facts about synapses.

3. Revision plan for F212 resits – evidence of revision needed by Lloyd, Georgina, Emily
By Monday 23rd Nov
Biological molecules – carbohydrates, proteins, lipids, water, enzymes, DNA, RNA
2) By Monday 30th Nov
Diet, food, antibodies, vaccination, smoking, cardiovascular disease
3) By Monday 7th December
Biodiversity, conservation, classification, natural selection and evolution

4. Resting potential
negative inside neurone plasma membrane and positive outside
-65 / -70 mV difference
produced by active transport using sodium – potassium pumps in the plasma membrane
3 Na+ out of cell and 2 K+ in
K+ diffuses back; Na+ does not
Resting potential

5. How do neurones carry information?
resting potential refractory period
action potential all or nothing law
depolarisation local circuits
repolarisation saltatory conduction
Action potential and transmission

7. Why do nervous impulses travel at different speeds
Why do nervous impulses travel at different speeds? Can you describe and explain this data?
type of neurone
diameter / um
myelinated or unmyelinated?
speed of impulses in m/s
cat axon 1
unmyelinated 3
squid axon
1000 30
frog axon 10 20
myelinated 50

8. Aims of today’s lesson Remind about SMART targets for Biology
Review resting potential and action potentials – notes and questions
Learn about function of myelin sheath
Learn about synapses – gaps between 2 neurones or a neurone and muscle cell

9. Resting potentials and action potentials

10. Resting potential
negative inside neurone plasma membrane and positive outside
-65 / -70 mV difference
produced by active transport using sodium – potassium pumps in the plasma membrane
3 Na+ out of cell and 2 K+ in
K+ diffuses back; Na+ does not
Resting potential

11. How do neurones carry information?
resting potential refractory period
action potential all or nothing law
depolarisation local circuits
repolarisation saltatory conduction
Action potential and transmission

12. synapses Synaptic cleft = gap between 2 neurones
Synapse = synaptic cleft + parts of neurones near cleft
Neuromuscular junction = where axon meets muscle

15. Aims of today’s lesson Complete individual research on synapses
Check exam questions 3 and 4 set yesterday
Answer exam questions 5, 6 and 7 - to be checked in tomorrow’s lesson
Start on exam questions 8, 9, 10 and 11 – to be checked on Monday 23rd Nov
All work on nerves to be learned by Tuesday 24th November – you will answer an exam question in the lesson
Complete progress reviews

18. Aims of today’s lesson
Check individual research on synapses and add notes on the function of synapses
Check exam questions 5, 6 and 7 set yesterday
Reminder - exam questions 8, 9, 10 and 11 – to be checked on Monday 23rd Nov
Reminder - all work on nerves to be learned by Tuesday 24th November – you will answer an exam question in the lesson
Reminder – 5 lessons next week (i.e. including Friday)
Overview of co-ordination by nerves

19. A cholinergic synapse How does it function
A cholinergic synapse How does it function? And what is the role of each organelle?

20. Drugs and synapses
Nicotine mimics acetylcholine and binds to receptors so more impulses occur
Amphetamines and cocaine mimic neurotransmitter (noradrenaline) in the synaptic cleft so more impulses occur
Heroin and morphine mimic the neurotransmitter endorphin (an inhibitor) so fewer impulses and pain not felt
Nerve gas and strychnine poison prevent acetyl cholinesterase enzyme working so impulses continually generated
Curare (a poison from plants) binds to receptors on postsynaptic membrane of muscles and causes paralysis as no impulses occur

21. Why have synapses?
Action potential transmitted from one neurone to the next
Action potentials only travel in one direction
Filters out weak stimuli – not enough neurotransmitter released so no action potential
Acclimatisation – repeated stimulation no longer produces response – vesicles of neurotransmitter not reformed
Co-ordination
convergence = several neurones  one
divergence = one neurone  many
summation – temporal or spatial – results in enough neurotransmitter being released
Memory – creating synaptic pathways

25. Receptors as transducers

28. Transmission down the axon
Local currents
are the
movement of
ions by diffusion
along the
neurone.

30. Action potential and transmission
Resting potential
Neuron Structure

31. Reflex actions and the reflex arc
Answer SAQ 6.10 about reflex actions.
State 5 characteristics of all reflex actions.
What is a reflex arc?
How many neurones are involved and what are their names?
Complete the drawing by adding a sensory neurone, an intermediate neurone and a motor neurone (excitatory).
Label the diagram fully and show the direction of the nervous impulse / action potential.

32. Brain warm up – nerve cells
Name 3 types of neurone.
What is an axon?
Why could impulses travel at different speeds?
What is a node of Ranvier?
Where are the cell bodies of neurones?
State 3 characteristics of reflex actions.
What are the grey matter and the white matter?
What is a synapse?

33. In mammals, changes in the internal and external environment are detected by receptors ( June 2004)
a) State the general name given to changes in the
environment that can be detected by receptors. (1)
b) Explain why it is important for mammals to be able to detect changes in their internal environment (3)
c) Receptors are often described as biological transducers, structures which convert energy from one form into another. Explain how receptors in mammals convert energy into action potentials. Use named examples of receptors in your answers. (8)

34. Jan 2002, number 6 - answer E synaptic cleft F postsynaptic membrane
G synaptic knob / bulb H vesicle / neurotransmitter
b) depolarisation of presynaptic membrane by action potential (reject impulse);
calcium channels open so calcium ions diffuse in;
vesicles fuse with presynaptic membrane;
acetylcholine / neurotransmitter released into synaptic cleft;
ACh diffuses across cleft;
binds to receptors on postsynaptic membrane;
sodium channels open and sodium ions diffuse in;
membrane depolarised;
if over threshold, action potential produced;
role of hydrolysis enzyme;
role of mitochondria e.g. active transport or synthesising ACh;
c) myelin sheath = electrical resistance/insulation;
depolarisation only at nodes;
action potential jumps from node to node / saltatory conduction;
fast conduction;
action potential has fixed size;
produced at full size if stimulus / depolarisation is greater than threshold or not at all;