6.5 Neurons and synapses
Teaching time: 3 hours Practical time: 0 hours
key vocabulary
prior learning & retrieval practice
Review 2.4 proteins
Review 1.4 membrane transport
The nervous system
Essential idea: Neurons transmit the message, synapses modulate the message.
U1: Neurons transmit electrical impulses.
U7: Synapses are junctions between neurons and between neurons and receptor or effector cells.
Exercise 1: Watch this video and connect-extend-challenge. Outline the key features of neurons that allow them to carry out their function.
Guidance: The details of structure of different types of neuron are not needed. Only chemical synapses are required, not electrical, and they can simply be referred to as synapses.
U2: The myelination of nerve fibres allows for saltatory conduction.
Exercise 2: Read your textbook and summarise: Explain what myelination is and what saltatory conduction is and how the former leads to the latter.
Resting and Action Potentials
U3: Neurons pump sodium and potassium ions across their membranes to generate a resting potential.
Exercise 3: Using video capture software on your mobile and any playdoh or molymods, explain how the resting potential is maintained in terms of the action of sodium pumps and potassium channels.
U4: An action potential consists of depolarization and repolarization of the neuron.
Exercise 4: Using video capture software on your mobile and any playdoh or molymods, Explain how an the two stages of an action potential (depolarization and repolarization) are generated by the pumps and channels of the axon plasma membrane.
Topic 1.4 A1: Structure and function of sodium–potassium pumps for active transport and potassium channels for facilitated diffusion in axons.
Exercise 5: Read the relevant section of your textbook and create a table that summarises how the structure of the sodium pump relates to its function (note this will be in chapter 1.4 of your textbook).
Exercise 6: Read the relevant section of your textbook and create a table that summarises how the structure of the potassium channel relates to its function (note this will be in chapter 1.4 of your textbook).
S1: Analysis of oscilloscope traces showing resting potentials and action potentials.
Exercise 7: Complete the data analysis exercise on page 324 of the Allott & Mindorff course companion.
U5: Nerve impulses are action potentials propagated along the axons of neurons.
U6: Propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential.
Exercise 8: Read page 322 and 323 and connect-extend-challenge.
Synapses
U8: When presynaptic neurons are depolarized they release a neurotransmitter into the synapse.
Exercise 9: Explain how synapses release neurotransmitters into the synaptic cleft.
U9: A nerve impulse is only initiated if the threshold potential is reached.
Exercise 10: Explain how neurotransmitters initiate a nerve impulse in the postsynaptic neuron.
A1: Secretion and reabsorption of acetylcholine by neurons at synapses.
Exercise 11: Outline what acetylcholine is, where it is produced and secreted and what affects it has before being reabsorbed.
A2: Blocking of synaptic transmission at cholinergic synapses in insects by binding of neonicotinoid pesticides to acetylcholine receptors.
Exercise 12: Outline how neonicotinoid pesticides affect cholinergic synapses and what affects this has on the insect.
NoS: Cooperation and collaboration between groups of scientists—biologists are contributing to research into memory and learning. (4.3)
