• Neurons transmit electrical impulses.
• The myelination of nerve fibres allows for saltatory conduction.
• Neurons pump sodium and potassium ions across their membranes to generate a resting potential.
• An action potential consists of depolarization and repolarization of the neuron.
• Nerve impulses are action potentials propagated along the axons of neurons.
• Propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential.
• Synapses are junctions between neurons and between neurons and receptor or effector cells.
• When presynaptic neurons are depolarized they release a neurotransmitter into the synapse.
• A nerve impulse is only initiated if the threshold potential is reached.

Applications and skills:

• Application: Secretion and reabsorption of acetylcholine by neurons at synapses.
• Application: Blocking of synaptic transmission at cholinergic synapses in insects by binding of neonicotinoid pesticides to acetylcholine receptors.
• Skill: Analysis of oscilloscope traces showing resting potentials and action potentials.

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.

• An understanding of the workings of neurotransmitters and synapses has led to the development of numerous pharmaceuticals for the treatment of mental disorders.
  • Syllabus and cross-curricular links:
  • Biology
  • Topic 1.4 Membrane transport
  • Chemistry
  • Topic C6 Electrochemistry, rechargeable batteries and fuel cells
  • Psychology
  • Core: Biological level of analysis

Aims:

• Aim 8: The social effects of the abuse of psychoactive drugs could be considered, as could the use of the neurotoxin Botox for cosmetic treatments.