6.5 Neurons and synapses
Nature of science
Cooperation and collaboration between groups of scientists—biologists are contributing to research into memory and learning. (4.3)
Understandings
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
Secretion and reabsorption of acetylcholine by neurons at synapses.
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.
