Essential Idea:
Neurons transmit the message,
synapses modulate the message
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:
- 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
Skills:
- Analysis of oscilloscope traces showing resting potentials and action potentials