neural transmissions

first step

• Action potential arrives at the axon terminal of a neuron

calcium influx

impulse causes voltage-gated calcium channels to open, calcium ions enter the axon terminal

neurotransmitter release

calcium causes synaptic vesicles containing chemical messengers to fuse with the membrane and release NT into synaptic gap

receptor binding

NTs diffuse across the synapse and bind to specialize receptors on the dendrites of the neighboring neuron

5th step

sodium (NA+) enters the dendrites through ligand-gated ion channels, depolarizes

axon potential starts

if the axon hillock depolarizes enough to reach threshold, all or none action potential begins

voltage gated sodium channels on axons open

• when an action potential begins at the azon hillock, ion channels briefly open to allow sodium to flood into the axon