Chemical synapse.
<P>
<Li> Voltage-gated  Ca^2+  channels in the presynaptic membrane open in
response to an action potential.
<Li> Ca^2+ ions flow in.
<Li> Synaptic  vesicles  fuse with presynaptic membrane of the synaptic
terminal, releasing neurotransmitters.
<Li> Neurotransmitters  diffuse  across  synaptic  cleft  and  bind  to
ligand-gated channels in the postsynaptic membrane.
<Li> Ions flow in and generate a postsynaptic potential.
<Li> Neurotransmitters release from channels, which close.
<P>
   Review:  <A ClAsS=ACT Href="http://media.pearsoncmg.com/bc/bc_campbell_biology_7/media/activities/load.html?48&amp;C" oNClick="popact('http://media.pearsoncmg.com/bc/bc_campbell_biology_7/media/activities/load.html?48&amp;C');txtcolor('synapse1','gray');return false;" Id=synapse1><iMg sRc="/images/tutorial.gif" aLt='' boRDer=0></A>