Neurotransmiter Release and Reuptake

Neurotransmitters are responsible for transmitting information across the synaptic gap between neurones.

Neurotransmitters are stored in synaptic vesicles. When action potentials are conducted down an axon:

• synaptic vesicles attach themselves to the presynaptic membrane, then
• break open and spill neurotransmitter into the synaptic cleft.

Neurotransmitters in the synaptic cleft :

• attach to postsynaptic receptor sites and trigger an action potential in the postsynaptic membrane
• some neurotransmitter attaches to presynaptic receptors (autoreceptors) located on the membrane (pre-synaptic membrane) of the cell that originally released them
  

2. 'Mopping up' after information transmission

This animation illustrates the main events thought to be involved after transmitters have been released into the synaptic cleft.

Transmitters become detached from receptors and either:

• diffuse through extracellular fluid (red transmitter), or
• undergo reuptake (blue transmitter), or
• are broken down by enzymes (yellow transmitter)