What is the role of a synapse?
It allows an electrical impulse (message) to be passed from neuron to neuron.
A synapse allows an electrical impulse in one cell to be converted into a chemical impulse then an electrical impulse in another cell. This means that the message/ impulse to be passed on.
A neuron does this through releasing chemicals called neurotransmitters across the synapse where they cause an electrical impulse in the next neuron. This is useful as it lets a message travel from one area in the body to another (e.g. Your brain sending a message to your legs to say "Stop being lazy and move!").
So, to break it down into steps:
1 - An action potential (electrical signal) travels through the neuron sending the message until it reaches the synapse.
2 - The vesicles fuse with the cell membrane and release neurotransmitters.
3 - These neurotransmitters then slot into the receptor site on an ion channel.
4 - This causes the channel to change shape and allow ions to cross across the receiving neuron's membrane.
5 - These ions then trigger an action potential in the receiving cell.
! Note that the neurotransmitters are then returned to the original cell through reuptake. !
The neurotransmitters travel in synaptic vesicles - little packages that fuse with the cell membrane when an impulse arrives then releases the neurotransmitters inside. These vesicles are in turn delivered via a neurotubule.
Finally, here is a great little video to further explain anything:
Hope this helps, let me know if I can do anything else:)