1. Most communication between neurons occurs at a specialized structure called a synapse
2. A synapse is an area where two neurons come close enough to one another that they are able to pass chemical signals from one cell to another
3. The neurons are separated by a microscopically small space called the synaptic cleft, less than 40 nm wide
4. The neuron where the signal is initiated is called the presynaptic neuron, while the neuron that receives the signal is called the postsynaptic neuron
5. In the presynaptic neuron, there are chemical signals called neurotransmitters that are packaged into small sacs called vesicles
6. When the presynaptic neuron is excited by an electrical signal called an action potential, this causes the vesicles to fuse with the presynaptic membrane and release their contents into the synaptic cleft
7. Neurotransmitters interact with receptors on the postsynaptic membrane, binding to these receptors and causing an action to occur in the postsynaptic cell
8. The action may involve increasing or decreasing the likelihood that the postsynaptic cell will become activated and fire an action potential
9. Neurotransmitter molecules must be cleared from the synaptic cleft, some drift away in diffusion, while others are taken back up into the presynaptic neuron in reuptake
10. Enzymes break down neurotransmitters within the synaptic cleft, and the component parts can be sent back into the presynaptic neuron to make more neurotransmitter
