When any form of impulse strikes the nerve cell, it causes change in membrane potential by changing the ion permeability across the membrane.
If the membrane potential reach threshold potential (the minimum potential difference to elicit a response), then the action potential is generated. The action potential or nerve impulse travels along the axon and reach nerve terminals. Within the nerve terminals the neurotransmitters are stores, which are released out in response to the stimuli.
The steps in propagation of impulses from the axon terminals include the following:
1. Synthesis and storage of chemical transmitters in the nerve terminals
2. The transmitter is released from the nerve terminals and released into the synaptic cleft upon receival of action potential
3. The neurotransmitter diffuses across the synaptic cleft and binds to the post synaptic receptors
4. Finally, the neurotransmitter is deactivated.