The mechanism of synaptic transmission at the electrical synapse:
In this case, the pre-synaptic and post-synaptic membranes are in proximity.
Impulse in the form of electric current directly flows from the pre-synaptic neuron to the post-synaptic neuron.
Transmission is faster than the chemical synapse.
The mechanism of synaptic transmission at the chemical synapse:
the pre-synaptic and post-synaptic neurons are separated by the synaptic cleft.
When an impulse arrives at the axon terminal, the calcium ions present in the synaptic cleft enter the synaptic knobs present at the axon terminals of the pre-synaptic neuron.
The synaptic vesicles present in the synaptic knobs present in the pre-synaptic neuron move towards the plasma membrane and fuse with it.
The vesicles release the neurotransmitter acetylcholine in the synaptic cleft. (Empty synaptic vesicles return to the cytoplasm of the pre-synaptic neuron where they are refilled.
The molecules of the acetylcholine bind to the protein receptors present on the plasma membrane of the post-synaptic neurons.
This binding opens the channels, and sodium ions enter the post-synaptic neuron, while potassium ions leave the post-synaptic membrane.
This generates an action potential in the membrane of the post-synaptic neuron, and hence, the impulse is transmitted to the post-synaptic neuron.