What is the underlying reason for fast transmission synapse

Solution

In case of fast transmission synapse, neurotransmitter is released by pre-synaptic membrane which binds directly to the ion channels present on post-synaptic membrane, which in turn alters the permeability of the post-synaptic membrane that results in change in the electric potential. Due to the direct binding, the reaction is achieved rapidly.

In case of slow transmission synapse, neurotransmitter is released by pre-synaptic membrane which binds to receptors present on post-synaptic membrane. This binding results in release of an intra-cellular transmitter in post-synaptic cell, which in turn binds to the ion-channels, leading to change in their permeability which ultimately results in electric potential change