Synapse: The gap between axon of one neuron and dendron of other neuron is called synapse.
When an impulse comes to the axon end of neuron it releases neurotransmitter like acetylcholine, acetylcholine fills the gap between axon and dendron and helps in transmission of impulse. After transmission of impulse, the acetylcholine immediately destroyed by enzyme Acetylcholinesterase to avoid intervention of next impulse. 
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