SYNAPTIC KNOB
The synapse is located at the end of each axonal end branch. Here the end branch forms a small button-like knob (sn). This knob is adjacent to a tiny cleft or synapse (s). When a nerve impulse reaches this knob, a drug called a neurotransmitter is released from vesicles into the synapse The neurotransmitter diffuses across the gap and binds to receptors on the membrane of the adjacent neuron or muscle cell. This will initiate an electrical change in the membrane of the adlacent neuron leading to a nerve impulse in that cell.