going before another in time or order I'd like to follow up on an antecedent question from another reporter Synonyms previous, anterior, foregoing, former, precedent, preceding, priorRelated Words advance, early, premature; earliest, first, inaugural, initial, maiden, original, pioneer; preexisting; introductory, preliminary; erstwhile, whilomNear ...
Neurotransmitters are formed in a presynaptic neuron and stored in small membrane-bound sacks, called vesicles, inside this neuron. When this neuron is activated, these intracellular vesicles fuse with the cell membrane and release their contents into the synapse, a process called exocytosis.
The synapse is located at the end of each axonal end branch. Here the end branch forms a small button-like knob, referred to as the synaptic knob. This knob is adjacent to a tiny cleft or synapse. 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.