How does a nerve impulse travel from one neuron to another?
This has been answered before on this platform. Providing a couple of links for reading.
Nerve transmission occurs through an elaborate network of neurons. Neurons transport information by way of action potential.
The synapse is a neuronal junction which acts as the site for transmission of nerve impulse between two neurons. This synapse along with its neurotransmitters acts as a physiological valve, directing the conduction of nerve impulses in regular circuits and prevents random and chaotic stimulation of nerves.
The arrival of a nerve impulse at the presynaptic terminal causes a movement towards the synaptic vesicles. These fuse with the membrane and release neurotransmitters. The neurotransmitters transmit the nerve impulse to the post synaptic fibre, by diffusing across the synaptic cleft and binding to receptor molecules on the post synaptic membrane.
This results in a series of reactions that open "channel shaped" protein molecules. Electrically charged ions then flow through the channels in or out of the neurons. If the net flow of positively charged ions is large enough, it leads to the generation of a new nerve impulse called action potential.
Later the neurotransmitter molecules are deactivated by enzymes in the synaptic cleft. Binding of neurotransmitters may influence the receptor neuron in either an inhibitory or excitatory way.
Thus synaptic transmission is a chemical event which is involved in the transmission of the impulse via release, diffusion, receptor binding of neurotransmitting molecules and unidirectional communication between neurons.