How are action potentials transmitted from one nerve to another?

Action potentials need to be transmitted over the synaptic cleft. This is achieved by the electrical impulse being converted into chemical and then back to electrical. First the action potential reaches the synaptic knob which it depolarises opening voltage gated channels and causing an influx of Calcium ions. These ions bind to vesicles containing a chemical (in this case acetylcholine), causing it to bind and release the chemical into the synaptic cleft. This chemical diffuses across and binds to nicotinc receptors on the post synaptic membrane, and when 2 acetylcholine molecules bind it opens. This opening allows Sodium ions Into the nerve cell which depolarises it (if the threshold is reached) and causes an electrical impulse. This is how nerve impulses are transmitted over the synaptic cleft.