Answer:
Signal transmission at the synapse.
Explanation:
At the synapse, an electrical signal arrives at the pre-synaptic terminal an triggers vessicles to release neurotransmitters into the synaptic cleft.
These neurotransmitters activate receptors in the post-synaptic neuron and produce electrical signals.
Pain killers work by by preventing damaged or injured cells from producing prostagladins. Prostagladin is released when cells in the body are injured or damaged.