Sensitization response is the enhanced response to some stimulus, which is opposite of habituation.
In a sensory neuron, the amplification of response towards a stimulus occurs through the interneurons, which release the neurotransmitter “serotonin” onto the presynaptic membrane. The sensitivity of the presynaptic potassium channels changes and the influx of calcium ions (Ca+2) increases.
Thus, the blanks can be filled with interneurons; potassium; calcium ions.