At the most basic level, energy acts on receptor cells to affect the flow of ions across membranes. Receptor cells are signal transducers, specialized to transduce a chemical, mechanical, or light signal (chemoreception, mechanoreception, or photoreception) into a nerve impulse.

Step back and look at sense organs in the most basic way. Ear, nose, eye. What you have are receptor cells in combination with the anatomical parts that funnel stimuli to the receptor cells.