Depending upon the type of energy detected by receptors , they can classified into many groups but you need for so I'm going to write here only four with their functions
1. Thermoreceptors: they detect changes in temperature
2. Chemoreceptors: they detect chemicals dissolved in body fluid medium surrounding them.
3. Mechanoreceptors: they detect sound , motion , position in relation to gravity.
4. Photoreceptors: they detect visible and ultra violet light!
Hope so it would help!
