Humans have an array of sensory receptors on the skin (i. e. free nerve ending; pacinian corpuscle) Becomes the presynaptic terminal on other axons that travel up into higher brain regions. Cell bodies located in dorsal root ganglia near spinal cord. Axon terminal of pacinian corpuscle is surrounded by connective tissue. Sensory receptor: free/specialized nerve endings that is particularly sensitive to detect one form of environmental energy (i. e. modalities) Receptors for pain & temperature are different. Adequate stimulus: particular form of energy to which a receptor is most sensitive. Receptors can still respond to different forms of energy, but we perceive any stimulation of these receptors as that of its adequate stimulus: mechanisms of transduction. Mechanical stimulation: ion channels open up due to stretching. Chemical stimulation (i. e. pain nociceptors): binding of ligand with receptor opens ion channels elsewhere) Sometimes the same stimulus can be painful & non-painful (i. e. if your attention is. Thus, they are called nociceptors, not pain receptors.