PHGY 209 Lecture Notes - Lecture 4: Dorsal Root Ganglion, Posterior Column, Spinal Cord
Document Summary
Cns sensory and motor (lecture 4): we will focus on the somatosensory system, then the visual and finally auditory systems. Somatic (bodily) sensation is mediated by several types of receptors: temperature: channels that respond to different temperature ranges. Thermoreceptors are free nerve endings [in the skin] containing ion. 0-35oc (activated by menthol) afferents transmitting information: cold afferents: about cold stimuli, warm afferents, extreme temperatures (< 0oc or >50oc) activate pain receptors. 30-50oc (activated by capsaicin and ethanol): pain receptors are activated when the sensory stimuli causes tissue damage, the law of specific nerve energies applies here: we can activate a cold afferent with other than temperature. Normally, a somatosensory stimulation to your finger wouldn"t cause any pain, but now it does: this mechanism prevents you from using this part of the body until the tissue heals, this step is where most nociceptors are sensitized.
