PHGY 209 Lecture Notes - Lecture 4: Dorsal Root Ganglion, Posterior Column, Posterior Grey Column
Document Summary
We will focus on the somatosensory system, then the visual and finally auditory systems. Somatic (bodily) sensation is mediated by several types of receptors: Extreme temperatures (< 0oc or >50oc) activate pain receptors: 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. Pain afferents are highly modulated (enhanced and suppressed). Visceral pain receptors (inside organs): activated by inflammation: overlap between visceral pain receptors and somatosensory pain receptors. 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. As these nociceptors send their aps to the spinal cord, they also send aps back to mast cells located nearby. Extracellular chemicals/substances from the damaged tissue surrounding the nociceptors are also released, like serotonin,