touch and prorioception

somatosensory system

touch, pressure, vibration, limb position (proprioception), heat, cold, itch & pain

somatosensory afferent neurons are pseudounipolar

• action potentials begin at receptor endings, which turn into axons that travel to cns

• cell body is midway along path of axon, not at the beginning

• action potential largely bypasses cell body

cell bodies of afferent fibers reside in the _____________ alongside the spinal cord (body and ____________ alongside brainstem (head)

dorsal root ganglia; trigeminal ganglia

sensory transduction

converting energy in a stimulus into an electrical signal

common for all somatosensory afferents

• stimulus causes cation channels in afferent fiber endings to open

• channel openings generate a receptor potential

• if large enough, receptor potential triggers an action potential