Preparing for Christmas dinner, you accidently sliced your finger with a serrate
ID: 3483183 • Letter: P
Question
Preparing for Christmas dinner, you accidently sliced your finger with a serrated knife. Blood rapidly fills your hand as you cup the injured finger and race to the sink. The pain has set in. A trip to the ER yielded stitches and a prescription for an analgesic. Explain the pain projection pathway for this injury using the anatomically correct ascending pathways, chemicals involved in stimulating pain signals, endogenous neuromodulators produced, and the effect of the prescribed analgesic in the pain pathway
Explanation / Answer
Pain pathway:
Pain is received by nociceptors (free nerve endings), and the afferent nerve synapse in the dorsal horn of the spinal cord. Then the axons cross the midline and ascend as the anterolateral/ventrolateral spinothalamic pathway that synapses in venralposterolateral (VPL) nucleus of thalamus. From VPL nuclei, fibers ascend to terminate in somatosensory cortex.
Chemicals involved in stimulating pain signals: prostaglandin, 5-HT, bradykinin, K+, CGRP, substance P, histamine
Endogenous neuromodulators produced: glutamate, enkephalin, neropeptides
Effect of the prescribed analgesic in the pain pathway: decreases neurotransmitter release, increase in K+ conductance (causing hyperpolarization and decreased amplitude of EPSP)