spinal cord

• main excitatory neurotransmitter released by the A delta fibers and the C fibers is


  glutamate
• slow release and diffuses widely in the posterior horn and can influence many neurons

  substance p
• The initial sharp, pricking, fast-acting pain fibers stimulate the second-order neurons of the lateral spinothalamic tract
• The burning, aching, slow-acting pain fibers also stimulate the secondorder neurons of the lateral spinal thalamic tract in the posterior gray horn and ascend with the axons of the fast-acting pain fibers
• involved with the interpretation of the emotional aspect of pain

  cingulate gyrus
• can suppress both sharp pricking pain and burning pain sensations.

  analgesic system
• serves as neurotransmitter substances in the analgesic system of the brain, inhibit the release of substance p in post. gray column 


  enkephalin, endorphin, and serotonin