BIO SCI 47 Lecture Notes - Lecture 21: Posterior Grey Column, Glucocorticoid, Endorphins
6 Jun 2018
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Stress Lecture 21
● A delta, sharp pain
○ fast
● C fiber, slow throbbing pain
○ Slow
● A beta, soft fine touch
● First you feel a sharp pain, then a slow throbbing pain
○ Pain carried by myelinated A delta fibers
○ Then slow unmyelinated C fibers send signals for throbbing pain
○ Synapses in spinal cord to send signals to the brain
■ Also synapses onto interneuron inhibits excitation bc A delta
synapses then immediately stops itself bc interneuron
● When you stop A delta fiber you only have C fiber coming through
● A Delta shoots to spinal cord to synapse bc it is myelinated (sharp pain)
○ A Delta also synapses in interneuron, but slightly behind bc not myelinated
○ Once A Delta is inhibited, C fiber activates pain in spinal cord again
○ C fiber is deactivating interneuron, so interneuron won’t inhibit C fiber’s
reaction in spinal cord
■ Be able to draw this diagram
● Now A Delta is gone and just C fiber is firing
○ When you apply pressure, A Beta is activated
○ A Beta is myelinated, reduces pain bc it stops C fiber
Document Summary
First you feel a sharp pain, then a slow throbbing pain. Pain carried by myelinated a delta fibers. Then slow unmyelinated c fibers send signals for throbbing pain. Synapses in spinal cord to send signals to the brain. Also synapses onto interneuron inhibits excitation bc a delta synapses then immediately stops itself bc interneuron. When you stop a delta fiber you only have c fiber coming through. A delta shoots to spinal cord to synapse bc it is myelinated (sharp pain) A delta also synapses in interneuron, but slightly behind bc not myelinated. Once a delta is inhibited, c fiber activates pain in spinal cord again. C fiber is deactivating interneuron, so interneuron won"t inhibit c fiber"s reaction in spinal cord. Now a delta is gone and just c fiber is firing. When you apply pressure, a beta is activated. A beta is myelinated, reduces pain bc it stops c fiber.
