Pain & Gate Control Theory PDF

Chapter #13.5 Pain & the Gate Control Theory of Pain What is Pain? Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage - Pain is subjective - Pain may be reported when there is...

Chapter #13.5 Pain & the Gate Control Theory of Pain What is Pain? Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage - Pain is subjective - Pain may be reported when there is no tissue damage, so pain should not be tied to a particular stimulus - Pain is a psychological experience Nociceptors Stimulators The Peptides → bradykinin The Amines → Serotonin, Histamine The Arachidonic Acid Derivative → Prostaglandin - These substance often generated by injury to cells - A central mechanism is required to modulate and interpret these signals Specificity Theory of Pain Cells within the nervous system respond and relay signals received from nociceptors - Cells within laminae 1,2, and 5 of dorsal horn in the spinal cord are responsive to A delta and C fibers coming into the CNS - C fibers release neurotransmitter substance P - When pain signals conduct up spinal cord it usually ascends in lateral spinothalamic tract Pattern Theory of Pain Pain is produced by particular patterns of stimulation The Gate Control Theory Of Pain ( Ronald Melzack and Patrick Wall ) Receive afferent inputs from A - delta and C- fibers - Located in the substantia Gelatinosa of the Spinal Cord A- delta → low threshold, large in diameter, myelinated, fast adapting, 1 branch synapse at spinal cord another branch immediate ascension to the thalamus C - fibers → high threshold, small in diameter, unmyelinated, slow adapting, synapse only at level of the spinal cord * Diagram on Test* Five Proposition of Gate Of Control Theory 1. Spinal gating mechanism mdulates transmission of nerve impulses - Inhibits transmission of impulses from afferent fibers, provides a gate for pain impulses found in dorsal horn 2. Gating mechanism influenced by relative amounts of activity in large diameter and small diameter fibers - Large diameter fiber activity, inhibits and closes the gate - Small diameter fiber activity, facilitates transmission and opens the gate 3. Descending impulses from brain influence gating mechanism 4. A specialized system of large diameter rapidly conducting fibers activates selective cognitive process 5. When output of spinal cord transmission cells excess critical level, action system activated - Most important is the central nervous system gaining all control? Opiate Receptors - We do react to opiates which are derivative of the poppy plant thus we have receptors that bing with opiates ( postsynaptic membranes ) - Relieve pain by binding with certain cells found in laminae 1 & 2 of spinal cord - Also binds with other cells found within the thalamus If Drug is to be Effective - It must close gate ( leads to decrease in T - cell activity ) - Drug must be administered and must pass the blood brain barrier then must close correct gates