Pathophysiology Irritating substances bradykinins serotonin acetylchonie histamine 5-hydroxytypamine prostaglandins acid metabolites Sensation of nerve endings sending through posterior root of spinal cord cross to the other side through spinothalamic tract, lateral medulla pons, internal capsule, spread into parietal and frontal lobe Segmental distribution of sensationPathophysiology •Irritating substances bradykinins serotonin acetylchonie histamine 5-hydroxytypamine prostaglandins acid metabolites •Sensation of nerve endings: sending through posterior root of spinal cord cross to the other side through spinothalamic tract, lateral medulla pons, internal capsule, spread into parietal and frontal lobe •Segmental distribution of sensation