Zsa Zsa Weerts

General introduction 13 1 tract in the brain stem, the primary relay station for vagal afferent information 39,40 , and then transduced to other parts of the brain. The vagal nerve carries afferents from mechano- and chemoreceptors throughout the entire GI tract, with the exception of the descending colon and rectum that are innervated by splanchic nerves 41 , and is thereby a key nerve regarding viscero-sensory function. 42-44 When visceral stimuli reach the brain, perception of the sensation can occur depending upon the type and fortitude of the stimulation, but also depending on central, supraspinal, and spinal bidirectional modulation, and local reflexes. Figure 1.1 Pathophysiological mechanisms in Irritable Bowel Syndrome. Abdominal pain may originate from various anatomical levels: a) nerve endings and nerves can become abnormally activated or sensitized at the intestinal level; b) input can be altered at the spinal cord level; and c) stimuli can be modulated aberrantly at the spinal, supraspinal, and/or central level.