Irritable bowel syndrome (IBS) is a broad range of disorders described as abdominal discomfort and pain with changes in the bowel. IBS is known to cause cramps, abdominal pain, bloating, diarrhea and constipation. The colon's many nerves connect it to the brain and are partly controlled by the autonomic nervous system, which reacts to stress in a similar way to the heart. The ascending pathways that deal with pain are made up of three different tracts: the neospinothalamic tract, the paleospinothalamic tract, and the archispinothalamic tract. The dorsal root ganglion is where first-order neurons are found in all three tracts. Each tract begins in different spinal regions and ends in a different area of ​​the brain. The neospinothalamic tract is a lateral spinothalamic tract and has very few synapses. Each nociceptive neuron has a single axon that splits in two, sending one end to innervate with the tissue and the other into the dorsal horn. The A-delta fibers (which transmit fast pain and provide information about the exact location of the stimulus) and the C fibers (which transmit slow pain) end at the dorsal horn. A-delta fibers terminate and excite 2nd order neurons. The long fibers immediately pass through the anterior commissure and reach the brain. Most pain fibers under the neck terminate in the ventroposterolateral nucleus (VPL) and ventroposteroinferior nucleus (VPI) of the thalamus, which is a relay station that sends signals to the primary somatosensory cortex. A delta fibers terminate in the ventroposteromedial (VPM) thalamus and are somatotopic. The nociceptors of the visceral organ respond to stimulations such as pressure, tissue damage and chemicals (gastrointestinal lesions and/or tumors). The free nerve endings are scattered and... in the center of the paper... Elsevier. https://www.inkling.com/read/guyton-hall-textbook-of-medical-physiology-12th/chapter-48/dual-pathways-for-transmissionKolodziejak. (February 2008) MEDICINAL TREATMENT FOR IBS. http://www.rxfiles.ca/rxfiles/uploads/documents/GI-IBSyndrome.pdfPurves, Augustine, Fitzpatrick and associates. (2001). Neuroscience 2nd edition. Sunderland. BUT. Sinauer Associates. Chapter 10Swenson. (2006). Dartmouth School of Medicine. Clinical and functional neuroscience review. Chapter http://www.dartmouth.edu/~rswenson/NeuroSci/chapter_7A.htmlWasner, Lee, Engel, McLachlan. Brain. (2008). Residual spinothalamic tract pathways predict the development of central pain after spinal cord injury. http://brain.oxfordjournals.org/content/131/9/2387.full.pdf. 131.2387^240Mer MD. Irritable bowel syndrome and diarrhea. http://www.webmd.com/ibs/treating-diarrhea?page=2 (2005-2014)