Gastrointestinal motility is regulated by gastrointestinal hormones as well as by both the intrinsic (enteric) and extrinsic (central) nervous systems. Although it is important to remember that most gastrointestinal functions are regulated within the intrinsic system. In instances where drugs are used to try to control gastrointestinal motility (i.e. for the treatment of nausea, vomiting, constipation, diarrhea and gastro-oesophageal reflux disease) their mechanisms are aimed at neuronal mechanisms.
In the graphic, visceral receptors on the afferent fibers are represented by the larger nerve endings to represent the gathering of information. The efferent fibers have smaller nerve endings that depict the provision of information.
I Muscle contraction in a portion of the GI tract occurs prior to the bulk stimulus reaching it.
II Peristalsis is controlled by the CNS.
Extra info: Peristalsis , which is controlled by the enteric nervous system occurs by the systematic relaxation and contraction before and after a bulk in the GI lumen.