Migrating motor complex

Migrating motor complexes (or migrating myoelectric complex or migratory motor complex or migratory myoelectric complex or MMC) are waves of electrical activity that sweep through the intestines in a regular cycle during fasting. These motor complexes trigger peristaltic waves, which facilitate transportation of indigestible substances such as bone, fiber, and foreign bodies from the stomach, through the small intestine, past the ileocecal sphincter, and into the colon. The MMC occurs every 90-120 minutes during the interdigestive phase (between meals), and is responsible for the rumbling experienced when hungry.[1] It also serves to transport bacteria from the small intestine to the large intestine, and to inhibit the migration of colonic bacteria into the terminal ileum.

Phases

The MMC originates mostly in the stomach — although ~25% will arise from the duodenum or proximal jejunum — and can travel to the distal end of the ileum.[2] They consist of four distinct phases: Phase I — A prolonged period of quiescence; Phase II — Increased frequency of action potentials and smooth muscle contractility; Phase III — A few minutes of peak electrical and mechanical activity, and; Phase IV — Declining activity which merges with the next Phase I.[3]

Regulation

The MMC is thought to be partially regulated by motilin, which is initiated in the stomach as a response to vagal stimulation, and does not directly depend on extrinsic nerves.

Stimuli

Morphine, has been found at relatively low doses to stimulate phase III of the migrating motor complex.[4]

Trimebutine is one drug that as part of its therapeutic action causes a premature activation of phase III of the migrating motor complex in the digestive tract.[5]

References

  1. ↑ Poitras, P. & Peeters, T.L., 2008. Motilin. Current Opinion in Endocrinology, Diabetes, and Obesity, 15(1), pp.54–57.
  2. ↑ Boron, Walter F. & Emile L. Boulpaep, 2012. Medical Physiology, 2e Updated Edition: with STUDENT CONSULT Online Access, 2e 2 edition., Philadelphia, PA: Saunders.
  3. ↑ Boron, Walter F. & Emile L. Boulpaep, 2012. Medical Physiology, 2e Updated Edition: with STUDENT CONSULT Online Access, 2e 2 edition., Philadelphia, PA: Saunders.
  4. ↑ Lewis, TD. (Nov 1999). "Morphine and gastroduodenal motility.". Dig Dis Sci 44 (11): 2178–86. PMID 10573360.
  5. ↑ Hiyama, T.; Yoshihara, M.; Tanaka, S.; Haruma, K.; Chayama, K. (Apr 2009). "Effectiveness of prokinetic agents against diseases external to the gastrointestinal tract." (PDF). J Gastroenterol Hepatol 24 (4): 537–46. doi:10.1111/j.1440-1746.2009.05780.x. PMID 19220673.

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