Document Detail

Physiology and pathophysiology of colonic motor activity (2).
MedLine Citation:
PMID:  2070711     Owner:  NLM     Status:  MEDLINE    
The basic motor function of the colon is to mix and knead its contents, propel them slowly in the caudad direction, hold them in the distal colon until defecation, and provide a strong propulsive force during defecation. Infrequently, it also produces mass movements in the proximal colon. These motor functions are achieved in most species by three different types of contractions: the individual phasic contractions that include the short- and long-duration contractions, organized groups of contractions that include the migrating and nonmigrating motor complexes, and special propulsive contractions (giant migrating contractions). The spatial and temporal patterns of all of these contractions are controlled by myogenic, neural, and chemical control mechanisms. The individual phasic contractions are highly disorganized in time and space in the colon. For this reason, they are effective in mixing and kneading and slow distal propulsion. The underlying cause of the disorganization of short duration contractions is the irregularity in the frequency and waveshape of colonic electrical control activity and its phase unlocking throughout the colon. The individual contractions in many species occur in cyclic bursts called contractile states. At least in some species, these contractile states exhibit mostly caudad and sometimes orad migration. However, there are also nonmigrating or randomly migrating contractile states in the colon. These two patterns of contractile states are called colonic migrating motor complexes and colonic nonmigrating motor complexes, respectively. The giant migrating contractions provide the strong propulsive force for defecation and mass movements. The neural control of colonic contractions is organized at three levels--enteric, autonomic, and central. The enteric nervous system contains cholinergic and peptidergic neurons and plays a major role in the control of colonic contractions. The autonomic nerves, the vagi, pelvic, lumbar colonic, hypogastric, and splanchnic nerves, seem to continuously monitor the state of the colon and provide a modulatory input when necessary. These nerves play a major role in the reflexive control of colonic motor function. The voluntary input from the central nervous system coordinates the motor activity of the colon, rectum, anal canal and sphincters for orderly evacuation of feces during defecation. The role of acetylcholine, nonadrenaline, and the yet to be completely identified nonadrenergic, noncholinergic neurotransmitter, possibly VIP, in the control of contractions is fairly well established. Besides these, there are several other peptides and chemicals that are localized in the colonic wall; their physiological roles remain unknown. Colonic motor activity has been studied in several disease states. The findings have not always been consistent.(ABSTRACT TRUNCATED AT 400 WORDS)
S K Sarna
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.; Review    
Journal Detail:
Title:  Digestive diseases and sciences     Volume:  36     ISSN:  0163-2116     ISO Abbreviation:  Dig. Dis. Sci.     Publication Date:  1991 Jul 
Date Detail:
Created Date:  1991-08-21     Completed Date:  1991-08-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7902782     Medline TA:  Dig Dis Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  998-1018     Citation Subset:  AIM; IM    
Department of Surgery, Medical College of Wisconsin, Milwaukee 53295.
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MeSH Terms
Aging / physiology
Colon / physiology*
Colonic Diseases / physiopathology*
Eating / physiology
Exercise / physiology
Gastrointestinal Motility / physiology*
Gastrointestinal Transit / physiology
Pregnancy / physiology*
Reference Values
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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