These contractions are generated by the muscularis externa stimulated by the myenteric plexus. When pressure within the rectum becomes increased, the gastrocolic reflex acts as a stimulus for defecation. A number of neuropeptides have been proposed as mediators of the gastrocolic reflex. These include serotonin, neurotensin, cholecystokinin, prostaglandin E1, and gastrin.
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Clinically, the gastrocolic reflex has been implicated in pathogenesis of irritable bowel syndrome (IBS): the very act of eating or drinking can provoke an overreaction of the gastrocolic response in some patients with IBS due to their heightened visceral sensitivity, and this can lead to abdominal pain and distension, flatulence, and diarrhea.Sjölund K, Ekman R, Lindgren S, Rehfeld J (1996): Disturbed motilin and cholecystokinin release in the irritable bowel syndrome in Scand J Gastroenterol, 31:11, pp 1110–4, , DOI 10.3109/00365529609036895 The gastrocolic reflex has also been implicated in pathogenesis of functional constipation, where patients with spinal cord injury and diabetics with gastroparesis secondary to diabetic neuropathy suffer from a decreased colonic transit time. The gastrocolic reflex can also be used to optimise the treatment of constipation. Since the reflex is most active in the mornings and immediately after meals, consumption of stimulant laxatives, such as sennosides and bisacodyl, during these times will augment the reflex and help increase colonic contractions and therefore defecation.
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The gastrocolic ligament is a portion of the greater omentum that stretches from the greater curvature of the stomach to the transverse colon. It forms part of the anterior wall of the lesser sac. Dividing the gastrocolic ligament provides access to the anterior pancreas and the posterior wall of the stomach. This is commonly done for Whipple procedures, distal pancreatectomy, some forms of the Roux-en-Y gastric bypass, and exploratory laparotomy.
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The gastrocolic reflex or gastrocolic response is a physiological reflex that controls the motility, or peristalsis, of the gastrointestinal tract following a meal. It involves an increase in motility of the colon consisting primarily of giant migrating contractions, or migrating motor complexes, in response to stretch in the stomach following ingestion and byproducts of digestion entering the small intestine. Thus, this reflex is responsible for the urge to defecate following a meal. The small intestine also shows a similar motility response.
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The gastrocolic reflex's function in driving existing intestinal contents through the digestive system helps make way for ingested food. The reflex was demonstrated by myoelectric recordings in the colons of animals and humans, which showed an increase in electrical activity within as little as 15 minutes after eating. The recordings also demonstrated that the gastrocolic reflex is uneven in its distribution throughout the colon. The sigmoid colon is more greatly affected than the rest of the colon in terms of a phasic response, recurring periods of contraction followed by relaxation, in order to propel food distally into the rectum; however, the tonic response across the colon is uncertain.
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They are named in such a way as to show what they connect typically. For example, the gastrocolic ligament connects the stomach and colon and the splenocolic ligament connects the spleen and the colon, or sometimes by their shape as the round ligament or triangular ligament.
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The bowel is run from the ligament of Treitz to the terminal ileum. The gastrocolic ligament is incised and the lesser sac is explored, including the posterior stomach and the anterior pancreas. The surface of the spleen is examined for evidence of laceration and fracture. The liver is similarly examined.
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Although the large intestine has peristalsis of the type that the small intestine uses, it is not the primary propulsion. Instead, general contractions called mass movements occur one to three times per day in the large intestine, propelling the chyme (now feces) toward the rectum. Mass movements often tend to be triggered by meals, as the presence of chyme in the stomach and duodenum prompts them (gastrocolic reflex).
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The enterogastric reflex is one of the three extrinsic reflexes of the gastrointestinal tract, the other two being the gastroileal reflex and the gastrocolic reflex. The enterogastric reflex is stimulated by duodenal distension. It can also be stimulated by a pH of 3-4 in the duodenum and by a pH of 1.5 in the stomach. Upon initiation of the reflex, the release of gastrin by G-cells in the antrum of the stomach is shut off.
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When administered rectally in suppository form, it is usually effective in 15 to 60 minutes. For optimal use, if used as a suppository, it is recommended that bisacodyl be given after breakfast to synchronize with the gastrocolic reflex. Two suppositories can be inserted at once if a very strong, purgative, enema-like result is needed. A few hours after the initial evacuation, there can be a secondary action which will continue as long as there is unexpelled bisacodyl present in the rectum.
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The gastroileal reflex is one of the three extrinsic reflexes of the gastrointestinal tract, the other two being the gastrocolic reflex and the enterogastric reflex. The gastroileal reflex is stimulated by the presence of food in the stomach and gastric peristalsis. Initiation of the reflex causes peristalsis in the ileum and the opening of the ileocecal valve (which allows the emptying of the ileal contents into the large intestine, or colon). This in turn stimulates colonic peristalsis and an urge to defecate.
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The greater omentum (also the great omentum, omentum majus, gastrocolic omentum, epiploon, or, especially in animals, caul) is a large apron-like fold of visceral peritoneum that hangs down from the stomach. It extends from the greater curvature of the stomach, passing in front of the small intestines and doubles back to ascend to the transverse colon before reaching to the posterior abdominal wall. The greater omentum is larger than the lesser omentum, which hangs down from the liver to the lesser curvature. The common anatomical term "epiploic" derives from "epiploon", from the Greek epipleein, meaning to float or sail on, since the greater omentum appears to float on the surface of the intestines.
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