Gastroparesis: NORMAL GASTRIC MOTOR FUNCTION Part 2

GastroparesisThe proximal region of the stomach primarily stores ingested food. During swallowing, vagally mediated transient receptive relaxation is followed by a more prolonged relaxation known as accommodation, so that an increase in gastric volume is not usually associated with a substantial rise in intragastric pressure. The contractions of the distal stomach are controlled by electrical signals generated by a pacemaker region located on the greater curvature, which discharges at a rate of about three contractions/min. The conduction of the slow wave within the gastric wall involves the interstitial cells of Cajal. Distal stomach contractile activity is always associated with the gastric slow wave; however, the slow wave persists in the absence of gastric contractile activity. Normal fasting antral motility is cyclical; this is termed the migrating motor complex (MMC). The MMC consists of three phases that have a cycle time of about 100 min: phase 1 is motor quiescence (about 40 min), phase 2 is irregular contractions (about 50 min), and phase 3 is regular, high amplitude contractions at the maximal rate of three/min for 5 to 10 min. During phase 3, indigestible residues are emptied from the stomach into the small intestine, to be carried to the colon by the small intestinal MMC. Antral contractions play a major role in grinding solid food into small particles. Both fasting and postprandial patterns of intraluminal pressure in the distal stomach are complex. Phasic and tonic pyloric contractions occur over a narrow zone, either in isolation or in temporal association with antral contractions, and probably play a major role in the regulation of gastric emptying by acting as a brake; transpyloric flow can only occur when the pylorus is open. The mechanical determinants of individual flow episodes are poorly defined. Flow may reflect a local increase in the antroduodenal pressure difference due to peristaltic antral contractions, or be associated with a common cavity pressure difference between the distal antrum and proximal duodenum during periods of relative antral quiescence. A recent study suggested that the latter mechanism (so-called ‘pressure’ as opposed to ‘peristaltic’ pump) may be of primary importance. Duodenal contractions may facilitate or retard gastric emptying; patterns of duodenal motility are also complex with substantial regional variations. Learn how to save money – yasmin birth to enjoy your shopping and your treatment.

Category: Gastroparesis

Tags: Gastric emptying, Gastroparesis

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