Gastric motility factors

It may take many hours for the contents of the stomach to be processed and moved into the small intestine. Several factors influence gastric motility and therefore the rate of gastric emptying. These include ... 

The major gastric factor that affects motility and the rate of emptying is the volume of chyme in the stomach. As the volume of chyme increases, the wall of the stomach becomes distended and mechanoreceptors are stimulated. This elicits reflexes that enhance gastric motility by way of the intrinsic and vagus nerves. The release of the hormone gastrin from the antral region of the stomach further contributes to enhanced motility. 

The most important factors that regulate gastric motility and the rate of emptying of the stomach involve the volume and chemical composition of chyme in the duodenum. Receptors in the duodenum are sensitive to ... 

Gastric motility Secretion of pepsin Secretion of gastric acid Secretion of intrinsic factor... 

The other important factors controlling the rate of gastric emptying by influencing the gastric motility are the volume of the meal, its temperature, its viscosity and physical position. 

Recent advances in enteral access techniques have contributed to the expanded use of EN for conditions in which PN had previously been used. In particular, improved methods of achieving jejunal access for feeding have allowed for the use of EN during the early postoperative and postinjury period when gastric motility is typically delayed. As outlined in Table 138-5, various factors influence the selection of access site, including anticipated duration of use (short-term or longterm) and whether to feed into the stomach or small bowel. A review... 

Motilin is a 22-amino-acid polypeptide isolated by Brown et al. [2] in the search for duodenal factors stimulating gastric motility in dogs by intraduodenal alkalization. Although differences in the amino acid sequence among animal species are seen, the 6-amino-acid sequence of the N terminal is common to the species. Pearse et al. [3] reported that, using an indirect immunofluorescence technique, motilin is produced by a type of endocrine cell that is abundant in the duodenum and jejunum. 

Walter B. Cannon knew nothing of the facts just summarized when as a first- and second-year medical student at Harvard in 1896-98 he made his first observations on the effect of gastric motility in mixing gastric contents. He had read the literature by the time he pasted together his papers on the mechanical factors of digestion and published them as a book in 1911 Cannon s earliest reference then was Home, Lectures on Comparative Anatomy. London, 1814, i, p. 140. ... 

Hirono Y, Fushida S, Yonemura Y et al. (1996) Expression of autocrine motility factor receptor correlates with disease progression in human gastric cancer. Br J Cancer 74(12), 2003-2007. 

Decreased gastric acidity (antacids, acid-inhibitors), lack in personal hygiene, decreased intestinal motility (opiates, antiperistaltic agents), a disturbed enteric microflora and malnutrition are risk factors for a GTI. In contrast, breast-feeding reduces GTI incidence in infants. 

Q6 Describe the normal motility of the stomach and the factors which promote gastric emptying. 

---