Stomach motility

PNS—relaxation of the smooth muscles of the bronchi constriction of blood vessels, sphincters of tlie stomach dilatation of coronary blood vessels decrease in gastric motility... 

Gastrointestinal tract-decrease in secretions of the stomach, decrease in gastric and intestinal movement (motility)... 

Anticholinergics (cholinergic blocking drug) reduce gastric motility and decrease the amount of acid secreted by the stomach (see Chap. 25). Examples of anticholinergics used for GI disorders include propantheline (Pro-Banthine) and glycopyrrolate (Robinul). 

V. cholerae is a gram-negative bacillus. Vibrios pass through the stomach to colonize the upper small intestine. Vibrios have filamentous protein extensions that attach to receptors on the intestinal mucosa, and their motility assists with penetration of the mucus layer.2 The cholera enterotoxin consists of two subunits, one of which (subunit A) is transported into the cells and causes an increase in cyclic AMP, which leads to a deluge of fluid into the small intestine.20 This large volume of fluid results in the watery diarrhea that is characteristic of cholera. The stools are an electrolyte-rich isotonic fluid, the loss of which results in blood volume depletion followed by low blood pressure and shock.2 Of note, the diarrheal fluid is highly infectious. 

KA Kelly. Motility of the stomach and gastroduodenal junction. In LR Johnson, ed. Physiology of the Gastrointestinal Tract. New York Raven Press, 1981, pp 393-410. 

Gastrin G cells in pyloric region of the stomach Protein in stomach vagal stimulation Stimulates parietal cells (HC1) and chief cells (pepsinogen) in stomach enhances gastric motility... 

Gastric motility. In addition to the circular and longitudinal layers of smooth muscle, the stomach contains an extra layer of smooth muscle. Beginning at the UES, the oblique layer of smooth muscle fans out across the anterior and posterior surfaces of the stomach and fuses with the circular layer in the lower region. This extra layer of muscle enhances gastric motility and therefore mixing and mashing of food. 

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 ... 

An important gastric secretion is the hydrochloric acid that performs a number of functions in the stomach. This stomach acid is neutralized by pancreatic bicarbonate ion in the duodenum. Excess acid in the chyme stimulates chemoreceptors in the duodenum. This receptor stimulation elicits reflex inhibition of gastric motility. Excess acid also causes the release of secretin and gastric inhibitory peptide from the duodenum. These hormones contribute to inhibition of gastric contractions so that the neutralization process may be completed before additional acid arrives in chyme from the stomach. 

Acute physiological responses to opiate administration occur rapidly and include constricted pupils, decreased pulse rate, reduced body temperature, slowed respiration rate and impaired reflexes. In addition, there is a marked slowing of the digestive system through an altering of the tonus and motility of the stomach and intestines, allowing for greater water absorption. This last effect is not subject to tolerance, and constipation is a common side effect even for chronic users. Indeed, some report that this is the worst side effect of opiate use. 

The physiological changes and other aspects in the elderly makes this even more complicated. Example of this is decreased stomach acidity decreased motility decreased blood-flow to liver and gastrointestinal tract changed pharmacokinetics and -dynamics polypharmacy swallowing problems bad nutritional status and lack of documentation. 

Digestive system g agonists decrease secretion of stomach acid, reduce gastric motility, and prolong gastric emptying. Pancreatic, biliary, and intestinal secretions are reduced. Intestinal transit is also slowed. Peristaltic movements are reduced, but tone is increased, sometimes causing spasm. As a result, constipation is a frequent problem with opioid use. Bile duct pressure is also increased by opioids. 

Gastrointestinal tract. Serotonin released from myenteric neurons or enterochromaffin cells acts on 5-HT3 and 5-HT4 receptors to enhance bowel motility and enteral fluid secretion Cisapride is a proldnetic agent that promotes propulsive motor activity in the stomach and in small and large intestines. It is used in motility disorders. Its mechanism of action is unclear, but stimulation of 5HT4 receptors may be important... 

Acute abdominal conditions Narcotics may obscure diagnosis or clinical course. Do not give SR morphine to patients with Gl obstruction, particularly paralytic ileus, as there is a risk of the product remaining in the stomach for an extended period and the subsequent release of a bolus of morphine when normal gut motility is restored. Special risk patients Exercise caution in elderly and debilitated patients and in those suffering from conditions accompanied by hypoxia or hypercapnia when even moderate therapeutic doses may dangerously decrease pulmonary ventilation. Also exercise caution in patients sensitive to CNS depressants, including those with cardiovascular disease myxedema convulsive disorders increased ocular pressure acute alcoholism delirium tremens cerebral arteriosclerosis ulcerative... 

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