Migrating Motor Complex (MMC) and Vomiting Dr. Alzoghaibi

Migrating Motor complex (MMC) Digestive state: When nutrients are present and digestive process are ongoing Interdigestive state When the digestion and absorption of nutrients are complete, 2-3 hrs after a meal

Migrating Motor complex (MMC) Characteristics & functions: Pattern of motility in the interdigestive state - bursts of electrical & contractile activities are separated by longer quiescent periods - pattern of motility in fasting, conscious & sleep stages - begins at distal stomach to ileum - antral contraction to propel the remaining materials bigger than 7mm

Migrating Motor complex (MMC) Characteristics & functions (cont): - takes 80-120 min for one activity front (from antrum to ileum) - 3-6 cm/min in duodenum - 1-2 cm/min in ileum MMC organizer - ENS - CCK & gastrin MMC - motilin MMC

Migrating Motor complex (MMC) Cycling of the MMC continues until it is ended by the ingestion of food Termination requires the physical presence of a meal in the upper digestive tract Vagal efferent signals to ENS interrupt the MMC and initiate mixing motility during ingestion of a meal After vagus nerves are cut, a large quantity of ingested food is necessary to interrupt the interdigestive motor pattern (MMC), and the interruption is often incomplete Intravenous feeding does not end the fasting pattern

Migrating Motor complex (MMC) Adaptive significance of MMC Gallbladder contraction and delivery of bile to the duodenum is coordinated with the onset of MMC in the intraduodenal region Appears also to be a mechanism for cleaning indigestible debris Plays a housekeeper role in preventing the overgrowth of microorganisms that might occur in the small intestine

Peptic Ulcer and Vomiting

Peptic Ulcer Specific causes of peptic ulcer: Bacterial infection by Helicobacter Pylori Increased secretion of acid-peptic juices Smoking, because of increased nervous stimulation Alcohol, because it tends to break down the mucosal barrier Aspirin, which also has a strong propensity to break down this barrier

Peptic Ulcer General features: Reduced mucosal defense & acid amounts # of parietal cells sensitivity to gastrin stomach emptying inhibition of gastrin release by acid rate of duodenal HCO3- secretion For duodenal ulcer: Pain is felt during fasting and relieved by eating which the opposite to gastric ulcer

Helicobacter pylori (H. pylori) Correlation between H. pylori infection and the incidence of gastric and duodenal ulcer (peptic ulcer) Remove of bacterial infection reduce ulcer recurrence Mechanism of H. pylori in the genesis of ulcers: urea urease ammonia neutralizes acid (protect bacteria) Ammonia destroys the protective mucosa H. pylori gastrin secretion antibiotic is effective in eradication of H. pylori

Vomiting Expulsion of gastric contents Preceded by: retching, nausea, sweating, dilation of pupil, heartbeat, dizziness - controlled by vomiting center - different areas have receptors & input to vomiting center: -distention of stomach -tickling back of throat -injury of genitourinary system

Vomiting The events: 1- wave of reverse peristalsis (Retroperistalsis) 2- forced inspiration (abdominal pressure) 3- forceful abdominal muscles 4- relaxed pyloric sphincter, stomach and lower esophageal sphincter (LES)