Download Migrating myoelectric complex (MMC) and Vomiting

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:
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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:
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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)