Lecture 9: Motility Flashcards
Mucosal plexus = ; Myenteric plexus =
Meissner’s, Auerbach’s
Peristalsis
Slow movement, longitudinal smooth muscle
Segmentation
Contractile, circular smooth muscle
Interstitial Cells of Cajal
Pacemaker cells of the gut
Two types of electrical activity of GI tract
Slow waves (phasic contractions) and spike activity
What controls peristalsis?
Serotonin, contraction: ACh, substance P; relaxation: NO
GI motility disorders: sx
N/V, pain, early satiety, D, C, gas/bloat
When we start to eat, what does the fundus do?
Relax to accept contents
How fine must the antrum grind food?
1-2 mm particles
Which part of the stomach regulates emptying of liquids? Solids?
Fundus/body; antrum
Gastroparesis: associated diseases (account for 2/3)
50% w/ diabetes due to neuropathy, thyroid, CT disorders, pregnancy
Another name for accelerated gastric emptying
Dumping syndrome
Test for gastric motility
Gastric emptying scan
Small intestinal motility: 2 states
Fed: segmental, promote mixing/absorbing; Fasting: cyclic, keeps intestine clean of bacteria/residue, “Migrating Motor Complex” (MMC)
Small bowel dysmotility (5 classes)
Neurologic (PD, post-viral); SM (collagen vascular disorder, etc); Endocrine (diabetes/thyroid); Drugs (opiates, anticholinergics); Myenteric Plexus Disorders
Chronic intestinal pseudo-obstruction: definition and classes of causes
Disease that behaves as if there is a bowel obstruction due to a variety of reasons: myopathy, enteric neuropathy, idiopathic (note: sx the same as other motility disorders)
Tests of small bowel motility (2)
Small bowel manometry with a catheter; breath test (calculate H produced…higher early H is related to slow motility)
Normal colonic motility (2 types of activity)
High amplitude propagating contractions = associated with defecation, 6x day, > 100 mmHg and; Low amplitude propagating contraction = associated with fluid transport, distension and flatus, 100x day,
Primary causes of constipation
Slow transit constipation, defecation disorders, functional constipation (most common)
Functional constipation: definition
2 of the following: straining, hard stools, sense of incomplete evacuation, sense of anorectal block (can’t get it out), manual maneuvers, less than 3 defecations per week
IBS: definition
Abdominal pain/discomfort with: improvement with defecation, change in stool freq, change in stool form
Other causes of constipation (4)
Diet (low fiber), eating disorders, surgerical history (change in anatomy or post-op), medications (narcotics, calcium)
Ogilvie’s Syndrome/Acute Pseduoobstruction: define, etiology, tx
Non-obstructive colonic dilatation due to drugs, post-op, immobility; tx = underlying condition, decompress colon, neostigmine (stimulate parasympathetics)
IBS: women or men?
Women
Types of IBS
IBS w/ diarrhea, constipation, mixed, unsubtyped
Four “causes”/highlights of IBS
Increased motor reactivity to luminal contents, altered visceral sensation (decreased pain threshold), involves small and large intestine, CNS-ENS dysregulation
Describe serotonin normally and IBS hypothesis
5-HT release stimulates motility and secretion via enteric nerve reflexes; in IBS there is less 5-HT, so feces sit in colon causing pain, and also less secretion
5-HT hypothesis works best for patient with what kind of IBS?
Constipation
How to deal with IBS syndrome (2 main categories)
Dietary and behavior modification (decrease stress, therapy), pharmacology (laxatives, anti-diarrheal medications, anti-depressants, 5-HT receptor agents)
Tests for colonic motility (2)
Sitz marker study (give markers that should be expelled for a certain amount of time) and scintigraphy (nuclear medicine)
Describe process of defecation
Propagation of intraluminal contents to rectum associated with rectal fullness –> internal anal sphincter relaxation (signal to brain) –> external anal sphincter contraction –> socially acceptability –> squatting –> puborectalis muscle and pelvic floor muscles relax –> strain –> defecation
Maintenance of continence: structure
Internal/external anal sphincter, levator ani muscles (creates angle), rectal curvature and transverse rectal folds (delays passage)
Maintenance of continence: function
Anal sensation must be intact, storage capacity must be intact, nerve integrity must be maintained, stool volume/consistency are factors, and mental status
Fecal incontinence: %, who, tx
8%, common in women (related to number of pregnancies), elderly, institutionalized; tx = anti-diarrheal medications, fiber, biofeedback (training), surgery
Pelvic floor function tests (2)
MRI defecography w/ contrast enema while trying to have defecation; anorectal manometry
