Lecture 9: Motility

Question 1

Mucosal plexus = ; Myenteric plexus =

Answer 1

Meissner’s, Auerbach’s

Question 2

Peristalsis

Answer 2

Slow movement, longitudinal smooth muscle

Question 3

Segmentation

Answer 3

Contractile, circular smooth muscle

Question 4

Interstitial Cells of Cajal

Answer 4

Pacemaker cells of the gut

Question 5

Two types of electrical activity of GI tract

Answer 5

Slow waves (phasic contractions) and spike activity

Question 6

What controls peristalsis?

Answer 6

Serotonin, contraction: ACh, substance P; relaxation: NO

Question 7

GI motility disorders: sx

Answer 7

N/V, pain, early satiety, D, C, gas/bloat

Question 8

When we start to eat, what does the fundus do?

Answer 8

Relax to accept contents

Question 9

How fine must the antrum grind food?

Answer 9

1-2 mm particles

Question 10

Which part of the stomach regulates emptying of liquids? Solids?

Answer 10

Fundus/body; antrum

Question 11

Gastroparesis: associated diseases (account for 2/3)

Answer 11

50% w/ diabetes due to neuropathy, thyroid, CT disorders, pregnancy

Question 12

Another name for accelerated gastric emptying

Answer 12

Dumping syndrome

Question 13

Test for gastric motility

Answer 13

Gastric emptying scan

Question 14

Small intestinal motility: 2 states

Answer 14

Fed: segmental, promote mixing/absorbing; Fasting: cyclic, keeps intestine clean of bacteria/residue, “Migrating Motor Complex” (MMC)

Question 15

Small bowel dysmotility (5 classes)

Answer 15

Neurologic (PD, post-viral); SM (collagen vascular disorder, etc); Endocrine (diabetes/thyroid); Drugs (opiates, anticholinergics); Myenteric Plexus Disorders

Question 16

Chronic intestinal pseudo-obstruction: definition and classes of causes

Answer 16

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)

Question 17

Tests of small bowel motility (2)

Answer 17

Small bowel manometry with a catheter; breath test (calculate H produced…higher early H is related to slow motility)

Question 18

Normal colonic motility (2 types of activity)

Answer 18

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,

Question 19

Primary causes of constipation

Answer 19

Slow transit constipation, defecation disorders, functional constipation (most common)

Question 20

Functional constipation: definition

Answer 20

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

Question 21

IBS: definition

Answer 21

Abdominal pain/discomfort with: improvement with defecation, change in stool freq, change in stool form

Question 22

Other causes of constipation (4)

Answer 22

Diet (low fiber), eating disorders, surgerical history (change in anatomy or post-op), medications (narcotics, calcium)

Question 23

Ogilvie’s Syndrome/Acute Pseduoobstruction: define, etiology, tx

Answer 23

Non-obstructive colonic dilatation due to drugs, post-op, immobility; tx = underlying condition, decompress colon, neostigmine (stimulate parasympathetics)

Question 24

IBS: women or men?

Answer 24

Women

Question 25

Types of IBS

Answer 25

IBS w/ diarrhea, constipation, mixed, unsubtyped

Question 26

Four “causes”/highlights of IBS

Answer 26

Increased motor reactivity to luminal contents, altered visceral sensation (decreased pain threshold), involves small and large intestine, CNS-ENS dysregulation

Question 27

Describe serotonin normally and IBS hypothesis

Answer 27

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

Question 28

5-HT hypothesis works best for patient with what kind of IBS?

Answer 28

Constipation

Question 29

How to deal with IBS syndrome (2 main categories)

Answer 29

Dietary and behavior modification (decrease stress, therapy), pharmacology (laxatives, anti-diarrheal medications, anti-depressants, 5-HT receptor agents)

Question 30

Tests for colonic motility (2)

Answer 30

Sitz marker study (give markers that should be expelled for a certain amount of time) and scintigraphy (nuclear medicine)

Question 31

Describe process of defecation

Answer 31

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

Question 32

Maintenance of continence: structure

Answer 32

Internal/external anal sphincter, levator ani muscles (creates angle), rectal curvature and transverse rectal folds (delays passage)

Question 33

Maintenance of continence: function

Answer 33

Anal sensation must be intact, storage capacity must be intact, nerve integrity must be maintained, stool volume/consistency are factors, and mental status

Question 34

Fecal incontinence: %, who, tx

Answer 34

8%, common in women (related to number of pregnancies), elderly, institutionalized; tx = anti-diarrheal medications, fiber, biofeedback (training), surgery

Question 35

Pelvic floor function tests (2)

Answer 35

MRI defecography w/ contrast enema while trying to have defecation; anorectal manometry