7: GI Tract Motility Flashcards

1
Q

Slow waves

A

Depols and repols of membrane potential in GI smooth muscle

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2
Q

How do slow waves cause contraction

A

Greater number of APs on top of slow waves creates larger contraction

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3
Q

Three things that increase slow wave amplitude

A

Ach, parasymps, stretch

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4
Q

Two things that decrease slow wave amplitude

A

NE, sympathetics

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5
Q

ICCS: Interstitial Cells of Cajal

A

GI pacemakers that spontaneously generate and propagate slow waves; slow waves spread to smooth muscle via gap junctions

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6
Q

Where are ICCs located?

A

Myenteric plexus and smooth muscle

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7
Q

Phasic vs tonic contraction

A

Phasic: periodic contraction and relaxation
Tonic: maintain constant contraction

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8
Q

4 places where tonic contraction occurs

A

Stomach, lower esophagus, ileocecum, internal anal sphincter

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9
Q

Which cannot occur after a vagotomy, primary or secondary peristaltic waves?

A

Primary

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10
Q

What controls the involuntary swallowing reflex

A

Medulla

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11
Q

Involuntary swallowing reflex steps

A
  1. Food in pharynx -> sensory input via CN 9 and 10
  2. Swallowing center in medulla -> brainstem nuclei
  3. Efferent input to pharynx
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12
Q

Achalasia

A

Impaired peristalsis and incomplete LES relaxation during swallowing

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13
Q

What causes achalasia?

A

Decreased ganglion cells in myenteric plexus -> LES stays mostly closed during swallowing

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14
Q

Presentation of achalasia

A

Regurgitation, heartburn, dysphagia

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15
Q

How to Dx achalasia

A

Barium swallow study

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16
Q

What causes GERD

A

Motor abnormalities -> low pressure in LES -> persistent reflux -> inflammation

17
Q

Secondary causes of GERD

A

Increase in intra-gastric pressure; after a large meal, pregnancy, heavy lifting, etc.

18
Q

Complications associated with GERD

A

GI bleed, esophagitis, scar tissue/strictures, Barrett’s esophagus

19
Q

Max frequency of peristalsis in caudad stomach

A

3-5 waves/min

20
Q

Why is gastric emptying closely regulated

A

Provide time for digestion and neutralizing gastric H in duodenum

21
Q

SIBO

A

Colonic bacterial overabundance that can disturb SI motility -> nausea, anorexia, bloating

22
Q

Slow gastric emptying sx

A

Fullness, loss of appetite, nausea, sometimes vomiting

23
Q

What can cause slow gastric emptying

A

Gastric ulcer, cancer, eating disorders, vagotomy

24
Q

Tx for slow gastric emptying

A

Pyloroplasty, balloon dilation

25
Gastroparesis
Slow emptying of stomach in absence of mechanical obstruction
26
What can cause gastroparesis?
DM, injury to vagus nerve
27
Sx of gastroparesis
N/V, early feeling of fullness, weight loss, abd bloating and discomfort
28
IPAN stands for?
Intrinsic primary afferent neuron
29
Slow waves in SI vs stomach
In SI, slow waves dont initiate contractions, they just set max frequency for contractions
30
Vomiting reflex events
reverse peristalsis in SI -> stomach and pyloric relaxation -> forced inspiration to increase abdominal pressure -> movement of larynx -> LES relaxation -> glottis closes -> forceful expulsion of gastric contents
31
Regulation at ileocecal junction: distention of ileum vs colon
Ileum distention -> relaxes ileocecal sphincter | Colon distention -> contracts sphincter to prevent backflow
32
Where is the ENS in the LI?
Concentrated beneath tenia coli
33
What type of nerve innervates external anal sphincter?
Somatic pudendal nerves