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COM - GI Final > Motility Of GI Tract - Lopez > Flashcards

Motility Of GI Tract - Lopez Flashcards

(67 cards)

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1
Q

When circular muscle contracts what happens?

A

Diameter decreases

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2
Q

When longitudinal muscle contracts what happens?

A

Length of segment decreases

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3
Q

Describe phasic contractions

A

Periodic contraction, followed by relaxation

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4
Q

What body parts use phasic contraction?

A

Esophagus, stomach (antrum), small intestine

ESS

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5
Q

Describe tonic contractions

A

Constant level of contraction, no relaxation

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6
Q

What body parts use tonic contractions?

A

Stomach (orad), lower esophagus, ileocecal, internal anal sphincters

SLEii

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7
Q

What are slow waves a unique feature of?

What are they not?

A

Smooth muscle

Action Potential

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8
Q

TRUE or FALSE: Subthreshold depolarization can produce contractions in GI smooth m.?

A

TRUE, but weak

Aka basal contractions

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9
Q

What neurotransmitter increases the amplitude of slow waves and # of APs?

Decreases?

A

ACh

NE

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10
Q

What else increases amplitude of slow waves and # of APs?

What else decreases?

A

Stretch, PS

Sympathetics

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11
Q

Where do slow waves originate?

A

Interstitial cells of Cajal (ICC)

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12
Q

How do slow waves spread through ICC to smooth m.?

A

Gap junctions

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13
Q

What are the 3 phases of swallowing and which are voluntary/involuntary?

A

Oral (V)
Pharyngeal (IV)
Esophageal (IV)

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14
Q

Describe the pharyngeal phase of swallowing

A

Soft palate pulled up -> epiglotis movies -> UES relaxes -> peristaltic wave initiated -> food propelled through open UES

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15
Q

What controls the esophageal phase of swallowing?

A

Swallowing reflex and ENS

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16
Q

Where is the swallowing center located?

A

Medulla

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17
Q

What nerves sense food in the pharynx?

A

Vagus and glossopharyngeal

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18
Q

What inhibits the respiratory center during the pharyngeal stage of swallowing?

A

Swallowing center

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19
Q

Describe the primary peristaltic wave

A

Continuation of pharyngeal peristalsis

Cannot occur after vagotomy

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20
Q

What does the secondary peristaltic wave do?

A

Occurs when primary wave fails to clear gastric contents
Induced by distention of esophagus
Involves swallowing center and ENS
Occurs after vagotomy

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21
Q

What nerve acts through the Myenteric nervous system?

This controls what part of the esophagus?

A

Vagus

Mid and lower regions

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22
Q

When does gastroesophageal reflux occur?

A

Intra-abdominal pressure is increased (due to pregnancy, obesity)

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23
Q

What is released to mediate opening of the LES for receptive relaxation?

A

VIP and possibly NO

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24
Q

What is GERD?

Symptoms?

Result?

A

Abnormal relaxation of the LES

Heartburn, chest pain, dysphagia, lump in throat

Barret’s, stricture, asthma, sinusitis

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25
What is achalasia? Cause? Symptoms?
Impaired peristalsis or lack of LES relaxation during swallowing or elevation of LES resting pressure Damage to nerves in esophagus or abnormal immune system response Weight loss, regurgitation, dysphagia, vomiting, chest pain
26
What layers of muscles does the stomach have?
Circular Longitudinal Oblique
27
What happens in the orad region of the stomach during receptive relaxation? What kind of reflex is this?
DEC pressure, INC volume Vagovagal reflex
28
What effect does CCK have on the stomach?
DEC contractions INC gastric secretions
29
What does phase lag do as the peristaltic wave approaches teh antrum of the stomach?
DECREASES
30
What happens in the caudad region of the stomach to further mix and reduce particle size of stomach contents?
Retropulsion
31
What factors INC AP and force of contractions in the stomach?
PS Gastrin Motilin
32
What factors DECREASE AP and force of contractions?
Sympathetics Secretin GIP
33
How does the rate of gastric emptying INCREASE?
DEC distensibility of the orad, DEC tone of the pylori so INC peristaltic contractions of caudad INC diameter and inhibition of segmenting contractions of prox duodenum
34
What factors inhibit gastric emptying?
DEC peristaltic contractions | INC tone of pyloric sphincter
35
What receptors inhibit gastric emptying via what hormone?
Fat and proteins via CCK (INC gastric distensibility)
36
What does hypertonicity in the duodenum lead to?
Inhibition of gastric emptying
37
What is the most common problem associated with disorders of gastric motility?
Slow gastric emptying
38
What is gastroparesis? Cause? Symptoms?
Slow emptying of stomach/paralysis of stomach Damage to the vagus nerve or high blood glucose Nausea, vomiting, abdominal bloating, weight loss
39
How are large particles of undigested residue in the stomach emptied? How is this mediated and how often?
MMC Via Motilin in 90 minute intervals
40
Absence of MMCs in the stomach is assoc. with what?
Gastroparesis
41
What does segmentation contractions do?
Mix the chyme and expose it to pancreatic enzymes
42
What do peristaltic contractions do?
Propel the chyme towards large intestine
43
What contracts behind the bolus? In front of?
Circular Longitudinal
44
Describe initiation of contractions in the small intestine
Slow waves DO NOT initiate contraction APs necessary Slow wave freq. sets the max freq. of contractions
45
What has a higher higher slow wave frequency: Duodenum or ileum? What is the general trend?
Duodenum (12 cycles/min) DECREASE in freq. toward ileocecal junction
46
What releases serotonin? Where does it bind? What does it initiate?
ECCs Receptors in IPAN (intrinsic primary afferent neuron) Peristaltic reflex (stimulates contractions)
47
What hormones stimulate contractions of the intestine? Inhibit?
PGs, Gastrin, CCK, Motilin, insulin Epi, secretin, glucagon
48
What coordinates the vomiting reflex?
Medulla
49
Describe the order of events of reverse peristalsis in vomiting
``` Reverse peristalsis of s.i. Relaxation of stomach and pylorus Force inspiration to INC abdominal pressure Movement of larynx Relaxation of LES Closure of glottis Forceful expiration of gastric contents ```
50
What stimulates the chemical trigger zone in the vomiting reflex?
Morphines, opioids
51
What relaxes the sphincter and excites peristalsis at the ileocecal junction?
Pressure and chemical irritation
52
What inhibits peristalsis of ileum and excites sphincter at the ileocecal junction?
Pressure or chemical irritation in cecum
53
What prevents passage of contents from the colon to the ileum?
Distention of the colon --> contraction of sphincter
54
Main fx of l.i.?
Absorb water and Vits | Convert digested food into feces
55
What portions of the Sympathetic N.S. Innervates the large intestine?
T10-L2
56
What is the sympathetic innervation of the distal rectum and anal canal?
Hypogastric plexus
57
What is the sympathetic innervation of the proximal large intestine?
SM ganglion
58
What is the sympathetic innervation of the distal large intestine?
IM ganglion
59
What is the sympathetic innervation of the external anal sphincter?
Somatic pudendal nerves
60
What are the major excitatory mediators of the large intestine? Inhibitory?
ACh and Substance P NO and VIP
61
Where do segmentation contractions occur? Fx?
Cecum and ascending colon Mix contents
62
What do mass movements stimulate? How often?
Defecation reflex, propels feces into rectum 1-3 times/day
63
What does poor motility cause in large intestine? Excess motility?
Greater absorption therefore hard stool --> constipation Less absorption --> diarrhea
64
Where do rectal distention senses and voluntary control of the external anal sphincter pathways travel to?
Spinal cord to cerebral cortex
65
What is the rectosphincteric reflex under control of? What happens in paraplegic patients?
Neural control Lack tonic contractions, defecation
66
What is diverticulitis? What causes it? Where is the most common location?
Small sacs of intestinal lining that bulge outward in a weak spot Excess pressure in colon Left side of colon
67
What is motility important for?
Preparation of ingested food for digestion and absorption

COM - GI Final (5 decks)

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