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GI > Gastrointestinal Physiology: Motility I > Flashcards

Gastrointestinal Physiology: Motility I Flashcards

(100 cards)

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1
Q

The only exception to the net mouth to anus (aboral) movement

A

Vomiting

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2
Q

Generate the force to move material along the GI tract

A

Phasic contractions

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3
Q

Create resistance to movement

-normally in the sphincters or pathologically elsewhere

A

Tonic contractions

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4
Q

What are the three primary functions of mastication?

A
  1. ) Reduction in particle size
  2. ) Mixing
  3. ) Enhance stimulation of taste buds and other receptors
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5
Q

Mixing of the food with saliva is needed to libricate the mass and increase the exposure to which two things?

A
  1. ) Salivary amylase (carbohydrate digestion)

2. ) Lingual lipase (lipid digestion)

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6
Q

Mastication enhances stimulation of taste buds and other receptors in the oral cavity to increase salivation and appreciation of the food. Some of these receptors initiate the

A

Cephalic phase of digestion

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7
Q

Control of mastication is primarily

A

Reflexive

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8
Q

Plays a much larger role in indigestion than most people realize

A

Impaired chewing

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9
Q

Moving food and liquid from the mouth into the stomach, is an example of integration within the neural system. This is referred to as

A

Swallowing

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10
Q

Swallowing is divided into which 3 phases?

A
  1. ) Oral
  2. ) Pharyngeal
  3. ) Esophageal
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11
Q

When not swallowing (i.e. at rest), the upper esophageal sphincter (UES) and the lower esophageal sphincter (LES) are

A

Contracted

-effectively isolates the esophagus

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12
Q

The esophageal muscles do not maintain any tonic contractions, thus the esophagus is

A

Flaccid

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13
Q

The pressures in the upper and lower esophagus reflect the pressure in the

A

Thoracic and abdominal cavities respectively

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14
Q

The buccal or oral phase of swallowing is under

A

Voluntary control

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15
Q

A bolus, approx. 5-15 cm3, is moved to the back of the mouth by elevating the front of the tongue against the surface of the hard palate in the

A

Buccal (oral) phase

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16
Q

In the buccal (oral) phase of swallowing, the bolus is moved into the oropharynx by

A

Retraction and depression of the tongue

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17
Q

The driving force for movement of the bolus in the buccal phase is a pressure gradient of approximately

A

4-10 mmHg

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18
Q

An involuntary reflex coupled to the primary esophageal peristaltic wave

A

Pharyngeal phase of swallowing

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19
Q

Pharyngeal phase is an involuntary reflex coupled to the primary esophageal peristaltic wave. Both are controlled by the

A

Swallowing center

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20
Q

The pharyngeal phase is initiated by the bolus touching the pillars of fauces, tonsils, soft palate, base of tongue and

A

Posterior wall of the pharynx

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21
Q

When this happens, afferent impulses go to the swallowing center. Efferent fibers convey impulses back to the

A

Pharyngeal muscles, UES, esophageal muscles, LES, and orad portion of the stomach

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22
Q

The swallowing center also interacts with other centers controlling

A

Respiration and speech

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23
Q

Relaxes as the pharyngeal peristaltic wave starts (pressure gradient up to 100 mm Hg), and the bolus is propelled into the esophagus

A

UES

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24
Q

At the end of the pharyngeal contraction, the UES contracts to a level above resting tone. This prevents

A

Reflux

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25
The air passages close simultaneously with the onset of the
Pharyngeal wave
26
The soft palate presses against the posterior pharyngeal wall sealing the
Nasopharynx
27
In the pharyngeal phase, the vocal cords come together, the epiglottis deflects horizontally and the larynx moves forward and upward under the base of the tongue closing the
Larynx
28
A primary peristaltic wave is initiated by the swallowing center, and mediated by the vagus to the striated circular and longitudinal muscles in the
Esophageal phase
29
This peristaltic wave goes to the myenteric plexus in the smooth muscle, thus, activating the
Enteric System
30
The primary peristaltic wave starts just below the sphincter and spreads downwards pushing the bolus toward the stomach when the
UES pressure is high
31
Almost simultaneously, a wave of inhibition starts in the
Proximal LES (LES relaxes)
32
The likely neurotransmitters for this LES inhibition are
VIP and NO
33
This continues into the stomach (receptive | relaxation), and is mediated by
Vagal inhibitory fibers acting on ENS
34
The temporary inhibition of resting tone in the fundus and orad area
Receptive Relaxation
35
This maintains the esophageal-gastric pressure gradient to prevent
Reflux during swallowing
36
After the peristaltic wave passes the LES, the LES contracts to a level above resting tone. This is mediated by -prevents reflux
ACh and enkephalins
37
May move through the LES before the peristaltic wave in response to gravity
Liquids
38
Air in the pharynx at the start of a swallow passes into the
Trachea
39
Air trapped in saliva and food, or voluntarily swallowed, passes into the stomach. This results in
Burping
40
A peristaltic wave not preceded by pharyngeal activity or relaxation of the UES
Secondary Peristalsis
41
Functions to clear the esophagus of retained food and/or refluxed gastric contents
Secondary peristalsis
42
Initiated by distention in the body of the esophagus that stimulates stretch receptors in the wall
Secondary peristalsis
43
What is secondary peristalsis mediated by in 1. ) Striated muscle? 2. ) Smooth muscle
1. ) Vagus | 2. ) Vagus and ENS
44
Is there any sensation associated with secondary peristaltic contractions?
No (little to none)
45
Normally maintains a pressure that is 20-40 mmHg higher than the stomach which prevents reflux
LES
46
This anti-reflux mechanism is particularly important during the third-trimester pregnancy as other mechanisms are weakened
Secondary peristalsis
47
Another anti-reflux mechanism is the pinching action of the diaphragm on the
Esophagus
48
Infants rely primarily on this anti-reflux mechanism, while awaiting other mechanisms to develop
Pinching of diaphragm on esophagus
49
Another anti-reflux mechanism is that increases in intra-gastric and intra abdominal pressures lead to increased
LES pressure
50
Occur in humans and are centrally controlled (does not occur in rats)
Retching and Vomiting
51
However, reverse esophageal peristalsis does not usually occur in
Humans
52
Starts with orally directed peristalsis in the small intestine that leads to movement of intestinal contents into the stomach
Retching and Vomiting
53
Then forceful contractions of duodenal and gastric antral muscles, coupled with deep inspiration and decreased LES tone leads to
Retching
54
Movement of contents into the esophagus but with inadequate force to move contents through UES
Retching
55
Subsequent additional contraction of the\ diaphragm and abdominal muscles (increases intraabdominal pressure), coupled with further decreases in LES and UES tone leads to
Vomiting
56
Storage in the stomach is accomplished by both
1. ) Receptive relaxation | 2. ) Accommodation
57
Muscle relaxation in response to stretching or distension by food
Accommodation
58
Gastric filling leads to changes in volume with little to no change in
Wall pressure
59
Increasing gastric volume with 1.6L of air increases intragastric pressure by
10mmHG or less
60
Allows digestion of foo by salivary and gastric enzymes, as well as controlled gastric emptying
Gastric storage
61
The storage site in the stomach
Upper stomach
62
Causes the mixing of food, salivary secretions and gastric secretions
Antral muscle contraction
63
Mixing facilitates gastric
Digestion
64
The antrum grinds the solid food into small particles which the pylorus allows to pass into the
Duodenum
65
The rate of gastric emptying is controlled to deliver chyme to the small intestine for optimized
Digestion and absorption
66
Sweep luminal contents (e.g. undigestible materials) out of the stomach, down through the small intestine and into the large intestine
Migrating Myoelectric Complexes (MMCs)
67
MMCs are only active during the
Interdigestive period
68
At the onset of eating, shallow and slow peristaltic contractions start over the corpus, and increase in strength and velocity as they move into the
Antrum
69
With increased time after eating, contractions start higher up in the corpus and are
Stronger
70
The simultaneous contraction of the terminal antrum and pylorus
Antral Systole
71
Results in 1) retrograde movement of chyme back into the stomach, leading to effective mixing, and 2) shearing forces, which reduces particle size
Antral systole
72
Leave the stomach prior to antral systole
Chyme and liquids
73
During the interdigestive period, when the stomach and small intestine empty, they generate
Strong peristaltic waves (MMCs)
74
Results in semi-liquid chyme or liquids passing through the pylorus prior to antral systole and closure of pyloric sphincter
Gastric Emptying
75
The emptying rate is controlled by the interactions of gastric and duodenal motilities, and pyloric sphincter tone, which are modified by
Enteric, spinal, and vago-vagal reflexes and GI peptides
76
Increased gastric volume increases gastric emptying rate via
Gastric stretch receptors
77
Particle size: 0.25 mm3 empty faster than 10 mm3 due to the
Pyloric lumenal diameter
78
What empties faster, carbohydrates or proteins?
Carbohydrates
79
What empties faster, proteins or fats?
Proteins
80
Duodenal chemo-receptors, CCK, GIP and secretin, all have what effect on the rate of gastric emptying?
Decrease rate
81
What empties faster, acidic or neutral species?
Neutral
82
What empties faster, hypotonic, isotonic, or hypertonic solutions?
Isotonic faster than hypotonic Hypotonic faster than hypertonic
83
The duodenogastric reflex i.e. excessive duodenal distention activates duodenal stretch receptors, leading to
Reduced gastric contraction and emptying rate
84
Ileal distension decreases
Gastric emptying
85
Functions in gastric and small intestine interdigestive motility
Migrating myoelectric complex (MMC)
86
The strongest peristaltic contractions observed in healthy individuals are from
MMCs
87
"Clean out" residual material from the stomach and small intestine and moves it into the large intestine
MMCs
88
MMCs require an intact
Enteric nervous system
89
The beginning of the MMC is associated with rising blood levels of
Motilin
90
Stop with rising blood gastrin levels and feeding
MMCs
91
Not related to 'hunger pangs' but could contribute to the discomfort and pain of ulcers
MMCs
92
Slow movement of the chyme through the intestine maximizes
Absorption of nutrients
93
Mixing in the small intestine facilitates intraluminal digestion by mixing chyme with secretions and facilitates absorption by increasing exposure of the chyme to the
Epithelial surface
94
In the small intestine, functions to empty unabsorbed residue and secreted material into the large bowel
MMCs
95
Muscularis mucosae and villus muscle activity is responsible for movement of the
Mucosa and Villi of small intestine
96
Muscularis mucosae and villus muscle contractions are independent of contractions in the
Muscularis externa
97
Activity in these muscles serves to increase absorption and aids
Lymph flow
98
Sympathetic stimulation and chyme stimulating touch receptors on the epithelial surface of the small intestine induces
Rapid shifts in mucosal surface
99
This can be seen in X-rays after administering
Barium salts
100
Responsible for intraluminal mixing and propulsion
Muscularis externa

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