03b: GI Motility Flashcards
There are two nerve plexi in GI tract. The myenteric plexus is in (X) tissue layer (be specific). Where is the second?
X = muscularis externa (between inner circular and outer long muscle layers)
Submucus nerve plexus in submucosa layer
Mastication’s purpose is to (increase/decrease) (X) of food.It is under (voluntary/involuntary) control.
Increase;
X = exposed surface area (to secretions)
Initially voluntary, but rhythmicity is reflexively maintained
What’s deglutition?
Transport/propulsion of bolus from mouth to stomach
Precise orchestration of movements of several structures is important in deglutition. List some nerves that are important here.
- CN VII, IX, X, XII;
2. Lingual and medial pterygoid nerves
Deglutition occurs in which phases?
- Oral
- Pharyngeal
- Esophageal
T/F: Initiation and continuation of swallowing is voluntary.
False - initiation is, but then swallowing is reflexly controlled
During swallowing, aka (X) phase of deglutition, (Y) closes (Z) so that food doesn’t go into nose.
X = oral Y = soft palate (elevation) Z = nasopharynx
During (X) phase of deglutition, UES opens to allow food into (Y). At this phase, it’s important to block food from entering which space(s)?
X = pharyngeal Y = esophagus
Airways
Passage of bolus into airways is prevented via which mechanisms?
- Larynx elevated (glottis closed)
- Epiglottis tilts downward
- Respiration stops briefly
During (X) phase of deglutition, peristalsis is important for propelling food toward (UES/LES).
X = esophageal
LES
Normally, (X) (contraction/relaxation) prevents reflux of gastric contents.
X = LES
Contraction
The velocity of peristaltic wave is normally (X).
X = 3-5 cm/s
T/F: Liquids can bypass the peristaltic wave due to gravity.
Ture
The primary esophageal peristalsis is associated with (X). The secondary esophageal peristalsis is associated with (Y).
X = original swallowing Y = residual bolus or reflux
Control of deglutition is coordinated by swallowing center in (X) part of brain. Sensory afferent inputs via (Y) nerves and efferents via (Z) nerves.
X = medulla Y = CN IX and X Z = CN X
Initiation of peristalsis in upper portion of esophagus is innervated (directly/indirectly) by (X) nerve.
Directly;
X = vagus
T/F: A peristaltic wave, once initiated, can proceed in vagally denervated esophagus.
True
In lower 2/3 of esophagus, propagation of bolus (via peristalsis) is principally dependent on (X) nerves.
X = plexus of neurons in wall
Innervation of esophagus by (X) is absolutely necessary for proper motility.
X = myenteric plexus
LES is under neural control. Excitatory via (X), inhibitory via (Y). Both influenced by (Z).
X = Y = myenteric plexus Z = vagus
T/F: Peristalsis only at lower esophagus will inhibit LES tone (opening of sphincter).
False - peristalsis at ANY level of esophagus