Motility Of The GI Tract Flashcards
(51 cards)
What organs primarily use Tonic contractions?
1) Stomach (orad part)
2) lower esophagus
3) ileocecal
4) internal anal sphincters
What is it called when a sub threshold depolarization produces a weak contraction?
Basal contractions
What 3 things increase the amplitude of the slow wave?
1) stretch
2) Acetylcholine
3) parasympathetics
What 2 things cause cause hyper polarization?
Norepinephrine and sympathetics
What plexus controls GI secretions and local blood flow?
Submucosal (meissners)
What plexus controls GI movements?
Myenteric (Auerbach’s)
Where do slow waves originate from?
Interstitial cells of cajal (ICC)
How do slow waves move from pacemaker region to smooth muscle?
Gap junctions
Smooth muscle cells respond to slow wave depolarizations with increased what?
Permeability of Ca+2 because probability of channels opening increases
What are the 3 phases of swallowing?
1) Oral Phase (voluntary)
2) Pharyngeal phase
3) Esophageal phase
Walk through what happens in the pharyngeal phase of swallowing
Soft palate is pulled upward –> epiglottis moves –> UES relaxes –> peristaltic wave of contractions is initiated in pharynx –> food is propelled through open UES
Which phase of swallowing takes the longest?
Esophageal phase (8-10 seconds)
What 2 things control the esophageal phase of swallowing?
Swallowing reflex and the ENS
The involuntary swallowing reflex is controlled by what?
The medulla
What is the somatosensory information that signals from the pharynx to the swallowing center in the medulla?
Food in the mouth
What 3 nerves can carry afferent info from the pharynx to the medulla in response to food in the mouth?
1) Vagus
2) Glossopharyngeal
3) Trigeminal
During the pharyngeal phase of swallowing, the swallowing center inhibits what?
The respiratory center
The primary peristaltic wave of the esophageal phase of swallowing is controlled by what?
Medulla (swallowing center)
The primary peristaltic wave CANNOT occur after this procedure?
Vagotomy
What induces a secondary peristaltic wave?
- if primary contraction fails to empty the esophagus or when gastric contents reflux into the esophagus
- Induced by distention of the esophagus itself by the retained food
What controls the secondary peristaltic wave?
Both the swallowing center and the ENS
Can a secondary peristaltic wave occur after Vagotomy?
YES
What organs primarily use Phasic contractions?
1) esophagus
2) Stomach (Antrum/caudad)
3) small intestine
4) all tissues involved in mixing and propulsion
Gastroesophageal reflux occurs when intra-abdominal pressure is increased. Give two examples of when this happens.
Pregnancy and morbid obesity
