GI Motility Flashcards
Which of the regional motility patterns involves intestinal smooth and regular skeletal muscle?
Swallowing and defacation
opiods have (constipating/laxative) effect. How so?
Constipating, promote absorption of fluid and electrolytes
Parasympathetic regulation of the myenteric plexus involve (pre/post) ganglionic neurons while sympathetic involve (pre/post) gaglionic neurons.
Parasympathetic = pre ganglionic
sympathetic = post ganglionic
3 important inhibitory motor neurons of the ENS
VIP, ATP, and NO
List 6 important interneurons of the ENS
5HT GABA Ach Dopamine Enkephalin Somatostatin
Serotonin
- Net effect on motility:
- Net effect on mucosal secretion/absorption:
- pro-kinetic
- stimulates fluid and electrolyte secretion
Dopamine
- Net effect on motility:
- Net effect on mucosal secretion/absorption:
- anti-kinetic
- complicated
Enkephalin (opiate)
- Net effect on motility:
- Net effect on mucosal secretion/absorption:
- promotes symmetric segmentation
- stimulates fluid and electrolyte absorption
Acetylcholine
- Net effect on motility:
- Net effect on mucosal secretion/absorption:
- pro-kinetic
- stimulates fluid and electrolyte secretion
Vasoactive Intestinal Peptide (VIP)
- Net effect on motility:
- Net effect on mucosal secretion/absorption:
- as neurotransmitter: relaxes ISM
- In excess: secretory diarrhea
- stimulates fluid and electrolyte secretion
Which region(s) of the GI tract contains only skeletal striated muscle?
Mouth, pharynx, and upper esophageal sphincter (UES)
Which region(s) of the GI tract contains a mixed striated/smooth muscle?
Esophagus (1/3 striated, 1/3 striated/smooth, 1/3 smooth muscle) and anal sphincter
Which 6 regions only contain smooth muscle?
- stomach
- duodenum
- jejunum
- ileum
- colon
- rectum
The motility patterns of these two regions involve mostly segmentation, periodic local peristalsis, and mass movement
Colon and rectum
Once we start chewing and the food reaches a certain part of the pharynx, a ____ occurs which includes a swallow, then an _____ of contraction that goes down entire esophagus
- peristaltic wave
- orderly wave
What must happen way ahead of the arrival of the orderly wave? Why?
The lower esophageal sphincter relaxes (LES)
-ensures that bolus of food enters the stomach
In contrast to vascular smooth muscle, intestinal smooth muscle cannot respond to synaptic input unless it is also innervated by what?
Intestinal Cells of Cajal (ICC) (they are the pacemakers!)
What are the Intestinal Cells of Cajal? What is an important feature they contain?
- Cells that form a network over the ISM and are auto-excitatory
- pacemaker activity to generate rhythmic depolarization-repolarization pattern in ISM = slow wave rhythm = bioelectric rhythm
ISM only responds to synaptic input from enteric neurons when the ISM membrane potential is in the ____ phase of the slow wave pattern
Plateau phase
When the ISM is innervated only by the intestinal Cells of Cajal, what happens? What doesn’t happen?
It develops muscle tone but no motility patterns.
Motility patterns are programmed in the ___
enteric ganglia