GI Motility Flashcards
List the 3 types of GI motility
- Peristalsis
- segmentation
- Migrating motility complexes
Which motility is only occurring during fasting/interdigestive/postabsorptive period?
Migrating motility complexes - MMC
Where does peristalsis occur?
Esophagus, Stomach, SI
Segmentation occurs in ___________ and ___________
SI and LI
When nutrient are present and the dig/absorptive process is called_________________ period
Digestive/Absorptive
Interdegistive/Postabsorptive/Fasting is when?
Digestion/absorption of nutrients is completed
~2-3 hrs after meal
What is the electrical membrane potential in GI smooth muscle cells called?
basic electrical rhythm (BER)
What initiates the slow wave of BER?
Pacemaker cells (interstitial cells of Cajal - ICC)
The ________________ induces the major contractions of GI smooth muscle cells.
Spike potential
Spike potential and slow wave is cause by ?
Opening of voltage gated Ca channels
Which Ca channel is responsible for the slow wave?
T- type (transient)
T/F the slow wave reaches the action potential
False
_____ type Ca channels give the action potential
L-type (Long-lasting)
The 3 stimuli of spike potentials are:
- Stretch
- Acetylcholine
- Parasympathomimetics (pilocarpine)
The circular contraction behind the bolus stretch and a relaxed area in front is called ________________
Peristalsis
What is required for peristalsis?
Myenteric plexus and ENS integration
The bolus of chyme will stimulate (extrinsic/intrinsic) afferents that activate enteric interneurons.
Intrinsic
The peristaltic longitudinal smooth contraction for anterograde direction is stimulated by _________
ACh
The peristaltic circular contraction is stimulated by ACh and ______
Substance P
Nitric Oxide and Vasoactive intestinal peptide (VIP) do what in peristalsis?
Stimulated Peristaltic circular relaxation below the bolus
What process helps chyme mixing in the intestine?
Segmentation
What are the contractions in segmentation called?
Rhythmic phasic contraction (RPCs)
Describe RPCs
Localized contractions in circular smooth mm only
The housekeeping wave is the ________________
Migrating Motor complex (MMC)
The MMC induces a ________________
giant migrating contraction - peristalsis
During fasting, how often does MMC occur?
90-120 mins
The stomach growling when hungry is due to ?
MMC during fasting
An impairment of MMC can result in what in the SI?
Bacterial overgrowth
How many phases in MMC?
4 (1 and IV are merged)
Phase I MMC
No spike potential/contraction
4-120 mins
MMC phase ______:
Irregular sporadic potential and contraction for about 20 - 30 mins
Phase II
MMC Phase ______:
Regular intense spike potential and contraction
Phase III
In Phase IV of MMC there is:
Declining activity
