Feb19 M2-Intestinal Motor Function Flashcards
SI motor activity
- effective mixing
- slow propulsion
BER in SI charact (electrical control activity)
- f fixed for certain region
- origin is ICCs*****
- DOESN’T CAUSE contractions
ERA charact
- triggered by stretch or Ca
- spikes freq on BER plateau. proportional to magnitude of stimuus
- max freq is max freq of BER
how action potentials travel in SI (and stomach)
gap-junctions (ICCs and muscle fibers)
intrinsinc freq of BER in diff SI regions and colon
duod: 12 per min
jejunum: 10.5-12
ileum: 10.5
colon: 4-6 per min
proximal vs distal SI peristalsis
- f of BER higher
- SM more excitable
- thicker SM
- frequency and amplitude of contractions greater in proximal SI
(EXAM) 2 types of contractions in SI
segmentation and peristalsis
segmentation def + why exists
rings of circular contraction. to slow down and mix (bouncing back)
peristalsis def
1 propagating circulating ring.
segmentation charact
- stimulus is DISTENSION (not automatic)
- CIRCULAR only
- ANS, hormones and ENS modul long distance
segmentation what exactly modulates it (what structure)
Auerbach’s plexus
consequence of issue in segmentation
diarrhea (bc segmentation offers resistance)
peristalsis charact (+ how differs from segmentation)
- infrequent
- irregular
- SHORT DISTANCE
- WEAK
trigger of peristalsis
stretching (like for segmentation): local reflexes against stretching + circ and longit interaction
muscles behind bolus in peristalsis
circ contracts
longit relaxes
muscles ahead of bolus in peristalsis
circ relaxes
longit contracts
peristalsis and segmentation: what is necessary for them to work
integrity of ENS
modulation of peristalsis
ANS, hormones (vagus, Ach, PSS)
ileocecal sphincter charact
high P, normally closed. opens when ileum distended. closes harder when cecum distended
roles of colon
mixing and abso of water
rectum fct
storage
colon time to transit vs intestines
intestines = 6 hours colon = 50-60 hours
freq of BER in colon
5-12 in ascending
8-12 TC
6-8 descending
17 sigmoid
segmentation and peristalsis in colon: trigger
always there, governed by irregular BER
3 reflexes for intestine and colon motility
- gastrocolic reflex and 2. gastroileal (when stomach full)
3. ileocolic: food in ileum = feel need to go to the bathroom
interdigestive period charact
cyclic myoelectric activity. intervals of 90 min from stomach to ileum
MMC (migrating myoelectric complex) phase 1 charact
60 min. no BER, no ERA.
MMC phase 2
20 minutes. irregular ERA and contractions
MMC phase 3
10 minutes regular spikes of contraction (ERA) ring moving down GI tract
what initiates MMC
ENS. (CNS? ANS? gut peptides? too)
what propagates MMC
ENS + MODULATION by ANS and gut peptides
what interrupts MMC
meal intake
MMC 2 fcts
- housekeeping and prevent bacterial overgrowth
2. non digestible particles clearance
constipation on bristol stool chart
1-2
IBS def
dx of exclusion: chronic abd pain and discomfort, high visceral sensitivity, constipation vs diarrhea dominant IBS
bleeding in IBS
none
3 possible causes of IBS
- ICC disorder
- serotonin pathway problem
- post infectious IBS (surgery of H pylori)
constipation IBS rx
anti cramps meds
diarrhea IBS rx
rule out bacterial overgrowth. anxiety and psychological interventions
