GI 7 Flashcards
What do the Rhythmic contracts of peristalsis have their basis in?
The membrane potential of smooth muscles = Basic electrical rhythm (BER)
Where does the Rhythmic activity for segmentation originate?
Pacemaker cells (interstitial cells of Cajal)
How does the BER for segmentation work?
There is fluctuating membrane potential in the cells. One the cells reach threshold there is firing of action potentials will be triggered resulting in contraction of muscle
What can modulation of BER impact?
Intestinal mobility
How can the BER be modulated in segmentation?
- Acetylcholine increases activity and stimulates contraction
- Epinephrine decreases activity and depresses contraction
Where is the rate of BER most intense?
In the Duodenum
Where is the rate of the BER lease intense?
The Cecum
What happens after a meal has been absorbed?
Segmentation stops and is replaced by Migrating Myoelectric Complex (MMC)
What is Migrating Myoelectric Complex (MMC)?
A sweeping wave of contraction that occurs after absorption to propel the remaining contents along
What is the function of MMC?
To move undigested food to the large intestine
What are the three phases of the MMC?
1: Quiescent phase: No activity
2: Irregular electrical and mechanical activity
3: Burst of regular electrical and mechanical activity (tonic contraction)
When does the Quiescent phase of MMC occur?
During digestion and absorption
When does the MMC stop?
During ingestion of a meal
What triggers MMC?
Increased plasma concentration of motilin
