September 21, 2015 - GI Motility Flashcards
Enteric Nervous System
Known as the “second brain”.
The nerves and system that directly controls the gastrointestinal system. Needs to move food along the length of the body, digest the food and absorb nutrients, as well as protect itself from this process.
Interstitial Cells of Cajal
An “intermediate” between muscles and nerves. They act as pacemakers and govern the frequency of slow waves and are linked to the smooth muscle cells.
Calcium and Contraction
A rise in intracellular calcium activates the contractile apparatus in smooth muscle cells.
Smooth muscle is not as strong as skeletal muscle, but may stay contracted for much longer.
Wave Activity in Small and Large Bowel
Small intestine has frequent wave propogation. In the colon, large movements only happen several times per day.
5-HT and Bowel Movement
5-HT stimulates the enteric nervous system (ENS) which stimulates contraction and relaxation of motor neurons.
Acetylcholine and Bowel Movement
Acetylcholine causes the contraction of smooth muscle behind the food bolus.
Nitric Oxide and Bowel Movement
Nitric oxide causes relaxation of the smooth muscle ahead of the food bolus.
Stomach Digestion Mechanism
Food goes into the fundus where it accumulates. Food is then moved into the antrum of the stomach through contractions where it is digested more. Once the food is in a slurry, food is sent out through the pylorus.
Migrating Motor Complex
MMC flushes the whole stomach and the upper GI into the colon several times per day. This is important for keeping the upper GI relatively sterile.
Gastroparesis
Impaired gastric emptying.
This can be a cause of vomiting, nausea, abdominal pain, weight loss, and early satiety.
It usually occurs as a result of surgery (1/3), diabetes (1/3), or is idiopathic (1/3).
Bezoar
When the stomach is not emptied and a large amount of crud (such as hair) accumulates in the stomach.
