Week 2: Gastric Motility Flashcards
Functions of the stomach
4 listed
size of bolus ejected into the duodenum
1 mm^3
General divisions of the stomach
Gastric musculature external
Internal gastric musculature
Receiving and storage functions of the stomach
top of the stomach opens before the bolus arrives which allows liquids or other fast dropping boli to enter the stomach before the peristaltic wave arrives
Question
C. VIP/ATP/NO Release from myenteric neurons
Receptive relaxation of the fundus and body
Recovery of the stomach
Mixing and propulsion functions of the stomach: Peristaltic contractions
Mixing and propulsion functions of the stomach: Gastric pacemakers
Describe electrical slow waves
amplitude and duration dictate how much calcium can enter cells
Describe the relationship of electrical slow waves to smooth muscle contraction
Describe the gradient of gastric slow waves
The higher in the stomach doesn’t really have slow waves but as you get lower the slow waves get stronger and more spikey which is due to greater Ca2+ influx
What drives slow waves
Interstitial cells of Cajal
ICCs AKA
Interstitial cells of Cajal
Describe interstitial cells of Cajal
Most gastric tumors arise from what cell type?
Interstitial Cells of Cajal
What happens if interstitial cells of Cajal are knocked out
still have electric potential but no slow waves and animals have difficulty thriving
Where do peristaltic contractions originate in the stomach
Describe retropulsion
Describe retropulsion II
Describe the regulation of gastric emptying
What mechanisms underlie inhibition of emptying?
Especially in response to fat
Describe gastric factors that promote emptying
What is the migrating motor complex?
robust coordinated contractions to sweep out residue in the stomach
How often does MMC occur?
every ~90 minutes or so
Classes of disorders of gastric emptying
- Gastroparesis
- Dumping syndrome
Gastroparesis causes
- Tumors
- ulcers
- Vagal nerve damage
How does a tumor or ulcer lead to gastroparesis
physical obstruction contributes to pyloric resistance
How does vagal nerve damage lead to gastroparesis?
Loss of vagal coordination limits pyloric opening
Causes of vagal nerve damage that can lead to gastroparesis
- diabetes
- surgical vagotomy for ulcer
Symptoms of gastroparesis due to vagal nerve damage
bloating
nausea
reflux
loss of appetite
Treatments of gastroparesis due to vagal nerve damage
- Diet modification
- Drugs
- Surgical treatment to reduce the tone of the pylorus
Dumping syndrome is what?
Rapid emptying
Complications of Dumping syndrome
An Excessive osmotic load presented to small intestine -> excessive insulin release -> hypoglycemia
Dumping syndrome is associated with?
Gastric bypass surgery
Treatments of Dumping syndrome
- Diet modifications
- surgery
Summary of gastric motility
