Gastric Motility and Secretions Flashcards
What is gastric accomodation?
The second step in stomach filling in which the stomach is able to fill in the absence of an increase in pressure.
Loss of vagal tone has what effect on the stomach in filling phases?
The stomach is unable to fill without an increase in pressure.
What effect does secretin have on the GI and what stimulates its release?
Secretin is released in response to HCL in the duodenum.
It slows down gastric emptying.
What effect does CCK have on the GI and what stimulates its release?
Fat in the duodenum stimulates the release.
It slows down gastric emptying.
What effect does gastrin have on the GI and what stimulates its release?
Protein in the stomach stimulates the release of gastrin.
Gastrin impairs gastric emptying.
What effect does ENS have on the GI and what stimulates its release?
Stimulated by duodenal distension.
Impairs gastric emptying.
What vagal mediators impair gastric emptying?
Ach
Opioid
5-HT
What vagal mediators promote gastric emptying?
NO
VIP
Where is the emetic center located that controls the emetic response?
Located within the medulla of the brain.
Blood borne emetics activate what receptor type in the stomach?
Activate 5-HT3 receptors leading to vagal and sympathetic afferents being turned on.
This ultimately leads to activation of the solitary tract nucleus and chemo-receptor trigger zone.
Gastroparesis is commonly found in what patient population type?
typically found in poorly controlled diabeti mellitus patients or in infantile pyloric stenosis.
(Impaired motility of the stomach)
What cell in the stomach relases HCL?
Parietal cells
aids to steralize, digest protein, and absorb nutrients.
What cells in the stomach release intrinsic factor?
Parietal cells
Aids in B12 absorbtion.
What cells in teh stomach release pepsinogen and what does it do?
Chief cells
Allows for the digestion of proteins.
What cell type releases mucus and bicarbonate in the stomach?
Th superficial epithelial/ neck cells.
This allows for protection of the stomach.
What cell in the stomach releases histamine and what does it do?
ECL cells release histamine causing the stomach to release HCL (from the parietal cells).
What cell in the stomach releases Gastrin and what function does Gastrin have?
G cells release gastrin which promotes HCL secretion
What cell in the stomach releases acetylcholine and what function does it have?
Acetylcholine is released from nerve cells and it has three functions:
Promotes mucus secretion
Promotes Bicarbonate secretion
Promotes HCl secretion
What cell in the stomach releases somatostatin and what function does it have?
Released from D cells and suppresses HCL secretion.
What membrane protein is HCL production linked with?
HCL pumps are linked with H+ K- ATPase pumps.
What sort of hormone is Gastrin?
Acts as an endocrine hormone that is released into the blood by G cells in the stomach.
Describe how gastrin works directly vs indirectly
Gastrin works directly when it is secreted into the blood and upregulates the parietal cells which kick up the H/K ATPase.
Gastrin works indirectly by inducing the release of histamine from ECL cells.
Neurocrine regulation of acid secretion is controlled directly and indirectly by what substance?
Acetylcholine.
What is the mechanism for how histamine works?
Histamine from ECL cells via indirect activation by either acetylcholine or Gastrin works by stimulating H/K ATPase on adjacent parietal cells.
Paracrine release of Prostaglandins have what effect on parietal cell K/H ATPase/
Downregulates the activity of the H/K ATPase.
The release of somatostatin by gastric D cells will result in what?
Results in the decrease of acid secretion
Inhibits release of gastrin from G cells a
Inhibits histamine release from ECL cells
Inhibits H/K ATPase
