GI Hormones Flashcards
Gastrin
- Site of secretion?
- Stimuli for secretion?
- ACTIONS???
Site of secretion: --G cells of the stomach Stimuli for secretion: --Small peptides and amino acids, digestion ---of the stomach, vagal stimulations ACTIONS: 1. Increases Gastric H+ secretion 2. Stimulates growth of gastric mucosa
Cholecystokinin
- Site of secretion?
- Stimuli for secretion?
- ACTIONS???
Site of secretion:
– I cells of the duodenum and jejunum
Stimuli for secretion:
– Small peptides, amino acids, fatty acids, and monoglycerides (NOT triglycerides)
ACTIONS:
1. Increase pancreatic enzyme secretion
2. Increase pancreatic HCO3- secretion
3. Stimulates contraction of the gallbladder and relaxation of the sphincter of oddi
4. Stimulates exocrine pancreas and gallbladder
5. Inhibit Gastric emptying
Secretin
- Site of secretion?
- Stimuli for secretion?
- ACTIONS???
Site of secretion: -- S cells of the duodenum Stimuli for secretion: -- H+ in the duodenum, fatty acids ACTIONS: 1. Increase Pancreatic HCO3- secretion 2. Increase Biliary HCO3- secretion 3. Decrease Gastric H+ secretion 4. Inhibits trophic effect of gastrin on gastric mucosa
Glucose-Dependent Insulinotropic Peptide (GIP)
- Site of secretion?
- Stimuli for secretion?
- ACTIONS???
Site of secretion: --K cells Duodenum and Jejunum Stimuli for secretion: --Fatty acids, amino acids, oral glucose ACTIONS: 1. Increase Insulin secretion from Beta cells 2. Decrease Gastric H+ secretion
Gastrin coordinates to promote Hydrogen ion secretion by the gastic _________ cells.
Parietal
Gastrin cells are secreted by G cells in the ______ part of the stomach?
Antrum
The neurocrine released from vagal nerve endings onto the G cells is ___________?
Gastrin-Releasing Peptide (GRP) or Bombesin
Gastrin secretion is inhibited by a ____ pH and by ______?
LOW pH and somatostatin
Zollinger-Ellison syndrome is a person who has a gastrin-secreting tumor. What secretion will be increase and what will happen to the gastric mucosa?
Hydrogen ion secretion goes up and the gastric mucosa with hypertrophy
A common sign that someone has Zollinger-Ellison syndrome is if the patient has ______ caused by the unrelenting secretion of Hydrogen ions.
Duodenal ulcers
The acidification of the intestinal lumen causes what enzyme to inactivate?
Pancreatic lipase (dietary fats will not be adequately digested or absorbed) —> Steatorrhea
Treatment of Zollinger-Ellison Syndrome includes blocking of the H2 receptor and administration of inhibitors of the H+ pump. What two drugs are commonly used?
Cimetidine (H2-receptor blocker)
Omeprazole (H+ pump inhibitor)
Functions of CCK?
Promote fat digestion and absorption
Why is it important that secretin increases secretion of HCO3- from the pancreas and biliary?
Neutralizes the H+ in the lumen of the small intestine.
Neutralization of H+ is essential for fat digestion, pancreatic lipases that a pH optimum between ____ and ___?
pH 6 and 8
Secretin inhibits what?
The effects of gastrin on the parietal cells
Glucose-Dependent Insulinotropic Peptide (GIP) is inhibits what?
Gastric H+ secretion
Candidate Hormones?
Motilin
Pancreatic polypeptide
Enteroglucagon
Motilin
Site of secretion?
Stimuli for secretion?
Actions?
Upper duodenum
During fasting states
Increase gastrointestinal motility and initiate interdigestive myoelectric complexes that occur at 90 minute intervals
Pancreatic Polypeptide
Site of secretion?
Stimuli for secretion?
Actions?
Pancreas
Response to ingestion of carbohydrates, proteins, or lipids.
Inhibits secretion of HCO3- and enzymes
Enteroglucagon
Site of secretion?
Stimuli for secretion?
Actions?
Intestinal cells
Response to decrease in blood glucose
Directs the liver to increase glycogenolysis and gluconeogenesis
PARACRINES of GI??
Somatostatin and Histamine
Somatostain
Site of secretion?
Stimuli for secretion?
Actions?
Secreted by D cells of gastrointestinal mucosa
In response to decreased luminal pH
Inhibits secretion of other GI hormones and inhibits gastric H+ secretion
**
— Don’t forget somatostatin is secreted by hypothalmus and by delta cells in pancreas
Histamine
Site of secretion?
Stimuli for secretion?
Actions?
Secreted by endocrine-type cells of GI mucosa; in H+ secreting region of stomach
– Gastrin, ACh, and histamine stimulate H+ secretion by gastric parietal cells
