gastrointestinal regulatory substances and secretory productsp. 380-381 Flashcards
Gastrin: source?
G cells
G-cells: produce what?
gastrin
G-cells: where?
antrum of stomach (most lower part before pylorus), duodenom
gastrin producing cells: where?
antrum of stomach (most lower part before pylorus), duodenom
(G-cells)
gastrin: actions? (3)
gastric H+ secretion
growth of gastric mucosa
gastric motility
gastric H+ secretion
growth of gastric mucosa
gastric motility
functions of which substance?
gastrin
what increases gastrin secretion by g-cells? (3 things)
- stomach distention/alkalinization
- amino acids and peptides
- vagal stimulation via GRP (gastrin releasing peptide)
what decreases gastrin secretion by g-cells?
pH < 1.5
chronic use of which medication increase gastrin?
PPI
chronic use of PPI increases what?
gastrin secretion
which pathologies increase gastrin secretion? (2)
- chronic atrophic gastritis (H pylori)
- Zollinger-Ellison syndrome (gastrinoma)
gastrinoma is a gastrin-secreting tumor
Zollinger-Ellison syndrome: increased secretion of what?
gastrin
what is Zollinger-Ellison syndrome?
gastrinomas in pancreas or upper part small intestine -> produce gastrin -> too much acid -> peptic ulcers
rare
chronic atrophic gastritis can lead to what?
overproduction of Gastrin
Somatostatin: source?
D cells
Where are D cells?
pancreatic islets, GI mucosa
what do D cells produce?
somatostatin
Effects of somatostatin? (4)
- less gastric acid and pepsinogen secretion
- less pancreatic and intestine fluid secretion
- less gallbladder contraction
- less insulin and glucagon release
what leads to increased secretion of somatostatin?
more acid
what leads to decreased secretion of somatostatin?
vagal stimulation
what is octeotride?
a mimic of somatostatin
which medication is the analog of somatostatin?
octeotride
what can you treat with octeotride (mimic of somatostatin)? (4)
- agromegaly
- carcinoid syndrome
- VIPoma
- variceal bleeding
carcinoid tumor: neuroendocrine tumors
VIPoma: neuroendocrine tumor secreting vasoactive intestinal peptide (VIP) -> severe diarrhea
cholecystokinin: which cells secrete this?
I cells
where are I cells?
duodenum, jejunum
I cells: secrete what?
cholecystokinin
cholecystokinin: functions? (4)
- more pancreatic secretion
- more gallbladder contraction
- slows down gastric emptying
- relaxes the sphincter of Oddi
what increases cholecystokinin secretion?
fatty acids, amino acids
fatty acids and amino acids increase secretion of what?
cholecystokinin
via what pathways does cholecystokinin cause pancreatic secretion?
neural muscarinic pathways
secretin: secreted via which cells?
S cells
where are S cells?
duodenum
what are the actions of S cells? (3)
- pancreatic HCO3 secretion
- less gastric acid secretion
- bile secretion
what increases secretion of secretin
acid and fatty acids in lumen of duodenum
acid and fatty acids in lumen of duodenum: increased secretion of what?
secretin