GI Hormones Flashcards
describe the parasympathetic and sympathetic innervation of the gut
parasympathetic- comes from cranial (vagus) and sacral plexi w/ short post ganglionic fibers
associated w/ AcH
sympathetic- celiac ganglia- everything down to duodenum
superior mesenteric ganglia- duodenum to descending colon
inferior mesentreic ganglia- descending colon to rectum
sympathetic associated w/ Norepi
describe the intrinsic nervous system
enteric nervous system- located in submucosal layer (meisners) and myenteric layer (auerbach)
secretin family
secretin, VIP, GIP, GLP-1, glucagon, bombesin
gastrin family
gastrin, CCK, motilin, encephalin, cerulean
hormones that are neither in secretin or gastrin families
somatostatin, pancreatic polypeptide, urogastrone, chymodenin, tachykinins (substance P)
effects of gastrin
- stimulation of gastric acid from oxyntic (parietal) cells (leads to release of pepsinogen from cheif cells)
- trophic action on mucosa in stomach
3 stimulates gastric motility
what two messengers are need for gastrin-mediated H release?
need both AcH and histamine actin on oxyntic cells
what affect does vagal activity have on gastrin? how does it do this?
vagal activity produces bombesin- causes gastrin release
what affect does amino acids have on gastrin?
causes release
what affect does Ca have on gastrin?
causes release
what affect does stomach pH have on gastrin
inhibits release (via somatostatin cells)
what affect does secretin have on gastrin?
inhibits release
what affect does CCK have on gastrin
inhibits effect
zollinger-ellinson syndrome
tumor causes gastrin hypersecretion and acid hypersecretion and ulcers
diagnostic test- administer secretin, which normally inhibits release, but in this case will increase it
where is gastrin released from?
mainly g-cells in stomach pylorus
duodenum, pancreas
how are gastrin/CCK family hormones similar?
their C terminals are very similar
effects of CCK
pancreatic proenzyme release (acts on acinar cells)
contraction of gall bladder
relaxation of spincter of Oddi
reduction of gastrin induced
acid via competitive inhibition
synergistic action w/ secretion
on pancreatic bicarb release
what causes CCK release?
peptides and amino acids (major)
also facts and acidity (minor)
how is CCK used clinically
1 diagnose pancreatic and gall bladder disease
2 remove obstructions from bile duct
secretin effects
secretion of water and bicarb from pancreas (w/ CCK)
inhibits gastrin release
promotes release of pancreatic enzymes
promotes pepsinogen release
inhibits gastrin secretion
promotes bile release and bicarb in bile
secretin stimulants
major- introduction of acid into upper duodenum
where are S cells?
duodenum
ghrelin
elevated during fasting or insulin-induced hypoglycemia
increases desire to eat
(also)
GHRP- stimulates growth hormone release both directly and inhibiting somatostatin
leptin and adiponectin
protein hormones from adipose tissue that inhibit the desire to eat in hypo
increase insulin responsiveness in T2 diabetes
