lecture 46 - Gastrointestinal regulatory substances Flashcards
what organ does the following describe
- contraction/relaxation of smooth muscles and sphincters
- secretion of enzymes, fluid and electrolytes
- trophic effects on tissues
- secretion of other GI hormones
GI tract functions
-
-
-
- GI peptides
- hormones
- neurocrines
- paracrine
functions of the GI tract
- contraction/relaxation of smooth muscles and sphincters
- secretion of enzymes, fluid and electrolytes
- trophic effects on tissues
- secretion of other GI hormones
what is the purpose of trophic effects on tissues
growth hormones
secretion of other GI peptides cause
- hormone release of other hormones
- negative feedback mechanism
GI peptides can be
hormones
paracrines
neurocrines
define endocrine
travels in the blood
define paracrine
acts on/where it was secreted
GI peptides released from _______ cells of the GIT, not ____
endocrine cells
NOT glands
GI peptides enter _____ _______, liver, ______ ______ , and target cells
portal circulation
systemic circulation
four GI hormones
- gastrin
- CCK
- secretin
- GIP
GI paracrine are released from ____ and act on ______
endocrine cells
locally within same tissue that secretes them
Major GI paracrine hormine is
somatistatin
what is the purpose of somatostatin hormone
inhibitory actions if the GIT always
GI neurocrines are synthesized in neurons of GIT and released after an _____ _____
action potential
the following are major ______
- Ach
- NE
- VIP
- GRP
- substance P
- neuropeptide Y
neurocrines
GI hormones are secreted in response to _______ ______ carried in blood to distant site
physiological stimulus
GI hormones functions ________ of neural activity
independent
*because it uses portal vein and not the neural stem
gastrin functions to promote _______ ion secretion by gastric parietal cells, stimulate the growth of gastric mucosa, increase gastric motility
hydrogen
gastrin functions to promote hydrogen ion secretion by gastric _______ cells, stimulate growth of gastric mucosa, increase gastric motility
parietal cells
gastrin functions to promote hydrogen ion secretion by gastric parietal cells, stimulate ______ of gastric mucosa, increase gastric motility
growth
gastrin functions to promote hydrogen ion secretion by gastric parietal cells, stimulate growth of gastric mucosa, increase gastric _______
motility
gastrin is secreted by _______ in the stomach
G cells
_______ gastrin is secreted between meals and secreted at low basal levels
big
_______ gastrin is secreted in reponse to a meal and in the presence of amino acids and distenion of the stomach
little
gastrin caused GRP release from vagal nerves onto G cells from _______ _______ reflex
local vagal reflex
define negative feedback
desired response of hormones you need causes another hormone or itself to stop/decrease
inhibition of gastrin secretion by _______ gastric pH and _______
low gastric pH
somatostatin
what is the diease
- gastrinoma in non beta-cell pancreas (gastrin secreting tumor developing in pancreas)
- humans, dogs, and cats
- increase in hydrogen secretion and hypertrophy of gastric mucosa
Zollinger-Ellison syndrome
CCK is secreted by _______ of duodenal and jejunal mucosa
I cells
CCK is secreted by I cells of _______ and _______ mucosa
duodenal
jujunal
_______ is secreted in response to presence of fatty acids, amino acids and peptides
CCK
CCK effect on constriction of gallbladder
eject bile into the small intestines
amulsify lipids
considered the first step of digestion
constriction of gallbladder
CCK effect of secretion of pancreatic enzymes
release fatty acids from fat
release amylase from starch
release protease from proteins
CCK effect on secretion of bicarbonate from pancreas
buffer pH entering the small intestine
protect SI from acids
Enzymes DO NOT work at _______ pH
low