gastrointestinal hormones Flashcards
what blood flow is gastrin secreted into ?
portal vein blood
what are the two gastrin molecules ?
little gastrin
big gastrin
where are the g cells ?
mucosal layer of the antrum
where are parietal cells found ?
in the body of the stomach
what are the three functions of gastrin ?
stimulation of parietal cells to secrete hydrogen
increase gastric motility
growth of gastric mucosa
what are the stimuli of gastrin release ?
stomach distention
alkalinization
amino acids ( phenylalanine , tryptophan )
vagal stimulation through GRP
what is gastrin inhibited by ?
low pH, somatostatin
what is a gastrinoma ?
causes the zollinger ellison syndroome
occurs in the duodenum and in the pancreas
excessive acid secretion
hypertrophy and hyperplasia of the stomach mucosa
what are the symptoms of a gastrinoma ?
abdominal pain that increases with food
chronic diarrhea - steatorrhea
ulcers in the distal duodenum
GERD
what is special about the ulcers in zollinger ellison syndrome ?
refractory to PPI therapy
in the distal duodenum
how is gastrinoma diagnosed ?
fasting levels of gastrin levels
secretin test
what is secretin ?
hormone released by the duodenum in response to too much acid
1- inhibits gastrin release
2- stimulates bicarb secretion
how does a secretin test work in a patient with a gastrinoma ?
normally secretin would decrease gastrin levels
but in a gastrinoma the secretin will increase gastrin levels due to abnormal G cells
what are the treatment options for gastrinoma ?
high dose of PPI
octeotride ( somatostatin analogue)
surgical excision
what is pernicious anemia and what are the associated findings ?
associated with autoimmune gastritis due to destruction of the parietal cells and hence a loss of intrinsic factor leading to B12 deficiency
g cell hyperplasia
megalobalstic anemia
high levels of gastrin
what are the effects of cholecystokinin ?
gall bladder contraction
allows for release of pancreatic enzymes
decreases gastric emptying
allows for relaxation of the sphincter of oddi
what cell is responsible for the release of cholecystokinin ?
I cells
how dos cholecystokinin allow for the release of pancreatic enzymes ?
CCK receptors on the vagus nerve
releases Ach which works on the pancreas
what are the stimuli for cholecystokinin ?
fatty acids and monoglycerides
amino acids and proteins
when is CCk used for diagnostic purposes ?
in a HIDA scan , to test and evaluate RUQ pain
what cells release secretin ?
s cells of the duodenum
what is the action of secretin ?
1- increases pancreatic HCO3 secretion from pancreatic ductal cells
2- decreases acid secretion by inhibiting gastrin
3- increases bile secretion
promotes pancreatic flow
what is the action of somatostatin ?
decreases kol 7aga
what are the major stimuli for somatostatin ?
increasing acid production - low pH
what is octeotride and what is the main use for it ?
somatostatin analogue
used for bleeding varicies
what are the other uses for octeotride ?
carcinoid tumor
acromegaly
gastrinoma/glucagonoma
what is the function of GIP ?
glucose dependent insulinotropic peptide
stimulates insulin release from the pancreas
decreases hydrogen ion release
what cells release GIP ?
k cells
what is the only hormone that is release by all types of foods ?
GIP from k cells
why is oral glucose metabolized faster than IV glucose ?
GIP
IV glucose does not trigger GIP
what is vasoactive intestinal peptide and where is it synthesized ?
synthesized by parasympathetic ganglia
causes relaxation of the LES ,and mainly smooth muscles
increases intestinal water and electrolytes secretion
raises pH - inhibit gastric H
what are the symptoms of VIPoma ?
rare tumor of the islet cells
watery diarrhea hypokalemia
achlorydia
what is special about the diarrhea associated with VIPoma ?
tea coloured odorless watery diarrhea
resembles cholera
other name for VIPoma ?
pancreatic cholera syndrome
WDHA syndrome
what is the typical case associated with VIPoma ?
adult
long standing watery diarrhea
no response to diet change
what is the treatment for VIPoma ?
fluid/electrolyte replacement
octreotide
where is motilin secreted from and what is its function ?
promotes motility in the fasting state
released by kolo
when are the highest levels of motilin found ?
in between meals when you are not eating
what drug is used to treat gastroparesis ?
erythromycin - as it binds to motilin receptors
what are the digestive phases ?
cephalic phase - just thinking about food - allows for vagus stimulation
gastric phase - consume food
intestinal phase
