Regulation of the GI tract Flashcards
what is an endocrine signal
a signal which acts on distal cells to exert its effect through the blood
what is a paracrine signal
a cellular signal which acts very locally to exert its affects through diffusion
what is lumen
the bore of a tubular structure
(insides of the small intestine)
what is secretogogue
luminal contents of the GI tract
activate receptors or trasnporters on endorcrine cells
what role does the duodenem play
absoprtion and digestion
in the enteroendocrine system, peptides acr as endocrine, paracrine, or neurocrine (neurotransmitter) signals to…
stimulate secretion
stimulate emptying
stimulate growth
stimulate motility
what 3 families are part of the enteroendocrine system
and what do they all share
gastrin
secretin
motilin
morphology (all look the same)
the difference in location of enteroendocrine cells is due to what
what secretagogues theyre responding to and what theyre secreting
where are G cells primarily expressed
and what is their functioon
stomach
help secrete hydrogen ions (acidic)
where are S cells located
and what is their function
duodenum
(secretin) primarily stimulates bicarbonate rich fluid - helps neutralise content from the stomach
what 4 main areas is the stomach consisted of
(BPFC)
Fundus
Cardia
Body
Pylorus (antrum and canal)
how many phases of gastric function are there
3
what are the three phases of gastric function when eating
CGI
cephalic
Gastric
Intestinal
the stomach is rich in what kind of enteroendocrine cells
G cells
what is the role of the cephalic stage in eating
uptake in digestion enzymes
drive increase secretion of digestive hormones and hormones like G cells
what is the role of the gastric phase when eating
distention occurs and secretagogues
what is the role of intestinal stage when eating
tipping contents into small intestine to continue digestion
secretion of H+ forms what kind of cells
parietal cells
where are parietal cells located
crypts lining epithelial in stomach
secretion of H+ form parietal cells through one of hoe many routes
3
what are the names of the three routes that secretion of H+ can form parietal cells
histamine stimulated secretion
neuronal stimulation by the enteric and parasympathetic nervous system
hormonal stimulation by gastrin
in the Cephalic phase
what stimulates the vagus nerve to initiate H+ secretion
smell and sight of food
in the cephalic phase,
the smell and sight of food stimulates what
the vagus nerve to initiate H+ secretion
In the cephalic phase
the secretion of H+ by the vagus nerve forms what and why
HCl in anticipation of the incoming meal
in the gastric phase
the distention of the stomach and secretagogues further increase what
H+ release
in the gastric phase
what further increases H+ release
distention of stomach and secretagogues
in the intestinal phase
a decrease in what, leads to reduction in gastrin secretion
peptides and amino acids
reduced distention
the exocrine pancreas is responsible for secreting digestive enzymes in what part of the small intestine
duodenum
what stimulates the tipping of bicarbonate fluid into pancreatic ducts
activity of S and I cells
where is secretin secreted from
S cells in bot
duodenum and jejenum
S sells stimulates to secrete secretin by fall of what
pH
what is secreted by S cells due to a fall in pH
secretin
Secretin stimulates the release of
bicarbonate rich fluid from pancreas into the duodenum
mucus from the stomach
where are other places that have secretin receptors in the body
cerebellum
hippocampus
kidneys
where is CCK secreted from
I cells in the duodenum ND JEJENUM
I cells stimulate secretion of CCK by
ingested protein and fats entering the duodenum
CCK stimulates release of what to help aid digestion
pancreatic lipases
pancreatic proteases
why does CCK stimulates release of pancreatic lipases and pancreatic proteases
to help aid digestion
CCK stimulates the gall bladder to..
contract to help facilitate movement of bile acids
CCK also stimulates the vagal afferents to …
help recognise when you are full
How and where is motilin secreted
M cells in the duodenum and jejenum
M cells stimulate secretion of motilin by what
alkalisation of the duodenum and jejunum
what does motilin stimulate
MMC
gastric emptying
gallbladder emptying
what is the main function of ghrelin
drives you to eat food
where and how is ghrelin secreted
P/D1 cells
in the fundus of the stomach
what pathways does ghrelin stimulate
orexigenic pathways
ingestion of food stimulates secretion of what hormone
insulin
enteroendocrine hormones play a role in stimulating insulin secretion by releasing what 2 incretins
Gastric inhibitory peptide (GIP)
Glucagon like peptide 1 (GLP-1)
Dulaglutide and semaglutide stimulate release of what in the pancreas
beta cells
where is GIP secreted from
K cells in the duodenum and jejunum
GIP causes what
inhibition of gastric acid seceretion
reduced intestinal motility
insulin secretion
GLP-1 is secreted from where
L cells
in the ileum and intestines (small and large)
L cells stimulate secretion GLP-1 by
fats and glucose entering the ileum and large(and small) intestine
K cells stimulate to secrete GIP by
protein, long chain fatty acids, mono/disaccharides, fats and glucose i n entering the small intestine
GLP-1 causes what secretion
insulin secretion
reduction in glucagon secretion
satiety
GLP-1 manages what kind of concentration in the blood
blood glucose concentration
GI peptides can stimulate tropic effects where
GI tract
what does gastrin do do gastrin mucosa
growth and differentiation
what does CCK stimulate to maintain
growth of pancreatic acinar cells
secretin inhibitts growth of what
inhibits pancreatic ductal cell growth
VIP (vasoactive intestinal peptide) stimulates growth of what
ductal cell growth
what stimulates growth in the small and large intestines
GLP-2
