Choudhury II Flashcards
proximal portionof stomach secretes what
HCl, pepsinogen, IF, mucus, bicarb, water
distal portion of stomach secretes what
gastrin, mucus, somatostatin (endocrine paracrin actions)
parietal or oxyntic cells secrete what
HCl, IF
chief cells secrete what
pepsinogen, renin
endocrine cells in stomach secrete what
ECL cells that secrete histamine
G cells secrete gastrin
D cells secrete somatostatin
what is role of HCl
protein breakdown, pepsinogen activation, kills most microbe
peptic chief cells secrete what
pepsinogen and its converted to pepsin
what is the purpose of the mucus that is secreted by mucous cells
lubrication to protect epithelial cells
pyloric glands are where
antrum and pyloric regions of the stomach
have G cells
what does gastrin do
stimulates pareital cells HCl and peptic cells (pepsinogen)
describe the mucus secreted by surface epithelial cells in stomach and the neck cells
surface is thick alkaline mucus
neck cells secrete thin watery mucus
chief cells secrete what
pepsinogen and gastric lipase
what stimulates D cells to secrete somatostatin
acid in the stomach
how do H+ and Na+ levels in the stomach change as the rate of gastric secretion increases
inverse relationship, more H+ less Na+ the faster the secretion
and- always high in Cl, always low in K
H+ concentration in gastric lumen compared to blood
3M fold higher
key player in maintaining low pH in gastric lumen
H-K ATPase on the parietal membrane facing gastric lumen
What stimulate parietal cells to secrete acid
ACh, gastrin and histamine
What R does ACh bind to
M3
what R does gastrin bind to
CCKb
what R does histamine bind to
H2
what are the inhibitors on parietal cells
somatostatin and PGs
what are the phases of gastric secretion
which has most acid secretion?
cephalic phase
gastric phase- most acid secretion
Intestinal phase
What is a vagotomy and what is it used for?
side effects?
cutting vagus nerve
inhibits gastric acid secretion
used to Tx peptic ulcers
side effects: delay in gastric emptying, diarrhea
what is a selective vagotom=y
cutting vagal nerves supplying parietal cells
what occurs in cephalic phase
conditioned reflexes from impulses to medulla stimulate vagus n Ach release gastrin release pepsinogen release inhibition D cells
what hormones does the duodenum release in intestinal phase?
role?
secretin
GIP
CCK
inhibit acid secretion
what stimulates cephalic phase
sight, smell, taste, chewing
what is rennin or chymosin
made by gastric chief cells in infants
proteolytic enzyme that causes milk to curdle in stomach so that it is retained and released more slowly
what replaces rennin in adults
pepsinogen
What converts pepsinogen to pepsin
pepsin and HCl
what stimulates secretion pepsinogen
vagal sitmulation, mediated by Ach
Direct response to gastric acid
what is pernicious anemia
absence of IF or B12 leading to neurological disturbances like paresthesias
what can cause B12 deficiency
decreased dietary intake decreased absorption (decreased IF or autoAb)
the mucus layer on gastric surface is a diffusion barrier for what
H and pepsin
how does aspirin lead to ulcer formation
suppresses the protective mucosal barrier production
cycle of acid causing mucosal damage
acid and pepsin break through mucosal barrier and the acid stimulates histamine release which then causes more acid release = viscous cycle
what is more common gastric or duodenal ulcer disease
duodenal
what is zollinger ellison syndrome
gastrin secreting tumor
What pathogen causes gastric ulcers and how
H pylor because increases gastrin secretion
what is used to evaluate gastric function
serum gastrin levels and gastric acid secretion
what is used clinically to stimulate acid secretion
pentagastrin
what is atrophic gastritis
chronic inflammation, with lack of parietal cells, of gastric mucosa from H pylori
serum gastrin way elevated by basal acid output and after pentagastrin remain zero
most likely?
pernicious anemia
serum gastrin super elevated with increased before and after pentagastrin aci output
most likely?
gastric ulcer
what part of H pylori leads to gastric ulcers
mucosal damage
what component of H pylori escapes pH
urease neutralizes gastric acid
What muscarinic antagonists are used in PUD
atropine and scopolamine
what H2 antagonists are used in PUd
cimetidine ranitidine
what PPI are used in PUD
omeprazole and lansoprazole
what drug is a PGE1 analog
misoprostol
How is sucralfate useful in PUD
polymerizes on GI luminal surface to form protective gel like coating on ulcers
what Antacids are usedul in PUD
Al(OH)3
Mg (OH)2
CaCo3
