GI - Stomach Flashcards
cardia
area immediately surrounding esophageal opening
fundus
area above esophageal opening
fundus histo
thick secretory mucosa that form folds (rugae)
body histo
thick secretory mucosa that form folds (rugae)
pyloric antrum
heavy musculature for motility; smooth, no rugar
pyloric sphincter
to duodenum - thickening of circular muscle
gastric gland location
fundus and body
pyloric gland location
antrum
gastric glands secrete
HCl Pepsinogens IF mucus HCO3
pyloric glands secrete
mucus
gastrin
somatostatin
gastric glands (components)
epithelial cells
mucous neck cells
parietal cells
chief cells
epithelial cells secrete
mucous
HCO3
mucous neck cells
parent cells
migrate up –> surface epi
down –> parietal/chief
entire mucosa replaced every 3 days
parietal cells secrete
HCl
IF
chief cells secrete
pepsinogens
only essential substance secreted by stomach
IF
mucosal barrier components
mucous
HCO3
mucosal barrier fxn
protect mucosa from its own secretions
mucosal barrier aka
unstirred layer
pepsin fxn
digest proteins (split interior peptide linkage)
pepsinogen to pepsin conversion
activated by acidity (HCl - pH < 5)
autocatalysis to pepsin
stimulation of pepsinogen secretion
vagal activation (during cephalic and gastric phase) ACh
intrinsic factor aka
vitamin B12 binding protein
secretion of IF stimulation
vit B12 in food: meat, eggs, dairy
vit B12 absorption steps
- B12 binds to IF in duodenum when previous binding factor (saliva/stomach) is degreaded
- IF resistant of intestinal proteases
- IF/B12 complex absorbed in terminal ileum
absence of IF consequences
pernicious anemia
parietal cell transport on lumen side
- proton pump (H into lumen, K into cell, need ATP)
- Cl into lumen through channel
- K into lumen
parietal cell transport on blood side
- Na-K-ATPase (Na into blood, K into cell)
- K into blood through channel
- HCO3/Cl exchanger (HCO3 into blood, Cl into cell)
alkaline tide
outflow of HCO3 into blood elevates blood pH (used to maintain cell pH and electrical balance)
pyloric gland components
G cells
D cells
G cells secrete
gastrin
D cells secrete
somatostatin
gastrin fxns
- stim secretion of parietal/chief cells
- enhance gastric motility
- stim ileal motility
- relax ileocecal sphincter
- promote growth to stomach/SI mucosa
gastrin stimulated by
distension
proteins/AA in food
somatostatin fxns
- stop HCl secretion
- stop gastrin secretion
- stop histamine release
Enterochromaffin-like cells (ECL cells) secrete
histamine
things that control HCl secretion
ACh
gastrin
histamine
somatostatin
gastrin type of control
endocrine (circulating hormone)
ACh type of control
neurocrine (neurotransmitters)