gastric secretion Flashcards
function of stomach fundus
storage
function of stomach body
storage mucus HCl pepsinogen intrinsic factor
antrum
mixing/grinding
gastrin
what do cheif cells make
pepsinogens
what do parietal cells make
HCl
intrinsic factor
how is HCl made
CO2 combines w water in cytoplasm (carbonic anydrase) to make carbonic acid
dissociates to H+ and bicarbonate
H+ pumped out cell duye to conc gradient
bicarbonate pumped out in exchange for Cl-
Cl- pumped into stomach lumen
Cl- and H+ combine
gastric acid secretion is controlled by three mechanisms….
neurocine (vagus/local relfexes)
endocrine (gastrin)
paracrine (histamine)
Gastric acid secretion - cephalic phase
sight/smell/taste food –> vagus nerve –> more Ach to paritel cells
or vagus nerve –> G cells –> more gastrin to parietal cells
or
gastrin/Acl –> ECL cells –> huistamine to parietal cells
Gastric acid secretion - gastric phase
distension stomach –>vagal reflex –> Ach –> pariteal cells
peptides in lumen –> G cells –> gastrin –> parietal cells
gastrin/Ach –> ECL cells –> histamine –> parietal cells
mechanisms inhibiting gastric acid secretion: cephalic phase
stopping eating –> decreased vagal activity
mechanisms inhibiting gastric acid secretion: gastric phase
decrease pH (more HCl) –> less gastrin
mechanisms inhibiting gastric acid secretion: intestinal phase
acid in duodenum –> enterogastirc reflex and secretin release –> decrease gastrin release –> less gastrin stimulation of parietal cells
fat/CHO in duodenum –> GIP release –> less gastrin secretion
enterogastrones
hormones released from gland cells in duodneal mucosa
secretin, CCK, GIP
enterogastrones: what are they released in response to
acid, hypertonic solutions, fatty acids or monoglycerides in duodenum
enterogastrones: what do they do and how do they do it
act to collectively prevent further acid build up in duodenum
2 strategies
- inhibit gastric acid secretion
- reduce gastric emptying (inhibit motility/contract pyloric sphincter)
