Gastric Secretion Flashcards
Functional anatomy of stomach
Fundus
Body
Antrum
Fundus
Storage
Body
Storage Mucus HCl Pepsinogen Intrinsic factor
Antrum
Mixing/grinding
Gastrin
Cellular composition of gastric glands
Mucous neck cells
Chief cells
Parietal cells
Mucous neck cells
Produce mucus
Chief cells
Pepsinogens
Parietal cells
HCl Intrinsic factor (essential)
Mechanisms
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Gastric acid secretion mechanisms
Neurocrine
Endocrine
Paracrine
Neurocrine
Vagus/local reflexes
Endocrine
Gastrin
Paracrine
Histamine
Enterogastrones
Hormones released from gland cells in duodenal mucosa - secretin, cholecystokinin (CCK), GIP
When are enterogastrones released?
In response to acid, hypertonic solutions, fatty acids or monoglycerides in duodenum
Act collectively to prevent further acid build up in duodenum
Strategies of enterogastrones
Inhibit gastric acid secretion
Reduce gastric emptying (inhibit motility/contract pyloric sphincter)
Inactive precursor of pepsinogen
Zymogen
Purpose of zymogen storage
Prevents cellular digestion
When are pepsins inactivated
At neutral pH
Gastric mucus produced by
Surface epithelial cells and mucous neck cells
Purpose of gastric mucus
Cytoprotective - protects mucosal surface from mechanical injury Neutral pH (HCO3) => Protects against gastric acid corrosion and pepsin digestion
Intrinsic factor
Required for vitamin B12 absorption
Intrinsic factor/B12 complex absorbed from ileum
Intrinsic factor defect
Pernicious anaemia (failure of erythrocyte maturation)
