Gastric Acid Secretion
Ionic composition
- Major ion is chloride
- H+ diminishes at lower secretory rate
- K+ always higher than plasma (prolonged vomiting leads to hypokalaemia)
Control
Stimulants of acid secretion
- Acetylcholine
- Histamine
- Gastrin
Endogenous antagonists of acid secretion
- prostaglandins E & I
- somatostatin
- EGF
Stimulants of protective secretion (mucus & bicarbonate)
- acetylcholine
- mechanical stimulation
Antagonists of mucus and bicarb secretion
- alpha-adrenergic agonists (bicarb)
- aspirin & NSAIDS
Three phases
- Cephalic
- Gastric
- Intestinal
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