[Verse 1]
Alright, three phases running — cephalic hits first
Before the food arrives, the brain's already rehearsed
Vagus nerve fires, acetylcholine deployed
Gastrin drops from G-cells, ECL cells get employed
Histamine binds H2 receptors on the parietal wall
That triggers the proton pump — H plus K ATPase — standing tall
Hydrogen gets pumped out, potassium pulled in
pH drops to one or two, digestion can begin
Then gastric phase — food stretches the antrum wide
Amino acids, peptides flooding the inside
Intestinal phase brings secretin and CCK
Somatostatin from D-cells puts the brakes in play
[Chorus]
Parietal cell makes acid, intrinsic factor too
Pepsinogen from chief cells activates at low pH, it's true
Three stimulants — histamine, gastrin, acetylcholine
One inhibitor — somatostatin keeps the output clean
Cephalic, gastric, intestinal — three phases, memorise the chain
Pump the proton, buffer the mucosa, protect the terrain
[Verse 2]
Chief cells drop pepsinogen — inactive precursor form
Acid cleaves it into pepsin when conditions meet the norm
Goblet cells and mucus neck cells coat the gastric lining
Bicarbonate sits underneath — a two-layer pH designing
Prostaglandins E2 maintain that mucosal seal
Block COX enzymes with NSAIDs, you compromise the deal
Intrinsic factor — glycoprotein — binds to B12 tight
Carried to the terminal ileum, absorbed into the bloodstream right
GIP blunts acid output when fat hits the duodenal space
GLP-1 slows gastric emptying, glucose handled at a measured pace
Ghrelin rises fasting — hunger signal from the fundus wall
Gastrin from the antrum — trophic, secretory — answers every call
[Chorus]
Parietal cell makes acid, intrinsic factor too
Pepsinogen from chief cells activates at low pH, it's true
Three stimulants — histamine, gastrin, acetylcholine
One inhibitor — somatostatin keeps the output clean
Cephalic, gastric, intestinal — three phases, memorise the chain
Pump the proton, buffer the mucosa, protect the terrain
[Verse 3]
Motility now — receptive relaxation drops the fundal tone
Vagally mediated, VIP-assisted, stomach finds its zone
Antral pump grinds solid particles under four millimetres small
Pylorus acts as gatekeeper — regulates what gets through at all
Liquids empty faster — exponential curve decay
Solids need the antrum's work — linear emptying all the way
Interdigestive — migrating motor complex sweeps the floor
Phase three is the housekeeper, motilin-driven, clearing residue and more
[Bridge]
Now cut the vagus — truncal vagotomy —
Receptive relaxation fails, rapid emptying, you see
Dumping syndrome follows — osmotic load hits the jejunum fast
Early dumping, vasomotor collapse — the hypotension doesn't last
Late dumping — reactive hypoglycaemia two hours down
Gastrectomy removes the intrinsic factor, B12 depletes around
Iron absorption fails without the acid milieu
Calcium and vitamin D drop — osteoporosis comes through