A ring of muscle sits at the bottom of the esophagus. It is the lower esophageal sphincter (LES), and it should snap shut to keep stomach acid down where it belongs. When it stays loose, acid refluxes up into the esophagus. That is GERD. Do that for years and the lining changes, step by step, all the way to cancer. Explore both.
Esophagus, valve & stomach
The stomach is acidic, so its pH is low. Watch whether the LES holds that acid down. Or does it let acid splash up and burn the esophagus?
Pick a setup below to see the reflux.
Pick a setupthe valve, and the damage years of acid can do
① At the valve (LES)
② What years of acid can do
What's happening
The GERD staircase: acid → esophagitis (red and sore) → stricture (scar narrows it, so food sticks) and ulcers (bright red bleeding) → Barrett's (the lining turns pre-cancerous) → esophageal cancer. Three things stack the risk: long-term GERD, alcohol, and smoking.