A: They are different but related. It starts with the esophagus. The esophagus is made up of predominantly smooth muscle. It extends from the throat down through the chest cavity and, when it gets past the abdomen, joins up with the stomach. When you swallow, the esophagus opens and then squeezes food down.
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At the very bottom of the esophagus, there is a valve that separates it from the stomach. That valve should normally be closed. When you swallow, it opens so that food can pass through, and then it closes again. Acid reflux is a disorder that occurs when that valve opens when it’s not supposed to, so stomach contents (acid, digestive juices, enzymes and/or food) can flow backward from the stomach into the esophagus and cause symptoms.
Now, normal individuals can have up to an hour of reflux per day and not feel it. But if people have problematic reflux, it can cause heartburn, which is a burning that’s felt mid-chest, below the sternum, especially after meals or at night when you lie down. So heartburn is a symptom of acid reflux. Acid reflux can also cause regurgitation.
GERD stands for gastroesophageal reflux disease. It’s a more severe form of acid reflux where the stomach contents flowing back up into the esophagus becomes problematic. It can also cause a cough or the feeling that there’s a lump in the back of your throat.
GERD should be treated to avoid long-term problems.
— Gastroenterologist Scott Gabbard, MD