What is "excessive acidity"?

Acidity...what is that?
p.s. i'm in medical conservatory...thanks :]What is "excessive acidity"?
Hope that help:
http://nutrients.ifas.ufl.edu/nutrient%2...
Too much acid within the system makes your stomach and digetive areas more prone to ulcer, colitis, because excess acids are secreted. For instance, orange liquid and lemon juice are both caustic, while a cantelope is not.
acidity is not accurate for the body. you want your body to be alkiline with a biddable ph balance of 7-7.5. the tang causes your body to carry sicker.
Heartburn usually results from excess acidity surrounded by the stomach, or from improper functioning of your digestive system.
At the point where on earth the esophagus and stomach join, a special muscle open and closes the esophagus. When we swallow food this muscle relaxes to let the food overrun into the stomach after which it closes again.
But it can happen that the muscle malfunction. The contents of the stomach then rise backbone up the esophagus, irritating the area. And this results within the infamous feeling of heartburn/acidity.

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