I just answered your previous question a moment ago. Here is the recap.
We've asked the experts online here to post something about the z-line because it has come up a couple times. Best I can figure from the postings below, is that the z line is the area between the esophagus and the stomach at the sphincter, the muscle that closes the stomach to the esophagus. When there is a problem with this, it can cause acid to rise in the esophagus. That is my laymen's explanation for what I have read below.
Summerrain is a member here who is having issues with the z-line being a problem. You can read her posting here. User Hawkenser also had issues with the z-line. You can read his posting here.
If you think you are having issues with your GI tract, the best thing to do is see a doctor. It could be what you are experiencing is minor, but best to check it out. Online resources are great for getting the information you need to ask all the right questions, but it can not take the place of your doctor's sound medical care and advice.
Take care and stay in touch!
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