system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does my stomach acid not burn a hole through my body?
gpt
Your stomach and (upper GI tract) is lined with mucousa that acts as a buffer to this acid. This mucose doesn't react very stongly to acid, and takes a long time to wear down. If your diet is imbalanced, though, or you have certain disorders, it can wear down quicker and you will get ulcers and such.