Hydrochloric acid constitutes the majority of gastric acid, the human digestive fluid. In a complex process and at a large energy burden, it is secreted by parietal cells (also known as oxyntic cells). These cells contain an extensive secretory network (called canaliculi) from which the HCl is secreted into the lumen of the stomach. They are part of the fundic glands (also known as oxyntic glands) in the stomach.

Citric acid exists in a variety of fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit.

Umm seems as though acids are around in a great deal of living organisms - maybe it is just blind faith that stops them dissolving???