The stomach is a marvelous piece of biological engineering - exactly what is needed by the body to break down food with powerful acids while protecting the body.
The majority of people don’t chew up food as well as they should (40-50 chews for a bite of steak? Seriously?).
Still, somehow, within the relatively narrow confines of the digestive system, all that food does indeed get broken down and appropriately utilized within a fairly narrow window of time.
Most everyone knows that it's the stomach that does the brunt of this work, secreting gastric acid (which contains a frighteningly large amount of hydrochloric acid, with a pH level of between 2 and 3) which is quite effective in dissolving any sort of edible (and sometimes even inedible) objects.
What most are not aware of (or at least are not concerned by), is the fact that a potentially deadly acid is being constantly secreted not a foot away from the mouth (and, consequently, the brain) – and despite it all, most people are doing just fine.
The Wonders of Acid Containment
It is, therefore, the lining of the stomach which should cause wonder and amazement.
While it seems as if one must be living in constant danger of being dissolved painfully from the inside out by way of stomach acid, it is rather rare that this actually occurs (when it does it is known as a stomach ulcer)
The stomach itself is protected by a thin but vital layer of mucus which is secreted by goblet cells in the outer layer of the stomach lining – the mucosa – the outer layer of which is called the epithelium, and contains all of the necessary glands of the stomach.
Now, this layer of mucus does a fairly good job of blocking the stomach acid and is being constantly helped along by the many other methods the stomach has for regulating how much acid is actually secreted (such as elements of the nervous system which can detect an abundance of gastric acid and respond with a release of parietal cells, G cells, and D cells, all of which serve to regulate the actual amount of acid present in the stomach at any given moment).
Beyond this, however, one must also keep in mind that the stomach does possess openings on both ends, allowing the possibility of acid escaping this relatively protected environment.
One Way Valves
Below the stomach lies the duodenum, the very first section of the small intestine, and it certainly would not take kindly to being burned with acid every time some food passed through it. So what does the body do to prevent this?
It does so by way of simply another secretion, this time of sodium bicarbonate (which in crystallized form is more commonly known as baking soda), which neutralizes any wayward acid, and rids the partially digested food of any chemical which has a high level of acidity.
This has only just scratched the surface in explaining exactly how all of this works. Clearly, the body has a lot to keep track of just so a person can eat even one little cracker.
Stomach Problems
Like any other complex system, there are occasions when one or more of these interlinking pieces to the system break down temporarily. In terms of the stomach, these little “hiccups” in the system tend to result in such painful things as ulcers and heartburn, where the body is not able to fully regulate the gastric acid and it begins to do harm to your normally quite capable stomach lining.
In addition to this is acid reflux (also known as gastroesophageal reflux), wherein a valve at the top of the stomach (the gastroesophageal valve, of course) fails in its purpose and allows acid to leave the stomach and enter into the esophagus, which is not designed to withstand such an assault.
Generally, however, the stomach valves are remarkably adept at their job in a fully automatic manner. In fact, it has been shown that the gastroesophageal valve continues to function perfectly even in cadavers. Morbid, but interesting.
Hydrochloric Acid
If the body is so well-equipped to handle the stuff, why is it that any bottle of hydrochloric acid found in any store is probably going to have a Mr. Yuck sticker on it, along with a warning (Probably in bold lettering) warning you not to drink it?
In reality, a little HCl (that's hydrochloric acid, for the layman) probably won't hurt terribly, but it will eventually begin to dissolve teeth, which is generally considered to be a bad thing, and it would probably feel somewhat like vomiting backwards.
Any more will surely cause great pain and discomfort within the mouth, throat, and, yes, even the stomach (which can only handle a certain amount of acid at a time).
Yet, this is the stuff that is constantly at work inside each of our bodies, serving its purpose with great skill and efficiency.
This is just something that must be accepted.
References:
“Stomach Acid.” Newton: Ask a Scientist.
“The Stomach.” Cliffs Notes.
