When you swallow your food, your stomach is the first digestive compartment into which food passes. Here, acid secretions from cells in the stomach lining begin to break nutrient molecules into smaller pieces that your intestine can absorb into the bloodstream. The stomach secretions are quite acidic, however, which can sometimes cause problems.
Stomach Acid
Stomach acid, sometimes called gastric acid, consists of a mixture of strongly acidic HCl molecules and water. HCl, or hydrochloric acid, comes from parietal cells in the stomach lining, explains Dr. Lauralee Sherwood in her book "Human Physiology." While much of the human body has a relatively neutral pH, or acidity, the interior of the stomach is very strongly acidic. This helps in food digestion, as acid breaks down many of the nutrient molecules in your food.
Neutralization
One physiological challenge presented by the production of strong acid by stomach cells is that most body tissues aren't able to withstand strong acid. When food passes from the stomach into the small intestine, it's mixed with strong acid, which risks damaging the intestinal lining. As such, your pancreas produces a neutralizing solution of sodium bicarbonate, explains Dr. Gary Thibodeau in his book "Anatomy and Physiology." This mixes with food from the stomach and maintains the pH of the intestines at near-neutral.
Acid Benefits
In addition to helping you digest your food, the acid produced by your stomach helps to protect you from pathogens like bacteria. Most bacterial species can't withstand the strongly acidic interior of the stomach. As such, when you consume food contaminated with potentially pathogenic bacteria -- which occurs relatively frequently -- your stomach acid acts as a defense mechanism, working to prevent infection. In fact, those who frequently use antacids or acid-neutralizing drugs are more susceptible to infection than those who don't rely upon such drugs.
Acid Reflux
If your stomach overproduces acid or if acid from the stomach refluxes back into the esophagus, you can experience heartburn. This uncomfortable sensation is the result of irritation of the esophageal lining. You can treat heartburn with antacids, which neutralize existing stomach acid, or with over-the-counter or prescription drugs. MayoClinic.com explains that the two major classes of drugs for stomach acid production include H2 blockers, which reduce your acid production, and proton pump inhibitors, which inhibit acid production completely.
References
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- "Anatomy and Physiology"; Gary Thibodeau, Ph.D.; 2007
- MayoClinic.com: Acid Production
