Stomach Acid Homework Help: Why Doesn't It Eat Your Stomach?

Stomach Acid Homework Help: Why Doesn't It Eat Your Stomach?
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An Acid Bath

Acid is caustic and capable of eating away and destroying living organisms. The acid in your stomach is largely made up of its best known component, hydrochloric acid, along with potassium chloride and a tiny amount of sodium chloride. Chemically, it is an acid solution with a pH—the scientific measure of acidity—of 1.5 to 3.5 in the stomach with food—with 7 being equal to neutral. Simply put, solutions with low pH are highly acidic and the healthy stomach lies at a 4 or 5 when it’s empty.

Chew and Spew

Your muscles and other body parts are made up of proteins. The protein inside your body does not last forever and needs replenishing by proteins in the food. We take in the fuel our body needs by eating a variety of foods. We need about 13 vitamins and more than 20 minerals to keep our engines running properly.

The saliva in your mouth contains an enzyme that helps digest the carbohydrates in food while you are chewing, making them easier to swallow. The tongue and three salivary glands—located just below and in front of each ear, under the tongue and inside the jaw—create the needed spit. Your glands make about a quart (one liter) of saliva every day— enough that you could take a bath in your own spit every two months!

Chewing your food makes it smaller, spongier and slippery so it can be pushed into the back of your throat and past your trachea, which closes to prevent choking. The soft lump of food passes down through the pharynx, into your tube-like esophagus, past a sphincter muscle and into your stomach, where the function junction is ready to go to work on digestion.

Function Junction

The stomach is like a sack that holds about 0.4 gallon or 1.5 liter of stuff. The wall of the stomach has rugae—folds and wrinkles of tissue—that allow your stomach to expand in relation to the amount of food taken in. Through contractions, The stomach will mix and grind food with gastric secretions to liquefy the food mass before it goes to the small intestine.

A nervous system that influences the digesting foods called the enteric nervous system exerts control over the stomach muscles, the mucosa (mucus) and the thick lining of the stomach. They sense what’s in the stomach and inform the gastric wall. Then hormones, or body chemicals, increase the fluids that drip into the stomach. They also cause dilation or an expanding of blood vessels in the stomach wall.

A second system that controls digestive function is the endocrine system, which regulates food breakdown by secreting hormones. The gastrointestinal tract is the largest endocrine organ in the body and the endocrine cells within it are collectively referred to as the enteric endocrine system. Three of the best-studied digestive hormones that make acids and enzymes are:

  • Gastrin: Releases stomach juices
  • Cholecystokinin (CCK): Works in the small intestine to release bile from the gallbladder
  • Secretin: Cells that give off a bicarbonate-rich fluid from the pancreas and liver in the small intestine

This gastric juice breaks down food further.

Tumble & Rumble

The tiny holes in the rugae have numerous gastric pits. These gastric pits go into the mucosa or lining of the stomach forming little glands. There are four types of cells that cover the surface of the stomach and also go down into the gastric pits and glands:

  • Mucous cells: secrete an alkaline mucus that protects the epithelium—a thin layer of tightly packed stomach cells—against motion stress and stomach acid
  • Parietal cells: secrete hydrochloric acid
  • Chief cells: secrete pepsin, a proteolytic enzyme, as it breaks down proteins
  • G cells: secrete the hormone gastrin

The gastric or smooth stomach muscle does two things. It further grinds and mixes the food taken in, creating what’s called chyme. Chyme is eventually forced (through another sphincter muscle) into the pyloric canal of the small intestine for further processing.

Did you see it? The answer to the question why doesn’t the stomach dissolve itself? It’s because the mucous cells secrete slimy alkaline mucus. The acids can’t eat through the mucus, so the walls of your stomach are safe!

By the way, the growling and rumbling sounds your stomach makes are: borborygmi (pronounced BOR-boh-RIG-mee) The sounds are not normally due to the stomach telling us to eat more food—a common misconception—no, they are actually the contented sounds of digestion, the continued breaking down of food, liquid and gas.

Garbage In/Garbage Out

Your stomach holds good and bad bacteria. Stomach acid attacks and kills the bad tiny living organisms. Occasionally, though, the acid may sneak back up into the esophagus. You may experience a bad taste, burning and itching on the back of the throat. This is heartburn in a nutshell. Frequent heartburn can result in Gastroesophageal Reflux (GER).

Another problem with stomach acid is called Heliobacter pylori, which that is when the stomach bacteria attacks the stomach walls and creates an ulcer. It comes from contaminated water or food or person-to-person contact. According to, it is estimated that 30% of the population in the United States is infected. An antibiotic treatment is mostly the first step, followed by blood tests and even a biopsy (collecting a sample); and the diet will need to be adjusted until the bacteria are normalized.

That’s it for stomach digestion and the acids and wonders of the food processing phenomenon. Enjoy the fun facts below.

Fun Facts

The mouth has approximately 10,000 taste buds.

A meal can take up to three days to go through your body.

Your small intestine is only about an inch (2.5 centimeters) wide but stretched out, would be almost five times as tall as you are.

People who puke too often can suffer from rotted teeth.