What's in the Stomach's Gastric Juice? What's in the Stomach's Gastric Juice? Search the site By Shereen Lehman, MS - Reviewed by a board-certified physician. Updated August 24, 2016 The food you chew and swallow (called a bolus) mixes with the gastric juices secreted by special glands found in the lining of your stomach. They include the cardiac glands at the top part of the stomach, the oxyntic glands in the main body of the stomach and the pyloric glands, located in the antrum or the lowest part of the stomach. Each of the glands contains cells that make specific components that together are called the gastric juices. Neck cells secrete bicarbonate and mucous, parietal cells secrete hydrochloric acid, chief cells secrete pepsinogen, and enteroendocrine cells secrete various hormones. Not all stomach glands contain every type of cell. Breaking Down the Gastric Juices Gastric juice is made up of water, electrolytes, hydrochloric acid, enzymes, mucus and intrinsic factor.

Hydrochloric acid is a strong acid secreted by the parietal cells, and it lowers the pH of your stomach to around 2. Hydrochloric acid converts pepsinogen into pepsin and breaks various nutrients apart from the food you eat. It also kills bacteria that comes along with your food. Pepsinogen is secreted by chief cells, and when it's in the presence of hydrochloric acid, it's converted to pepsin. Pepsin breaks apart tertiary and secondary protein structures to make it easier for the digestive enzymes in the small intestines to work later. Gastric lipase is another digestive enzyme made by the chief cells. It helps break down short and medium chain fats. Amylase is also found in gastric juices, but it isn't made by the stomach, it comes from saliva and travels with the bolus into the stomach. Amylase breaks down carbohydrates, but it doesn't have much time to work on the stomach because the acidity stops it. But that's okay, your small intestine makes more amylase later on.

Intrinsic factor is secreted by parietal cells and is necessary for your body to absorb vitamin B-12 , which is essential for healthy nervous system function and blood cell production. Finally, the gastric juices contain water and mucus. The mucus is secreted by the neck cells and helps coat the protect your stomach lining from the acid environment. Your stomach muscles squeeze and churn to mix the bolus with the digestive juices. The liquidy mixture is called chyme, and when it's ready, your stomach squirts the chyme into the small intestine where digestion and absorption of food continues. Sources: Gropper SS, Smith JL, Groff JL. "Advanced Nutrition and Human Metabolism." Sixth Edition. Belmont, CA. Wadsworth Publishing Company, 2013. Smolin LA, Grosvenor, MB. "Nutrition: Science and Applications." Third Edition. Wiley Publishing Company, 2013. cedarbraechemistry - 8 neutralizing stomach acid = Thurka Thankathurai cedarbraechemistry Export (PDF) Neutralizing Stomach Acid Introduction – What is Stomach Acid?Stomach Acid is the acidic liquid in your stomach used to digest foods.

It is also known as Gastric Acid, and is composed of a mixture of hydrochloric acid, potassium chloride, and sodium chloride. Its pH level averages between 1 and 2, which is acidic enough to slowly dissolve a thin strip of zinc. This acid is also strong enough to eat through living tissue, which would be a serious problem if not for the stomach cells constantly coating the inside of the stomach with mucus which is a critical barrier that protects the stomach from the acid, as well as having those cells reproduce at a rate around half a million per minute. Ever get that heartburn feeling from eating certain foods? Why Stomach Acid might need to be neutralized: As would be expected of a substance inside the body that is able to digest the living tissue around it, some problems can arise with stomach acid that would require some of it to be neutralized. The most recognized problem is when the acid leaks upward through a valve into the esophagus, causing what is known as acid reflux or heartburn. Heartburn is when the stomach acids get into the esophagus and eat away at the lining, causing a burning sensation in the chest and throat.

Leakage into the esophagus can be caused by a variety of reasons, including spicy foods, too much food, too little food, being overweight etc. In order to reduce the leakage of stomach acid into the esophagus, neutralization of some of the acid would be required, lest the esophagus receives permanent damage. In order to do this, antacids, which contain base materials, are taken. This is called gastric esophageal reflux disease, GERD or the prefered word "reflux". This picture explains how reflux occurs. This video helps understand more about Heart Burn. How neutralization of Stomach Acid works: In order to expunge heartburn, some of the acid within the stomach needs to be neutralized. To do this, an antacid is taken. These antacids contain chemicals used to neutralize some of the acid in the stomach. In order to do so, a base chemical, generally aluminum hydroxide or magnesium hydroxide are used, as they're weak enough to not neutralize all of the acid, but strong enough to still neutralize enough of it.

These compounds are also not very soluble, which means that not enough hydroxide ions are produced during taking the antacid to cause any irritation in the throat or mouth. However, it is generally a good idea not to take too many antacids of any type at once, as not only would the neutralization of so much acid make digesting foods difficult, but certain antacids, such as Sodium Hydrogen Carbonate (NaHCO3), contain sodium ions we already receive from salted foods. Due to the chemical composition of the antacids, when they come in contact with the hydrochloric acid within the stomach acid, a chemical process occurs that neutralizes the acid. This is because the antacids contain weak base substances as mentioned previously. Although the chemical equation of neutralization differs based on what kind of antacid taken, an example using Aluminum Hydroxide would be: 3 HCl(aq) + Al(OH)3(s) → AlCl3(aq) + 3 H2O(l) The chemical equations for Sodium Hydrogen Carbonate and Calcium Carbonate antacids. These are two examples of Antacids. Tums contains CaCO3.

Rolaids contains CaCO3 and Mg(OH)2 In Conclusion..Stomach acid is an important fluid in our bodies even though it has the capability of eating us from the inside. That being said, without it, there would be no way for us to digest foods. Even though it is potentially harmful but also absolutely needed, there are times when the acid gets out of hand and causes heartburn which harms our esophagus'. When that arises, antacids are needed to neutralize some of the acid within the stomach. Be it Tums, Rolaids, Pepcid Complete or a simple teaspoon of baking soda, some kind of basic substance is needed to get the amount of acid back under control. Now that you have learned the risks of stomach acids and how to neutralize it, HAVE A NICE STOMACH! :) Bibliography Stomach acid-the why and the what - Stop The Thyroid Madness Home » Stomach acid–the why and the what Stomach acid–the why and the what Stomach acid is not something most people think about. Yet it’s one of the most important aspects of your digestive system!

Stomach acid, also called Gastric Acid, is made on demand when you eat via the parietal cells that line your stomach. Those parietal cells use various minerals to help make stomach acid–the latter which is mainly composed of hydrochloric acid, potassium and sodium, and will usually have a pH of 1.35 to 3.5 (Wiki), i.e. it’s all highly regulated. It’s purpose is to keep your pH levels down. Other cells in your stomach produce bicarbonate to help buffer the acidity, as well as mucus to help protect your stomach lining from the aciditiy. What does stomach acid do for me? Two key benefits: absorption and protection. When food hits your stomach, it’s your stomach’s gastric acid that begins the breakdown of protein and most minerals with pepsin to prepare for the important absorption of key nutrients (like iron B12, Vit. D and MORE) in those foods for your health and well-being. It also helps knock out bad or dangerous bacteria. Low stomach acid also leads to non-optimal levels of neurotransmitters/amino acids (chemicals which transmit signals from one cell to another and play a huge role in your health and well-being).

How hypothyroidism negatively affects your stomach acid levels Just as hypothyroidism can result in the drying out of your skin and hair, it also seems to lower the levels of stomach acid in many thyroid patients, possibly by lowering your amount of parietel cells or lowering their ability to produce gastric acid, aka hypochlorhydria. The result? he absorption of important nutrients is reduced, and you can find yourself with non-optimal or low levels of iron, B12, Vitamin D and more. And you won’t have the protection you once had against bad forms of bacteria, causing their over-growth (dysbyosis). Symptoms can include delayed excessive gas as that bacteria enters your intestine. (Long term antibiotic use can also cause the same overgrowth.) Those low levels also cause the diagnosis of “gastritis”–when the stomach becomes inflamed and irritated DUE to the low stomach acid causing food or supplements to sit too long, thus irritation of the stomach lining. Acid reflux (GERD), heartburn, and indigestion–high levels of stomach acid? Nope.

Turns out that it’s our low levels of stomach acid which cause the Big 3: acid reflux (where our undigested stomach contents press up into our esophagus via a now-relaxed esophagus value and we feel the small amount of acid), heartburn (the burning sensation in our esophagus) and indigestion (impaired digestion due to poor breakdown of bad bacteria). And sadly, our doctors have been putting us on Proton-pump inhibitors (PPIs) like Omeprazole (Prilosec) or Lansoprazole (Prevacid) or Esomepraxole (Nexium) and more, all acid suppressors…and as if our symptoms come from excess acid! Or we head to our local pharmacy or grocery store and load up on antacids like Rolaids, Tums or others. So though they can mask symptoms, we are now made even worse. You can even have diarrhea from low stomach acid due to the inadequate digestion and pH issue of low stomach acid. Some speculate that inflammatory bowel disease is the result of low levels of stomach acid. Aging and low stomach acid Research has found that the older your body gets, the lower your secretion of stomach acid can become.

This happened to the elderly mother-in-law of the creator of this site, even without being hypothyroid, and she did much better with her digestion once she added Apple Cider Vinegar to her morning and bedtime water. Low stomach acid and Candida Patients have discovered that increasing the acidic level of their stomachs can slow the growth of candida. (By the way, if you have candida, do an internet search for “baking soda candida”) Low stomach acid, Lactose and/or Gluten Intolerance Many patients are surprised to discover that their intolerance to milk products, called lactose intolerance, is actually a symptom of poor levels of stomach acid. And as happened to the husband of the creator of this site, his lactose intolerance completely went away once he started to give himself Apple Cider Vinegar (see below) in his morning drink. Even many cases of gluten intolerance can be connected to low stomach acid for some individuals. They have found that when they improve their acid levels, they are less sensitive to gluten to some degree. The solution? Treating one’s hypothyroidism, especially with natural desiccated thyroid (NDT) , has helped reverse the problem of low stomach acid.

It can also be important to treat low cortisol / low aldosterone to return stomach acid levels to normal. Swallowing daily supplements with healthy acids added to water or your favorite juice, such as one tablespoon Apple Cider Vinegar (ACV) or lemon juice, has helped many. Preferable brands of ACV are unfiltered, unheated, and unpasteurized (Braggs is one, but there are others). You can also disguise the ACV in water with flavored stevia, or Vitamin C packets, or more. Do NOT drink ACV by itself–it can burn your esophagus. Two notes: 1) if you have high potassium, you might want to avoid ACV and use lemon juice or Betaine below instead. 2) If you have a peptic ulcer, you’ll need to first work on healing that. Cabbage Juice can help, says this study . Other forms of healthy acids may do the trick as well. Over-the-counter hydrochloric acid, often known by the brand name Betaine, has helped.

(Note: if you get diarrhea with Betaine, it may reveal that you also have h-pylori ) The herb called Swedish Bitters may be worth a try, as it’s stated to help raise hydrochloric acid levels. It’s been recommended in the treatment of Candida, as well. Restoring your iodine levels may improve stomach acid production as well, as some articles suggest. Eradicating the bacteria H-Pylori can be key for some. As you give yourself back the acid you need, absorption of key nutrients returns, which helps your parietal cells produce acid better all over again. Many patients also turn to using a quality Probiotic along with their healthy acid supplements. Probiotics contain healthy bacteria as a way to start balancing out the abundance of bad bacteria. Note: If you have been on Proton-pump inhibitors (PPIs) like Prilosec or over-the-counter digestive aids like Rolaids or Tums etc for an extended period, and want to get off, it’s recommended not to stop cold turkey, but to wean off to avoid some side-effects of withdrawal. Janie’s husband went off cold turkey, and had heartburn for a week and poor tolerance for acids .

It eventually subsided, and he returned to using ACV until he could get his hypothyroidism better treated. Ways to test if you have low stomach acid (even though it’s a given for most thyroid patients if you find yourself with low nutrients like iron, B12, Vit. D or more) Baking Soda test (non-scientific): After you have gotten up in the morning, and before eating or drinking, mix about 1/4 tsp baking soda in a cup of water and drink it down. Watch to see if you have burped in the next 2 – 3 minutes (stomach acid and baking soda react to form carbon dioxide gas). If you do NOT, you probably have low stomach acid. NOTE: one test is not definitive. You have to do this test at least 3 mornings and see if you have more “No, I didn’t burp in 2-3 minutes”, then Yes, I did. This test is only a rough indication.

Betaine HCl Challenge Test (non-scientific and not to be done if you have peptic ulcers): You will need to purchase Betaine, preferably the 600 mg pills, at your local health food store–a man-made hydrochloric acid. Your goal is to find out how many tablets it takes to feel a warmth or burning in your stomach. Patients with normal stomach acid levels would feel this with one, or sometimes two pills. On the first day, take one right before or at the beginning of large meal. On the second day, take two before or at the beginning of a large meal. On the third day, take three before or at the beginning of a large meal….etc up to the 7th day and 7 tablets, if needed (some versions of this test go up to ten days and 10 tablets). The more tablets you have to take to feel that warmth, the more likely you have low stomach acid. NOTE: if this test produces excess burning in the beginning, it’s a sign you have too much stomach acid and this test should immediately stop. Otherwise, this test is only meant to be used until you feel that burn/warmth, which could happen before the seventh day.

The Heidelberg Stomach Acid test (scientific): This is a test you’ll have to ask your doctor about, and thus, is far more exact than the above, but can be costly–more than $300 US. You are instructed to drink a baking soda solution (sodium bicarbonate) as well as swallow a capsule with a tiny pH meter and radio transmitter (radiotelemetry). It will analyze the pH of your stomach acid. NOTE: you will need to be off any Proton Pump Inhibitors or over-the-counter stomach aides for about five days. This test takes about an hour or slightly more time. P.S. Low aldosterone , which causes low levels of sodium, can promote low stomach acid, since the acid needs salt to exist! ***A research study which connects hypothyroidism to low stomach here . ***Why is Hypochlorhydria Common in Thyroid Conditions article here . Search for: CHEMTUTOR ACIDS AND BASES Chemists or chemistry texts often use the hydrogen ion, H + to show a hydrogen ion released into water solution. In a way, there is no such thing as a hydrogen ion or proton without anything else.

The majority of hydrogen atoms are only a single proton and a single electron. If you remove the electron to make it an ion, the only thing that is left is a proton. Protons just don't exist naked like that in water solution. Remember that water is a very polar material. There is a strong partial negative charge on the side of the oxygen atom and a strong partial positive charge on the hydrogen side. Any loose hydrogen ion, having a positive charge, would quickly find itself near the oxygen of a water molecule. At close range from the charge attraction, the hydrogen ion would find a pair (its choice of two pairs) of unshared electrons around the oxygen that would be capable of filling the its outer shell. Each hydrogen ion unites with a water molecule to produce a hydronium ion, (H 3 O) + , the real species that acts as acid. The hydroxide ion in solution does not combine with a water molecule in any similar fashion. As we write reactions of acids and bases, it is usually most convenient to ignore the hydronium ion in favor of writing just a hydrogen ion, H + 2 ), acetic acid. Acids neutralize bases in a neutralization reaction.

An acid and a base combine to make a salt and water. A salt is any ionic compound that could be made with the anion of an acid and the cation of a base. The hydrogen ion of the acid and the hydroxide ion of the base unite to form water. Acids corrode active metals. Even gold, the least active metal, is attacked by an acid, a mixture of acids called 'aqua regia,' or 'royal liquid.' When an acid reacts with a metal, it produces a compound with the cation of the metal and the anion of the acid and hydrogen gas. Acids turn blue litmus to red. Litmus is one of a large number of organic compounds that change colors when a solution changes acidity at a particular point. Litmus is the oldest known pH indicator. It is red in acid and blue in base. The phrase, 'litmus test,' indicates that litmus has been around a long time in the English language. Litmus does not change color exactly at the neutral point between acid and base, but very close to it. Litmus is often impregnated onto paper to make 'litmus paper.' Acids taste sour.

TASTING LAB ACIDS IS NOT PERMITTED BY ANY SCHOOL. The word 'sauer' in German means acid and is pronounced almost exactly the same way as 'sour' in English. (Sauerkraut is sour cabbage, cabbage preserved in its own fermented lactic acid. ) Stomach acid is hydrochloric acid. Although tasting stomach acid is not pleasant, it has the sour taste of acid. Acetic acid is the acid ingredient in vinegar. Citrus fruits such as lemons, grapefruit, oranges, and limes have citric acid in the juice. Sour milk, sour cream, yogurt, kimchi, and cottage cheese have lactic acid from the fermentation of the sugar lactose. 1 - hydroiodic acid The acids on this short list are called strong acids, because the amount of acid quality of a solution depends upon the concentration of ionized hydrogens. Muriatic acid is the name given to an industrial grade of hydrochloric acid that is often used in the finishing of concrete. Less concentated hydrochloric acid can be found in the human stomach. Strong acids are completely ionized in water. You are not likely to see much HBr or HI in the lab because they are expensive.

You are not likely to see perchloric acid in a school setting because it can explode if not treated carefully. Other acids are incompletely ionized, existing mostly as the unionized form. Incompletely ionized acids are called weak acids, because there is a smaller concentration of ionized hydrogens available in the solution. Do not confuse this terminology with the concentration of acids. The differences in concentration of the entire acid will be termed dilute or concentrated. In the list of strong acids, sulfuric acid is the only one that is diprotic, because it has two ionizable hydrogens per formula (or two mols of ionizable hydrogen per mol of acid). (Sulfuric acid ionizes in two steps. The first time a hydrogen ion splits off of the sulfuric acid, it acts like a strong acid. The second time a hydrogen splits away from the sulfate ion, it acts like a weak acid.) The other acids in the list are monoprotic, having only one ionizable proton per formula. Phosphoric acid, H3PO 4 , is a weak acid. Phosphoric acid has three hydrogen ions available to ionize and lose as a proton, and so phosphoric acid is triprotic.

We call any acid with two or more ionizable hydrogens polyprotic. Likewise, there is a short list of strong bases, ones that completely ionize into hydroxide ions and a conjugate acid. All of the bases of Group I and Group II metals except for beryllium are strong bases. Again, like the strong acids, the strong bases are completely ionized in water solution. Lithium, rubidium and cesium hydroxides are not often used in the lab because they are expensive. The bases of Group II metals, magnesium, calcium, barium, and strontium are strong, but all of these bases have somewhat limited solubility. Barium hydroxide has a high enough solubility to really call it the only dibasic strong base. Magnesium hydroxide has a particularly small solubility. Potassium and sodium hydroxides both have the common name of lye. Soda lye (NaOH) and potash lye (KOH) are common names to distinguish the two compounds. LiOH Stomach Click to View Pic Stomach The stomach is the main food storage tank of the body.

If it were not for the stomach’s storage capacity, we would have to eat constantly instead of just a few times each day. The stomach also secretes a mixture of acid, mucus, and digestive enzymes that helps to digest and sanitize our food while it is being stored. Anatomy of the Stomach Gross Anatomy The stomach is a rounded, hollow organ located just inferior to the diaphragm in the left part of the abdominal cavity. Located between the esophagus and the duodenum, the stomach is a roughly crescent-shaped enlargement of the gastrointestinal tract. The inner layer of the stomach is full of wrinkles known as rugae (or gastric folds ). Rugae both allow the stomach to stretch in order to accommodate large meals and help to grip and move food during digestion. The stomach can be divided into four regions based on shape and function: The esophagus connects to the stomach at a small region called the cardia. The cardia is a narrow, tube-like region that opens up into the wider regions of the stomach. Within the cardia is the lower esophageal sphincter, a band of muscle tissue that contracts to hold food and acid inside of the stomach.

The cardia empties into the body of the stomach, which forms the central and largest region of the stomach. Superior to the body is a dome shaped region known as the fundus. Inferior to the body is a funnel shaped region known as the pylorus. The pylorus connects the stomach to the duodenum and contains the pyloric sphincter. The pyloric sphincter controls the flow of partially digested food (known as chyme) out of the stomach and into the duodenum. Microscopic Anatomy Microscopic analysis of the stomach’s structure reveals that it is made of several distinct layers of tissue: the mucosa, submucosa, muscularis, and serosa layers. The innermost layer of the stomach is known as the mucosa, and is made of mucous membrane. The mucous membrane of the stomach contains simple columnar epithelium tissue with many exocrine cells. Small pores called gastric pits contain many exocrine cells that secrete digestive enzymes and hydrochloric acid into the lumen, or hollow region, of the stomach. Mucous cells found throughout the stomach lining and gastric pits secrete mucus to protect the stomach from its own digestive secretions.

The mucosa of the stomach is much thicker than the mucosa of the other organs of the gastrointestinal tract due to the depth of the gastric pits. Deep inside the mucosa is a thin layer of smooth muscle known as the muscularis mucosae. The muscularis mucosae layer allows the mucosa to form folds and increase its contact with the stomach’s contents. Surrounding the mucosa is the submucosa layer of the stomach. The submucosa is made up of various connective tissues, blood vessels, and nerves. Connective tissues support the tissues of the mucosa and connect it to the muscularis layer. The blood supply of the submucosa provides nutrients to the wall of the stomach. Nervous tissue in the submucosa monitors the contents of the stomach and controls smooth muscle contraction and secretion of digestive substances. The muscularis layer of the stomach surrounds the submucosa and makes up a large amount of the stomach’s mass. The muscularis is made of 3 layers of smooth muscle tissue arranged with its fibers running in 3 different directions. These layers of smooth muscle allow the stomach to contract to mix and propel food through the digestive tract.

The outermost layer of the stomach surrounding the muscularis layer is the serosa – a thin serous membrane made of simple squamous epithelial tissue and areolar connective tissue. The serosa has a smooth, slippery surface and secretes a thin, watery secretion known as serous fluid. The smooth, wet surface of the serosa helps to protect the stomach from friction as it expands with food and moves to mix and propel the food. Physiology of the Stomach Storage In the mouth , we chew and moisten solid food until it becomes a small mass known as a bolus. When we swallow each bolus, it then passes through the esophagus to the stomach where it is stored along with other boluses and liquids from the same meal. The size of the stomach varies from person to person, but on average it can comfortably contain 1-2 liters of food and liquid during a meal. When stretched to its maximum capacity by a large meal or overeating, the stomach may hold up to 3-4 liters. Distention of the stomach to its maximum size makes digestion difficult, as the stomach cannot easily contract to mix food properly and leads to feelings of discomfort.

After the stomach has been filled with food from a meal, it stores the food for about 1-2 hours. During this time, the stomach continues the digestive process that began in the mouth and allows the intestines, pancreas , gallbladder , and liver to prepare to complete the digestive process. At the inferior end of the stomach, the pyloric sphincter controls the movement of food into the intestines. The pyloric sphincter is normally closed to keep food and stomach secretions within the stomach. Once chyme is ready to leave the stomach, the pyloric sphincter opens to allow a small amount of chyme to pass into the duodenum . This process, known as gastric emptying, slowly repeats over the 1-2 hours that food is stored in the stomach. The slow rate of gastric emptying helps to spread out the volume of chyme being released from the stomach and maximizes the digestion and absorption of nutrients in the intestines . Secretion The stomach produces and secretes several important substances to control the digestion of food. Each of these substances is produced by exocrine or endocrine cells found in the mucosa.

The main exocrine product of the stomach is gastric juice – a mixture of mucus, hydrochloric acid, and digestive enzymes. Gastric juice is mixed with food in the stomach to promote digestion. Specialized exocrine cells of the mucosa known as mucous cells secrete mucus into the lumen of the stomach and into the gastric pits. This mucus spreads across the surface of the mucosa to coat the lining of the stomach with a thick, acid- and enzyme-resistant barrier. Stomach mucus is also rich in bicarbonate ions, which neutralize the pH of stomach acid. Parietal cells found in the gastric pits of the stomach produce 2 important secretions: intrinsic factor and hydrochloric acid. Intrinsic factor is a glycoprotein that binds to the vitamin B12 in the stomach and allows the vitamin to be absorbed in the small intestine . Vitamin B12 is an essential nutrient for the formation of red blood cells. Hydrochloric acid protects the body by killing pathogenic bacteria naturally found in food. Hydrochloric acid also helps to digest proteins by denaturing them into an unfolded shape that is easier for enzymes to digest.

The protein digesting enzyme pepsin is activated by exposure to hydrochloric acid inside the stomach. Chief cells, also found within the gastric pits of the stomach, produce two digestive enzymes: pepsinogen and gastric lipase. Pepsinogen is the precursor molecule of the very potent protein-digesting enzyme pepsin. Because pepsin would destroy the chief cells that produce it, it is secreted in its inactive pepsinogen form. When pepsinogen reaches the acidic pH found in the stomach thanks to hydrochloric acid, it changes shape and becomes the active enzyme pepsin. Pepsin then breaks dietary proteins into their amino acid building blocks. Gastric lipase is an enzyme that digests fats by removing a fatty acid from a triglyceride molecule. G cells are endocrine cells found at the bottom of the gastric pits. G cells release the hormone gastrin into the bloodstream in response to many stimuli, such as signals from the vagus nerve ; the presence of amino acids in the stomach from digested proteins; and the stretching of the stomach wall during a meal. Gastrin travels through the blood to various receptor cells throughout the stomach where it stimulates the glands and muscles of the stomach.

Glandular stimulation by gastrin leads to increased secretion of gastric juice to increase digestion. Stimulation of smooth muscles by gastrin leads to stronger contractions of the stomach and the opening of the pyloric sphincter to move food into the duodenum. Gastrin also binds to receptor cells in the pancreas and gallbladder where it increases the secretion of pancreatic juice and bile. Digestion Digestion in the stomach can be divided into 2 classes: mechanical digestion and chemical digestion. Mechanical digestion is the physical division of a mass of food into smaller masses while chemical digestion is the chemical conversion of larger molecules into smaller molecules. The mixing action of the stomach walls allows mechanical digestion to occur in the stomach. The smooth muscles of the stomach produce contractions known as mixing waves that mix the boluses of food with gastric juice. This mixing leads to the production of the thick liquid known as chyme. While food is being physically mixed with gastric juice to produce chyme, the enzymes present in the gastric juice chemically digest large molecules into their smaller subunits. Gastric lipase splits triglyceride fats into fatty acids and diglycerides. Pepsin breaks proteins into smaller amino acids.

The chemical digestion begun in the stomach will not be completed until chyme reaches the intestines, but the stomach prepares hard-to-digest proteins and fats for further digestion. Hormonal control The activity of the stomach is under the control of several hormones that regulate the production of stomach acid and the release of food into the duodenum. Gastrin, produced by the G cells of the stomach itself, increases the activity of the stomach by stimulating increased gastric juice production, muscle contraction, and gastric emptying through the pyloric sphincter. Cholecystokinin (CCK), produced by the mucosa of the duodenum, is a hormone that acts to slow gastric emptying by contracting the pyloric sphincter. CCK is released in response to food rich in proteins and fats, which are difficult for the body to digest. By inhibiting gastric emptying, CCK allows food to be stored in the stomach longer to promote improved digestion by the stomach and to give the pancreas and gallbladder time to release enzymes and bile to increase digestion in the duodenum. Secretin, another hormone produced by the duodenum's mucosa, responds to the acidity of chyme entering the duodenum from the stomach.

Secretin travels through the bloodstream to the stomach where it slows the production of gastric juice by the exocrine glands of the mucosa. Secretin also promotes the production of pancreatic juice and bile that contain acid-neutralizing bicarbonate ions. The net effect of secretin is to protect the intestines from the damaging effects of acidic chyme. Prepared by Tim Taylor, Anatomy and Physiology Instructor Hydrochloric_acid Hydrochloric_acid Muriatic acid, Spirit of salt Identifiers 1.9 mPa·s at 25 °C, 31.5% solution (at 25 °C, 100 kPa) Infobox disclaimer and references Hydrochloric acid is the aqueous solution of hydrogen chloride gas ( H Cl ). It is a strong acid , the major component of gastric acid , and of wide industrial use. Hydrochloric acid must be handled with appropriate safety precautions because it is a highly-corrosive liquid . Hydrochloric acid, or muriatic acid by its historical but still occasionally-used name, has been an important and frequently-used chemical from early history, and was discovered by the alchemist Jabir ibn Hayyan around the year 800.

It was used throughout the Middle Ages by alchemists in the quest for the philosopher's stone , and later by several European scientists including Glauber , Priestley , and Davy in order to help establish modern chemical knowledge. From the Industrial Revolution, it became an important industrial chemical for many applications, including the large-scale production of organic compounds, such as vinyl chloride for PVC plastic , and MDI / TDI for polyurethane , and smaller-scale applications, such as production of gelatin and other ingredients in food, and leather processing. About 20 million metric tonnes of HCl gas are produced annually. Contents 8.2 References History Hydrochloric acid was first discovered around 800 AD by the alchemist Jabir ibn Hayyan (Geber), by mixing common salt with vitriol ( sulfuric acid ). Jabir discovered many important chemicals, and recorded his findings in over twenty books, which carried his chemical knowledge of hydrochloric acid and other basic chemicals for hundreds of years. Jabir's invention of the gold-dissolving aqua regia , consisting of hydrochloric acid and nitric acid , was of great interest to alchemists searching for the philosopher's stone .

In the Middle Ages, hydrochloric acid was known to European alchemists as spirit of salt or acidum salis. Gaseous HCl was called marine acid air. The old (pre-systematic) name muriatic acid has the same origin (muriatic means "pertaining to brine or salt"), and this name is still sometimes used. Notable production was recorded by Basilius Valentinus , the alchemist-canon of the Benedictine priory Sankt Peter in Erfurt, Germany in the fifteenth century. In the seventeenth century, Johann Rudolf Glauber from Karlstadt am Main, Germany used sodium chloride salt and sulfuric acid for the preparation of sodium sulfate in the Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, and in 1818 Humphry Davy of Penzance, England proved that the chemical composition included hydrogen and chlorine . During the Industrial Revolution in Europe, demand for alkaline substances such as soda ash increased, and the new industrial soda process by Nicolas Leblanc (Issoundun, France) enabled cheap large-scale production.

In the Leblanc process , salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the Alkali Act of 1863, excess HCl was vented to the air. After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale. When early in the twentieth century the Leblanc process was effectively replaced by the Solvay process without the hydrochloric acid by-product, hydrochloric acid was already fully settled as an important chemical in numerous applications. The commercial interest initiated other production methods which are still used today, as described below. Today, most hydrochloric acid is made by absorbing hydrogen chloride from industrial organic compounds production . Hydrochloric acid is listed as a Table II precursor under the 1988 Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances because of its use in the production of heroin, cocaine, and methamphetamine.

[1] Chemistry Hydrogen chloride (HCl) is a monoprotic acid, which means it can dissociate (i.e., ionize) only once to give up one H+ ion (a single proton ). In aqueous hydrochloric acid, the H+ joins a water molecule to form a hydronium ion, H3O+: HCl + H2O ⇌ H3O+ + Cl− The other ion formed is Cl−, the chloride ion . Hydrochloric acid can therefore be used to prepare salts called chlorides, such as sodium chloride . Hydrochloric acid is a strong acid , since it is fully dissociated in water. Monoprotic acids have one acid dissociation constant , Ka, which indicates the level of dissociation in water. For a strong acid like HCl, the Ka is large. Theoretical attempts to assign a Ka to HCl have been made. [2] When chloride salts such as NaCl are added to aqueous HCl they have practically no effect on pH , indicating that Cl− is an exceedingly weak conjugate base and that HCl is fully dissociated in aqueous solution.

For intermediate to strong solutions of hydrochloric acid, the assumption that H+ molarity (a unit of concentration ) equals HCl molarity is excellent, agreeing to four significant digits. Of the seven common strong acids in chemistry, all of them inorganic , hydrochloric acid is the monoprotic acid least likely to undergo an interfering oxidation-reduction reaction. It is one of the least hazardous strong acids to handle; despite its acidity, it produces the less reactive and non-toxic chloride ion. Intermediate strength hydrochloric acid solutions are quite stable, maintaining their concentrations over time. These attributes, plus the fact that it is available as a pure reagent, mean that hydrochloric acid makes an excellent acidifying reagent and acid titrant (for determining the amount of an unknown quantity of base in titration ). Strong acid titrants are useful because they give more distinct endpoints in a titration, making the titration more precise. Hydrochloric acid is frequently used in chemical analysis and to digest samples for analysis. Concentrated hydrochloric acid will dissolve some metals to form oxidized metal chlorides and hydrogen gas. It will produce metal chlorides from basic compounds such as calcium carbonate or copper(II) oxide .

It is also used as a simple acid catalyst for some chemical reactions. Physical properties The physical properties of hydrochloric acid, such as boiling and melting points , density , and pH depend on the concentration or molarity of HCl in the acid solution. They can range from those of water at 0% HCl to values for fuming hydrochloric acid at over 40% HCl. 48 °C -26 °C The reference temperature and pressure for the above table are 20 °C and 1 atmosphere (101 kPa). Hydrochloric acid as the binary (two-component) mixture of HCl and H2O has a constant-boiling azeotrope at 20.2% HCl and 108.6 °C (227 °F).

There are four constant- crystallization eutectic points for hydrochloric acid, between the crystal form of HCl·H2O (68% HCl), HCl·2H2O (51% HCl), HCl·3H2O (41% HCl), HCl·6H2O (25% HCl), and ice (0% HCl). There is also a metastable eutectic point at 24.8% between ice and the HCl·3H2O crystallization Production Main article: hydrogen chloride Hydrochloric acid is prepared by dissolving hydrogen chloride in water. Hydrogen chloride can be generated in many ways, and thus several different precursors to hydrochloric acid exist. The large-scale production of hydrochloric acid is almost always integrated with other industrial scale chemicals production . Industrial market Hydrochloric acid is produced in solutions up to 38% HCl (concentrated grade). Higher concentrations up to just over 40% are chemically possible, but the evaporation rate is then so high that storage and handling need extra precautions, such as pressure and low temperature .

Bulk industrial-grade is therefore 30% to 34%, optimized for effective transport and limited product loss by HCl vapors . Solutions for household purposes, mostly cleaning, are typically 10% to 12%, with strong recommendations to dilute before use. Major producers worldwide include Dow Chemical at 2 million metric tonnes annually (2 Mt/year), calculated as HCl gas, and FMC, Georgia Gulf Corporation , Tosoh Corporation, Akzo Nobel , and Tessenderlo at 0.5 to 1.5 Mt/year each. Total world production, for comparison purposes expressed as HCl, is estimated at 20 Mt/year, with 3 Mt/year from direct synthesis, and the rest as secondary product from organic and similar syntheses. By far, most of all hydrochloric acid is consumed captively by the producer. The open world market size is estimated at 5 Mt/year. Applications Hydrochloric acid is a strong inorganic acid that is used in many industrial processes. The application often determines the required product quality. Regeneration of ion exchangers An important application of high-quality hydrochloric acid is the regeneration of ion exchange resins .

Cation exchange is widely used to remove ions such as Na+ and Ca2+ from aqueous solutions, producing demineralized water. Na+ is replaced by H3O+ Ca2+ is replaced by 2 H3O+ Ion exchangers and demineralized water are used in all chemical industries, drinking water production, and many food industries. pH Control and neutralization A very common application of hydrochloric acid is to regulate the basicity ( pH ) of solutions. OH− + HCl → H2O + Cl− In industry demanding purity (food, pharmaceutical, drinking water), high-quality hydrochloric acid is used to control the pH of process water streams. In less-demanding industry, technical-quality hydrochloric acid suffices for neutralizing waste streams and swimming pool treatment. Pickling of steel Pickling is an essential step in metal surface treatment, to remove rust or iron oxide scale from iron or steel before subsequent processing, such as extrusion , rolling , galvanizing , and other techniques. Technical-quality HCl at typically 18% concentration is the most commonly-used pickling agent for the pickling of carbon steel grades.

Fe2O3 + Fe + 6 HCl → 3 FeCl2 + 3 H2O The spent acid has long been re-used as ferrous chloride solutions, but high heavy-metal levels in the pickling liquor has decreased this practice. In recent years, the steel pickling industry has, however, developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidized bed HCl regeneration process, which allow the recovery of HCl from spent pickling liquor. The most common regeneration process is the pyrohydrolysis process, applying the following formula: 4 FeCl2 + 4 H2O + O2 → 8 HCl+ 2 Fe2O3 By recuperation of the spent acid, a closed acid loop is established. The ferric oxide by product of the regeneration process is a valuable by-product, used in a variety of secondary industries. HCl is not a common pickling agent for stainless steel grades. Production of inorganic compounds Numerous products can be produced with hydrochloric acid in normal acid-base reactions , resulting in inorganic compounds. These include water treatment chemicals such as iron(III) chloride and polyaluminium chloride (PAC).

Fe2O3 + 6 HCl → 2 FeCl3 + 3 H2O Both iron(III) chloride and PAC are used as flocculation and coagulation agents in wastewater treatment , drinking water production, and paper production. Other inorganic compounds produced with hydrochloric acid include road application salt calcium chloride , nickel(II) chloride for electroplating , and zinc chloride for the galvanizing industry and battery production. Production of organic compounds The largest hydrochloric acid consumption is in the production of organic compounds such as vinyl chloride for PVC , and MDI and TDI for polyurethane . This is often captive use, consuming locally-produced hydrochloric acid that never actually reaches the open market. Other organic compounds produced with hydrochloric acid include bisphenol A for polycarbonate , activated carbon , and ascorbic acid , as well as numerous pharmaceutical products. Other applications Hydrochloric acid is a fundamental chemical, and as such it is used for a large number of small-scale applications, such as leather processing, household cleaning, and building construction.

In addition, a way of stimulating oil production is by injecting hydrochloric acid into the rock formation of an oil well, dissolving a portion of the rock, and creating a large-pore structure. Oil-well acidizing is a common process in the North Sea oil production industry. Many chemical reactions involving hydrochloric acid are applied in the production of food, food ingredients, and food additives. Typical products include aspartame , fructose, citric acid , lysine , hydrolyzed (vegetable) protein as food enhancer, and in gelatin production. Food-grade (extra-pure) hydrochloric acid can be applied when needed for the final product. Presence in living organisms Physiology and pathology 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.

Safety mechanisms that prevent the damage of the epithelium of digestive tract by hydrochloric acid are the following: Negative regulators of its release A thick mucus layer covering the epithelium Sodium bicarbonate secreted by gastric epithelial cells and pancreas The structure of epithelium (tight junctions) Adequate blood supply Prostaglandins (many different effects: they stimulate mucus and bicarbonate secretion, maintain epithelial barrier integrity, enable adequate blood supply, stimulate the healing of the damaged mucous membrane) When, due to different reasons, these mechanisms fail, heartburn or peptic ulcers can develop. Drugs called proton pump inhibitors prevent the body from making excess acid in the stomach, while antacids neutralize existing acid. In some instances, the stomach does not produce enough hydrochloric acid. These pathologic states are denoted by the terms hypochlorhydria and achlorhydria. They have the potential to lead to gastroenteritis. Chemical weapons Phosgene (COCl2) was a common chemical warfare agent used in World War I.

The main effect of phosgene results from the dissolution of the gas in the mucous membranes deep in the lung, where it is converted by hydrolysis into carbonic acid and the corrosive hydrochloric acid. The latter disrupts the alveolar-capillary membranes so that the lung becomes filled with fluid (pulmonary edema). Hydrochloric acid is also partly responsible for the harmful or blistering effects of mustard gas . In the presence of water, such as on the moist surface of the eyes or lungs, mustard gas breaks down forming hydrochloric acid. Safety Dangerous goods labels Hydrochloric acid in high concentrations forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines. Upon mixing hydrochloric acid with common oxidizing chemicals, such as bleach (NaClO) or permanganate (KMnO4) , the toxic gas chlorine is produced. To minimize the risks while working with hydrochloric acid, appropriate precautions should be taken, including wearing rubber or PVC gloves, protective eye goggles, and chemical-resistant clothing. The hazards of solutions of hydrochloric acid depend on the concentration.

The following table lists the EU classification of hydrochloric acid solutions: What Is Muriatic Acid? Facts and Uses Updated October 14, 2016. Question: What Is Muriatic Acid? Answer: Muriatic acid is one of the names for hydrochloric acid . It is also known as spirits of salt or acidum salis. "Muriatic" means "pertaining to brine or salt". The chemical formula for muriatic acid is HCl. Uses of Muriatic Acid Muriatic acid has many commercial and home uses, including: industrial synthesis of vinyl chloride and polyvinyl chloride (PVC) food additive production of inorganic chemical compounds pH control of water, food and drugs regenerating ion exchange resins

Question: Which chemical acid makes up around 0.5% of what is called gastric acid?
Answer: HYDROCHLORIC