Gastric acid and pepsin has a destructive effect, not only on the food, but also on the gastric mucosa which for this reason is equipped with various mechanisms to be able to resist this breakdown and not let the stomach be damaged. Several factors contribute to making the mucosa resistant.
Goblet cells in the mucosa of the stomach are important to the mucosal defence. The production of mucus is stimulated by mechanical and chemical actions and through the vagus nerve (cholinergic stimulation). There is mucus in the gastric juice and in a 0.2 mm. thick layer on the entire surface of the gastric mucosa. The layer is constantly re-formed and functions as a barrier to pepsin and acid. The thickness of the mucus layer is reduced by acetylsalicylic acid (e.g. Aspirin) and by rheumatic medicine of the NSAID type (e.g. ibuprofen).
Other cells in the gastric mucosa produce the acid neutralizing bicarbonate which is sent into the stomach. The production of bicarbonate is stimulated by calcium, the "good" prostaglandins of the E- and F-type, medication with cholinergic effects, etc. The production is on the other hand reduced by acetylsalicylic acid, NSAIDs, and alcohol.
Under normal conditions, the gastric acid will not be able to penetrate the mucus layer, but the barrier can be broken down by bile acids, acetylsalicylic acid, alcohol, and mild organic acids which can all make it possible for the acid to penetrate the mucosa and damage it. If the cells are damaged, histamine is liberated and this increases the production of acid which will then further damage the mucosa with the formation of wounds and bleeding from damaged blood vessels. A poor circulation of blood in the wall of the stomach can also be contributing to damages.
Smoking cigarettes does not increase the production of gastric acid but is said to lead to an increased emtying of acid into the duodenum in which the mucosa is not as resistant to acid.
This is the most common form of ulcers. The wounds in the duodenum are usually deep and sharply defined contrary to the wounds in the stomach which are usually more superficial and only located to the mucosa.
Wounds in the duodenum are present in 6 - 15% of people in the Western population. In many cases, it is a case of a chronic or re-occuring disease, but the prevalence is diminishing - the reason for this is not known.
There are many indications that the Helicobacter pylori bacterium is significant to the development of duodenal ulcers. The bacterium can be found in almost everyone suffering from this type of ulcer, but it can also be found in many people who do not suffer from ulcers. Only an estimated maximum of 20% of the people who carry the Helicobacter pylori in their duodenum actually develop an ulcer during the spand of their lifetime. Too little gastric acid and too few antioxidants - especially vitamin C - in the gastro-intestinal wall increase the risk of ulcers caused by Helicobacter pylori.
Smokers have an increased prevalence of duodenal ulcers. This can partly be explained by an increased emptying of gastric acid into the duodenum, and partly by the fact that nicotine or the smoke can result in a reduced secretion of the acid neutralizing bicarbonate from the pancreas which empties into the duodenum. Smoking also reduces the resistance towards bacteria - and thereby also weakens the immune system.
The frequency of duodenal ulcers is increased if suffering from renal failure, cirrhosis of the liver caused by alcohol, smoker's lungs, or if the production of parathyroid hormone is too high. It has not yet been established whether stress and other mental factors, such as anger, have any significance in the development of duodenal ulcers, but it cannot be excluded that these factors can also lead to reduced resistance to the formation of wounds.
Burning and gnawing pains in the upper side of the abdomen, possibly also under the right costal angle, are common but the pains might also be uncharacteristic. They most often come when the stomach has almost been emptied which is between 1½ and 3 hours after a meal.
The food neutralizes the gastric acid, but afterwards an increased secretion of gastrin occurs which again stimulates the production of gastric acid. The symptoms typically come in attacks which last from days to months. The upper part of the abdomen is very often sore. Food or acid neutralizing remedies often quickly relieve the pains. Many people suffering from duodenal ulcers, however, have no symptoms.
If food does not reduce the pains in case of duodenal ulcers, it might be a sign that the wound is penetrating the intestinal wall into the pancreas. If there is vomiting, it is an indication that there are problems with emptying the stomach. If violent pains quickly occur, it might be a sign that the intestine has been perforated into the abdominal cavity. Bleeding from the wound can occur, sometimes with vomiting with material that has the appearance of coffee grounds, and, if the blood moves the other way, the stools will be black and tar-like.
The diagnose is made after an X-ray examination which is most often combined with a telescope examination of the stomach and duodenum. Samples will also be taken in order to check for the bacterium Helicobacter pylori.
These wounds often penetrate the mucosa and are surrounded by gastric catarrh. They are almost always located in the bottom of the stomach. If they are located at the top, there is a significant risk of cancer. As is the case with duodenal ulcers, there is a clear connection with the bacterium Helicobacter pylori.
Gastric acid and pepsin are also involved in gastric ulcers just like in duodenal ulcers, but the production of gastric acid is also often normal or reduced.
The emptying of the gastric contents is often reduced and then pains will then be located at the top of the stomach but can be uncharacteristic and be provoked by food. Weight loss on account of nausea and uneasiness after meals as well as on account of vomiting in case of wounds in the area of the stomach outlet can occur.
Bleeding is a common complication to wounds in the stomach, but holes in the stomach is not that common.