If our stomach mucosa is compared to the “roof” of the house, it is always resisting the “wind and rain, snow and frost”, and sometimes there is “hail” attack. These “wind”, “frost”, “rain” and “snow” are the various things we eat, such as various Food, alcohol, medicine, and various microorganisms (such as bacteria, viruses, etc.), bile salts in liver and bile, and digestive juices secreted by the gastric mucosa itself, including gastric acid and pepsin, all these substances can cause damage to the gastrointestinal mucosa (that is, the attack factor). The “roof” consists of the mucous membrane of the stomach and intestines, mucus secreted by the gastric mucous membrane, rich blood supply to the gastric mucous membrane, cellular metabolism and various cytokines, etc. Together, they are like a “brick wall” (defense factor) that protects the gastric mucous membrane. Under normal circumstances, the defense factors and the attack factors are always in an “evenly matched” state, and our stomach is thus safe and sound. When emotional stress, mental stress or infection with H. pylori, improper diet (overeating, excessive intake of stimulating foods, etc.), alcohol consumption, intake of drugs that damage the stomach, bile reflux, etc., the power of the attack factor exceeds that of the defense factor. When the gastric mucosal blood flow is reduced for various reasons (e.g. serious systemic diseases), the gastric mucosal ischemia, hypoxia, malnutrition, hypoproteinemia, etc., the gastric mucosal “strength” is weakened and the defense factor is weakened. When the attack factor is strengthened and the defense factor is weakened, it is like a leaky roof, and gastritis and gastric ulcer occur.