Final answer:
Consuming foods with different pH levels can affect the acid already present in the stomach. The condition when the acidity is affected in the stomach is called acid reflux or GERD.
Step-by-step explanation:
When we consume foods with different pH levels, it can affect the acid already present in the stomach. The stomach is normally acidic due to the secretion of hydrochloric acid (HCl) to create an optimal environment for digestion. The pH of stomach acid is around 1-2, which is highly acidic. Consuming foods with low pH, such as citrus fruits or vinegar, can further decrease the pH of the stomach acid temporarily. On the other hand, consuming foods with high pH, such as antacids, can neutralize some of the stomach acid, resulting in a less acidic environment.
The pathological condition when the acidity is affected in the stomach is called acid reflux or gastroesophageal reflux disease (GERD). In this condition, the stomach acid flows back into the esophagus, causing irritation and heartburn. It can occur when the lower esophageal sphincter (LES) doesn't close properly, allowing the stomach acid to move upwards. Factors such as obesity, certain foods, and certain medications can contribute to the development of GERD.