AAMC FL Practice Exam

What effect would the absence of HCl production in the stomach have on enzyme activity?

1. It would enhance enzyme activity

2. It would prevent enzyme activation

3. It would stabilize enzyme structure

4. It would increase stomach pH

The correct answer is: It would increase stomach pH

The absence of HCl production in the stomach would indeed lead to an increase in stomach pH. Normally, hydrochloric acid (HCl) is secreted by the parietal cells in the stomach lining and plays a crucial role in maintaining a highly acidic environment with a low pH. This acidic environment is essential for the activation and functioning of digestive enzymes, particularly pepsinogen, which is converted into pepsin in the presence of acid. When HCl is not produced, the stomach's pH rises, becoming less acidic. This increase in pH can significantly affect enzyme activity. Many enzymes in the digestive system are optimized for activity at specific pH levels, and pepsin, for example, is most active at a low pH. If the pH increases, pepsin's activity would diminish, leading to inefficient digestion of proteins. Therefore, the absence of HCl leads to a higher pH in the stomach, which disrupts the proper activation and functioning of enzymes essential for digestion. This understanding illustrates the importance of HCl in enzyme activity within the gastric environment.