Certified Neuroscience Registered Nurse (CNRN) Practice Exam

What is the role of hydrochloric acid in the stomach?

1. To emulsify fats

2. To aid in the absorption of nutrients

3. To create an acidic environment for protein digestion

4. To stimulate appetite

The correct answer is: To create an acidic environment for protein digestion

Hydrochloric acid plays a crucial role in the stomach primarily by creating an acidic environment that is essential for protein digestion. The presence of hydrochloric acid (HCl) lowers the pH of the stomach contents, activating pepsinogen to pepsin, the enzyme responsible for breaking down proteins into peptides. This acidic environment also helps in denaturing proteins, making them more accessible for enzymatic breakdown, and provides a barrier against pathogens, contributing to the overall digestive process. While emulsifying fats, aiding nutrient absorption, and stimulating appetite are all important aspects of digestion, they are not the primary functions of hydrochloric acid in the stomach. Emulsification is primarily facilitated by bile in the small intestine rather than by the stomach’s acidic content. Nutrient absorption occurs largely in the small intestine, where bile acids and pancreatic enzymes further process digested food. Appetite stimulation is more related to hormonal signals and neurological factors rather than directly influenced by the presence of hydrochloric acid. Thus, option C accurately captures the main function of hydrochloric acid in the digestive process.