Kaplan Nursing Entrance Practice Exam

Pepsin is primarily used by the body to perform which function?

1. Break down fats

2. Break down proteins

3. Break down carbohydrates

4. Neutralize acids

The correct answer is: Break down proteins

Pepsin is an enzyme that plays a critical role in the digestive system, specifically in the stomach where it aids in the digestion of proteins. It is secreted as an inactive precursor called pepsinogen, which is then activated by the acidic environment of the stomach (primarily hydrochloric acid) into its active form, pepsin. Once activated, pepsin hydrolyzes peptide bonds in proteins, breaking them down into smaller peptides. This process is essential because proteins, which are large and complex molecules, must be broken down into smaller units (amino acids and peptides) before they can be absorbed by the body for various physiological functions, including muscle repair, enzyme production, and hormone synthesis. In the context of the options, while the other substances listed (fats, carbohydrates, and acids) are indeed important components of digestion, pepsin specifically and primarily targets proteins, making this answer the most accurate. The other enzymes and mechanisms in the digestive system are responsible for the breakdown of the other macromolecules.