Which of the following statements about the acidic nature of gastric juice is true?

• A. The acidic environment of the stomach is maintained by the secretion of mucus.
• B. Gastric juice has a high pH due to the presence of bicarbonate.
• C. Gastric juice is neutralized by pepsin.
• D. The acidity of gastric juice is primarily due to hydrochloric acid.

Answer: (D)

Verified step by step guidance

1. Understand the composition of gastric juice: Gastric juice is a mixture of hydrochloric acid (HCl), pepsinogen, mucus, and intrinsic factor. The primary component responsible for its acidity is hydrochloric acid.
2. Recognize the role of hydrochloric acid: Hydrochloric acid is secreted by the parietal cells in the stomach lining. It creates a highly acidic environment with a pH ranging from 1.5 to 3.5, which is crucial for digestion and killing bacteria.
3. Clarify the function of mucus: Mucus is secreted by the stomach lining to protect it from the corrosive effects of hydrochloric acid. It does not contribute to the acidity but rather serves as a protective barrier.
4. Understand the role of bicarbonate: Bicarbonate is not a component of gastric juice that contributes to acidity. Instead, it is secreted by the pancreas into the duodenum to neutralize the acidic chyme coming from the stomach.
5. Identify the role of pepsin: Pepsin is an enzyme activated by the acidic environment of the stomach. It does not neutralize gastric juice but rather functions optimally in acidic conditions to break down proteins.