Gastric juice is highly acidic. How is stomach tissue protected from this acid?

• A. Mucous prevents gastric juice from being in direct contact with the tissue.
• B. Gastric juice is secreted in its inactive form and only becomes active when it touches food.
• C. Gastric pits also released bicarbonate to neutralize the acid.
• D. Peristalsis mixes the gastric juice into the chyme before it has a chance to interact with the tissue.

Answer: (A)

Verified step by step guidance

1. Understand the composition of gastric juice: Gastric juice contains hydrochloric acid (HCl), which is highly acidic and essential for digestion. However, this acidity can damage the stomach lining if not properly managed.
2. Learn about the protective role of mucus: The stomach lining is coated with a thick layer of mucus, which acts as a physical barrier. This mucus prevents the gastric juice from coming into direct contact with the stomach tissue, protecting it from damage.
3. Recognize the role of inactive enzymes: Gastric juice contains enzymes like pepsinogen, which are secreted in their inactive forms. These enzymes only become active (e.g., pepsin) when they come into contact with the acidic environment and food, reducing the risk of self-digestion of the stomach lining.
4. Understand the role of bicarbonate: Gastric pits in the stomach lining release bicarbonate ions (HCO₃⁻), which help neutralize the acid near the stomach lining. This creates a less acidic microenvironment close to the tissue, further protecting it.
5. Acknowledge the role of peristalsis: Peristalsis, the wave-like muscular contractions of the stomach, mixes the gastric juice with food to form chyme. This mixing action ensures that the gastric juice is diluted and less likely to harm the stomach lining before it interacts with the tissue.