What is the function of mucus in the stomach?
emulsifies fats
neutralizes stomach acid
protects stomach walls from gastric juices
activates digestive enzymes
The Correct Answer and Explanation is:
Correct Answer: protects stomach walls from gastric juices
Explanation (300+ words):
The primary function of mucus in the stomach is to protect the stomach walls from gastric juices, particularly from hydrochloric acid (HCl) and digestive enzymes like pepsin. The stomach produces gastric juice to break down food as part of the digestive process. This juice is highly acidic (with a pH of 1.5 to 3.5) and is effective in denaturing proteins and activating enzymes, but it is also potentially damaging to the tissues of the stomach itself.
To prevent self-digestion, the mucosal lining of the stomach secretes a thick, viscous layer of mucus, which is rich in bicarbonate ions. This mucus performs several key functions:
- Protective Barrier: The mucus forms a physical and chemical barrier between the gastric lining and the acidic environment. It traps bicarbonate ions, which help neutralize acid at the epithelial surface. This buffering creates a pH gradient from very acidic in the stomach lumen to almost neutral near the stomach lining.
- Prevents Tissue Damage: Without this protective mucus, hydrochloric acid and pepsin could erode the stomach lining, leading to inflammation, ulceration, or even perforation of the stomach wall—a condition known as a peptic ulcer.
- Supports Healing: Mucus also plays a role in the healing process of minor abrasions or irritations that occur naturally due to the constant churning and chemical exposure during digestion.
Why the Other Options Are Incorrect:
- Emulsifies fats: This is the role of bile, produced by the liver and stored in the gallbladder, not mucus.
- Neutralizes stomach acid: While mucus contains bicarbonate which helps in localized neutralization, its main role is protection, not full neutralization.
- Activates digestive enzymes: Hydrochloric acid, not mucus, activates pepsinogen into pepsin, which digests proteins.
Thus, the main function of stomach mucus is to act as a protective layer, preventing damage to the stomach from its own digestive secretions.