Chemical Structure of Stomach Acid

Anatomical model

Gastric glands line the inside of the stomach and secrete 2 to 3 qt. of gastric juices into the stomach daily. Each secretion contributes to digestion and maintenance of the stomach. Gastric juice contains mucus, intrinsic factor, hydrochloric acid, pepsinogen and gastric lipase.

Mucus

Mucus secretions protect the stomach from the other chemicals in gastric juice. If mucus were not produced, your stomach would digest itself. In fact, your stomach makes a new lining every seven days for that very reason.

Hydrochloric Acid

The stomach cells secrete hydrogen ions and chloride ions, which is the equivalent to hydrochloric acid. The acid kills bacteria, slightly denatures food protein, and causes bile and pancreatic juice production.

Intrinsic factor

Parietal cells produce intrinsic factor, which aids in the absorption of vitamin B12, a nutrient used in red blood cell formation.

Pepsinogen

Pepsinogen is the inactive form of pepsin. Hydrochloric acid activates pepsinogen, converts it to pepsin and allows it to begin protein digestion by breaking the bonds between amino acids.

Gastric Lipase

Gastric lipase is a stomach enzyme that breaks down fat molecules' short-chain triglycerides into monoglycerides and fatty acids. Gastric lipase works best in a pH of 5 to 6.

References

• Principles of Anatomy and Physiology; Gerard Tortora and Bryan Derrickson; 2006

Resources

• Digestion Lab
• Stomach anatomy, microsopy and content