What is the primary function of pepsin in the gastric environment?
Solution
Correct Answer: Option C
The primary function of pepsin in the gastric environment is to break down proteins into smaller peptides. Pepsin is an enzyme secreted by the chief cells of the stomach in an inactive form called pepsinogen. Once exposed to the acidic gastric environment (pH 1.5 to 3.5), pepsinogen is converted into active pepsin. This enzyme catalyzes the hydrolysis of peptide bonds, specifically targeting the proteins ingested in the diet, initiating protein digestion in the stomach.
It is important to note that pepsin does not emulsify fats (which is the role of bile in the small intestine), nor does it hydrolyze carbohydrates (which is performed by enzymes like amylase). Additionally, pepsin is not involved in the activation of intrinsic factor, a glycoprotein produced by parietal cells that is essential for vitamin B12 absorption.
Key points:
- Pepsin breaks down proteins into peptides.
- It functions optimally in the acidic pH of the stomach.
- Pepsinogen is the inactive precursor converted to pepsin by stomach acid.
- It plays a central role in protein digestion during gastric processing.
Reference: Ganong's Review of Medical Physiology, 26th Edition, Chapter 25: Digestive System, Page 457
It is important to note that pepsin does not emulsify fats (which is the role of bile in the small intestine), nor does it hydrolyze carbohydrates (which is performed by enzymes like amylase). Additionally, pepsin is not involved in the activation of intrinsic factor, a glycoprotein produced by parietal cells that is essential for vitamin B12 absorption.
Key points:
- Pepsin breaks down proteins into peptides.
- It functions optimally in the acidic pH of the stomach.
- Pepsinogen is the inactive precursor converted to pepsin by stomach acid.
- It plays a central role in protein digestion during gastric processing.
Reference: Ganong's Review of Medical Physiology, 26th Edition, Chapter 25: Digestive System, Page 457
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