STOMACH SECRETION

Question 1

Gastric juice

Answer 1

2 to 3 L per day produced by the gastric glands

mainly a mixture of water, hydrochloric acid, and pepsin

pH as low as 0.8

Question 2

Hydrochloric Acid

Answer 2

• produce by parietal cells
• activates pepsin and lingual lipase
• liquefy food to form chyme
• contributes to nonspecific disease resistance by destroying most ingested pathogens

Question 3

Pepsin

Answer 3

• produce by chief cells
• secretes pepsinogen
• hydrochloric acid removes some of its amino acids and forms pepsin that digests proteins
• pepsin digests dietary proteins into shorter peptide chains

Question 4

Gastric lipase

Answer 4

• produced by chief cells
• gastric lipase and lingual lipase play a minor role in digesting dietary fats
• digests 10% to 15% of dietary fats in the stomach and the rest digested in the small intestine

Question 5

Intrinsic Factor

Answer 5

• parietal cells secrete glycoprotein called intrinsic factor
• essential to absorption of vitamin B₁₂ by the small intestine
• binds vitamin B₁₂ and then intestinal cells absorb this complex by receptor-mediated endocytosis