23. The Digestive System

How does each of the three phases of gastric secretion promote and facilitate gastric control?

Describe the regulation of the cephalic, gastric, and intestinal phases of gastric secretion.

Proton Pump Inhibitors (or PPIs) are some of the widely used drugs in the world and are prescribed for chronic heartburn/acid reflux. They work by inhibiting the movement of H⁺ ions across the membrane into the gastric juice, thereby lowering the concentration of HCl. As described, which cell of the gastric glands would you expect PPIs to affect?

More than one choice may apply.

Where in the stomach do the strongest peristaltic waves occur?

Trace the path of a single protein molecule that has been ingested.

The protein molecule will be digested by enzymes made by

a. The mouth, stomach, and colon

b. The stomach, liver, and small intestine

c. The small intestine, mouth, and liver

d. The pancreas, stomach, and small intestine

A surgical procedure known as gastric bypass involves removing all or part of the stomach.

How would stomach removal affect absorption of vitamin B12? Explain.

Troy Francis, a middle-aged salesman, complains of a burning pain in the 'pit of his stomach,' usually beginning about two hours after eating and abating after drinking a glass of milk. When asked to indicate the site, he points to his epigastric region. The GI tract is examined by X-ray fluoroscopy. A gastric ulcer is visualized, and drug therapy using a proton pump inhibitor and antibiotics is recommended.

a. Why is this treatment suggested?

b. What are the possible consequences of nontreatment?