A 55-year-old male presents with a history of recurring episodes of gastric pain, particularly after meals. He describes the pain as a burning sensation in the upper abdomen, which improves with antiacid use. Upper gastrointestinal endoscopy reveals erosions in the duodenal mucosa. Which of the following is the most likely diagnosis?

Correct Answer: B

Rationale: Duodenal ulcers typically present with burning epigastric pain after meals, relieved by antacids, and are associated with mucosal erosions in the duodenum, as seen on endoscopy.

Correct Answer: A

Rationale: The upper third of the esophagus, with striated muscle, requires CNS input (via the vagus nerve) for primary peristalsis.

Correct Answer: B

Rationale: Saliva contains salivary amylase (ptyalin) for starch digestion and lysozyme for antibacterial action. Pepsin is in the stomach, lipase is mainly pancreatic, and renin is unrelated to saliva.

Correct Answer: C

Rationale: The autonomic nervous system regulates involuntary digestive processes like peristalsis and secretion.

Correct Answer: B

Rationale: The pancreas produces insulin and glucagon to regulate blood sugar.