Digestive System Structure, Absorption, Regulation (3B) Practice Test

In a study of carbohydrate absorption, researchers perfuse a short ileal segment with a solution containing 20 mM glucose. They compare two luminal conditions: (i) normal Na+ (140 mM) and (ii) low Na+ (10 mM), with osmolarity held constant using a non-absorbable solute. Definitions: SGLT-type transport uses the Na+ gradient to move glucose into enterocytes; GLUT-type transport is facilitated diffusion down a glucose gradient.

Based on this model, which outcome is most consistent with lowering luminal Na+?

A clinical case examines regulation of gastric emptying. A patient has reduced secretion of cholecystokinin (CCK), a small-intestinal hormone released in response to fatty acids and amino acids in the duodenum. Provided definitions: CCK slows gastric emptying and stimulates pancreatic enzyme secretion; secretin is released in response to acidic chyme and stimulates bicarbonate secretion.

After a high-fat meal, the patient reports early postprandial hunger and has a duodenal aspirate showing larger-than-expected fat droplets 30 minutes after eating.

Which statement best explains the regulation of the patient’s digestive process?