Specific enteroendocrine cells of the stomach, called G cells, are stimulated by partially digested proteins, caffeine, and rising pH. When stimulated, G cells secrete

A. Decrease in the concentration of the blood plasma: A decrease in plasma concentration (hypoosmolarity) suppresses ADH, leading to less water reabsorption.
B. Decrease in the production of ADH: This would reduce water permeability of the collecting ducts.
C. Increase in the production of aldosterone: Aldosterone increases sodium reabsorption, not water permeability.
D. Increase in the production of ADH: ADH (vasopressin) increases aquaporin insertion into collecting duct membranes, enhancing water reabsorption and increasing permeability.

A. Cephalic: The cephalic phase occurs before food enters the stomach, triggered by sight, smell, or thought of food, and stimulates gastric secretion via the vagus nerve.
B. Gastric: The gastric phase begins when food enters and stretches the stomach, triggering myenteric and vagovagal reflexes that stimulate acid and enzyme secretion.
C. Intestinal: The intestinal phase involves chyme entering the duodenum, which moderates gastric activity, mostly inhibitory.
D. Gastrointestinal: “Gastrointestinal” is a general term and not one of the specific phases of gastric secretion.
E. Mesenteric: “Mesenteric” refers to the mesentery (tissue supporting the intestines), not a phase of digestion.