Question

name the 3 phases of digestion and what occurs at the stomach in each phase

Answer 1

The three stages of digestion are,
1. cephalic phase
2. Gastric phase
3. Intestinal phase

1. Cephalic phase: It is the initial stage of the digestion process, where the stomach responds to sight, smell and taste of food, the acids responsible for the digestion are secreted befor the food enters the stomach. The vagal postganglionic muscarinic nerves release Acetylcholine, Ach stimulates the cell H+ secretion.
2. Gastric phase: Gastric acid secretion occurs in this phase. the swallowed food activate the gastric activity by stretching the stomach by gastric contents and stimulating receptors in the stomach. Gastric secretion is stimulated by three chemicals, Ach, histamine and gastrine. these chemicals stimulate parietal cells to screte HCL and intrinsic factor.
3. Intestinal phase: In the intestinal phase, the duodenum responds to chyme and moderates gastric activity through hormones and nervous reflexes.