Certified Gastroenterology Registered Nurse Practice Exam

The cephalic phase of digestion is characterized by the brain's anticipatory response to food. This phase is initiated even before food enters the stomach and includes sensory responses to seeing, smelling, or thinking about food. These sensory stimuli trigger the brain to send signals that prepare the digestive system for the upcoming meal, stimulating the secretion of saliva, gastric juices, and digestive enzymes. This physiological readiness enhances digestion, making the subsequent phases (gastric and intestinal) more effective.

In the gastric phase, the focus shifts to the stomach itself, where the presence of food and its chemical composition further stimulate digestion. The intestinal phase involves responses after food has left the stomach, primarily within the small intestine, managing digestion and absorption processes. The post-absorptive phase occurs after nutrient absorption, where the body shifts its energy sources and metabolic processes. Each of these phases follows the cephalic phase and does not directly involve the brain's anticipatory responses.