Final answer:
The short-term regulation of feeding is managed through the cephalic, gastric, and intestinal phases. These involve the release of intestinal peptides and insulin, as well as the activation of specific sensory and hypothalamic neurons, which together control hunger, satiety, and the coordination of the digestive process.
Step-by-step explanation:
Short-term Regulation of Feeding:
Short-term regulation of feeding involves three distinct phases: the cephalic phase, the gastric phase, and the intestinal phase. The cephalic phase is initiated by sensory experiences such as sight, smell, and thought of food, which trigger neural responses that stimulate salivation and gastric juice secretion. In the gastric phase, the presence of food in the stomach further stimulates gastric juice production. During the intestinal phase, chyme entering the small intestine prompts the release of intestinal peptides, insulin, and the activation of sensory and hypothalamic neurons which regulate the rate of gastric emptying and coordinate digestive processes.
Intestinal peptides such as cholecystokinin (CCK) and peptide YY (PYY) signal satiety and slow down gastric emptying. Insulin release, triggered by elevated blood glucose levels after eating, also affects satiety signaling and nutrient storage. Sensory and hypothalamic neurons integrate hunger and satiety signals, ultimately determining engagement in feeding behavior.
These complex interactions between the nervous system and hormonal responses ensure a coordinated and regulated process of digestion, nutrient absorption, and satiety. Throughout the phases, feedback loops are essential; for example, the stimulus of hunger initiates eating, but the signal of fullness will eventually inhibit further intake, demonstrating a form of positive feedback regulation.