Final answer:
Physiological mechanisms serve as the basis for hunger. When the stomach is empty, it contracts, causing hunger pangs. Chemical messages are then sent to the brain to initiate feeding behavior.
Step-by-step explanation:
Physiological mechanisms serve as the basis for hunger. When the stomach is empty, it contracts, causing hunger pangs. Chemical messages are then sent to the brain to initiate feeding behavior. Additionally, low blood glucose levels stimulate the pancreas and liver to generate chemical signals that induce hunger. Once the stomach is full, satiety signals are sent to the brain, reducing hunger.