Final answer:
The true statements about the signals that stop a meal are that there are at least two sources of satiety signals and that long-term satiety signals are generated by the consequences of eating a meal. Leptin is a long-term, not short-term, satiety signal and is secreted by fat cells.
Step-by-step explanation:
Satiety Signals and Eating Behavior
Regarding the signals that stop a meal, it is true that there are multiple sources of satiety signals that act to stop a meal. The pancreas and liver send signals to shut off hunger and eating as blood glucose levels increase. Additionally, the gastrointestinal tract provides vital satiety signals to the brain as food passes through it. As for the hormones, leptin, which is secreted by fat cells, represents a long-term satiety signal, not a short-term one, and it is part of the physiological mechanisms that regulate appetite based on the body's fat reserves. Therefore, statements 1 and 4 are correct in asserting that there are at least two sources of satiety signals and that long-term satiety signals are generated by the consequences of eating a meal. Statement 3 is incorrect as leptin is not a short-term satiety signal, but rather related to long-term energy balance. Lastly, statement 2 is incorrect as short-term satiety signals are not generated from adipose tissue; rather, they are more immediate signals generated during the ingestion and digestion of food.