The organ system that releases a signal when you are hungry is the digestive system, which produces signals like ghrelin that indicate hunger. The organ system that receives and processes this stimulus is the nervous system. The nervous system interprets signals from the digestive system to create the sensation of hunger.
So, the correct answers are:
- Digestive system (releases the signal)
- Nervous system (receives the stimulus)
If you need to select only one response for the system that receives the signal, then it would be the nervous system.