What are the three overlapping functions of the nervous system, and how do they work together in the example of a thirsty person lifting a glass of water?

The nervous system has three overlapping functions: sensory input, integration, and motor output. Sensory input gathers information from receptors, integration processes and interprets that information, and motor output activates muscles or glands to respond. In the thirsty person example, sensory input detects the glass of water, integration decides to reach for it, and motor output activates the arm and hand muscles to lift the glass.