Suppose you sit in the same position so long that your leg starts to hurt. How do different body systems interact to stop the pain?

When our body experiences an external stimuli such as pain or discomfort, our sensory receptors transmit the signal using the sensory neurons into the interneurons. Once the central nervous system receives the message, it registers the message as a pain sensation. In turn, the brain directs a response through the spinal cord, which sends impulses through the motor neurons. In turn, the motor neurons direct the muscles to execute the response. The end result is when you try to stand or stretch your legs to relieve the discomfort.

The answer your looking for is a food chain grid. it describes how nature can support itself and survival of the fittest comes into play..