Homeostasis—the monitoring and adjusting that goes on in the human body at any given time—is astounding. Your body continually makes adjustments to the body systems you use during everyday activities. In this interactive, make adjustments in respiration or heart rate or energy delivery in response to changing activities, and anticipate how a change in one system changes the balance in another system. Use your knowledge of the body system interactions to maintain the harmony in this virtual body as well as your nervous system does in yours.