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Even while sitting completely motionless, countless activities are happening inside the body. The heart continues beating, the lungs keep breathing, nerves send electrical signals, and cells constantly repair damaged tissue. Hormones are released, blood circulates, and the brain remains active around the clock.
Millions of chemical reactions occur every second to keep the body functioning. Most of these processes happen automatically without any conscious effort. Being "still" is only an illusion—the human body is always hard at work.
© National Institutes of Health