What is Human Body? The human body is a machine which have 206 bones in elders body, and 650 muscles, and 75 trillion smaller unit called cells. Scientists have studied the human body in detail, the human body is diveded in some regions according to their functions, these are 1. Nervous system 2. Respiratory system 3. Circulatory system. 4.Digestive system 5. Reproductive system 6. Muscular system 7. Immune system 8. Skeleton system. Let's discuss these functions in detail. 1. Nervous system: This system allows your body to react with speed. Thousand of nerves run through the body, carrying electric signals, to and from the brain. Some nerves brings signals from sense organs to the brain. Other sends signals to muscles to make the body react. 2. Respiratory system: All your body's cell require a supply of life - giving oxygen, which comes from air. Your respiratory job is to take in oxygen and pass it a blood. The main organ in this system are the lungs which suck in air whe...