Our body functions automatically independently. We raise, kick, throw etc our either left or right hands and legs independently or dependably; we reacts to anything that we sense on us; we breath; we think etc because of the nerves that connects our body system with or without external system e.g. direct sunlight, drinking fluids etc. Central to all is our heart that pump in and out bloods. Blood is a mixture of all kind of nutrients we deserve to live, breath because with it comes the water, sliver, tear, flue etc. Our nerves reacts to both in and out pressures, problems, consequences etc e.g. extreme heat makes it inform the heart to pump blood faster and in the process our body gain excess heat combusting into carbon dioxide, hydrogen etc and when it is cold the opposite happens. Imagine leaving inside our hearts and you own or control flow of all to our nerves as saying that is not enough try to think that you are our heart out side our body and become our skin. Heart is hot to be absolute with you, however, does it take the outside heat?