Arpit, Human body is built up of 206 bones, more than 100 organs, 100 billion nerve cells, arteries, ventricles, vertebrae, etc. It is one of the complex mechanism and it is quite difficult to describe it here. We would suggest you to read any Human Physiology book like the one by Guyton or for Anatomy, you may read Gray's. These have detailed description of Human Anatomy and Physiology.