Each of the chakras governs specific areas of your body. Your body is biological so it needs a soul and allows the presence of a soul. Therefore the chakras (which are components of the soul) govern parts of this physical body of yours. If you were a robot, you would not need a soul (in fact engineers do not insert souls into robots to make them work, but program them with algorithms, etc.). Since you are life, and since your life is composed and supported by your biological organism, you have a soul which is exactly what controls what is called "life" of you. Therefore if you take care of your soul, you must also take care of your physical body and vice versa, since the two things are closely interconnected.