What type of equation is it and balance it

This drawing shows a human body system. what is the primary function of this body system?

How do you identify the anode on a power source such as a battery? how do you identify the cathode? how are terms anion and cation?

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space