Any study guide is out there to help you. Physiology can get complicated with trying to remember if Na+ equilibrium potential is important for the cardiovascular system or the nervous system. The study of life has become advanced, with people understanding every part of the body while still having mysteries. There are still diseases that need to be conquered, so understanding the systems of the body can be made easier with a study guide. Once school is over, someone could spend a few years working with a pharmaceutical company and need a guide to help them if they start teaching.