Physiology is only explainable in terms of the underlying anatomy.
Physiology is essential because it is the basis upon which we build our understanding of what "life" is, in what ways we use to treat disease, and how we can cope up with tensions inflicted upon our bodies by various environments.
Physiology is explicable only in terms of the underlying anatomy because the Anatomy is the knowledge of these structures correlated with the human body. It is used to analyze the structure of body parts and the knowledge of the relationships to one another.