After puberty and through middle age, cyclic hormonal changes control a roughly _____ day _____ cycle. (The exact length varies.) It includes a few days of mild bleeding, the onset of which is easily noted and is thus designated as _____.

3000+ review questions on anatomy and physiology. 

Anatomy refers to the internal and external structures of the body and their physical relationships, whereas physiology refers to the study of the functions of those structures.