Educational knowledge as a part of a textbook implicates a great responsibility about students' ideas what is necessary to be achieved as a result of a discipline in high education. So it is important lecturers to have a criterial construct to analyze and, if necessary, to change some aspects in educational knowledge. We suggest a kind of criterial frame that consists of three basic units: unit of educational needs; unit of educational aims and logico-technological unit. These units are hierarchically connected. In order to apply this criterial construct in analyzing educational knowledge in physiology textbooks for medical students we traced them through the other three levels that are related with physiology discipline: frameworks of high education, of medicine education and of physiology education between tradition and challenges. Applying this criterial construct to the subject of smooth muscles have shown that understanding structure and function of smooth muscles is important milestone in studying and comprehension of physiology, pharmacology and pathology of gastrointestinal tract, reproductive system, blood circulation, etc. Our analyses on educational knowledge in several textbooks of physiology for students of medicine have shown that in most of them smooth muscles are covered inadequately taking into account their role in human physiology and educational needs of medical students. Generally information in textbooks as quantity and quality is in contrast (and sometimes in contradiction) with the achievements of scientific knowledge concerning function and structure of smooth muscles. A good illustration for this discrepancy could be shown by comparison of information covering skeletal muscles and smooth muscles. Although in modern medicine smooth muscles are much more frequently targeted than skeletal, the last ones are traditionally covered much more exhaustively.