[The theory of functional systems in medicine: methodological aspects].

P.K. Anokhin's theory of functional systems (TFS) is a unique scientific development extending an original field of biomedical research initiated in this country by I.M. Sechenov, I.P. Pavlov, and A.A. Ukhtomsky. Unique methodology of TFS is based on the integrated approach to the study of human vital activity including psychic and somatic processes. The main results of the studies in the framework of TFS methodology and prospects for its further development are reviewed with special reference to the key mechanisms of eitiopathogenesis of chronic non-infectious diseases.