Abstract
Author(s): Sergey Lleonchuk*The individual development of an organism is a negentropy process. The body fights against entropic degradation through growth, maturation, complication of its structural and functional organization, systemic integration of organs and tissues, and an increase in the power of hemostats. The source of development is the internal struggle of the organism with the ecosystem, which seeks to increase its entropy and dictates the morphological and functional structure through natural selection. The development of an organism in ontogenesis is not a straightforward, progressive and painless process, but always an internally contradictory, multidimensional, undulating process through internal crises and conflicts. The consequence of the internal struggle and the contradictory nature of the relationship between the organism and the ecosystem are diseases of the organism's development.