(from the Greek pathos – suffering, disease and genesis – origin) – a set of successive processes that determine the occurrence and course of a disease; It includes physiological, biochemical, morphological, immune and other processes that develop in the human body after the impact of a causative factor. The triggering mechanism of pathogenesis is the action of the etiological factor on the body, which determines the specificity of the disease. The nature of the pathological reaction also depends on the reactivity of the organism and environmental conditions, therefore, in some cases, different etiological factors cause a similar or even the same pathological process, in others, the same causative factor entails the development of pathological processes or pathological reactions that are not the same in intensity and nature.