The digestive system helps to meet the body's need for energy and plastic body requirements. This is achieved via digestive, secretory, motor, endocrine, absorbing, excretory, and barrier functions. Thus, GI tract lesions lead to a wide spectrum of diseases. However, there are a lot of causes of disorders and diseases in the digestive tract. They include lesions of the esophageal, gastric, and intestinal mucous membranes related to the effects of physical, chemical, and biological factors. Besides, digestive disorders often accompany CNS and autonomous nervous system diseases, endocrine and cardiovascular, hepatic and renal diseases. However, apart from integral functions, each part of the digestive system has its own specifics and typical features of the development and course of pathological processes.