[An overview of the regulation of basic functions of the digestive system]

The gastrointestinal system is the gate through which nutritive substances, vitamins, minerals, and fluids enter the body. Proteins, fats and complex carbohydrates are broken down into absorbable units (products of the digestion) in the digestive tract and finally they are absorbed together with vitamins, minerals and water into the blood or the lymph. The digestive and absorptive functions of the gastrointestinal tract depend on the various mechanisms, which adjust the food, put it through the gastrointestinal tract and mix it together with digestive enzymes secreted by the salivary glands, stomach, pancreas, small intestine and with bile. Some of these mechanisms depend on the spontaneous activity of the smooth muscles, others involve the somatic and autonomous reflexes, paracrine effects of the chemical substances, hormones and local gastrointestinal hormones. The aim of this paper is to review the essential factors participating in the regulation of these processes (mainly motility and secretion) from the mouth cavity, stomach, duodenum, gallbladder, pancreas, small intestine and large intestine to the defecation. The basic regulatory factors are summarized in the schemes from the sources of the physiological textbooks, which are accepted in the whole world for the education of physiology in the medical faculties.