Gastric juice secretion is stimulated by food entry into stomach, as well as by hormonal and neural regulation. In 1890 Ivan Pavlov, Russian physiologist, applied an imaginary feeding to study a role of central nervous system in regulation of gastric secretion. For this purpose animal's (dog's, as a rule) esophagus was cut, ends of the esophagus were brought out into the open in the region of neck. A stomach of the operated animal was connected with an environment by special opening (fistula). When the dog started to eat, the food did not get the stomach though gastric secretion was initiated anyway, as receptor stimulation in oral region was transduced into medulla and from there the signal by nerve fibers passed toward stomach. The gastric secretion could last during several hours. During a single session of imaginary feeding one dog could produce up to one liter of pure gastric juice that may be used for medical purposes. To initiate the animation press the "Start" button. The "Stop" and "Reset" buttons interrupt and returns the animation into initial state, respectively.