Phenomenological-Based model of human stomach and its role in glucose metabolism.

The stomach is a segment of the gastrointestinal (GI) tract which receives food from the esophagus, mixes it, breaks it down, and then passes it on to the small intestine in smaller portions. In the stomach, the main secretory functions and digestion process begin. However, the most critical and important function of the stomach in digestive physiology is perhaps gastric motility. In this way, the functions of the stomach are mainly three: (i) the storage of large quantities of food to be further processed in the duodenum, and lower intestinal tract, (ii) the mixing of this food with gastric secretions to form a semi-fluid mixture, and (iii) to slow down the emptying of that semi-fluid mixture into the small intestine at a rate suitable for proper digestion and absorption. Regarding the motor activity, the stomach must consume glucose to generate the power necessary to carry out the digestion process. Although glucose consumption in the stomach is relatively low, it can affect the glucose concentration in the bloodstream. In order to know the variations in the glucose levels in the bloodstream during the stomach digestion, a Phenomenological Based Semi-physical Model (PBSM) of the role of the stomach in the glucose homeostasis is developed. The simulation of the stomach model is able to mimic physiological results without risking the life of the patient, in order to test the impact of diverse medicines and foods on glucose homeostasis. The model may then be integrated to existing models of glucose homeostasis to improve the simulation scenario with respect to the glucose appearance from a mixed meal. Our model allows the change of the macronutrient composition and rheological properties of the meal as well as the digestion particularities of every subject. In this way, the integrated model will be fitted to real patient physiology providing a better model to use in, for example, automated insulin delivery systems like the artificial pancreas (AP).