Modeling of enzymatic processes in the duodenum to predict areas with elevated risks of functional disorders

The present work focuses on developing a model of the duodenum considering motility, biochemical reactions occurring under effects produced by secreted digestive juices, and absorption of reaction products in normal conditions and in case of functional disorders. Analysis of literature sources allowed identifying basic bile components and pancreatic and intestinal juice enzymes influencing fats, proteins and carbohydrates that enter the duodenum. The paper provides a simplified scheme showing how food components are transformed allowing for the neural-humoral mechanism of digestion regulation. Chyme that enters the duodenum is considered a homogenous mixture, which changes its composition during chemical reactions. Mathematical tasking includes mass and momentum conservation equations for a multi-component viscous fluid. The secretion of digestive juices and absorption of components resulting from chemical reactions are described with mass effluents in a pipe in the wall layer. The peristaltic law of the duodenum wall movement was applied to describe the tract motility; the movement characteristics do not depend on the composition of the mixture. Numeric experiments produced necessary results to describe the hydrolysis of the 5 % starch solution under exposure to pancreatic amylase. Obviously, not all the amount of starch enters a chemical reaction and this is well in line with experimental data. The paper provides data on concentration fields for the components of glucose, amylase, and starch at different moments in time and the fluid velocity field. The next stage in the model development is expected to consider absorption of food components, functional disorders of secretion / absorption and intestinal motility as well as influence exerted by neural and humoral mechanisms. In future, the developed model can be applied to predict areas with elevated risks of developing functional disorders, ulcer formation, and other defects of the intestinal mucosa. This will help a physician to prescribe personified therapy and diet.