A Stoichiometric Model of Human Metabolism

The present study deals with the “Human” component of the bioregenerative life support system.
\nHere we develop a model that allows calculating metabolic mass flow rates of the “Human” component
\nand monitoring the production of toxic substances – ammonia, hydrogen sulfide, and methanethiol. The
\nmodel is designed as an Excel-VBA interactive program. The “Human” component is considered as an
\nobject with incoming and outgoing flows of matter. Food ingredients, water, and oxygen constitute the
\ninput flows, and the outgoing flows consist of metabolic products. The input flows are distributed along
\nmetabolic channels. To specify the characteristics of the “Human” component, a calorie counter and a
\nspace diet planner are connected to the model. The calorie counter is designed to determine a crewman’s
\ndaily energy requirements depending on age, weight, height, gender, and level of physical activity. In
\nturn, the numerical energy value is transmitted to the diet planner, which determines the food set. To
\nmore accurately present the metabolism of phosphorus, nucleic acids and phospholipids are included
\nin the food composition. Each substance in the model is assigned a stoichiometric formula. The core
\nof the model consists of seven stoichiometric equations and the water exchange unit, which are the
\nlink between the incoming and outgoing flows of matter. The solution of stoichiometric equations and
\nbalancing the water exchange unit are carried out using the Solver Add-in for Excel, which is embedded
\nin the metabolic circuit. To show the validity of the model, a calculation of the human metabolism
\ndepending on calorie counter and diet planner is presented