Systems Thinking and Investigation of Digestive Secretion

As a rule, a model of a system takes account of a few most obvious externally expressed parameters considered to be of paramount significance in the aspect of external operation of this system. This approach does not allow to consider such a system internally, as a horaeostatic unit, and, consequently, to obtain reliable estimates of its stability, flexibility of its operation, its survivability, to make forecasts of its operation. When one investigates such a large-scale interconnected and multilevel system as human organism, such account of intra- and inter-system functions (considered in time) is of principal importance in order to understand and model it. Secondly, interconnected systems of high degree of complexity are generally investigated in part, and functions of a set of parts can hardly be understood systematically. Thirdly, an investigator must take into account that structures and organs of organisms are functionally specific. But direct decomposition into structural blocks, which seem to be obviously responsible for certain functions, only seems obvious: organs co-operate in systems intended for definite functions. Decomposition into co-operating functional systems is a problem, which necessitates the combined (functional + structural) approach.