ENTROPY GENERATION AND CONTROL OF PHYSIOLOGICAL FLOWS

• Grant number: 23/10507-7
• Support Opportunities: Regular Research Grants
• Duration: December 01, 2023 - November 30, 2025
• Field of knowledge: Biological Sciences - Physiology - General Physiology
• Principal Investigator: José Guilherme de Souza Chaui Mattos Berlinck
• Grantee: José Guilherme de Souza Chaui Mattos Berlinck
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The maintenance of life depends on keeping the organic system out of thermodynamic equilibrium. This, in turn, implies the existence of flows both crossing the boundaries of the system and internally, due to differences in sustained potentials. The evolutionary process by natural selection, despite not being teleological, generates optimizations in biological systems. This statement is, however, less simple than we might be led to believe, for two reasons: the supposed optima are not global optimal as they depend on the historical constraints of the system in focus and the selection process is always in progress. Furthermore, and essential, is the fact that the search for recognizing an optimization implies having a process model, the recognition of the imposed/inherent constraints and the specification of the performance criterion used (Kirk 2004). In this last aspect, biological optimizations are seen, mostly, as a result of energy optimization in a given flow. From another point of view, flows must be regulated to maintain the internal environment (homeostasis) as a result of both external and internal conditions experienced at a given moment. Flows are associated with entropy generation by the system, which means loss of ability to perform useful work. Thus, the issue of optimizations can be seen from the entropic viewpoint, that is, "what is the best way to control a flow in order to minimize the generation of entropy associated with this regulation". For this approach, the flow and entropy generation control coefficient was developed (equation (7) in the text). This coefficient indicates the entropic impact that a given control parameter "k" causes on the regulated flow, and the coefficient was recently used to solve two phylogenetic scale problems (constancy of arterial pressure and proportion of blood volume). The present proposal aims to explore the use of this coefficient in other scenarios, such as: cardiac output regulation; thermoregulation and metabolic depression; mammalian nephron evolution. (AU)