ABSTRACT
The thermodynamics principles, recalled so far, only apply to closed systems. However, the living cells are not closed systems. They are open systems. They exchange matter with their surroundings, together with energy and work. All the principles developed before are devoted to the thermodynamics of the equilibrium, the use of which is not very well adapted in the present case since biological cells are open systems. The latter ones are rather justiciable of a theoretical treatment within the framework of “non-equilibrium thermodynamics”. By definition, in any of the points of their process, the intensive parameters defining open stationary systems (temperature, pressure, concentrations of its components, partial molal energies, etc.) are independent of the time, despite the exchanges which exist between them and the surroundings.
