Dynamic Equilibrium

DYNAMIC EQUILIBRIUM, a concept used to designate states where the constancy of the studied substrate is the result of directly opposing processes. It can refer to physiological, chemical, and physicochemical processes.—1. As an example of physiological dynamic equilibrium, one can point to the constancy of the number of formed elements of the blood in the body. Having lived for a short period, some elements perish, and to replace them, the hematopoietic organs produce new ones; thus, as a result of two opposite processes—destruction and creation—the constancy of the number of these elements is maintained in the body.—2. In the study of certain chemical reactions, it can be established that as the initial reactants are broken down, they are simultaneously synthesised anew from their breakdown products. For example, if we take equal parts of the molecular weight of ether and water, the breakdown of which yields alcohol and acid, after some time it will turn out that ether, water, alcohol, and acid are all present. By calculating the number of their molecules, one can find that there are half as many molecules of ether and water as there are molecules of alcohol and acid. The same result is reached starting from a mixture of alcohol and acid. This state remains constant, and therefore it can be called balanced. It is due to the fact that the reactions of breakdown and synthesis proceed at equal rates. According to the law of mass action, the rate of a reaction is proportional to the concentration of the active masses of the reactants, whereby the concept of activity must be determined by the degree of their electrical dissociation. The rate of chemical reactions in the animal organism obeys the above-mentioned laws, with the speed of the reaction being determined by the presence of the corresponding catalysts—enzymes.—3. An example of physicochemical dynamic equilibrium is the reaction of blood in the organism. Under all apparent conditions, blood maintains its active reaction. Acids formed in the body as a result of metabolism are neutralised either by combining with NH₃ or by displacing CO₂ from carbonates, which is removed by respiration. Alkalies formed in the body are neutralised by carbon dioxide and phosphates constantly present in the body. Thus, the reaction of the blood remains almost unchanged; only its reserve alkalinity changes.