Equations for Tracer Experiments

The use of isotopes makes possible quantita-tive measurements of many biochemical and physiological processes, hitherto secure from such detailed observation. Perhaps the most fre-quent use of this tool is in the observations of physiology that are concerned with the transfer of fluid from one portion of the body to another, and in the biochemical observations of the forma-tion of one compound from another. It is the purpose of this paper to present in detail some of the mathematical equations that govern such flow and synthesis, and to show incidentally that many of these equations are common to the fields of physics, and chemistry, as well as to the biological disciplines to which they will be ap-