E. Heinz – författare

This book deals with energetics of transport processes, largely expressed in terms of the thermodynamics of irreversible pro­ cesses. Since at the present time too little is known about the molecular mechanism of transport, the present treatment is based largely on hypothetical models. Care has been taken, however, to define the crucial features of these models as generally as pos­ sible, so that the equations do not depend too much on hypotheti­ cal details. Accordingly, most equations, though developed on the basis of a mobile carrier (ferryboat) model, should apply equally to a conformational model, with an appropriate reinterpretation of the symbols. To better elucidate the essentials, the models are greatly simplified by special assumptions. Maximally, only two flows are assumed to be present in each model at one time: e. g. , two solute flows, the flow of solvent and of one solute, the flow of solvent and of heat. The simplifying assumptions may often be unreal. Hence the equations should not be applied un­ critically to actual mechanisms. They may at best serve as a ba­ sis on which the more appropriate equations may be developed. The book is not designed to give a complete kinetic analysis of the transport processes described. The kinetic equations are kept to the minimum required to describe the model concerned and to relate it to the corresponding thermodynamic equations. The in­ tention is to stress the close relationship between bioosmotic (transport) and biochemical processes in metabolism.

This book deals with energetics of transport processes, largely expressed in terms of the thermodynamics of irreversible pro­ cesses. Since at the present time too little is known about the molecular mechanism of transport, the present treatment is based largely on hypothetical models. Care has been taken, however, to define the crucial features of these models as generally as pos­ sible, so that the equations do not depend too much on hypotheti­ cal details. Accordingly, most equations, though developed on the basis of a mobile carrier (ferryboat) model, should apply equally to a conformational model, with an appropriate reinterpretation of the symbols. To better elucidate the essentials, the models are greatly simplified by special assumptions. Maximally, only two flows are assumed to be present in each model at one time: e. g. , two solute flows, the flow of solvent and of one solute, the flow of solvent and of heat. The simplifying assumptions may often be unreal. Hence the equations should not be applied un­ critically to actual mechanisms. They may at best serve as a ba­ sis on which the more appropriate equations may be developed. The book is not designed to give a complete kinetic analysis of the transport processes described. The kinetic equations are kept to the minimum required to describe the model concerned and to relate it to the corresponding thermodynamic equations. The in­ tention is to stress the close relationship between bioosmotic (transport) and biochemical processes in metabolism.

The material of this volume was originally planned to be incorporated in the preceding monograph Mechanics and Energetics of Biological Transport. A separate and coherent treatment ofthe variety of bioelectrical phenomena was considered preferable, mainly for didactic reasons. Usually, the biologist has to gather the principles of bioelectricity he needs from different sources and on different levels. The present book intends to provide these principles in a more uniform context and in a form adjusted to the problems of a biol­ ogist, rather than of a physicist or electrical engineer. The main emphasis is put on the molecular aspect by relating the bioelectrical phenomena, such as the membrane diffusion potentials, pump potentials, or redox potentials, to the properties of the membrane concerned, and, as far as pOSSible, to specific steps of transport and metabolism of ions and nonelectrolytes. Little space is devoted to the familiar and widely used representation of bioelectrical phe­ nomena in terms of electrical networks, of equivalent circuits with batteries, resistances, capacities etc. In order to elucidate the basic principles, the formal treatment is kept as simple as pOSSible, using highly Simplified models, based on biological systems. The corresponding equations are derived in two ways: kinetically, i. e. in terms of the Law of Mass Action, as well as energetically, i. e. , in terms of Nonequilibrium Thermodynamics.