Membrane Transport Processes in Organized Systems is a softcover book containing portions of Physiology of Membrane Disorders (Second Edition). The parent volume contains six major sections. This text encompasses the fourth and fifth sections: Transport Events in Single Cells and Transport in Epithelia: Vectorial Transport through Parallel Arrays. We hope that this smaller volume, which deals with transport processes in single cells and in organized epithelia, will be helpful to individuals interested in general physiology, transport in single cells and epithelia, and the methods for studying those transport processes. THOMAS E. ANDREOLI JOSEPH F. HOFFMAN DARRELL D. FANESTIL STANLEY G. SCHULTZ Vll Preface to the Second Edition The second edition of Physiology of Membrane Disorders represents an extensive revision and a considerable expansion ofthe first edition . Yet the purpose of the second edition is identical to that of its predecessor, namely, to provide a rational analysis of membrane transport processes in individual membranes, cells, tissues, and organs, which in tum serves as a frame of reference for rationalizing disorders in which derangements of membrane transport processes play a cardinal role in the clinical expression of disease. As in the first edition, this book is divided into a number of individual, but closely related, sections. Part V represents a new section where the problem of transport across epithelia is treated in some detail. Finally, Part VI, which analyzes clinical derangements, has been enlarged appreciably.