Authorand ExecutiveEditor Robert B.Dunn, Ph.D. Adjunct Associate Professor Department of Medicine Loyola University Medical Center Chicago, IL Contributors Susan DeMesquita, Ph.D. Professor, Department of Physiology Marshall School of Medicine Huntington, WV Directorof MedicalIllustration ChristineSchaar Directorof PublishingandMedia Michelle Covello Stanley S. Passo, Ph.D. Associate Professor, Department of Physiology New York Medical College Valhalla, NY MedicalIllustrators Rich LaRocco and Christine Schaar James Porter, Ph.D. Professor, Department of Physiology University of Louisville Louisville, KY ProductionEditors Kathlyn McGreevy Ruthie Nussbaum Kenneth H. Ibsen, Ph.D. Director of Academic Development Kaplan Medical Professor Emeritus Biochemistry University of California Irvine, CA ProductionArtist Michael Wolff CoverDesign Joanna Myllo Mary Ruebush, Ph.D. Adjunct Professor of Microbiology Montana State University Bozeman, MT CoverArt Rich LaRocco