The inspiration for this basic science series occurred at an educational retreat led by Dr. L. Maximilian Buja, who at the time was the Dean of the University of Texas Medical School at Houston and is currently Executive Vice President for Academic Affairs. It has been such a joy to work together with Drs. Weisbrodt, Dubinsky, O'Neil, and Walters, who are accomplished scientists and teachers. It has been rewarding to collaborate with Dr. Konrad Harms, a friend, a scholar, and an excellent teacher. Dr. Harms found collaborating with his father, Dr. Paul Harms, a neuroendocrinologist and reproductive physiologist at Texas A&M University, to be a true privilege, joy, and honor. I appreciate the many hours and talent of Alaina Johnson, who reviewed the entire manuscript and served as a major consultant. I would like to thank McGraw- Hill for believing in the concept of teaching by clinical cases. I owe a great debt to Catherine Johnson, who has been a fantastically encouraging and enthusiastic editor. At the University of Texas Medical School at Houston, I would like to recognize the bright and enthusiastic medical students who have inspired us to find better ways to teach. At Methodist Hospital, I appreciate Drs. Mark Boom, Alan L. Kaplan, Karin Pollock-Larsen, H. Dirk Sostman, and Judy Paukert, and Mr. Reggie Abraham. At St. Joseph Medical Center, I would like to recognize our outstanding administrators: Phil Robinson, Pat Mathews, Laura Fortin, Dori Upton, and Drs. John Bertini and Thomas V. Taylor. I appreciate Marla Buffington's advice and assistance. Without the help from my colleagues, Drs. Simmons, Schachel, and McBride, this book could not have been written. Most important, I am humbled by the love, affection, and encouragement from my lovely wife, Terri, and our four children, Andy, Michael, Allison, and Christina.