In medicine, time is always limited. In the USMLE Step 1 examination, students have roughly 70 seconds to answer each question-when on clinical rotations, attending physicians expect immediate answers without hesitation. Using Essentials: Renal, Gastrointestinal and Hepatobiliary Systems, students can gain a complete understanding of the physiology, pathology, and pharmacology of each system with the proficiency required to rapidly answer even the most difficult questions. Within this book students will find a learning method designed to test immediate recall through a series of questions ranging from simple to complex. This book serves as both a solitary source of review, as well as a complementary source to any reference text. A few of the things inside: A time tested method for making the most out of time spent reviewing. Recommended reference sources which best compliment this book. Stratification of questions based on difficulty. Complete review encompassing all pathology, physiology and pharmacology.