“Digestive System” is a part of the college-level Principles of Biology course series textbooks. It is a tutorial written in questions and answers format to describe the anatomy and physiology of the digestive system, including the food intake, energy balance, chemical and physical digestion, food groups, essential nutrients, excretion and evolution of the digestive system.
It is a study guide with in-depth explanations. Each section is a modular unit that is self-contained for easy reading. The principles and concepts are introduced systematically so students can learn and retain the materials intuitively.