From homeostasis to the five senses of the human body, the systems in our bodies keep us alive. Learn how each body system works, why maintaining and supplying the body with food and oxygen is important, and how each part is connected with one another. Along the way, meet the great thinkers who have studied our body systems and their functions. Extraordinary photos and real-world examples invite readers to discover the world of biology, while an encyclopedic-entry-style format makes the text approachable and highly browsable. Final comprehension questions engage readers to check what they have learned to reenforce comprehension.