Investigating Body Systems introduces readers to the main organ systems of the human body. The science that makes each system function is clearly explained, and new research on the body's processes are explored. Fact-check boxes help separate fact from fiction, and key figures in the development of the scientific method are identified. Investigating the Digestive System Your digestive system is like a production Line. Nutrients in food, drinks, or pills begin their journey at the mouth. From there they travel through tubes, filters, and holding rooms, as body chemicals work to extract what is needed-and flush the rest This fascinating book explores gut microbiomes, human waste, and how over 100 million nerve cells monitor the digestive system to identify problems.