Cassie M. Lawton 
Human Circulatory System [PDF ebook] 

The human circulatory system is essential for pumping blood throughout a person’s body. Without it, humans wouldn’t be able to live. This guide explores the main elements of the circulatory system, introduces key parts such as blood vessels and the heart, and examines problems with this system. Complete with fact boxes and intriguing sidebars, accessible language, discussion questions, and descriptive photographs and diagrams, this introduction will appeal to readers of all levels.