Explains how the five senses supply constant input to the master control center, how nerves respond, and describes the biology behind the mysteries of thought, feelings, and actions.

Explains how skin, the largest organ in the body, encloses and protects muscles, bones, and internal tissues while playing a key role in keeping a person comfortable and healthy. Explores the differences between the three types of muscle fibers and their locations. Describes the arrangement of the bones and how their placement gives the body form and assists in movment.

Describes the structure and function of the immune system and also discusses allergies, autoimmune diseases, and vaccines.

Discusses the organs and function of the human circulatory system, the vital functions of blood, and the medical diagnosis and treatment of heart disease and other circulatory disorders.