Volume 2 topics include the digestive system and metabolism, the reproductive system, and a chapter on special systems–which includes blood and the lymphatic system, immune system, urinary system, endocrine and integumentary system. Includes a look at genetics and inherited characteristics and diseases. The section on the Immune System briefly mentions HIV and AIDS infections. This topic is handled discretely. Vaccines are also discussed, including a look at the new experimental mRNA vaccine. Information presented is based on the current understanding of the mRNA technology. Families with a special interest in this topic could easily include additional research and discussion assignments.