"For almost 3,000 years, scientists have explored the depths of the human body: not just how it is put together, but how and why it functions as it does. Exploration continues today with new discoveries further illuminating how various cells and organ systems not only work but work together to support human life. Most recently, a global pandemic focused attention on the immune system, and researchers scrambled to understand how the immune system responded, or sometimes failed to respond, to a virus to which it had never before been exposed. This edition of Understanding Anatomy & Physiology contains more information than ever about the immune system, including types of immunity, how epidemics and pandemics develop, and how vaccines work. However, before you can understand a body in illness, you must understand how it functions in health. For example, without a thorough knowledge of fluid and electrolyte balance, how can you explain why chronic vomiting or diarrhea can cause an abnormal heartbeat? By the end of this course, understanding the body's form and function should become second nature"--