Lesson 1, Topic 1
In Progress


May 3, 2021

There are many wonders in our world, but none is more wondrous than the human body. This is a textbook about that incomparable structure. It deals with two very distinct and yet interrelated sciences: anatomy and physiology.

As a science, anatomy is often defined as the study of the structure of an organism and the relationships of its parts. The word anatomy is derived from two word parts that mean “cutting apart.” Anatomists learn about the structure of the human body by cutting it apart. This process, called dissection, is still the principal technique used to isolate and study the structural components or parts of the human body.
Physiology, on the other hand, is the study of the functions of living organisms and their parts. Physiologists use scientific experimentation to tease out how each activity of the body works, how it is regulated, and how it fits into the complex, coordinated operation of the whole human organism.
In the chapters that follow, you will see again and again that anatomical parts have structures exactly suited to perform specific functions. Each has a particular size, shape, form, or position in the body related directly to its ability to perform a unique and specialized activity. This principle—that structure fits function—is the key to understanding all of human biology.
Although an understanding of the normal structure and function of the body is important, it is also important to know the mechanisms of disease. Disease conditions result from abnormalities of body structure or function that prevent the body from maintaining the internal stability that keeps us alive and healthy. Pathology, the scientific study of disease, uses principles of anatomy and physiology to determine the nature of particular diseases. The term pathology comes from pathos, the Greek word for “disease.” Chapter 6 provides an overview of the basic mechanisms of disease, such as infection and cancer.
Throughout the rest of this textbook, explanations of normal structure and function are supplemented by discussions of related disease processes. By knowing the structure and function of the healthy body, you will be better prepared to understand what can go wrong to cause disease. At the same time, having knowledge of disease states will enhance your understanding of normal structure and function.