The structures of body parts make possible their functions: (a) the hand is adapted for grasping, (b) the heart for pumping blood, and (c) the mouth for receiving food. (Arrows indicate movements associated with these functions.)
As you read this book, you will begin to learn how the human body maintains life by studying two major areas of medical science, anatomy (ah-natco-me) and physiology. (fiz9e-olco-je) Anatomy deals with the structures (morphology) of body parts—what are their forms, and how are they arranged? Physiology considers the functions of these body parts—what do they do, and how do they do it? Although anatomists tend to rely more on examination of the body and physiologists more on experimentation, together their efforts have provided us with a solid foundation upon which to build an understanding of how our bodies work as living organisms.
It is difficult to separate the topics of anatomy and physiology because anatomical structures make possible their functions. Parts form a well-organized unit—the human organism—and each part plays a role in the operation of the unit as a whole. This functional role depends upon the way the part is constructed. For example, the arrangement of parts in the human hand with its long, jointed fingers makes grasping possible. The heart's powerful muscular walls are structured to contract and propel blood out of the chambers and into blood vessels, and valves associated with these vessels and chambers ensure that the blood will move in the proper direction. The shape of the mouth enables it to receive food; teeth are shaped so that they break solid foods into smaller pieces; and the muscular tongue and cheeks are constructed to help mix food particles with saliva and prepare them for swallowing (fig. 1.2).
Anatomy and physiology are ongoing as well as ancient fields. Research frequently expands our understanding of physiology, particularly at the molecular and cellular levels, and unusual, new anatomical findings are also reported. Recently, researchers discovered a previ ously unknown muscle between two bones in the head, providing physiologists with a new opportunity to understand body function.
D What are the differences between anatomy and physiology?
Why is it difficult to separate the topics of anatomy and physiology?
List several examples that illustrate how the structure of a body part makes possible its function.
How are anatomy and physiology both old and new fields?
A scene such as Judith R.'s accident and injury underscores the delicate balance that must be maintained in order to sustain life. In those seconds at the limits of life—the birth of a baby, a trauma scene, or the precise instant of death following a long illness—we often think about just what combination of qualities constitutes this state that we call life. Indeed, although this text addresses the human body, the most fundamental characteristics of life are shared by all organisms (orcgah-nismz). As living organisms, we can move and respond to our surroundings. We start out as small individuals and then grow, eventually to possibly reproduce. We gain energy by taking in or ingesting food, by breaking it down or digesting it, and by absorbing and assimilating it. The absorbed substances circulate throughout the internal environment of our bodies. We can then, by the process of respiration, use the energy in these nutrients for such vital functions as growth and repair of body parts. Finally, we excrete wastes from the body. Taken together,
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.