Human Body I

How can we understand what we are? What are we made of? Are we aware that all that we do—including reading this book—is the work of a marvelous machine? We know very little about how we are able to be conscious of our own actions; nevertheless, even though we are usually not very aware of it, this community of organs that is the body—an integrated system that includes the brain, heart, lungs, liver, kidneys, muscles, bones, skin, and endocrine glands— acts together in exquisitely regulated harmony. It is interesting that various mechanisms work together to keep the temperature of the body at 98.6° F (37° C); thanks to the dynamic structure of bones and cartilage, the body is maintained in perfect balance. The body also has a fantastic ability to transform the food it ingests into living tissues, bones, and teeth, all of which contribute to its growth. By this same process, we obtain the energy for working and playing. It is hard to imagine that not long ago the cells of the body of the person reading this book were autonomous and were duplicating themselves freely within the walls of a mother's uterus. Certainly no one reading this book could recognize herself or himself in those cells. Nevertheless, each cell carried within it the information necessary for the development of that person. Everything that happens inside us is truly fascinating. Therefore, we invite you to enjoy this book. It is full of incredible facts and illustrations that will show you the complex ways each part of the body works.