Your Body. How It Works. The Skeletal and Muscular Systems PDF Free Download
Recently, one of the major television networks featured a “strongman” competition. In one phase of the contest, the competitors balanced a metal beam across their knees and supported thousands of pounds of weight on their lower legs. On another occasion, several years earlier, I attended a performance of the American Ballet Theater to watch in awe, as the lead dancer, in performing a series of leaps and turns, appeared to defy gravity. In both cases my immediate response was, “That is impossible; how can they do that?” In this book we will learn the answers to these and many other mysteries. The skeletomuscular system, a combination of the body’s skeletal system and muscular system, is responsible for these acts of strength, power, and grace. We will see that what at first appears impossible is probably better described as difficult but possible (Figure 1.1). The secret to the heavy weight-balancing act is actually the incredible strength of the bones of the legs. By balancing the weight directly over the long line of the bones of the lower legs, and by not attempting to move the weight once in place, the amazing. As we move through this book, we will discover the importance of our skeleton and muscles and how these combined systems contribute to our ability to function in the world. INSIDE VERSUS OUTSIDE ARMOR The human skeleton (Figure 1.2), which is made up of 206 bones, is critical for positioning and stabilizing the other organ systems. Because our skeleton is inside the tissues of our body, it is referred to as an endoskeleton. Not all organisms have skeletons.