The Muscular System
Do you like to dance? Most of us do, or we may simply enjoy watching good dancers. The grace and coordination involved in dancing result from the interaction of many of the organ systems, but the one you think of first is probably the muscular system.
There are more than 600 muscles in the human body. Most of these muscles are attached to the bones of the skeleton by tendons, although a few muscles are attached to the undersurface of the skin. The primary function of the muscular system is to move the skeleton. The muscle contractions required for movement also produce heat, which contributes to the maintenance of a constant body temperature. The other body systems directly involved in movement are the nervous, respiratory, and circulatory systems. The nervous system transmits the electrochemical impulses that cause muscle cells to contract. The respiratory system exchanges oxygen and carbon dioxide between the air and blood. The circulatory system brings oxygen to the muscles and takes carbon dioxide away.
These interactions of body systems, which focuses on the skeletal muscles. You may recall that there are two other types of muscle tissue: smooth muscle and car-diac muscle. These types of muscle tissue will be discussed in relation to the organs of which they are part. Before you continue, you may find it helpful to go back and review the structure and characteristics of skeletal muscle tissue. In this chapter we will begin with the gross (large) anatomy and physiology of muscles, then discuss the microscopic structure of muscle cells and the bio-chemistry of muscle contraction.