Beginning of Essay
The musculoskeletal system is made up of bones, joints, and muscles. This system gives the body form and support, and protects the body while allowing it to move. Basically, the muscles in this system perform three important body functions: the movement of body pa ....

Middle of Essay
.... are short and strong, providing the force needed for movement. The muscle contractions produce and provide some heat needed in the body. Skeletal muscle tissue is made up of smaller fibers called myofibrils. These myofibrils are composed of even smaller protein filaments. These filaments can be either thick or thin. The thick filaments are made of the protein myosin, and the thin filaments are made of the protein actin. The arrangement of the myosin and actin gives skeletal muscle its striated (or striped) appearance. Each section of a myofibril is called a sarcomere, and is the functional unit of muscle. How muscles contract is directly rel ....