The muscular system plays a very important role in the daily life of an organism. Muscles not only aid in movement, but also help maintain posture, circulate blood, and move substances throughout the body. Additionally, there are three different types of muscles: smooth, skeletal, and cardiac muscle. Skeletal muscle is responsible for movement and behavior, such as walking, running, kicking, or throwing a ball. Most skeletal muscles are attached to bones via tendons. Because you consciously control the contraction of the muscles, the contraction is considered voluntary (Allen and Harper 2013). Smooth muscles are found in blood vessels, the alimentary canal, the urinary bladder, and other hollow organs. They push things through the body, for example, food through the stomach and urine through the bladder. Smooth muscles are considered involuntary and contract even with neuronal stimuli. The third type of muscle is cardiac. Cardiac muscles are located in the walls of the heart. This type of muscle is responsible for pumping the heart so that blood can circulate throughout the body. Furthermore, skeletal muscles are surrounded by sarcomeres made up of thick and thin filaments called myofilaments (Cooper 2000). The thick filaments are made of myosin. On the other hand, thin filaments are made up of actin, tropomyosin, and troponin. Actin and myosin are often referred to as contractile proteins (Cooper 2000). When these two substances interact with each other, muscle shortening occurs (Allen and Harper 2013). Muscle contraction occurs when myosin heads interact with thin filaments to form cross bridges (Sheir, Butler, and Lewis 2004). This process begins when the brain sends a signal that releases calcium. Calcium is a fundamental substance that must be present for muscle contraction to occur. It exposes actin binding sites by interacting with tropomyosin (Sheir, Butler and Lewis