The Muscular System
The muscular system is made of all of the muscles in your body. There are 3 types of muscles in the body; skeletal muscle, smooth muscle, and cardiac muscle. Skeletal muscles allow your bones to move. They are attached to bones by tendons, work in pairs, and are voluntary. In other words, they move at your will when you want them to. They also appear to look striated. Smooth muscle moves food throughout the digestive system. They are located next to the stomach, large and small intestine, and in the throat. Smooth muscles are involuntary and work all of the time, nonstop. You also cannot control them. Smooth muscles, as you can imagine, appear smooth. The last type of muscle is cardiac muscle. Your heart is made of cardiac muscles. Cardiac muscle is also what makes your heart beat. They too are involuntary. They are uncontrollable and work nonstop throughout the day. Cardiac muscles appear to be smooth and striated at the same time. There are also levers in the body. The most common is a class 3 lever. A class 3 lever is one with a fulcrum on one side, the load on the other, and the effort in the middle. In addition, there are also examples of class 1 and 2 levers in the body. The neck is an example of a class 1 lever with the fulcrum in the center, the load on one end, and effort on the other. An example of a class 2 lever would be the foot. The load is on one end, the effort on the other, and the load in the center. The muscular system is integrated with the human body in many ways. The heart (which belongs to the cardiovascular system) is made of several cardiac muscles. The skeletal system relates to the skeletal system because muscles are attached to and move bones. The muscular system relates to the nervous system because nerves send specialized messages from the brain to the muscle. The muscular system relates to the respiratory system because the muscle cells need oxygen which comes from the lungs.
The picture to the left depicts a diagram of the human muscle system.
This picture shows a human skeleton with parts of it overlapped in muscles. The skull shows the jaw and eyes.