As the name suggests, the muscular system is made up of all the muscles in your body. The job of your muscles is to create movement in your body, like the movement of your arms and legs as your run, the movement of your esophagus pushing food to your stomach, or even the movement as your pupil gets bigger or smaller. Your muscles also keep you warm! Your muscle cells burn fuel to create energy as well as most of the heat used to maintain your body temperature.
There are three main categories of muscles: skeletal muscle, smooth muscle, and cardiac muscle. Each type of muscle has a different structure and therefore, a different role in your body. Skeletal muscle is connected to your bones by tendons. These muscles are the ones involved in voluntary movement, the movements you can control. Smooth muscles are involved in involuntary movements, the movements that just happen without you thinking about it. Your intestines, veins, and reproductive tracts are all examples of smooth muscle. The last type of muscle, cardiac muscle, is an involuntary muscle type that is only found in your heart. Your heart’s job, controlling the blood pumping through your body, is so specialized that it has its own muscle group! Learn more about your heart in the Cardiovascular System section.
Because your muscles are responsible for your movement, it’s important to keep them healthy by doing exercises that target specific muscles. When you work out your muscles, you actually breaking tissues in your muscles so that they will regrow stronger!
Written using information from NIH National Cancer Institute and NIH National Institute of Arthritis and Musculoskeletal and Skin Diseases.