The muscular system is the largest system in the body. Muscles are unique because they can contract. There are three different types of muscle tissue, skeletal, smooth and cardiac. Skeletal muscle cells are long ,narrow and contain many nuclei.
Skeletal muscle is under voluntary control.
Smooth muscle tissue is found in the walls of the organs of the GI and urinary tracts, respiratory passages, vascular system. Smooth muscle cells are spindle shaped and contain a single nucleus. Smooth muscle is under involuntary control. Cardiac muscle tissue is only found in the heart. Cardiac muscle cells are branched, contain a single nucleus and are joined by intercalated discs.