Parts of Nervous System. Nervous System: Nervous system is the chief controlling and coordinating system of the body. It controls and regulates all activities of the body, whether voluntary or involuntary, and adjusts the individual (organism) to the given surroundings.
Compared to skeletal muscle, smooth-muscle cells are small. They are spindle-shaped, about 50 to 200 microns long and only 2 to 10 microns in diameter. They have no striations or sarcomeres. Instead, they have bundles of thin and thick filaments (as opposed to well-developed bands) that correspond to myofibrils.
Both cardiac and smooth are involuntary. Skeletal is voluntary. Skeletal muscles are the muscles you use to move your bones. You do these things voluntarily, like raising your arm. Skeletal muscle tires out quickly. Cardiac muscle is only found in your heart. This muscle type keeps your heart running and does not tire.