These are about 8 nm in diameter and, being the thinnest of the cytoskeletal filaments, are also called microfilaments. (In skeletal muscle fibers they are called thin filaments.) Some functions of actin filaments: 1  form a band just beneath the plasma membrane that.  provides mechanical strength to the cell.
The microfilaments are arranged so that the fibers appear to have stripes (striations) in them. These are also called voluntary muscles.. Smooth muscle is involuntary, and is not under conscious control; the muscles in your digestive system are smooth muscles.The cells are individual and are found in sheets instead of long fibers. (Cardiac muscle has characteristics of both, but are not referred to in the question).here skeletal muscle is voluntary, cardiac muscle is autorhythmic (beats involuntarily; generates its own action potentials). 3. Smooth muscle: refers to the muscles that are controlled involuntarily by the brain, like those attached to the base of hair follicles or in the walls of the gastro-intestinal tract.
The structure of an involuntary muscle cell consists of a long, spindle-shaped cell without striations. The cells may occur as individual cells, in groups or as sheets. Contractions occur either in slow, spontaneous rhythms or as sustained contractions for longer durations. The involuntary muscle is one of three types of muscles found. The other two types are skeletal and cardiac. Skeletal muscle is a type of voluntary muscle, meaning it is controlled by the organism's will. The skeletal muscle is also referred to as a striated muscle because of the alternating muscle fibers that are light and dark colored.