Contraction and Excitation of Smooth Muscle
CONTRACTION OF SMOOTH MUSCLE The same principles as with Skeletal muscle, actin and myosin. The internal physical structure is different. TYPES OF SMOOTH MUSCLE: MULTI-UNIT SMOOTH MUSCLE Each fiber can contract independently of the others and that the control is exerted mainly by nerve signals. Smooth muscle fibers of the ciliary muscle of the eye, the iris of the eye. SINGLE UNIT SMOOTH MUSCLE Unitary smooth muscle, syncytial smooth muscle and viseral smooth muscle. Millions of fibers contract together as a single unit. The cell membranes are joined together by gap junctions so that action potentials can travel from fiber can to the next and cause muscle fibers to contract together. Walls of the gut, bile ducts, ureters, uterus, and blood vessels. Physical Basis for Smooth Muscle Contraction Smooth muscle does not have the same stritated arrangement of actin and myosin filaments as that found in skeletal muscle. Actin filaments attach to dense bodies. Some of the