The smooth muscle is a muscle that functions involuntarily which means that it works without you thinking about it. This muscles are found in the digestive system, blood vessels, air ways, and for female in the uterus. These muscles can stretch and retain tension for a long period of time. They also contract involuntarily. There are two types of smooth muscles, the single unit and the multiunit smooth muscle. In single unit smooth muscles, the nerves innervates a single cell within a single sheet or bundle and the action potential is propegated by gap junctions to neighbouring cells like in a bundle.In multiunit muscles the tissue innervate indivdual cells, hence they allow for greater control and gradual responses, much like motor recruitment in skeletal muscles. Smooth muscle fibers have a fusiform shape and they can tense and relax. However, smooth muscles that have tissue tend to have greater elasticity and function within a within a larger tension curve than straited muscles. The ability to strech and maintain tension is important for organs like the intestines and the urinary bladder. Smooth muscles which is also call unstriated muscle or unstripped muscle. This muscle is under control of the autonomic nervous system. Below is the smooth muscles cells and structure.