Smooth muscle

Smooth muscle is involuntarily controlled muscle tissue that unlike striated muscle contracts without the active input of the conscious mind. It constitutes a majority of the musculature of our internal organs and digestive system. Smooth muscle consists of spindle-shaped cells with a central nucleus. In smooth muscle waves of muscle contraction can propagate through sheets of muscle fibers which is key for motions such as moving food through the digestive systems many twists and turns. It is also capable of contracting at different intensities depending on the levels of ATP, something which striated muscle fibers cannot, they are only on or off. Smooth muscle can therefore not contract or relax as fast as skeletal or cardiac muscle but can instead provide more consistent and powerful tension.