Smooth muscle fibers are a type of muscle tissue found in various organs throughout the body, including the digestive tract, blood vessels, and respiratory system. Unlike skeletal muscle, which is under voluntary control, smooth muscle operates involuntarily, meaning it functions automatically without conscious effort. These fibers are non-striated and have a spindle shape, allowing them to contract and relax efficiently. Smooth muscle fibers play a crucial role in regulating bodily functions. For example, they help control the movement of food through the intestines and regulate blood flow by adjusting the diameter of blood vessels. Their rhythmic contractions are essential for maintaining homeostasis and supporting various physiological processes.