Which of the following describes smooth muscle?

Smooth muscle is characterized by its unique properties and locations within the body. This type of muscle tissue is primarily found in the walls of hollow organs, such as blood vessels, the digestive tract, and the respiratory passages. Its function is to facilitate involuntary movements, such as the contraction and relaxation that helps move substances through these various systems.

In contrast to other muscle types, such as cardiac and skeletal muscle, smooth muscle does not have the striations typical of those tissues; instead, it appears uniform and smooth under a microscope. Moreover, smooth muscle operates involuntarily, meaning it is not under conscious control, which distinguishes it from voluntary muscles, like skeletal muscles.

This understanding highlights why the choice indicating that smooth muscle lines blood vessels and organs is the most accurate description of its characteristics and function within the body.