What type of muscle tissue is involuntary and can be found in the walls of organs?

Smooth muscle is the type of muscle tissue that is involuntary and found in the walls of various organs, such as the intestines, blood vessels, and the bladder. This type of muscle operates without conscious control, allowing it to perform essential functions automatically. Smooth muscle fibers are non-striated, spindle-shaped, and can contract rhythmically to facilitate processes such as peristalsis in the digestive tract or regulation of blood flow through vasoconstriction and vasodilation.

In contrast, skeletal muscle is under voluntary control, allowing for conscious movement of the body, and it is striated in appearance. Cardiac muscle, while involuntary like smooth muscle, is specifically found in the heart and has a unique structure that includes intercalated discs, which are not present in smooth muscle. Thus, when identifying the specific tissue type that is involuntary and located in the walls of various organs, smooth muscle is the correct answer.