What type of muscle is responsible for involuntary movements in internal organs?

• A. Skeletal muscle
• B. Cardiac muscle
• C. Visceral muscle
• D. Smooth muscle

Answer: (D)

Smooth muscle is responsible for involuntary movements in internal organs. This type of muscle is found in various structures such as the walls of hollow organs, including the intestines, stomach, blood vessels, and the bladder. Unlike skeletal muscle, which is under voluntary control and enables movements like walking or lifting, smooth muscle operates autonomously without conscious thought.

Smooth muscle fibers have a non-striated appearance and are arranged in sheets, allowing for coordinated contractions that facilitate functions such as peristalsis in the digestive tract or the regulation of blood flow in blood vessels. This involuntary control is essential for maintaining various physiological processes within the body, ensuring that bodily functions continue smoothly and efficiently.

Cardiac muscle, while also involuntary, is specifically found only in the heart and is responsible for pumping blood. Skeletal muscle, as mentioned, is under conscious control, while visceral muscle is a broader term that can sometimes refer to smooth muscle in a general sense but is not the precise term used for this type of muscle. Thus, smooth muscle is the most accurate answer for the question regarding involuntary movements in internal organs.