Which muscle type is described as involuntary and smooth?

The muscle type that is described as involuntary and smooth is non-striated muscle. This type of muscle is found in various internal organs, such as the intestines and blood vessels. Non-striated muscle fibers do not have the characteristic banding (striations) that are seen in other muscle types, such as striated and cardiac muscles.

Involuntary muscle is controlled automatically by the autonomic nervous system, which means it operates without conscious control. This is crucial for many bodily functions, such as digestive movement and blood vessel regulation, where smooth muscle continuously contracts or relaxes to maintain essential functions.

Striated muscle, which is also known as skeletal muscle, is voluntary and is primarily responsible for body movements that can be consciously controlled. Cardiac muscle, while it is involuntary like smooth muscle, is striated and specifically makes up the heart, distinguishing it from smooth muscle.

Therefore, non-striated muscle fits the description of being both involuntary and smooth, highlighting its unique role in the body's muscular system.