ANATOMY

Detailed explanation-1: -Smooth muscle is present in all of the organ systems below: Gastrointestinal tract. Cardiovascular-blood vessel and lymphatic vessels. Renal-urinary bladder.

Detailed explanation-2: -Smooth muscle fibers are located in walls of hollow visceral organs (such as the liver, pancreas, and intestines), except the heart, appear spindle-shaped, and are also under involuntary control.

Detailed explanation-3: -Smooth muscle, found in the walls of the hollow internal organs such as blood vessels, the gastrointestinal tract, bladder, and uterus, is under control of the autonomic nervous system. Smooth muscle cannot be controlled consciously and thus acts involuntarily.

Detailed explanation-4: -Smooth muscle can tense and relax but has greater elastic properties than striated muscle. This is important in organ systems like the urinary bladder where contractile tone must be preserved. Actin and myosin form continuous chains within the smooth muscle cell which are anchored at the dense bodies.

Detailed explanation-5: -Termed unitary smooth muscle or visceral muscle, this type of smooth muscle is the most common observed in the human body, forming the walls of hollow organs. Single-unit smooth muscle produces slow, steady contractions that allow substances, such as food in the digestive tract, to move through the body.