(3) stomach Explanation: The term smooth muscle refers to a muscle of the human body that is part of a involuntary muscle group. The walls of hollow organs are the primary place that smooth muscles can be found. Some of those locations include: Walls of blood vessels, walls of stomach, intestines, large (aorta) and small arteries, arterioles and veins, urinary bladder, uterus, male and female reproductive tracts, respiratory tract etc.