By Michael Weiss. âSectarian violence in Syria raises fears,â screamed the headline of a Washington Post article on the murder Tuesday of 16 Syrians in the city of Homs, which lies 100 miles north of Damascus.
Multi-unit smooth muscle is found in the walls of large blood vessels, in large airways in the lungs, in the muscle of the eye that adjusts the lens and alters the size of the pupil, and in the base of hair follicles in the skin. SINGLE-UNIT muscle is the more common. It is commonly called visceral muscle and is found in the walls of hollow organs (e.g. digestive, reproductive, urinary system). Sheets of single-unit muscle fibres contract as a single unit as they are electrically linked by gap junctions (like cardiac muscle). This permits coordinated contraction of a whole organ. Single unit smooth muscle is self-excitable as clusters of specialised smooth muscle cells display spontaneous electrical activity.
Types of Smooth Muscle. Single-unit (unitary) smooth muscle, called visceral muscle, is the most common type of smooth muscle. It contracts rhythmically as a unit, is electrically coupled by gap junctions, and exhibits spontaneous action potentials.mooth muscle cells are small, spindle-shaped cells with one central nucleus, and lack the coarse connective tissue coverings of skeletal muscle. Smooth muscle cells are usually arranged into sheets of opposing fibers, forming a longitudinal layer and a circular layer.