18 Facts About Smooth muscle

Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations .

Smooth muscle is found in the walls of hollow organs, including the stomach, intestines, bladder and uterus; in the walls of passageways, such as blood, and lymph vessels, and in the tracts of the respiratory, urinary, and reproductive systems.

Single-unit visceral smooth muscle is myogenic; it can contract regularly without input from a motor neuron .

Multiunit smooth muscle is found in the trachea, the iris of the eye, and lining the large elastic arteries.

However, smooth muscle tissue tends to demonstrate greater elasticity and function within a larger length-tension curve than striated muscle.

Smooth muscle cell is a spindle-shaped myocyte with a wide middle and tapering ends, and a single nucleus.

Smooth muscle alpha-actin is the predominant isoform within smooth muscle.

Isolated single smooth muscle cells have been observed contracting in a spiral corkscrew fashion, and isolated permeabilized smooth muscle cells adhered to glass demonstrate zones of contractile protein interactions along the long axis as the cell contracts.

Smooth muscle-containing tissue needs to be stretched often, so elasticity is an important attribute of smooth muscle.

Smooth muscle has specific elastin and collagen receptors to interact with these proteins of the extracellular matrix.

Smooth muscle is excited by external stimuli, which causes contraction.

Generally, arterial smooth muscle responds to carbon dioxide by producing vasodilation, and responds to oxygen by producing vasoconstriction.

Smooth muscle contraction is caused by the sliding of myosin and actin filaments over each other.

Still, smooth muscle has the ability of sustained maintenance of force in this situation as well.

Clams and other bivalve mollusks use this catch phase of smooth muscle to keep their shell closed for prolonged periods with little energy usage.

Embryological origin of smooth muscle is usually of mesodermal origin, after the creation of muscle cells in a process known as myogenesis.

Multisystemic smooth muscle dysfunction syndrome is a genetic condition in which the body of a developing embryo does not create enough smooth muscle for the gastrointestinal system.

Smooth muscle tumors are most commonly benign, and are then called leiomyomas.