Smooth muscle (photo) is a type of non-striated muscle, found within the tunica media layer of arteries and veins, the bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye.The glomeruli of the kidneys contain a smooth muscle-like cell called the mesangial cell. Smooth muscle is fundamentally different from skeletal muscle and cardiac muscle in terms of structure, function, excitation-contraction coupling, and mechanism of contraction.
Smooth Muscle Human smooth muscle is composed of slender, spindle-shaped cells, each with a single nucleus. Smooth muscle cells contract in rhythmic waves to propel food through the digestive tract and provide tension in the urinary bladder, blood vessels, uterus, and other internal organs.
Muscle is composed of spindle-shaped cells, each having a central nucleus. The cells have no cross striations, although they do exhibit faint longitudinal striations. Stimuli for the contractions of smooth muscles are mediated by the autonomic nervous system. Smooth muscle is found in the skin, internal organs, reproductive system, major blood vessels, and excretory system.
source:wiki/encarta encyclopedia
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