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Unformatted text preview: in oxygen supply. Smooth Muscle Smooth muscles are long and somewhat bulbous in shape. They have no visible striations (hence the term smooth). The lack of striations indicates that smooth muscles do not have myofilaments that are organized into sarcomeres. Instead the myofilaments are attached to dense bodies scattered throughout cytoplasm and on the cell membrane. Furthermore, smooth muscles have little SR and no T-tubules and the calcium necessary for contraction comes exclusively from the extracellular fluid. The innervation of smooth muscle is from the autonomic nervous system and the cells respond to either ACh or norepinephrine . The response of smooth muscles to these neurotransmitters varies depending upon their location....
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- Fall '10