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Smooth Musde: Structure

MUSCLE PHYSIOLOGY

J. Pcrkins

Ms. MFA

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Figurę 3.8 Smooth Muscle Structure_

Myofibrils are not found in smooth musde? cdls. Instead, actln fila-ments are anchoied to the plasma membranę and to dense bodics within the cytoplasm. Myosin interaction with the actin tllaments causes the celi to contract. Smooth muscle cells do not contain T tubules. Instead. caveolae serve a similar function and are a site for enlry of extracellular Ca-' into the celi. Smooth muscle serves a wide rangę of functions. even within the same oigan, and is rapable of changing its morphobgy as circumstances demand <e.g., hypertro-phy, or in instances where the number of gap junctions changes).

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