Section 5.7 Smooth Muscle Fibers and Tissue Comparison

Caveolae

Tiny inward pouching invaginations of the smooth muscle sarcolemma that facilitate extracellular Ca2+ influx in place of T-tubules.

Dense Bodies

Protein structures in smooth muscle attached to the sarcolemma and sarcoplasm (functionally equivalent to Z-discs) that anchor thin filaments.

Desmin

Non-contractile intermediate filament proteins that form a structural crisscross framework connecting dense bodies across smooth muscle cells.

Calmodulin

The calcium-binding regulatory protein in smooth muscle cells that replaces troponin.

Myosin Light Chain Kinase (MLCK)

An enzyme activated by the Ca2+-calmodulin complex that phosphorylates myosin heads to initiate cross-bridge formation in smooth muscle.

Phosphorylation

The enzymatic transfer of a phosphate group from ATP to a target molecule to activate it.

Corkscrew Contraction

The characteristic twisting