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nmdcat.online July 28, 2026

Concerning the attachment of actin filaments, what is the functional equivalent of Z-lines in smooth muscle?

A. Intercalated discs
B. Dense bodies
✓
C. M-lines
D. Caveolae

📝 Explanation

In striated muscles, actin filaments are anchored to Z-lines. In smooth muscle, which lacks Z-lines and sarcomeres, the actin filaments are anchored to protein structures called dense bodies, which are distributed throughout the cytoplasm and attached to the sarcolemma.

📖 Additional Information

  • Intercalated discs
  • Dense bodies
  • M-lines
  • Caveolae

In striated muscles, actin filaments are anchored to Z-lines. In smooth muscle, which lacks Z-lines and sarcomeres, the actin filaments are anchored to protein structures called dense bodies, which are distributed throughout the cytoplasm and attached to the sarcolemma.

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