Cardiac Muscle Mechanics
The cardiac muscle cells, also called fibers, branch and interdigitate. They are typically 40 μm long and about 10 μm in diameter; the fibers contain fibrils that are built up by the basic contractile units the sarcomeres (Fig. 12.1). Each sarcomere is bounded at the ends by Z-discs about 2 µm apart. The thin actin filaments about 1 µm long, are attached to the Z-discs, and extend towards the center of the sarcomere. They can either meet in the center, when sarcomere length is about 2.0 µm, overlap each other when sarcomere length is <2.0 µm, or not quite reach each other when sarcomere length >2.0 µm. Spanning the center of the sarcomere length are the thick myosin filaments, 1.6 µm long, which interdigitate with the thin filaments.
KeywordsCardiac Muscle Fiber Length Thin Filament Sarcomere Length Clinical Heart Failure
- 5.van der Velden J, Klein LJ, van der Bijl M, Huybregts MA, Stooker W, Witkop J, Eijsman L, Visser CA, Visser FC, Stienen GJ. Isometric tension development and its calcium sensitivity in skinned myocyte-sized preparations from different regions of the human heart. Cardiovasc Res 1999;42:706–719.PubMedCrossRefGoogle Scholar
- 6.Herzog W, Lee EJ, Rassier DE. Residual force enhancement in skeletal muscle. J Physiol 2007;578:613–615.Google Scholar
- 11.Drake-Holland AJ, Lee JA, Hynd J, Clarke SB, Noble MI. Beneficial effect of the calcium-sensitizing drug EMD 57033 in a canine model of dilated heart failure. Clin Sci (Lond) 1997;93:213–218.Google Scholar