microfilaments versus myofilaments

[tym]

Whats the difference? Are they both referring to thick&thin filaments?

Thanks!

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[sillyjoe]

Whats the difference? Are they both referring to thick&thin filaments?

Thanks!

Microfilaments generally refer to the actin polymers that create filaments within cells. Actin has a wide range of functionalities from cytoskeletal in epithelial, contractile elements in muscles and cytokinesis in mitosis.

Myofilaments specifically refer to the actin (thin filament) and myosin (thick filament) contractile elements within muscle cells.

Edit: I removed sarcomere.

 

[Shirafune]

Microfilaments generally refer to the actin polymers that create filaments within cells. Actin has a wide range of functionalities from cytoskeletal in epithelial, contractile elements in muscles and cytokinesis in mitosis.

Myofilaments specifically refer to the actin (thin filament), myosin (thick filament), troponin, tropmomyosin structure of the sarcomere.

I wanted to add that myofilaments are not limited to the sacromere. It's just that the organization of myofilaments is well-defined in the basic unit of contraction for striated muscles: sarcomeres. Smooth muscle doesn't have sarcomeres, but still has myofilaments in another orientation that does not lead to striations in the muscle.

 

[The Brown Knight]

smallest --> largest:
actin (microfilaments) + myosin = myofilaments --> myofibrils (repeated sarcomere units) --> myofibers (muscle cells) --> fascicles (bundles of myofibers)
--> muscle organ (bundle of fascicles)