myofilament

Examples of myofilament in the following topics:

• Sliding Filament Model of Contraction

  • Actin myofilaments attach directly to the Z-lines, whereas myosin myofilaments attach via titin molecules.
  • Surrounding the Z-line is the I-band, the region where actin myofilaments are not superimposed by myosin myofilaments.
  • Another protein, nebulin, is thought to perform a similar role for actin myofilaments.
  • During muscle contraction, the heads of myosin myofilaments quickly bind and release in a ratcheting fashion, pulling themselves along the actin myofilament.
  • The myofilaments themselves do not contract or expand and so the A-band remains constant.

• Skeletal Muscle Fibers

  • Skeletal muscles are composed of striated subunits called sarcomeres, which are composed of the myofilaments actin and myosin.
  • Myofibrils are composed of long myofilaments of actin, myosin, and other associated proteins.
  • Myofibrils are composed of smaller structures called myofilaments.
  • There are two main types of myofilaments: thick filaments and thin filaments.
  • The molecular model of contraction which describes the interaction between actin and myosin myofilaments is called the cross-bridge cycle.

• Force of Muscle Contraction

  • Muscles exist in this state to optimize the force produced during contraction, which is modulated by the interlaced myofilaments of the sarcomere.
  • If a sarcomere is stretched too far, there will be insufficient overlap of the myofilaments and the less force will be produced.
  • Simply put,  the tension generated in skeletal muscle is a function of the magnitude of overlap between actin and myosin myofilaments.
  • However, cross-bridge formation is not immediate, so if myofilaments slide over each other at a faster rate the ability to form cross bridges and resultant force are both reduced.

• Characteristics of Muscle Tissue

  • Muscle cells, or myocytes, contain myofibrils comprised of actin and myosin myofilaments which slide past each other producing tension that changes the shape of the myocyte.
  • Smooth muscle is non-striated, although it contains the same myofilaments they are just organised differently, and involuntary.

• Types of Muscle Tissue

  • The banding pattern of the striations reflects the alignment of the myofilament fibers.

• Velocity and Duration of Muscle Contraction

  • However, cross-bridge formation is not immediate and if myofilaments slide over each other at a faster rate, their ability to form cross-bridges and subsequent force are both reduced.

• Structure and Function of the Muscular System

  • Muscle cells, or myocytes, contain myofibrils comprised of actin and myosin myofilaments which slide past each other producing tension that changes the shape of the myocyte.

• Muscle Tone

  • Both are similar to muscle fibers in that they contain actin and myosin myofilaments that allow them to stretch with the muscle.