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  1. Factors, such as hormones and stress (and artificial anabolic steroids), acting on the muscle can increase the production of sarcomeres and myofibrils within the muscle fibers, a change called hypertrophy, which results in the increased mass and bulk in a skeletal muscle.

    • Lindsay M. Biga, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Mat...
    • 2019
  2. Feb 24, 2023 · Without sufficient dystrophin, muscle contractions cause the sarcolemma to tear, causing an influx of Ca ++, leading to cellular damage and muscle fiber degradation. Over time, as muscle damage accumulates, muscle mass is lost, and greater functional impairments develop.

    • The Sliding Filament Model of Contraction. When signaled by a motor neuron, a skeletal muscle fiber contracts as the thin filaments are pulled and then slide past the thick filaments within the fiber’s sarcomeres.
    • ATP and Muscle Contraction. For thin filaments to continue to slide past thick filaments during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, re-cock, etc.
    • Sources of ATP. ATP supplies the energy for muscle contraction to take place. In addition to its direct role in the cross-bridge cycle, ATP also provides the energy for the active-transport Ca pumps in the SR.
    • Relaxation of a Skeletal Muscle. Relaxing skeletal muscle fibers, and ultimately, the skeletal muscle, begins with the motor neuron, which stops releasing its chemical signal, ACh, into the synapse at the NMJ.
    • The Sliding Filament Model of Contraction. When signaled by a motor neuron, a skeletal muscle fiber contracts as the thin filaments are pulled and then slide past the thick filaments within the fiber’s sarcomeres.
    • ATP and Muscle Contraction. For thin filaments to continue to slide past thick filaments during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, re-cock, etc.
    • Sources of ATP. ATP supplies the energy for muscle contraction to take place. In addition to its direct role in the cross-bridge cycle, ATP also provides the energy for the active-transport Ca pumps in the SR.
    • Relaxation of a Skeletal Muscle. Relaxing skeletal muscle fibers, and ultimately, the skeletal muscle, begins with the motor neuron, which stops releasing its chemical signal, ACh, into the synapse at the NMJ.
  3. Aug 28, 2024 · The sliding filament theory is a fundamental concept in muscle physiology that explains how muscles contract to generate force. This theory is based on the interactions between two types of protein filaments—actin (thin filaments) and myosin (thick filaments)—within the muscle fibers.

  4. Factors, such as hormones and stress (and artificial anabolic steroids), acting on the muscle can increase the production of sarcomeres and myofibrils within the muscle fibers, a change called hypertrophy, which results in the increased mass and bulk in a skeletal muscle.

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  6. The sequence of events that result in the contraction of an individual muscle fiber begins with a signal — the neurotransmitter, acetylcholine (ACh) — from the motor neuron innervating that fiber.