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Although the term excitation-contraction coupling confuses or scares some students, it comes down to this: for a skeletal muscle fiber to contract, its membrane must first be “excited”—in other words, it must be stimulated to fire an action potential.
24 Φεβ 2023 · 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. This process is known as the sliding filament model of muscle contraction (Figure 10.4.3 10.4. 3).
Muscle contraction is described by the sliding filament model of contraction. ACh is the neurotransmitter that binds at the neuromuscular junction (NMJ) to trigger depolarization, and an action potential travels along the sarcolemma to trigger calcium release from SR.
The cell membrane of a muscle fiber is called the sarcolemma, and the cytoplasm is called the sarcoplasm. Muscle fibers also have a structure called the sarcoplasmic reticulum , which is similar to the endoplasmic reticulum and stores calcium ions (Ca 2+ ).
The muscle fiber membrane refers to the highly corrugated membrane of a muscle cell that contains primary and secondary clefts with a large surface area. It plays a crucial role in signal transduction and muscle contraction by containing high densities of receptors and channels such as AChRs and Na+ channels.
The plasma membrane of a skeletal muscle fiber is called the sarcolemma. The sarcolemma is the site of action potential conduction, which triggers muscle contraction. Within each muscle fiber are myofibrils—long cylindrical structures that lie parallel to the muscle fiber.
The plasma membrane of a skeletal muscle fiber is called the sarcolemma. The sarcolemma is the site of action potential conduction, which triggers muscle contraction. Within each muscle fiber are myofibrils —long cylindrical structures that lie parallel to the muscle fiber.
