In neurons, action potential propagation occurs along the axon. The analogous structure in skeletal muscle fibers that enables action potential propagation is the:

Question

In neurons, action potential propagation occurs along the axon.  The analogous structure in skeletal muscle fibers that enables action potential propagation is the:

Quizplus · Accepted Answer

11ecba2d_100b_dbd9_a3bf_d3c044bba612_MD0008_00 An action potential is a rapid change in the electric potential across a cellular membrane, where electric potential is the difference in charge between the intracellular and extracellular fluids. In the nervous system, the propagation of these electrical impulses from the presynaptic neuron can result in an action potential in the postsynaptic neuron; in the musculoskeletal system, action potential propagation through the muscle fiber leads to contractile activity. Muscle fiber action potentials propagate along the sarcolemma, the plasma membrane of the muscle fiber. The sarcolemma burrows deep into the muscle fiber, forming hollow structures known as transverse (T) tubules. Action potentials propagate along T-tubules just as they propagate along the superficial sarcolemma, resulting in the rapid and complete depolarization of the muscle fiber. This promotes calcium release from the sarcoplasmic reticulum, leading to muscle fiber contraction. (Choice A) Actin filaments are one component of the muscle fiber contractile apparatus. However, actin filaments are not involved in the transmission of action potentials. (Choice C) The motor endplate refers to the muscle fiber component of the neuromuscular junction (NMJ). The NMJ facilitates signal transmission between, but not within, cells. (Choice D) The myelin sheath is a fatty layer of insulation that surrounds certain axons and increases the conduction speed of an action potential along the axon of the neuron. Although muscle fibers can be innervated at the NMJ, they do not contain neurons. Educational objective: Electrical depolarization caused by action potential propagation leads to the contraction of skeletal muscle fibers. As extensions of the plasma membrane that penetrate deep into muscle fibers, transverse (T) tubules are specialized muscle fiber structures that facilitate action potential propagation throughout individual muscle fibers.

In Neurons, Action Potential Propagation Occurs Along the Axon