In the last chapter, interactions between nerve and muscle were considered in which neuronal action potentials release a chemical transmitter. For many muscles of lower animals and a few specialized muscles of mammals, graded depolarizations of the muscle fiber membrane are produced which lead to graded contractions. In most types of skeletal muscle in mammalian systems, the transmitter produces enough ionic current through the muscle membrane to generate action potentials. As will be discussed in this chapter, the action potential leads to a characteristic twitch contraction. The process whereby the electrical activity of the muscle membrane activates the contractile proteins contained within the muscle cells is referred to as excitation—contraction coupling.
KeywordsThin Filament Myosin Head Thick Filament Myosin Molecule Transverse Tubule
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