Z-Line

Z-Line The structure indicated is the Z-disc/Z-line formed between adjacent sarcomeres. A sarcomere is the name given to the basic unit of muscle, composed of sliding protein filaments of actin and myosin. Myosin filaments are thick, actin filaments are thin. These two filaments overlap each other, and their ability to slide past each other forms the basis of the theory of muscle contraction and relaxation. Under electron microscopy, the overlapping pattern of these thick and thin protein filaments gives rise to darker and lighter areas (bands), as well as distinct lines. The thinner actin filaments are all bound to the …

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