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Glossary Term

Z Disk

The Z-disk, a dark line separating adjacent I-bands in muscle cells, acts as the border of the sarcomere and is composed of connectin protein that anchors actin filaments. A sarcomere is a segment of a myofibril between two Z-disks. Synonyms for the Z-disk include Z-line, Z-band, and Z-plate. Related terms include myofibril, sarcomere, actin, and connectin.

Z disk - Refers to a dark line between adjacent I-bands under a microscope. This area is the border, or walls of the "sarcomere", and is comprised of connectin protein that acts as an anchor for the actin filaments. Example, a sacromere (the smallest functional unit of a muscle cell) may be defined as a segment of a myofibrile between two Z disks.

  1. Saladin, K. (2014). Anatomy & physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717