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Glossary of Physiology Terms
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Z disk
Definition:
The Z disk (or Z line) defines the boundaries of a muscle sarcomere. Two adjacent Z disks along the myofibril mark the boundaries of a single sarcomere. The Z disks are the attachment sites for the thin filaments. Therefore, from each Z disk, thin filaments extend to two neighboring sarcomeres. When a muscle fiber contracts, the Z disks of a sarcomere move closer together (i.e., the sarcomere also shortens).

Related glossary terms/phrases:
A band
H zone
I band
M line






Posted: Thursday, January 8, 2015
Last updated: Thursday, January 8, 2015