Retrieving "Myofibrils" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Sarcoplasmic Reticulum

   Linked via "myofibrils"

   Longitudinal Tubules
   The longitudinal tubules constitute the main body of the $\text{SR}$ network. These tubules run parallel to the myofibrils, spanning the distance between adjacent Z-disks. Their membranes are densely packed with the Sarco/Endoplasmic Reticulum $\text{Ca}^{2+}$-ATPase ($\text{SERCA}$), the primary pump responsible for actively transporting $\text{Ca}^{2+}$ back into the lumen against a steep electrochemical gradient following [muscle relaxation](/entries/muscle-relaxat…