Which of the following causes rigor in skeletal muscle?

Question

Quizplus · Accepted Answer

$[\mathrm{VI} B]$. Rigor is a state of permanent contraction that occurs in skeletal muscle when adenosine triphosphate (ATP) levels are depleted. With no ATP bound, myosin remains attached to actin and the cross-bridge cycle cannot continue. If there were no action potentials in motoneurons, the muscle fibers they innervate would not contract at all, since action potentials are required for release of $\mathrm{Ca}^{2+}$ from the sarcoplasmic reticulum (SR). When intracellular $\mathrm{Ca}^{2+}$ concentration increases, $\mathrm{Ca}^{2+}$ binds troponin $\mathrm{C}$, permitting the cross-bridge cycle to occur. Decreases in intracellular $\mathrm{Ca}^{2+}$ concentration cause relaxation.

Which of the Following Causes Rigor in Skeletal Muscle? A) Ca2+\mathrm{Ca}^{2+}Ca2+

Which of the Following Causes Rigor in Skeletal Muscle?
A) $\mathrm{Ca}^{2+}$