Question

The cross bridge cycle starts when _________.

Answer 1

Answer:

b) Ca2+ from the sarcoplasmic reticulum binds to troponin

Explanation:

The release of the calcium ions initiates the muscle contractions. The release is triggered from the storage in sarcoplasmic reticulum. These ions initiates contraction that is sustained by the ATP .The $Ca^{2+}$ ions from sarcoplasm bind to the troponin which drive cross-bridge cycling and pulling of the actin strands by the myosin.