Which of the Following Events Occurs First

Question

Which of the following events occurs first?
A) Myosin cross-bridges attach to actin.
B) Calcium ions are released from the sarcoplasmic reticulum.
C) Calcium binds to troponin.
D) The myosin head pivots toward the M line.
E) The myosin head binds ATP and detaches from actin.

Accepted Answer

The release of calcium ions from the sarcoplasmic reticulum is the first event in the process of skeletal muscle contraction, triggering a cascade of events that lead to the interaction between actin and myosin.