Question

Put the events in order regarding excitation-contraction coupling in muscle cells.

A) Calcium release, Action potential, Cross-bridge formation
B) Action potential, Calcium release, Cross-bridge formation
C) Cross-bridge formation, Action potential, Calcium release
D) Cross-bridge formation, Calcium release, Action potential

Answer 1

The correct order of events in excitation-contraction coupling in muscle cells is: action potential, calcium release, cross-bridge formation.

Step-by-step explanation:

The correct order of events in excitation-contraction coupling in muscle cells is:

1. Action potential
2. Calcium release
3. Cross-bridge formation

During excitation-contraction coupling, an action potential is generated in the sarcolemma of the muscle fiber. This action potential then triggers the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm. The presence of calcium ions allows for the formation of cross-bridges between the myosin heads and actin filaments, leading to muscle contraction.