Excitation-Contraction Coupling

Excitation-Contraction Coupling

The process linking the action potential to muscle contraction via calcium as the intermediary.

Steps

1. Action potential spreads along sarcolemma and into T-tubules

2. L-type Ca²⁺ channels open → small Ca²⁺ influx

3. Calcium-induced calcium release from sarcoplasmic reticulum

4. Ca²⁺ binds to troponin C

5. Tropomyosin shifts, exposing actin binding sites

6. Cross-bridge cycling → contraction