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Muscle Contraction Steps

Step 1. An action potential in a motor neuron causes acetylcholine (ACh) to release in the synaptic cleft.

Step 2. ACuli re wild reaCtine all membrane on the muscle fiber, opening Cat-Nat channels

Step 3.Calcium is released from the sarcoplasmic reticulum into the muscle fiber.

Step 4. Calcium binds to troponin.

step 5. Troponin shifts tropomyosin, which was blocking the binding site on the actin.

step 6.Myosin heads attach to actin by breaking down ATP to ADP + P.

Step 7. The Myosin head forms a 'cross-bridge' on the active site of the actin filament.

step 8. The cross bridge pulls actin, which slides over the myosin - known as the 'Power Stroke."

strep 9. The release of ADP completes the cross-bridge movement and ATP attaches to myosin, breaking the actin-myosin cross-bridge.

step 10. Every time ATP is split into ADP + P, the myosin head 'cocks' into place to form another cross bridge with actin.