18 Steps of Muscle Contractions

Step 8 of Muscle Contraction

Binding of calcium to troponin

Step 9 of Muscle Contraction

Shifting of tropomyosin; exposure of active sites on actin.

Step 16

Reabsorption of calcium ions by sarcoplasmic reticulum.

Step 1

Arrival of nerve signal.

Step 2

Acetylcholine (ACh) release.

Step 3

Binding of ACh to receptor.

Step 4

Opening of ligand-regulated ion gate; creation of end-plate potential.

Step 5

Opening of voltage-regulated ion gates; creation of action potentials.

Step 6

Action potentials propagated down T tubules

Step 7

Calcium released from terminal cisternae

Step 10

Hydrolysis of ATP to ADP + Pi; activation and cocking of myosin head.

Step 11

Formation of myosin-actin cross-bridge

Step 12

Power stroke; sliding of thin filament over thick filament.

Step 13

Binding of new ATP; breaking of cross-bridge.

Step 14

Cessation of nervous stimulation and ACh release.

Step 15

ACh breakdown by acetylcholinesterase (AChE)

Step 17

Loss of calcium ions from troponin

Step 18

Return of tropomyosin to position blocking active sites of actin.