A band is bigger than I band.
___When muscle contract, myosin begin to be short.
___When muscle relax, A band disappears.
___When muscle contract, Sacromere will be shorted.
___When muscle contract, I bands will be came closer.
___Z line is surrounded by actin.
___M line will be closer when the muscle contract.
___Actin begin to be long when the muscle relax.
___Dark zone will disappear when muscle relax.
___Light zone will disappear when muscle contract.