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Muscle cells

Long, have bundles of myofibrials


Part of muscle cells, made up of repetive units called sarcomeres


Make up myofibirals and are where contractions happen


Seperate each sarcomere

A Bands

Thick myosin filaments (red)

I bands

Thin actin filaments (blue)

H zone

Space between actin filamints

Contracted sarcomere

Shorter, H zone becames smaller

Sarcomere shortens

The thick filiments (myosin) pull the thin filaments (actin) twards the H zone. When the pull occurs, the Z lines are pulled in and causes the s
arcomeres to shorten.

Muscle fibers shorten

When several hundred of these sarcomeres shorten

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