Biology / Unit 13 Bio 3113 short lesson, about 20 seconds
Sarcomere Structure
Captions available
The idea
A sarcomere spans from one Z-disc to the next and contains overlapping thick myosin filaments and thin actin filaments, arranged so the whole unit shortens when they slide together.
In practice
The H-zone and I-band both narrow as a sarcomere contracts, while the A-band's length stays constant.
Where people slip
The filaments themselves do not shrink during contraction — they slide past each other without changing length.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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