Mon Prof Augmenté
Sliding Filament Segment
Muscle fibres contain repeating units built from thick and thin protein strands. During contraction, the thin strands slide over the thick strands, pulling each unit shorter and shortening the whole fibre.
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Age 15: open this week
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In the picture
- The whole muscle belly.
- One long fibre extending from the muscle belly.
- The upper close-up segment with thick pink rods and thin blue rods spread apart.
- The lower close-up segment where the rods overlap closer and small bridges touch between them.
Examples
- Bending your elbow to lift a backpack.
- Closing your fingers to grip a pencil.
Key takeaways
- Thick and thin protein strands slide past each other to shorten each repeating unit.
- Cross-bridges attach, pull, and release in a ratchet-like cycle.
Carry on in the app
Three questions on this lesson. It has left the free week, so its quiz is for subscribers.
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