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Page Facing Up

Theme B - Form & Function

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Direct Hit

Theme A - Unity & diversity

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Pill

Theme C - Interaction &  Interdependence

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Keycap Digit One

Theme D - Continuity & Change

What&#39;s inside? Muscle fibres are like packed tubes with many parallel myofibrils.

Myofibrils = Series of sarcomeres linked end-to-end at mysterious places called Z-discs.

<ul>
	<li>Looks like a patterned band: light bands on the sides, dark band in the middle.</li>
	<li>Relaxed vs. Contracted: When chilling (relaxed), the sarcomere stretches longer, with Z-discs far apart and light bands wider.</li>
	<li>Electron microscopes can show us these cool Z lines, dark bands, and light bands. Like seeing the threads in a fabric up-close!</li>
</ul>

<ul>
	<li>Actin: Thin protein filaments hooked to Z-discs.</li>
	<li>Myosin: Thick protein filaments hanging in the sarcomere&#39;s center. They&#39;re like interlocking fingers with actin. Imagine hugging your friend - that&#39;s actin and myosin hugging!</li>
	<li>Fun fact: Each myosin is surrounded by six actin filaments and they can even form &quot;cross-bridges&quot; between them.</li>
</ul>

<ul>
	<li>The core move: Actin and Myosin filaments slide past each other. Who&#39;s leading? Myosin!</li>
	<li>Myosin has &quot;heads&quot; at intervals that attach to actin - think of them as Velcro!</li>
	<li>Energy Alert! 🚨 Myosin uses energy from ATP to push actin towards the sarcomere&#39;s center.</li>
	<li>Ratchet Mechanism: Myosin heads bind, swivel (like a dance twist!), exert force, and push actin a tiny bit (8-10 nm). They detach, twist back, and reattach to the next actin site.</li>
</ul>

<ul>
	<li>Myosin heads and actin binding sites are so regularly spaced that multiple heads bind at once.</li>
	<li>And guess what? There are tons of myosin heads across the muscle!</li>
	<li>Though each myosin head pushes with tiny force, all together they&#39;re like a super-powered team. Imagine one ant (strong for its size) vs. a million ants! 🐜💪</li>
</ul>

Real-World Example: Ever tried arm wrestling? When you push against your opponent&#39;s arm, it&#39;s not just one or two myosin heads working - it&#39;s millions, sliding and contracting your muscle fibers. That&#39;s the collective force of teamwork!

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💡 Takeaway: Muscles contract due to the fantastic dance between actin and myosin filaments. It&rsquo;s a bit like many tiny robots working together in sync to lift something heavy. Every small motion combines to create the larger motion we see and feel! 🤖💪🎉

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Happy Studying! 📚🌟

Theme B - Form & Function

Unlocking Muscle Mysteries Sliding Filament Model!

Table of content

Introduction to muscle fibres

Zooming into myofibrils 🔍

The mystical sarcomere

Unlock the Full Content!

Theme B - Form & Function

Unlocking Muscle Mysteries Sliding Filament Model!

Table of content

Introduction to muscle fibres

Zooming into myofibrils 🔍

The mystical sarcomere

Unlock the Full Content!