pill.png

Pill

Theme C - Interaction &  Interdependence

direct-hit.png

Direct Hit

Theme A - Unity & Diversity

page-facing-up.png

Page Facing Up

Theme B - Form & Function

keycap-digit-one.png

Keycap Digit One

Theme D - Continuity & Change

<ul>
	<li>Picture a cylinder (kinda like a soda can). That&#39;s the shape of a nerve fibre!</li>
	<li>It has a plasma membrane that surrounds a small space filled with cytoplasm.</li>
	<li>Diameter? Usually about 1&micro;m, but some are wider (like those jumbo-sized soda cans!).</li>
	<li>Speedy Fact: With just this simple setup, nerve impulses speed along at about 1 metre per second. It&#39;s like walking briskly!</li>
</ul>

<ul>
	<li>Refer to: Section C2.2.4 for a full scoop.</li>
	<li>Myelin: Think of it as a cozy blanket made of multiple layers of phospholipid membrane wrapped around the nerve fibre.</li>
	<li>Who does this? Good ol&#39; Schwann cells! They wrap around the nerve fibre like you&#39;d wrap a scarf around your neck. And each wrap leaves a double layer of phospholipid bilayer.</li>
	<li>When Schwann cells are done, there might be 20 (or even more!) layers of this &quot;blanket.&quot;</li>
</ul>

<ul>
	<li>The myelin sheath is like a no-entry zone. It prevents ions from moving about willy-nilly.</li>
	<li>This means action potentials (that electric thing that makes nerves work) only happen at special spots called nodes of Ranvier.</li>
	<li>The action stuff (like sodium-potassium pumps and their channel buddies) hangs out at these nodes, not much where the axon&#39;s got the myelin coat.</li>
</ul>

<ul>
	<li>Imagine playing hopscotch. Instead of moving step by step, you jump from square to square. This is similar to how nerve impulses work with myelin!</li>
	<li>They jump from one node of Ranvier to the next. This jumping action is known as saltatory conduction.</li>
	<li>Why&#39;s this cool? Speed! With this jump-jump action, nerve impulses can speed up to 100 metres per second. That&#39;s faster than a cheetah!</li>
</ul>

Real-World Example: 🚗💨 Think of a highway. Cars (nerve impulses) move faster on highways than on regular roads. The myelin sheath acts like a speedy highway lane, and the nodes of Ranvier are like rest stops or exits. Instead of stopping at every small town (or nerve point), the car (impulse) zips past most of them, only making pitstops (or activating) at the main exits (nodes of Ranvier). This makes the journey super-fast!

&nbsp;

Remember, our body is a cool machine with so many shortcuts and hacks to make things efficient. The myelination of nerve fibres and saltatory conduction is one such speedy hack! 🌟🚀🧠

Unlock Faster Nerve Impulses Explore Saltatory Conduction!

ib-standard-level.webp

Standard Level

Biology SL

Theme C - Interaction & Interdependence

Unlock Faster Nerve Impulses Explore Saltatory Conduction!

Table of content

What's a nerve fibre?

What's the big deal about myelination? 🤷‍♂️

Unlock the Full Content!

Theme C - Interaction & Interdependence

Unlock Faster Nerve Impulses Explore Saltatory Conduction!

Table of content

What's a nerve fibre?

What's the big deal about myelination? 🤷‍♂️

Unlock the Full Content!