Summary
Insulating myelin makes the impulse jump between nodes of Ranvier, greatly increasing speed.
In depth
Myelin insulation reduces capacitance and leakage; current flows quickly between nodes of Ranvier where channels cluster. Speeds reach up to about 120 m/s versus 1 m/s in unmyelinated axons.
Myelin increases speed without increasing axon diameter, saving space. Nodes contain concentrated sodium channels. Demyelination leads to conduction block.
Key idea: signals jump from node to node.
Myelin is a spiralled extension of oligodendrocyte or Schwann cell membrane, about 70 percent lipid. Nodes of Ranvier are about 1 micrometre gaps with dense Na+ channels. Conduction in myelinated fibres can reach 120 m/s, compared with about 1 m/s in unmyelinated axons of similar size, and uses less energy since fewer ions cross the membrane. Internodes are about 1 mm long. Myelin thickness and node spacing are tuned to conduction timing.
Demyelination in multiple sclerosis slows or blocks conduction, causing numbness, weakness and vision problems; treatments aim to reduce immune attack and promote remyelination. Other examples include Charcot-Marie-Tooth disease and leukodystrophies. Myelination continues into the twenties, and learning can alter it. Invertebrates such as squid use thick axons for speed instead.
Frequently asked questions
What is Myelin and Saltatory Conduction?
Insulating myelin makes the impulse jump between nodes of Ranvier, greatly increasing speed.
Which area of biology covers Myelin and Saltatory Conduction, and how advanced is it?
Myelin and Saltatory Conduction is one of the 54 topics in Neuroscience. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Glial Cells, Action Potential, Eye and Vision.
Why does Myelin and Saltatory Conduction matter?
Myelin lets animals have fast signals in thin axons, which makes compact big brains possible.
Can you give an example of Myelin and Saltatory Conduction?
Demyelination in multiple sclerosis slows conduction.
What should I learn before Myelin and Saltatory Conduction?
Work through the Beginner topics in Neuroscience first, such as Nervous System, Neuron, Central and Peripheral Nervous Systems, then return to Myelin and Saltatory Conduction. Intermediate topics assume the Beginner vocabulary.
What topics are related to Myelin and Saltatory Conduction?
The closest topics to Myelin and Saltatory Conduction are Glial Cells, Action Potential, Eye and Vision, Hodgkin-Huxley Model. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Myelin and Saltatory Conduction?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Myelin and Saltatory Conduction. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Myelin and Saltatory Conduction different from Glial Cells?
Myelin and Saltatory Conduction: Insulating myelin makes the impulse jump between nodes of Ranvier, greatly increasing speed. Glial Cells: Support cells such as astrocytes and oligodendrocytes that nourish, insulate and protect neurons. Read both side by side and note what each one explains.
How should I study Myelin and Saltatory Conduction step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Glial Cells and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.