Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

Monthly Update sign up
Mailing List signup
Search
Follow The Annenberg Learner on LinkedIn Follow The Annenberg Learner on Facebook Follow Annenberg Learner on Twitter
Rediscovering Biology Logo
Home
Online TextbookCase StudiesExpertsArchiveGlossarySearch
Online Textbook
Back to Unit Page
Unit Chapters
Genomics
Proteins & Proteomics
Evolution & Phylogenetics
Microbial Diversity
Emerging Infectious Diseases
HIV & AIDS
Genetics of Development
Cell Biology & Cancer
Human Evolution
Neurobiology
Introduction
The Neuron as a Battery
Voltage-Gated Channels
The Action Potential
Myelin Speeds up Thought
Across the Synapse
Neurotransmitters and Receptors
Neurotransmitters, Psychoactive Drugs, and the Reward Pathway
The Molecular Basis of Learning and Memory
Memory and Hippocampus
Neuronal Stem Cells
Biology of Sex & Gender
Biodiversity
Genetically Modified Organisms
Unit 10: Neurobiology
Myelin Speeds Up Thought

Most neurons have a fatty outer layer called myelin, which insulates and protects the axons of neurons. In this way, myelin is like the plastic that surrounds electric wires. Myelin is actually made up of two special classes of glial cells, called the oligodendroglia and Schwann cells, which wrap themselves around the axon much like a jellyroll. Between these cells there are small gaps in the myelin sheath called the Nodes of Ranvier. Action potentials are able to jump from one node to the next one down the neuron incredibly rapidly. For this reason, impulses will travel down a myelinated neuron faster than they will across an unmyelinated neuron. In myelinated neurons, action potentials usually travel at over 100 meters per second, which is about half the speed of sound. In about one-hundredth of a second, an action potential can travel from the brain to the base of the spinal cord of an adult. Though seemingly instantaneous, this rate is still on the order of a million times slower than electricity.

Several degenerative diseases are due to the loss of myelin in certain neurons. The loss of muscle coordination that people with multiple sclerosis face is due to the degeneration of the myelin sheath in classes of neurons that are involved in the movement of muscles. The disease is suspected to be an autoimmune disorder - the immune system attacks the myelin sheaths. While MS is usually strikes first in early adulthood, many other diseases that are due to myelin degeneration occur in infancy or early childhood.

Back Next


  Home  |  Catalog  |  About Us  |  Search  |  Contact Us

| Follow The Annenberg Learner on Facebook
 

  © Annenberg Foundation 2013. All rights reserved.
Privacy Policy