myelination

Examples of myelination in the following topics:

• Introducing the Neuron

  • Some axons are covered with myelin, a fatty material that wraps around the axon to form the myelin sheath.
  • Periodic gaps in the myelin sheath are called nodes of Ranvier.
  • The myelin sheath is not actually part of the neuron.
  • Myelin is produced by glial cells (or simply glia, or "glue" in Greek), which are non-neuronal cells that provide support for the nervous system.
  • This neuron diagram also shows the oligodendrocyte, myelin sheath, and nodes of Ranvier.

• Cognitive Development in Childhood

  • Glial cells, which account for half of all brain mass in early childhood, are responsible for a process known as myelination.
  • The connection between neighboring neurons (which is made smoother through myelination) allows for advanced brain function, such as planning and implementing behaviors and integrating sensory information from the environment.
  • Due to synaptic pruning, myelination, and a child's environmental experiences, the developing brain will grow from 30 percent of its adult weight at birth to 70 percent by age 2.

• Stages of the Action Potential

  • In unmyelinated axons (axons that are not covered by a myelin sheath), this happens in a continuous fashion because there are voltage-gated channels throughout the membrane.
  • In myelinated axons (axons covered by a myelin sheath), this process is described as saltatory because voltage-gated channels are only found at the nodes of Ranvier, and the electrical events seem to "jump" from one node to the next.
  • Damage to the myelin sheath from disease can cause severe impairment of nerve-cell function.

• Cerebral Cortex

  • It contains glial cells, which guide neural connections, provide nutrients and myelin to neurons, and absorb extra ions and neurotransmitters.
  • Gray matter is the mass of all the cell bodies, dendrites, and synapses of neurons interlaced with one another, while white matter consists of the long, myelin-coated axons of those neurons connecting masses of gray matter to each other.

• Neural Networks

  • Some axons are encased in a lipid-coated myelin sheath, making them appear a bright white; others that lack myelin sheaths (i.e., are unmyelinated) appear a darker beige color, which is generally called gray.