Britannica
Sources used in this answer
How do glial cells support neurons in the nervous system?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
nervous system
In a myelinated axon, the myelin sheath prevents the local current (small black arrows) from flowing across the membrane. This forces the current to travel down the nerve fibre to the unmyelinated nodes of Ranvier, which have a high concentration of ion channels. Upon stimulation, these ion channels propagate the action potential (large green arrows) to the next node. Thus, the action potential jumps along the fibre as it is regenerated at each node, a process called saltatory conduction. In an unmyelinated axon, the action potential is propagated along the entire membrane, fading as it diffuses back through the membrane to the original depolarized region.
Glial cells, or neuroglia, provide essential support to neurons through several critical functions:
- Structural and Developmental Support: Glial cells help organize the nervous system. During development, astrocytes provide guidance for migrating neurons to reach their final locations. Following injury, they divide to occupy spaces left by damaged neurons.1
- Insulation: Oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system produce myelin, an insulating sheath that facilitates the efficient transmission of nerve impulses.12
- Environmental Regulation: Glial cells control the neuronal environment by exchanging substances like glucose, amino acids, and ions with the extracellular fluid. For example, they buffer potassium ions to maintain normal neuronal function.31
- Synaptic Modulation: Astrocytes regulate synaptic transmission by taking up neurotransmitters such as glutamate and GABA, which terminates their action and provides storage.14
- Immune Defense: Microglia act as the immune cells of the central nervous system, clearing cellular debris and dead neurons through phagocytosis.5