Question

What is the role of Glial cells?

Answer 1

Glial cells make up the white matter in the brain. They are also called glia or neuroglia. The word glia means neural glue. Glial cells lack axons and dendrites. They exist in the central nervous system (CNS) as well as the peripheral nervous system (PNS). Some glial cell types have the ability to move across the barrier between the CNS and PNS. Glial cells can be broadly classified into macroglia and microglia. They perform various important functions in the brain.

Complete answer:
The major function of glial cells is to provide physical support for neurons. Some glial types provide nutrients to neurons and also regulate the extracellular fluid of the brain. During embryogenesis, they direct the migration of neurons and produce certain molecules that modify the growth of axons and dendrites. They regulate the brain plasticity and immune responses in the brain.
Glial cells are crucial in processes such as synaptic plasticity and synaptogenesis. They help in the repair of neurons after injury. A type of microglia cell called astrocyte forms a scar and produces inhibitory molecules that stops the regrowth of a damaged axon. Another type of glial called Schwann cells in the PNS promote repair.
The Schwann cells cover the nerve fibres of the PNS by winding repeatedly around them creating a myelin sheath. Myelin sheath aids in signal conductivity and assists in the regeneration of damaged fibres.
The astrocytes have several crucial functions such as clearance of neurotransmitters from within the synaptic cleft, prevents toxic build-up of certain neurotransmitters such as glutamate, release gliotransmitters such as glutamate, ATP and D-serine in response to stimulation etc.

Note:
Macroglia cells exist in seven different forms namely oligodendrocytes, astrocytes, radial glia, Schwann cells, satellite cells, ependymal cells and enteric glia. Microglia play important roles such as inducing immunity responses in the brain and clearing away cellular debris and toxins. Generally glial cells exist more in numbers than neurons. The mature and differentiated glial cells can divide through mitosis. Glial gene mutations can cause psychological and neural disorders in humans (for example, Huntington’s disease).