Question

what are the neuroglia cells in the brain and spinal cord? What are their functions?

Answer 1

The nervous system is composed of brain, spinal cord, sensory receptor, neurons or nerves and glial cells. The functions of nervous system include the transmission of sensory input by regulation of external and internal stimuli. The 2 types of cells form the nervous system are called the neurons and the non-neural cells called glial cells. The neurons or nerve cells are involved in reception of sensory stimuli and transmission to the other neurons or effector organs. The non-neural cells or neuroglia act as major supporting cells of central nervous system. The non-neural or glial cells are six types called oligodendrocytes, ependymal cells, microglia, astrocytes, Schwann cells and satellite cells.

The non-neural cells such as oligodendrocytes contain cytoplasmic extensions that surround and wrap the axons and called myelin sheaths. The myelinated neurons have protection and electrical insulation of axons and the action potentials are rapidly passed through myelinated axons than in unmyelinated axons.

The myelin is secreted by Schwann cells that wrap around the axon of neurons. The Schwann cells are glial cells of peripheral nervous system (PNS).The Schwann cells are associated with unmyelinated neurons and rest in invaginations. The ependymal cells line the cavities of brain and spinal cord and also secrete and circulate cerebrospinal fluid. The microglia are phagocytic cells that phagocytize and destroy the microorganisms, foreign matter and other dead nerve cells.

The astrocytes are star shaped cells that cover the surface of the brain and nonsynaptic regions of the neurons. They produce a supportive frame work for CNS and also stimulate the formation of blood-brain barrier. They are involved in nourishment of neurons and secrete the growth stimulants. These cells also influence the synaptic signaling between neurons and help to regulate the composition of extra cellular fluid in the CNS. These cells produce scar tissue to replace the damaged nervous tissue. The satellite cells surround the somas of the neurons in the ganglia and insulate them. The cells regulate the chemical environment in the ganglia.

Therefore, the major function of neuroglia cells to insulate and protect the neurons, providing physical support and some glial cells act as phagocytes and remove cellular debris.