Which statement best describes glia?

• A. Neurons
• B. Non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons.
• C. Cells that transmit signals across synapses
• D. Cells that form blood-brain barrier

Answer: (B)

Glial cells are the non-neuronal support cells of the nervous system. They help keep the neural environment stable by regulating ions and neurotransmitters, supplying metabolic support, and protecting neurons. They also include cells that form myelin around axons (oligodendrocytes in the CNS and Schwann cells in the PNS), which speeds up signal transmission. Some glial types, like microglia, help with immune defense and debris clearance, while others provide structural support.

Neurons, by contrast, are the cells that transmit signals across synapses, which is why describing glia as the cells that transmit signals would be incorrect. The blood-brain barrier is formed mainly by endothelial cells with tight junctions; astrocyte end-feet contribute to its maintenance, but glia themselves do not form the barrier.