Glial cells
Once thought to simply be cells that provided structural support, glial cells are now known to play a variety of essential roles in the nervous system.
1) Start with this article: Know Your Brain - Glial Cells
2) Then, watch this video:
3) Read this article for some additional info:
How Many Glial Cells Are There in the Brain?
4) Finally, answer these questions to test your understanding:
1. These glial cells are responsible for myelinating neurons in the peripheral nervous system:
- A. Schwann cells
- B. microglia
- C. astrocytes
- D. oligodendrocytes
Show Answer
Correct answer: A
Myelin is an insulating material that covers the axons of most neurons in the nervous system. Oligodendrocytes are the cells responsible for myelinating central nervous system neurons, while Schwann cells myelinate neurons in the peripheral nervous system.
2. During neural development, which glial cells provide scaffolding that allows newly formed neurons to migrate from their origin to their final destination?
- A. oligodendrocytes
- B. satellite cells
- C. astrocytes
- D. radial glia
Show Answer
Correct answer: D
Radial glia are neural stem cells that play a key role in neurogenesis and brain development. They generate neurons and provide a scaffold that guides migrating neurons from their origin to their final position in the brain.
3. Which type of glial cell provides the primary immune defense of the brain?
- A. astrocyte
- B. oligodendrocyte
- C. microglia
- D. ependymal cell
Show Answer
Correct answer: C
Microglia are the brain’s resident immune cells. They act as macrophage-like phagocytes, clearing debris, pathogens, and damaged neurons while regulating inflammation.
4. These glial cells provide metabolic support to neurons and help maintain the blood-brain barrier:
- A. oligodendrocytes
- B. astrocytes
- C. ependymal cells
- D. microglia
Show Answer
Correct answer: B
Astrocytes are star-shaped glial cells with many functions, which include providing nutrient support to neurons, helping repair damage to nervous system tissue, regulating communication between neurons, and maintaining the blood-brain-barrier, which keeps potentially toxic substances in the blood from entering the brain.
5. According to our best estimates, there are about 86 billion neurons in the brain. About how many glial cells are there?
- A. 860 billion (10x more glial cells than neurons)
- B. 430 billion (5x more glial cells than neurons)
- C. 85 billion (about the same number of glial cells and neurons)
- D. 40 billion (about half as many glial cells as neurons)
Show Answer
Correct answer: C
Earlier estimates suggested glia outnumbered neurons 10 to 1, but more recent research using better cell-counting techniques (e.g., isotropic fractionation) has shown the neuron-to-glia ratio is closer to 1:1 across the whole brain.
