Lecture on Glial Cells (Neuroglia Cells)

Introduction

• Function: Support and nourish neurons.
• Location: Majority of nervous tissue cells.
• Types: 6 types total.
  • 4 in the Central Nervous System (CNS).
  • 2 in the Peripheral Nervous System (PNS).

Central Nervous System Glial Cells

1. Oligodendrocytes

• Meaning: Oligo (many) + Dendro (dendrites/extensions) + Cyte (cell).
• Function: Myelinate axons in the CNS.
  • Create a lipid protein layer (myelin sheath) on the axon.
  • Insulates, protects, and speeds up action potentials.
• Unique Feature: Can myelinate multiple axons at a time.
• Regeneration: Cannot regenerate if damaged.

2. Astrocytes

• Appearance: Star-like shape.
• Functions
  • Form the blood-brain barrier (BBB).
    • Wrap around capillaries and regulate entry/exit of substances.
  • Wrap around damaged axons to form scar tissue (fibrosis).

3. Ependymal Cells

• Shape: Similar to columnar, but also cuboidal, with microvilli and cilia.
• Location: Line brain ventricles.
• Function: Aid in production and circulation of cerebrospinal fluid (CSF).

4. Microglial Cells

• Function: Phagocytic - clean up debris, bacteria, old cells.
• Nickname: Trash cans or Pac-Man.

Peripheral Nervous System Glial Cells

1. Schwann Cells

• Function
  • Myelinate axons in the PNS.
    • Requires multiple Schwann cells to myelinate a single axon.
  • Provide protection to axons.
    • Can wrap around multiple axons for protection (single wrap).
• Regeneration: Can regenerate if the nucleus is intact.

2. Satellite Cells

• Location: Surround cell bodies in ganglions of the PNS.
• Function: Regulate entry/exit of substances in cell bodies (gatekeeper).
• Difference from CNS: Astrocytes wrap around blood capillaries, while satellite cells wrap around cell bodies.

Summary

• CNS Glial Cells: Oligodendrocytes, Astrocytes, Microglial Cells, Ependymal Cells.
• PNS Glial Cells: Schwann Cells, Satellite Cells.